| 1 | |
| 2 | * Generic process-grouping system.
|
| 3 | *
|
| 4 | * Based originally on the cpuset system, extracted by Paul Menage
|
| 5 | * Copyright (C) 2006 Google, Inc
|
| 6 | *
|
| 7 | * Notifications support
|
| 8 | * Copyright (C) 2009 Nokia Corporation
|
| 9 | * Author: Kirill A. Shutemov
|
| 10 | *
|
| 11 | * Copyright notices from the original cpuset code:
|
| 12 | * --------------------------------------------------
|
| 13 | * Copyright (C) 2003 BULL SA.
|
| 14 | * Copyright (C) 2004-2006 Silicon Graphics, Inc.
|
| 15 | *
|
| 16 | * Portions derived from Patrick Mochel's sysfs code.
|
| 17 | * sysfs is Copyright (c) 2001-3 Patrick Mochel
|
| 18 | *
|
| 19 | * 2003-10-10 Written by Simon Derr.
|
| 20 | * 2003-10-22 Updates by Stephen Hemminger.
|
| 21 | * 2004 May-July Rework by Paul Jackson.
|
| 22 | * ---------------------------------------------------
|
| 23 | *
|
| 24 | * This file is subject to the terms and conditions of the GNU General Public
|
| 25 | * License. See the file COPYING in the main directory of the Linux
|
| 26 | * distribution for more details.
|
| 27 |
|
| 28 |
|
| 29 | #include <linux/cgroup.h>
|
| 30 | #include <linux/cred.h>
|
| 31 | #include <linux/ctype.h>
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| 32 | #include <linux/errno.h>
|
| 33 | #include <linux/init_task.h>
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| 34 | #include <linux/kernel.h>
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| 35 | #include <linux/list.h>
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| 36 | #include <linux/mm.h>
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| 37 | #include <linux/mutex.h>
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| 38 | #include <linux/mount.h>
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| 39 | #include <linux/pagemap.h>
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| 40 | #include <linux/proc_fs.h>
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| 41 | #include <linux/rcupdate.h>
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| 42 | #include <linux/sched.h>
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| 43 | #include <linux/backing-dev.h>
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| 44 | #include <linux/slab.h>
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| 45 | #include <linux/magic.h>
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| 46 | #include <linux/spinlock.h>
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| 47 | #include <linux/string.h>
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| 48 | #include <linux/sort.h>
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| 49 | #include <linux/kmod.h>
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| 50 | #include <linux/module.h>
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| 51 | #include <linux/delayacct.h>
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| 52 | #include <linux/cgroupstats.h>
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| 53 | #include <linux/hashtable.h>
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| 54 | #include <linux/namei.h>
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| 55 | #include <linux/pid_namespace.h>
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| 56 | #include <linux/idr.h>
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| 57 | #include <linux/vmalloc.h>
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| 58 | #include <linux/flex_array.h>
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| 59 | #include <linux/kthread.h>
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| 60 |
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| 61 | #include <linux/atomic.h>
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| 62 |
|
| 63 | |
| 64 | * pidlists linger the following amount before being destroyed. The goal
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| 65 | * is avoiding frequent destruction in the middle of consecutive read calls
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| 66 | * Expiring in the middle is a performance problem not a correctness one.
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| 67 | * 1 sec should be enough.
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| 68 |
|
| 69 | #define CGROUP_PIDLIST_DESTROY_DELAY HZ
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| 70 |
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| 71 | |
| 72 | * cgroup_mutex is the master lock. Any modification to cgroup or its
|
| 73 | * hierarchy must be performed while holding it.
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| 74 | *
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| 75 | * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify
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| 76 | * cgroupfs_root of any cgroup hierarchy - subsys list, flags,
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| 77 | * release_agent_path and so on. Modifying requires both cgroup_mutex and
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| 78 | * cgroup_root_mutex. Readers can acquire either of the two. This is to
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| 79 | * break the following locking order cycle.
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| 80 | *
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| 81 | * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem
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| 82 | * B. namespace_sem -> cgroup_mutex
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| 83 | *
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| 84 | * B happens only through cgroup_show_options() and using cgroup_root_mutex
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| 85 | * breaks it.
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| 86 |
|
| 87 | #ifdef CONFIG_PROVE_RCU
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| 88 | DEFINE_MUTEX(cgroup_mutex);
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| 89 | EXPORT_SYMBOL_GPL(cgroup_mutex);
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| 90 | #else
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| 91 | static DEFINE_MUTEX(cgroup_mutex);
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| 92 | #endif
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| 93 |
|
| 94 | static DEFINE_MUTEX(cgroup_root_mutex);
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| 95 |
|
| 96 | #define cgroup_assert_mutex_or_rcu_locked() \
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| 97 | rcu_lockdep_assert(rcu_read_lock_held() || \
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| 98 | lockdep_is_held(&cgroup_mutex), \
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| 99 | "cgroup_mutex or RCU read lock required");
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| 100 |
|
| 101 | #ifdef CONFIG_LOCKDEP
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| 102 | #define cgroup_assert_mutex_or_root_locked() \
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| 103 | WARN_ON_ONCE(debug_locks && (!lockdep_is_held(&cgroup_mutex) && \
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| 104 | !lockdep_is_held(&cgroup_root_mutex)))
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| 105 | #else
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| 106 | #define cgroup_assert_mutex_or_root_locked() do { } while (0)
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| 107 | #endif
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| 108 |
|
| 109 | |
| 110 | * cgroup destruction makes heavy use of work items and there can be a lot
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| 111 | * of concurrent destructions. Use a separate workqueue so that cgroup
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| 112 | * destruction work items don't end up filling up max_active of system_wq
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| 113 | * which may lead to deadlock.
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| 114 |
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| 115 | static struct workqueue_struct *cgroup_destroy_wq;
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| 116 |
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| 117 | |
| 118 | * pidlist destructions need to be flushed on cgroup destruction. Use a
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| 119 | * separate workqueue as flush domain.
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| 120 |
|
| 121 | static struct workqueue_struct *cgroup_pidlist_destroy_wq;
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| 122 |
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| 123 | |
| 124 | * Generate an array of cgroup subsystem pointers. At boot time, this is
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| 125 | * populated with the built in subsystems, and modular subsystems are
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| 126 | * registered after that. The mutable section of this array is protected by
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| 127 | * cgroup_mutex.
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| 128 |
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| 129 | #define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys,
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| 130 | #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
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| 131 | static struct cgroup_subsys *cgroup_subsys[CGROUP_SUBSYS_COUNT] = {
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| 132 | #include <linux/cgroup_subsys.h>
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| 133 | };
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| 134 |
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| 135 | |
| 136 | * The dummy hierarchy, reserved for the subsystems that are otherwise
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| 137 | * unattached - it never has more than a single cgroup, and all tasks are
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| 138 | * part of that cgroup.
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| 139 |
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| 140 | static struct cgroupfs_root cgroup_dummy_root;
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| 141 |
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| 142 |
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| 143 | static struct cgroup * const cgroup_dummy_top = &cgroup_dummy_root.top_cgroup;
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| 144 |
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| 145 |
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| 146 |
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| 147 | static LIST_HEAD(cgroup_roots);
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| 148 | static int cgroup_root_count;
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| 149 |
|
| 150 | |
| 151 | * Hierarchy ID allocation and mapping. It follows the same exclusion
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| 152 | * rules as other root ops - both cgroup_mutex and cgroup_root_mutex for
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| 153 | * writes, either for reads.
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| 154 |
|
| 155 | static DEFINE_IDR(cgroup_hierarchy_idr);
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| 156 |
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| 157 | static struct cgroup_name root_cgroup_name = { .name = "/" };
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| 158 |
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| 159 | |
| 160 | * Assign a monotonically increasing serial number to cgroups. It
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| 161 | * guarantees cgroups with bigger numbers are newer than those with smaller
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| 162 | * numbers. Also, as cgroups are always appended to the parent's
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| 163 | * ->children list, it guarantees that sibling cgroups are always sorted in
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| 164 | * the ascending serial number order on the list. Protected by
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| 165 | * cgroup_mutex.
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| 166 |
|
| 167 | static u64 cgroup_serial_nr_next = 1;
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| 168 |
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| 169 | |
| 170 | * check for fork/exit handlers to call. This avoids us having to do
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| 171 | * extra work in the fork/exit path if none of the subsystems need to
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| 172 | * be called.
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| 173 |
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| 174 | static int need_forkexit_callback __read_mostly;
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| 175 |
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| 176 | static struct cftype cgroup_base_files[];
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| 177 |
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| 178 | static void cgroup_destroy_css_killed(struct cgroup *cgrp);
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| 179 | static int cgroup_destroy_locked(struct cgroup *cgrp);
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| 180 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
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| 181 | bool is_add);
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| 182 | static int cgroup_file_release(struct inode *inode, struct file *file);
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| 183 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp);
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| 184 |
|
| 185 | |
| 186 | * cgroup_css - obtain a cgroup's css for the specified subsystem
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| 187 | * @cgrp: the cgroup of interest
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| 188 | * @ss: the subsystem of interest (%NULL returns the dummy_css)
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| 189 | *
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| 190 | * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
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| 191 | * function must be called either under cgroup_mutex or rcu_read_lock() and
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| 192 | * the caller is responsible for pinning the returned css if it wants to
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| 193 | * keep accessing it outside the said locks. This function may return
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| 194 | * %NULL if @cgrp doesn't have @subsys_id enabled.
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| 195 |
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| 196 | static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
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| 197 | struct cgroup_subsys *ss)
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| 198 | {
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| 199 | if (ss)
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| 200 | return rcu_dereference_check(cgrp->subsys[ss->subsys_id],
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| 201 | lockdep_is_held(&cgroup_mutex));
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| 202 | else
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| 203 | return &cgrp->dummy_css;
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| 204 | }
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| 205 |
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| 206 |
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| 207 | static inline bool cgroup_is_dead(const struct cgroup *cgrp)
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| 208 | {
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| 209 | return test_bit(CGRP_DEAD, &cgrp->flags);
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| 210 | }
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| 211 |
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| 212 | |
| 213 | * cgroup_is_descendant - test ancestry
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| 214 | * @cgrp: the cgroup to be tested
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| 215 | * @ancestor: possible ancestor of @cgrp
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| 216 | *
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| 217 | * Test whether @cgrp is a descendant of @ancestor. It also returns %true
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| 218 | * if @cgrp == @ancestor. This function is safe to call as long as @cgrp
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| 219 | * and @ancestor are accessible.
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| 220 |
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| 221 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor)
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| 222 | {
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| 223 | while (cgrp) {
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| 224 | if (cgrp == ancestor)
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| 225 | return true;
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| 226 | cgrp = cgrp->parent;
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| 227 | }
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| 228 | return false;
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| 229 | }
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| 230 | EXPORT_SYMBOL_GPL(cgroup_is_descendant);
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| 231 |
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| 232 | static int cgroup_is_releasable(const struct cgroup *cgrp)
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| 233 | {
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| 234 | const int bits =
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| 235 | (1 << CGRP_RELEASABLE) |
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| 236 | (1 << CGRP_NOTIFY_ON_RELEASE);
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| 237 | return (cgrp->flags & bits) == bits;
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| 238 | }
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| 239 |
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| 240 | static int notify_on_release(const struct cgroup *cgrp)
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| 241 | {
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| 242 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
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| 243 | }
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| 244 |
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| 245 | |
| 246 | * for_each_css - iterate all css's of a cgroup
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| 247 | * @css: the iteration cursor
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| 248 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
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| 249 | * @cgrp: the target cgroup to iterate css's of
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| 250 | *
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| 251 | * Should be called under cgroup_mutex.
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| 252 |
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| 253 | #define for_each_css(css, ssid, cgrp) \
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| 254 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
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| 255 | if (!((css) = rcu_dereference_check( \
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| 256 | (cgrp)->subsys[(ssid)], \
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| 257 | lockdep_is_held(&cgroup_mutex)))) { } \
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| 258 | else
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| 259 |
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| 260 | |
| 261 | * for_each_subsys - iterate all loaded cgroup subsystems
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| 262 | * @ss: the iteration cursor
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| 263 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
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| 264 | *
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| 265 | * Iterates through all loaded subsystems. Should be called under
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| 266 | * cgroup_mutex or cgroup_root_mutex.
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| 267 |
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| 268 | #define for_each_subsys(ss, ssid) \
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| 269 | for (({ cgroup_assert_mutex_or_root_locked(); (ssid) = 0; }); \
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| 270 | (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
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| 271 | if (!((ss) = cgroup_subsys[(ssid)])) { } \
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| 272 | else
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| 273 |
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| 274 | |
| 275 | * for_each_builtin_subsys - iterate all built-in cgroup subsystems
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| 276 | * @ss: the iteration cursor
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| 277 | * @i: the index of @ss, CGROUP_BUILTIN_SUBSYS_COUNT after reaching the end
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| 278 | *
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| 279 | * Bulit-in subsystems are always present and iteration itself doesn't
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| 280 | * require any synchronization.
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| 281 |
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| 282 | #define for_each_builtin_subsys(ss, i) \
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| 283 | for ((i) = 0; (i) < CGROUP_BUILTIN_SUBSYS_COUNT && \
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| 284 | (((ss) = cgroup_subsys[i]) || true); (i)++)
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| 285 |
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| 286 |
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| 287 | #define for_each_active_root(root) \
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| 288 | list_for_each_entry((root), &cgroup_roots, root_list)
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| 289 |
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| 290 | static inline struct cgroup *__d_cgrp(struct dentry *dentry)
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| 291 | {
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| 292 | return dentry->d_fsdata;
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| 293 | }
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| 294 |
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| 295 | static inline struct cfent *__d_cfe(struct dentry *dentry)
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| 296 | {
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| 297 | return dentry->d_fsdata;
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| 298 | }
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| 299 |
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| 300 | static inline struct cftype *__d_cft(struct dentry *dentry)
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| 301 | {
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| 302 | return __d_cfe(dentry)->type;
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| 303 | }
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| 304 |
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| 305 | |
| 306 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
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| 307 | * @cgrp: the cgroup to be checked for liveness
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| 308 | *
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| 309 | * On success, returns true; the mutex should be later unlocked. On
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| 310 | * failure returns false with no lock held.
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| 311 |
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| 312 | static bool cgroup_lock_live_group(struct cgroup *cgrp)
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| 313 | {
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| 314 | mutex_lock(&cgroup_mutex);
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| 315 | if (cgroup_is_dead(cgrp)) {
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| 316 | mutex_unlock(&cgroup_mutex);
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| 317 | return false;
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| 318 | }
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| 319 | return true;
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| 320 | }
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| 321 |
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| 322 | |
| 323 | * release_list_lock
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| 324 | static LIST_HEAD(release_list);
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| 325 | static DEFINE_RAW_SPINLOCK(release_list_lock);
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| 326 | static void cgroup_release_agent(struct work_struct *work);
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| 327 | static DECLARE_WORK(release_agent_work, cgroup_release_agent);
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| 328 | static void check_for_release(struct cgroup *cgrp);
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| 329 |
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| 330 | |
| 331 | * A cgroup can be associated with multiple css_sets as different tasks may
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| 332 | * belong to different cgroups on different hierarchies. In the other
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| 333 | * direction, a css_set is naturally associated with multiple cgroups.
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| 334 | * This M:N relationship is represented by the following link structure
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| 335 | * which exists for each association and allows traversing the associations
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| 336 | * from both sides.
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| 337 |
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| 338 | struct cgrp_cset_link {
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| 339 |
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| 340 | struct cgroup *cgrp;
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| 341 | struct css_set *cset;
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| 342 |
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| 343 |
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| 344 | struct list_head cset_link;
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| 345 |
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| 346 |
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| 347 | struct list_head cgrp_link;
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| 348 | };
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| 349 |
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| 350 | |
| 351 | * hierarchies being mounted. It contains a pointer to the root state
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| 352 | * for each subsystem. Also used to anchor the list of css_sets. Not
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| 353 | * reference-counted, to improve performance when child cgroups
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| 354 | * haven't been created.
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| 355 |
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| 356 |
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| 357 | static struct css_set init_css_set;
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| 358 | static struct cgrp_cset_link init_cgrp_cset_link;
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| 359 |
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| 360 | |
| 361 | * css_set_lock protects the list of css_set objects, and the chain of
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| 362 | * tasks off each css_set. Nests outside task->alloc_lock due to
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| 363 | * css_task_iter_start().
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| 364 |
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| 365 | static DEFINE_RWLOCK(css_set_lock);
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| 366 | static int css_set_count;
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| 367 |
|
| 368 | |
| 369 | * hash table for cgroup groups. This improves the performance to find
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| 370 | * an existing css_set. This hash doesn't (currently) take into
|
| 371 | * account cgroups in empty hierarchies.
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| 372 |
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| 373 | #define CSS_SET_HASH_BITS 7
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| 374 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
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| 375 |
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| 376 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
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| 377 | {
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| 378 | unsigned long key = 0UL;
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| 379 | struct cgroup_subsys *ss;
|
| 380 | int i;
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| 381 |
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| 382 | for_each_subsys(ss, i)
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| 383 | key += (unsigned long)css[i];
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| 384 | key = (key >> 16) ^ key;
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| 385 |
|
| 386 | return key;
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| 387 | }
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| 388 |
|
| 389 | |
| 390 | * We don't maintain the lists running through each css_set to its task
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| 391 | * until after the first call to css_task_iter_start(). This reduces the
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| 392 | * fork()/exit() overhead for people who have cgroups compiled into their
|
| 393 | * kernel but not actually in use.
|
| 394 |
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| 395 | static int use_task_css_set_links __read_mostly;
|
| 396 |
|
| 397 | static void __put_css_set(struct css_set *cset, int taskexit)
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| 398 | {
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| 399 | struct cgrp_cset_link *link, *tmp_link;
|
| 400 |
|
| 401 | |
| 402 | * Ensure that the refcount doesn't hit zero while any readers
|
| 403 | * can see it. Similar to atomic_dec_and_lock(), but for an
|
| 404 | * rwlock
|
| 405 |
|
| 406 | if (atomic_add_unless(&cset->refcount, -1, 1))
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| 407 | return;
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| 408 | write_lock(&css_set_lock);
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| 409 | if (!atomic_dec_and_test(&cset->refcount)) {
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| 410 | write_unlock(&css_set_lock);
|
| 411 | return;
|
| 412 | }
|
| 413 |
|
| 414 |
|
| 415 | hash_del(&cset->hlist);
|
| 416 | css_set_count--;
|
| 417 |
|
| 418 | list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) {
|
| 419 | struct cgroup *cgrp = link->cgrp;
|
| 420 |
|
| 421 | list_del(&link->cset_link);
|
| 422 | list_del(&link->cgrp_link);
|
| 423 |
|
| 424 |
|
| 425 | if (list_empty(&cgrp->cset_links) && notify_on_release(cgrp)) {
|
| 426 | if (taskexit)
|
| 427 | set_bit(CGRP_RELEASABLE, &cgrp->flags);
|
| 428 | check_for_release(cgrp);
|
| 429 | }
|
| 430 |
|
| 431 | kfree(link);
|
| 432 | }
|
| 433 |
|
| 434 | write_unlock(&css_set_lock);
|
| 435 | kfree_rcu(cset, rcu_head);
|
| 436 | }
|
| 437 |
|
| 438 | |
| 439 | * refcounted get/put for css_set objects
|
| 440 |
|
| 441 | static inline void get_css_set(struct css_set *cset)
|
| 442 | {
|
| 443 | atomic_inc(&cset->refcount);
|
| 444 | }
|
| 445 |
|
| 446 | static inline void put_css_set(struct css_set *cset)
|
| 447 | {
|
| 448 | __put_css_set(cset, 0);
|
| 449 | }
|
| 450 |
|
| 451 | static inline void put_css_set_taskexit(struct css_set *cset)
|
| 452 | {
|
| 453 | __put_css_set(cset, 1);
|
| 454 | }
|
| 455 |
|
| 456 | |
| 457 | * compare_css_sets - helper function for find_existing_css_set().
|
| 458 | * @cset: candidate css_set being tested
|
| 459 | * @old_cset: existing css_set for a task
|
| 460 | * @new_cgrp: cgroup that's being entered by the task
|
| 461 | * @template: desired set of css pointers in css_set (pre-calculated)
|
| 462 | *
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| 463 | * Returns true if "cset" matches "old_cset" except for the hierarchy
|
| 464 | * which "new_cgrp" belongs to, for which it should match "new_cgrp".
|
| 465 |
|
| 466 | static bool compare_css_sets(struct css_set *cset,
|
| 467 | struct css_set *old_cset,
|
| 468 | struct cgroup *new_cgrp,
|
| 469 | struct cgroup_subsys_state *template[])
|
| 470 | {
|
| 471 | struct list_head *l1, *l2;
|
| 472 |
|
| 473 | if (memcmp(template, cset->subsys, sizeof(cset->subsys))) {
|
| 474 |
|
| 475 | return false;
|
| 476 | }
|
| 477 |
|
| 478 | |
| 479 | * Compare cgroup pointers in order to distinguish between
|
| 480 | * different cgroups in heirarchies with no subsystems. We
|
| 481 | * could get by with just this check alone (and skip the
|
| 482 | * memcmp above) but on most setups the memcmp check will
|
| 483 | * avoid the need for this more expensive check on almost all
|
| 484 | * candidates.
|
| 485 |
|
| 486 |
|
| 487 | l1 = &cset->cgrp_links;
|
| 488 | l2 = &old_cset->cgrp_links;
|
| 489 | while (1) {
|
| 490 | struct cgrp_cset_link *link1, *link2;
|
| 491 | struct cgroup *cgrp1, *cgrp2;
|
| 492 |
|
| 493 | l1 = l1->next;
|
| 494 | l2 = l2->next;
|
| 495 |
|
| 496 | if (l1 == &cset->cgrp_links) {
|
| 497 | BUG_ON(l2 != &old_cset->cgrp_links);
|
| 498 | break;
|
| 499 | } else {
|
| 500 | BUG_ON(l2 == &old_cset->cgrp_links);
|
| 501 | }
|
| 502 |
|
| 503 | link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link);
|
| 504 | link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link);
|
| 505 | cgrp1 = link1->cgrp;
|
| 506 | cgrp2 = link2->cgrp;
|
| 507 |
|
| 508 | BUG_ON(cgrp1->root != cgrp2->root);
|
| 509 |
|
| 510 | |
| 511 | * If this hierarchy is the hierarchy of the cgroup
|
| 512 | * that's changing, then we need to check that this
|
| 513 | * css_set points to the new cgroup; if it's any other
|
| 514 | * hierarchy, then this css_set should point to the
|
| 515 | * same cgroup as the old css_set.
|
| 516 |
|
| 517 | if (cgrp1->root == new_cgrp->root) {
|
| 518 | if (cgrp1 != new_cgrp)
|
| 519 | return false;
|
| 520 | } else {
|
| 521 | if (cgrp1 != cgrp2)
|
| 522 | return false;
|
| 523 | }
|
| 524 | }
|
| 525 | return true;
|
| 526 | }
|
| 527 |
|
| 528 | |
| 529 | * find_existing_css_set - init css array and find the matching css_set
|
| 530 | * @old_cset: the css_set that we're using before the cgroup transition
|
| 531 | * @cgrp: the cgroup that we're moving into
|
| 532 | * @template: out param for the new set of csses, should be clear on entry
|
| 533 |
|
| 534 | static struct css_set *find_existing_css_set(struct css_set *old_cset,
|
| 535 | struct cgroup *cgrp,
|
| 536 | struct cgroup_subsys_state *template[])
|
| 537 | {
|
| 538 | struct cgroupfs_root *root = cgrp->root;
|
| 539 | struct cgroup_subsys *ss;
|
| 540 | struct css_set *cset;
|
| 541 | unsigned long key;
|
| 542 | int i;
|
| 543 |
|
| 544 | |
| 545 | * Build the set of subsystem state objects that we want to see in the
|
| 546 | * new css_set. while subsystems can change globally, the entries here
|
| 547 | * won't change, so no need for locking.
|
| 548 |
|
| 549 | for_each_subsys(ss, i) {
|
| 550 | if (root->subsys_mask & (1UL << i)) {
|
| 551 | |
| 552 | * the subsystem state from the new
|
| 553 | * cgroup
|
| 554 | template[i] = cgroup_css(cgrp, ss);
|
| 555 | } else {
|
| 556 | |
| 557 | * don't want to change the subsystem state
|
| 558 | template[i] = old_cset->subsys[i];
|
| 559 | }
|
| 560 | }
|
| 561 |
|
| 562 | key = css_set_hash(template);
|
| 563 | hash_for_each_possible(css_set_table, cset, hlist, key) {
|
| 564 | if (!compare_css_sets(cset, old_cset, cgrp, template))
|
| 565 | continue;
|
| 566 |
|
| 567 |
|
| 568 | return cset;
|
| 569 | }
|
| 570 |
|
| 571 |
|
| 572 | return NULL;
|
| 573 | }
|
| 574 |
|
| 575 | static void free_cgrp_cset_links(struct list_head *links_to_free)
|
| 576 | {
|
| 577 | struct cgrp_cset_link *link, *tmp_link;
|
| 578 |
|
| 579 | list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) {
|
| 580 | list_del(&link->cset_link);
|
| 581 | kfree(link);
|
| 582 | }
|
| 583 | }
|
| 584 |
|
| 585 | |
| 586 | * allocate_cgrp_cset_links - allocate cgrp_cset_links
|
| 587 | * @count: the number of links to allocate
|
| 588 | * @tmp_links: list_head the allocated links are put on
|
| 589 | *
|
| 590 | * Allocate @count cgrp_cset_link structures and chain them on @tmp_links
|
| 591 | * through ->cset_link. Returns 0 on success or -errno.
|
| 592 |
|
| 593 | static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links)
|
| 594 | {
|
| 595 | struct cgrp_cset_link *link;
|
| 596 | int i;
|
| 597 |
|
| 598 | INIT_LIST_HEAD(tmp_links);
|
| 599 |
|
| 600 | for (i = 0; i < count; i++) {
|
| 601 | link = kzalloc(sizeof(*link), GFP_KERNEL);
|
| 602 | if (!link) {
|
| 603 | free_cgrp_cset_links(tmp_links);
|
| 604 | return -ENOMEM;
|
| 605 | }
|
| 606 | list_add(&link->cset_link, tmp_links);
|
| 607 | }
|
| 608 | return 0;
|
| 609 | }
|
| 610 |
|
| 611 | |
| 612 | * link_css_set - a helper function to link a css_set to a cgroup
|
| 613 | * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
|
| 614 | * @cset: the css_set to be linked
|
| 615 | * @cgrp: the destination cgroup
|
| 616 |
|
| 617 | static void link_css_set(struct list_head *tmp_links, struct css_set *cset,
|
| 618 | struct cgroup *cgrp)
|
| 619 | {
|
| 620 | struct cgrp_cset_link *link;
|
| 621 |
|
| 622 | BUG_ON(list_empty(tmp_links));
|
| 623 | link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link);
|
| 624 | link->cset = cset;
|
| 625 | link->cgrp = cgrp;
|
| 626 | list_move(&link->cset_link, &cgrp->cset_links);
|
| 627 | |
| 628 | * Always add links to the tail of the list so that the list
|
| 629 | * is sorted by order of hierarchy creation
|
| 630 |
|
| 631 | list_add_tail(&link->cgrp_link, &cset->cgrp_links);
|
| 632 | }
|
| 633 |
|
| 634 | |
| 635 | * find_css_set - return a new css_set with one cgroup updated
|
| 636 | * @old_cset: the baseline css_set
|
| 637 | * @cgrp: the cgroup to be updated
|
| 638 | *
|
| 639 | * Return a new css_set that's equivalent to @old_cset, but with @cgrp
|
| 640 | * substituted into the appropriate hierarchy.
|
| 641 |
|
| 642 | static struct css_set *find_css_set(struct css_set *old_cset,
|
| 643 | struct cgroup *cgrp)
|
| 644 | {
|
| 645 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { };
|
| 646 | struct css_set *cset;
|
| 647 | struct list_head tmp_links;
|
| 648 | struct cgrp_cset_link *link;
|
| 649 | unsigned long key;
|
| 650 |
|
| 651 | lockdep_assert_held(&cgroup_mutex);
|
| 652 |
|
| 653 | |
| 654 | * the desired set
|
| 655 | read_lock(&css_set_lock);
|
| 656 | cset = find_existing_css_set(old_cset, cgrp, template);
|
| 657 | if (cset)
|
| 658 | get_css_set(cset);
|
| 659 | read_unlock(&css_set_lock);
|
| 660 |
|
| 661 | if (cset)
|
| 662 | return cset;
|
| 663 |
|
| 664 | cset = kzalloc(sizeof(*cset), GFP_KERNEL);
|
| 665 | if (!cset)
|
| 666 | return NULL;
|
| 667 |
|
| 668 |
|
| 669 | if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) {
|
| 670 | kfree(cset);
|
| 671 | return NULL;
|
| 672 | }
|
| 673 |
|
| 674 | atomic_set(&cset->refcount, 1);
|
| 675 | INIT_LIST_HEAD(&cset->cgrp_links);
|
| 676 | INIT_LIST_HEAD(&cset->tasks);
|
| 677 | INIT_HLIST_NODE(&cset->hlist);
|
| 678 |
|
| 679 | |
| 680 | * find_existing_css_set()
|
| 681 | memcpy(cset->subsys, template, sizeof(cset->subsys));
|
| 682 |
|
| 683 | write_lock(&css_set_lock);
|
| 684 |
|
| 685 | list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) {
|
| 686 | struct cgroup *c = link->cgrp;
|
| 687 |
|
| 688 | if (c->root == cgrp->root)
|
| 689 | c = cgrp;
|
| 690 | link_css_set(&tmp_links, cset, c);
|
| 691 | }
|
| 692 |
|
| 693 | BUG_ON(!list_empty(&tmp_links));
|
| 694 |
|
| 695 | css_set_count++;
|
| 696 |
|
| 697 |
|
| 698 | key = css_set_hash(cset->subsys);
|
| 699 | hash_add(css_set_table, &cset->hlist, key);
|
| 700 |
|
| 701 | write_unlock(&css_set_lock);
|
| 702 |
|
| 703 | return cset;
|
| 704 | }
|
| 705 |
|
| 706 | |
| 707 | * Return the cgroup for "task" from the given hierarchy. Must be
|
| 708 | * called with cgroup_mutex held.
|
| 709 |
|
| 710 | static struct cgroup *task_cgroup_from_root(struct task_struct *task,
|
| 711 | struct cgroupfs_root *root)
|
| 712 | {
|
| 713 | struct css_set *cset;
|
| 714 | struct cgroup *res = NULL;
|
| 715 |
|
| 716 | BUG_ON(!mutex_is_locked(&cgroup_mutex));
|
| 717 | read_lock(&css_set_lock);
|
| 718 | |
| 719 | * No need to lock the task - since we hold cgroup_mutex the
|
| 720 | * task can't change groups, so the only thing that can happen
|
| 721 | * is that it exits and its css is set back to init_css_set.
|
| 722 |
|
| 723 | cset = task_css_set(task);
|
| 724 | if (cset == &init_css_set) {
|
| 725 | res = &root->top_cgroup;
|
| 726 | } else {
|
| 727 | struct cgrp_cset_link *link;
|
| 728 |
|
| 729 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
|
| 730 | struct cgroup *c = link->cgrp;
|
| 731 |
|
| 732 | if (c->root == root) {
|
| 733 | res = c;
|
| 734 | break;
|
| 735 | }
|
| 736 | }
|
| 737 | }
|
| 738 | read_unlock(&css_set_lock);
|
| 739 | BUG_ON(!res);
|
| 740 | return res;
|
| 741 | }
|
| 742 |
|
| 743 | |
| 744 | * There is one global cgroup mutex. We also require taking
|
| 745 | * task_lock() when dereferencing a task's cgroup subsys pointers.
|
| 746 | * See "The task_lock() exception", at the end of this comment.
|
| 747 | *
|
| 748 | * A task must hold cgroup_mutex to modify cgroups.
|
| 749 | *
|
| 750 | * Any task can increment and decrement the count field without lock.
|
| 751 | * So in general, code holding cgroup_mutex can't rely on the count
|
| 752 | * field not changing. However, if the count goes to zero, then only
|
| 753 | * cgroup_attach_task() can increment it again. Because a count of zero
|
| 754 | * means that no tasks are currently attached, therefore there is no
|
| 755 | * way a task attached to that cgroup can fork (the other way to
|
| 756 | * increment the count). So code holding cgroup_mutex can safely
|
| 757 | * assume that if the count is zero, it will stay zero. Similarly, if
|
| 758 | * a task holds cgroup_mutex on a cgroup with zero count, it
|
| 759 | * knows that the cgroup won't be removed, as cgroup_rmdir()
|
| 760 | * needs that mutex.
|
| 761 | *
|
| 762 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
|
| 763 | * (usually) take cgroup_mutex. These are the two most performance
|
| 764 | * critical pieces of code here. The exception occurs on cgroup_exit(),
|
| 765 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex
|
| 766 | * is taken, and if the cgroup count is zero, a usermode call made
|
| 767 | * to the release agent with the name of the cgroup (path relative to
|
| 768 | * the root of cgroup file system) as the argument.
|
| 769 | *
|
| 770 | * A cgroup can only be deleted if both its 'count' of using tasks
|
| 771 | * is zero, and its list of 'children' cgroups is empty. Since all
|
| 772 | * tasks in the system use _some_ cgroup, and since there is always at
|
| 773 | * least one task in the system (init, pid == 1), therefore, top_cgroup
|
| 774 | * always has either children cgroups and/or using tasks. So we don't
|
| 775 | * need a special hack to ensure that top_cgroup cannot be deleted.
|
| 776 | *
|
| 777 | * The task_lock() exception
|
| 778 | *
|
| 779 | * The need for this exception arises from the action of
|
| 780 | * cgroup_attach_task(), which overwrites one task's cgroup pointer with
|
| 781 | * another. It does so using cgroup_mutex, however there are
|
| 782 | * several performance critical places that need to reference
|
| 783 | * task->cgroup without the expense of grabbing a system global
|
| 784 | * mutex. Therefore except as noted below, when dereferencing or, as
|
| 785 | * in cgroup_attach_task(), modifying a task's cgroup pointer we use
|
| 786 | * task_lock(), which acts on a spinlock (task->alloc_lock) already in
|
| 787 | * the task_struct routinely used for such matters.
|
| 788 | *
|
| 789 | * P.S. One more locking exception. RCU is used to guard the
|
| 790 | * update of a tasks cgroup pointer by cgroup_attach_task()
|
| 791 |
|
| 792 |
|
| 793 | |
| 794 | * A couple of forward declarations required, due to cyclic reference loop:
|
| 795 | * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir ->
|
| 796 | * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations
|
| 797 | * -> cgroup_mkdir.
|
| 798 |
|
| 799 |
|
| 800 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode);
|
| 801 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry);
|
| 802 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask);
|
| 803 | static const struct inode_operations cgroup_dir_inode_operations;
|
| 804 | static const struct file_operations proc_cgroupstats_operations;
|
| 805 |
|
| 806 | static struct backing_dev_info cgroup_backing_dev_info = {
|
| 807 | .name = "cgroup",
|
| 808 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
|
| 809 | };
|
| 810 |
|
| 811 | static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb)
|
| 812 | {
|
| 813 | struct inode *inode = new_inode(sb);
|
| 814 |
|
| 815 | if (inode) {
|
| 816 | inode->i_ino = get_next_ino();
|
| 817 | inode->i_mode = mode;
|
| 818 | inode->i_uid = current_fsuid();
|
| 819 | inode->i_gid = current_fsgid();
|
| 820 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
|
| 821 | inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info;
|
| 822 | }
|
| 823 | return inode;
|
| 824 | }
|
| 825 |
|
| 826 | static struct cgroup_name *cgroup_alloc_name(struct dentry *dentry)
|
| 827 | {
|
| 828 | struct cgroup_name *name;
|
| 829 |
|
| 830 | name = kmalloc(sizeof(*name) + dentry->d_name.len + 1, GFP_KERNEL);
|
| 831 | if (!name)
|
| 832 | return NULL;
|
| 833 | strcpy(name->name, dentry->d_name.name);
|
| 834 | return name;
|
| 835 | }
|
| 836 |
|
| 837 | static void cgroup_free_fn(struct work_struct *work)
|
| 838 | {
|
| 839 | struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work);
|
| 840 |
|
| 841 | mutex_lock(&cgroup_mutex);
|
| 842 | cgrp->root->number_of_cgroups--;
|
| 843 | mutex_unlock(&cgroup_mutex);
|
| 844 |
|
| 845 | |
| 846 | * We get a ref to the parent's dentry, and put the ref when
|
| 847 | * this cgroup is being freed, so it's guaranteed that the
|
| 848 | * parent won't be destroyed before its children.
|
| 849 |
|
| 850 | dput(cgrp->parent->dentry);
|
| 851 |
|
| 852 | |
| 853 | * Drop the active superblock reference that we took when we
|
| 854 | * created the cgroup. This will free cgrp->root, if we are
|
| 855 | * holding the last reference to @sb.
|
| 856 |
|
| 857 | deactivate_super(cgrp->root->sb);
|
| 858 |
|
| 859 | cgroup_pidlist_destroy_all(cgrp);
|
| 860 |
|
| 861 | simple_xattrs_free(&cgrp->xattrs);
|
| 862 |
|
| 863 | kfree(rcu_dereference_raw(cgrp->name));
|
| 864 | kfree(cgrp);
|
| 865 | }
|
| 866 |
|
| 867 | static void cgroup_free_rcu(struct rcu_head *head)
|
| 868 | {
|
| 869 | struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head);
|
| 870 |
|
| 871 | INIT_WORK(&cgrp->destroy_work, cgroup_free_fn);
|
| 872 | queue_work(cgroup_destroy_wq, &cgrp->destroy_work);
|
| 873 | }
|
| 874 |
|
| 875 | static void cgroup_diput(struct dentry *dentry, struct inode *inode)
|
| 876 | {
|
| 877 |
|
| 878 | if (S_ISDIR(inode->i_mode)) {
|
| 879 | struct cgroup *cgrp = dentry->d_fsdata;
|
| 880 |
|
| 881 | BUG_ON(!(cgroup_is_dead(cgrp)));
|
| 882 |
|
| 883 | |
| 884 | * XXX: cgrp->id is only used to look up css's. As cgroup
|
| 885 | * and css's lifetimes will be decoupled, it should be made
|
| 886 | * per-subsystem and moved to css->id so that lookups are
|
| 887 | * successful until the target css is released.
|
| 888 |
|
| 889 | mutex_lock(&cgroup_mutex);
|
| 890 | idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
|
| 891 | mutex_unlock(&cgroup_mutex);
|
| 892 | cgrp->id = -1;
|
| 893 |
|
| 894 | call_rcu(&cgrp->rcu_head, cgroup_free_rcu);
|
| 895 | } else {
|
| 896 | struct cfent *cfe = __d_cfe(dentry);
|
| 897 | struct cgroup *cgrp = dentry->d_parent->d_fsdata;
|
| 898 |
|
| 899 | WARN_ONCE(!list_empty(&cfe->node) &&
|
| 900 | cgrp != &cgrp->root->top_cgroup,
|
| 901 | "cfe still linked for %s\n", cfe->type->name);
|
| 902 | simple_xattrs_free(&cfe->xattrs);
|
| 903 | kfree(cfe);
|
| 904 | }
|
| 905 | iput(inode);
|
| 906 | }
|
| 907 |
|
| 908 | static void remove_dir(struct dentry *d)
|
| 909 | {
|
| 910 | struct dentry *parent = dget(d->d_parent);
|
| 911 |
|
| 912 | d_delete(d);
|
| 913 | simple_rmdir(parent->d_inode, d);
|
| 914 | dput(parent);
|
| 915 | }
|
| 916 |
|
| 917 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
|
| 918 | {
|
| 919 | struct cfent *cfe;
|
| 920 |
|
| 921 | lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
|
| 922 | lockdep_assert_held(&cgroup_mutex);
|
| 923 |
|
| 924 | |
| 925 | * If we're doing cleanup due to failure of cgroup_create(),
|
| 926 | * the corresponding @cfe may not exist.
|
| 927 |
|
| 928 | list_for_each_entry(cfe, &cgrp->files, node) {
|
| 929 | struct dentry *d = cfe->dentry;
|
| 930 |
|
| 931 | if (cft && cfe->type != cft)
|
| 932 | continue;
|
| 933 |
|
| 934 | dget(d);
|
| 935 | d_delete(d);
|
| 936 | simple_unlink(cgrp->dentry->d_inode, d);
|
| 937 | list_del_init(&cfe->node);
|
| 938 | dput(d);
|
| 939 |
|
| 940 | break;
|
| 941 | }
|
| 942 | }
|
| 943 |
|
| 944 | |
| 945 | * cgroup_clear_dir - remove subsys files in a cgroup directory
|
| 946 | * @cgrp: target cgroup
|
| 947 | * @subsys_mask: mask of the subsystem ids whose files should be removed
|
| 948 |
|
| 949 | static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask)
|
| 950 | {
|
| 951 | struct cgroup_subsys *ss;
|
| 952 | int i;
|
| 953 |
|
| 954 | for_each_subsys(ss, i) {
|
| 955 | struct cftype_set *set;
|
| 956 |
|
| 957 | if (!test_bit(i, &subsys_mask))
|
| 958 | continue;
|
| 959 | list_for_each_entry(set, &ss->cftsets, node)
|
| 960 | cgroup_addrm_files(cgrp, set->cfts, false);
|
| 961 | }
|
| 962 | }
|
| 963 |
|
| 964 | |
| 965 | * NOTE : the dentry must have been dget()'ed
|
| 966 |
|
| 967 | static void cgroup_d_remove_dir(struct dentry *dentry)
|
| 968 | {
|
| 969 | struct dentry *parent;
|
| 970 |
|
| 971 | parent = dentry->d_parent;
|
| 972 | spin_lock(&parent->d_lock);
|
| 973 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
|
| 974 | list_del_init(&dentry->d_u.d_child);
|
| 975 | spin_unlock(&dentry->d_lock);
|
| 976 | spin_unlock(&parent->d_lock);
|
| 977 | remove_dir(dentry);
|
| 978 | }
|
| 979 |
|
| 980 | |
| 981 | * Call with cgroup_mutex held. Drops reference counts on modules, including
|
| 982 | * any duplicate ones that parse_cgroupfs_options took. If this function
|
| 983 | * returns an error, no reference counts are touched.
|
| 984 |
|
| 985 | static int rebind_subsystems(struct cgroupfs_root *root,
|
| 986 | unsigned long added_mask, unsigned removed_mask)
|
| 987 | {
|
| 988 | struct cgroup *cgrp = &root->top_cgroup;
|
| 989 | struct cgroup_subsys *ss;
|
| 990 | unsigned long pinned = 0;
|
| 991 | int i, ret;
|
| 992 |
|
| 993 | BUG_ON(!mutex_is_locked(&cgroup_mutex));
|
| 994 | BUG_ON(!mutex_is_locked(&cgroup_root_mutex));
|
| 995 |
|
| 996 |
|
| 997 | for_each_subsys(ss, i) {
|
| 998 | if (!(added_mask & (1 << i)))
|
| 999 | continue;
|
| 1000 |
|
| 1001 |
|
| 1002 | if (ss->root != &cgroup_dummy_root) {
|
| 1003 | ret = -EBUSY;
|
| 1004 | goto out_put;
|
| 1005 | }
|
| 1006 |
|
| 1007 |
|
| 1008 | if (!try_module_get(ss->module)) {
|
| 1009 | ret = -ENOENT;
|
| 1010 | goto out_put;
|
| 1011 | }
|
| 1012 | pinned |= 1 << i;
|
| 1013 | }
|
| 1014 |
|
| 1015 |
|
| 1016 | if (added_mask != pinned) {
|
| 1017 | ret = -ENOENT;
|
| 1018 | goto out_put;
|
| 1019 | }
|
| 1020 |
|
| 1021 | ret = cgroup_populate_dir(cgrp, added_mask);
|
| 1022 | if (ret)
|
| 1023 | goto out_put;
|
| 1024 |
|
| 1025 | |
| 1026 | * Nothing can fail from this point on. Remove files for the
|
| 1027 | * removed subsystems and rebind each subsystem.
|
| 1028 |
|
| 1029 | cgroup_clear_dir(cgrp, removed_mask);
|
| 1030 |
|
| 1031 | for_each_subsys(ss, i) {
|
| 1032 | unsigned long bit = 1UL << i;
|
| 1033 |
|
| 1034 | if (bit & added_mask) {
|
| 1035 |
|
| 1036 | BUG_ON(cgroup_css(cgrp, ss));
|
| 1037 | BUG_ON(!cgroup_css(cgroup_dummy_top, ss));
|
| 1038 | BUG_ON(cgroup_css(cgroup_dummy_top, ss)->cgroup != cgroup_dummy_top);
|
| 1039 |
|
| 1040 | rcu_assign_pointer(cgrp->subsys[i],
|
| 1041 | cgroup_css(cgroup_dummy_top, ss));
|
| 1042 | cgroup_css(cgrp, ss)->cgroup = cgrp;
|
| 1043 |
|
| 1044 | ss->root = root;
|
| 1045 | if (ss->bind)
|
| 1046 | ss->bind(cgroup_css(cgrp, ss));
|
| 1047 |
|
| 1048 |
|
| 1049 | root->subsys_mask |= bit;
|
| 1050 | } else if (bit & removed_mask) {
|
| 1051 |
|
| 1052 | BUG_ON(cgroup_css(cgrp, ss) != cgroup_css(cgroup_dummy_top, ss));
|
| 1053 | BUG_ON(cgroup_css(cgrp, ss)->cgroup != cgrp);
|
| 1054 |
|
| 1055 | if (ss->bind)
|
| 1056 | ss->bind(cgroup_css(cgroup_dummy_top, ss));
|
| 1057 |
|
| 1058 | cgroup_css(cgroup_dummy_top, ss)->cgroup = cgroup_dummy_top;
|
| 1059 | RCU_INIT_POINTER(cgrp->subsys[i], NULL);
|
| 1060 |
|
| 1061 | cgroup_subsys[i]->root = &cgroup_dummy_root;
|
| 1062 |
|
| 1063 |
|
| 1064 | module_put(ss->module);
|
| 1065 | root->subsys_mask &= ~bit;
|
| 1066 | }
|
| 1067 | }
|
| 1068 |
|
| 1069 | |
| 1070 | * Mark @root has finished binding subsystems. @root->subsys_mask
|
| 1071 | * now matches the bound subsystems.
|
| 1072 |
|
| 1073 | root->flags |= CGRP_ROOT_SUBSYS_BOUND;
|
| 1074 |
|
| 1075 | return 0;
|
| 1076 |
|
| 1077 | out_put:
|
| 1078 | for_each_subsys(ss, i)
|
| 1079 | if (pinned & (1 << i))
|
| 1080 | module_put(ss->module);
|
| 1081 | return ret;
|
| 1082 | }
|
| 1083 |
|
| 1084 | static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry)
|
| 1085 | {
|
| 1086 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
|
| 1087 | struct cgroup_subsys *ss;
|
| 1088 | int ssid;
|
| 1089 |
|
| 1090 | mutex_lock(&cgroup_root_mutex);
|
| 1091 | for_each_subsys(ss, ssid)
|
| 1092 | if (root->subsys_mask & (1 << ssid))
|
| 1093 | seq_printf(seq, ",%s", ss->name);
|
| 1094 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR)
|
| 1095 | seq_puts(seq, ",sane_behavior");
|
| 1096 | if (root->flags & CGRP_ROOT_NOPREFIX)
|
| 1097 | seq_puts(seq, ",noprefix");
|
| 1098 | if (root->flags & CGRP_ROOT_XATTR)
|
| 1099 | seq_puts(seq, ",xattr");
|
| 1100 | if (strlen(root->release_agent_path))
|
| 1101 | seq_printf(seq, ",release_agent=%s", root->release_agent_path);
|
| 1102 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags))
|
| 1103 | seq_puts(seq, ",clone_children");
|
| 1104 | if (strlen(root->name))
|
| 1105 | seq_printf(seq, ",name=%s", root->name);
|
| 1106 | mutex_unlock(&cgroup_root_mutex);
|
| 1107 | return 0;
|
| 1108 | }
|
| 1109 |
|
| 1110 | struct cgroup_sb_opts {
|
| 1111 | unsigned long subsys_mask;
|
| 1112 | unsigned long flags;
|
| 1113 | char *release_agent;
|
| 1114 | bool cpuset_clone_children;
|
| 1115 | char *name;
|
| 1116 |
|
| 1117 | bool none;
|
| 1118 |
|
| 1119 | struct cgroupfs_root *new_root;
|
| 1120 |
|
| 1121 | };
|
| 1122 |
|
| 1123 | |
| 1124 | * Convert a hierarchy specifier into a bitmask of subsystems and
|
| 1125 | * flags. Call with cgroup_mutex held to protect the cgroup_subsys[]
|
| 1126 | * array. This function takes refcounts on subsystems to be used, unless it
|
| 1127 | * returns error, in which case no refcounts are taken.
|
| 1128 |
|
| 1129 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
|
| 1130 | {
|
| 1131 | char *token, *o = data;
|
| 1132 | bool all_ss = false, one_ss = false;
|
| 1133 | unsigned long mask = (unsigned long)-1;
|
| 1134 | struct cgroup_subsys *ss;
|
| 1135 | int i;
|
| 1136 |
|
| 1137 | BUG_ON(!mutex_is_locked(&cgroup_mutex));
|
| 1138 |
|
| 1139 | #ifdef CONFIG_CPUSETS
|
| 1140 | mask = ~(1UL << cpuset_subsys_id);
|
| 1141 | #endif
|
| 1142 |
|
| 1143 | memset(opts, 0, sizeof(*opts));
|
| 1144 |
|
| 1145 | while ((token = strsep(&o, ",")) != NULL) {
|
| 1146 | if (!*token)
|
| 1147 | return -EINVAL;
|
| 1148 | if (!strcmp(token, "none")) {
|
| 1149 |
|
| 1150 | opts->none = true;
|
| 1151 | continue;
|
| 1152 | }
|
| 1153 | if (!strcmp(token, "all")) {
|
| 1154 |
|
| 1155 | if (one_ss)
|
| 1156 | return -EINVAL;
|
| 1157 | all_ss = true;
|
| 1158 | continue;
|
| 1159 | }
|
| 1160 | if (!strcmp(token, "__DEVEL__sane_behavior")) {
|
| 1161 | opts->flags |= CGRP_ROOT_SANE_BEHAVIOR;
|
| 1162 | continue;
|
| 1163 | }
|
| 1164 | if (!strcmp(token, "noprefix")) {
|
| 1165 | opts->flags |= CGRP_ROOT_NOPREFIX;
|
| 1166 | continue;
|
| 1167 | }
|
| 1168 | if (!strcmp(token, "clone_children")) {
|
| 1169 | opts->cpuset_clone_children = true;
|
| 1170 | continue;
|
| 1171 | }
|
| 1172 | if (!strcmp(token, "xattr")) {
|
| 1173 | opts->flags |= CGRP_ROOT_XATTR;
|
| 1174 | continue;
|
| 1175 | }
|
| 1176 | if (!strncmp(token, "release_agent=", 14)) {
|
| 1177 |
|
| 1178 | if (opts->release_agent)
|
| 1179 | return -EINVAL;
|
| 1180 | opts->release_agent =
|
| 1181 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
|
| 1182 | if (!opts->release_agent)
|
| 1183 | return -ENOMEM;
|
| 1184 | continue;
|
| 1185 | }
|
| 1186 | if (!strncmp(token, "name=", 5)) {
|
| 1187 | const char *name = token + 5;
|
| 1188 |
|
| 1189 | if (!strlen(name))
|
| 1190 | return -EINVAL;
|
| 1191 |
|
| 1192 | for (i = 0; i < strlen(name); i++) {
|
| 1193 | char c = name[i];
|
| 1194 | if (isalnum(c))
|
| 1195 | continue;
|
| 1196 | if ((c == '.') || (c == '-') || (c == '_'))
|
| 1197 | continue;
|
| 1198 | return -EINVAL;
|
| 1199 | }
|
| 1200 |
|
| 1201 | if (opts->name)
|
| 1202 | return -EINVAL;
|
| 1203 | opts->name = kstrndup(name,
|
| 1204 | MAX_CGROUP_ROOT_NAMELEN - 1,
|
| 1205 | GFP_KERNEL);
|
| 1206 | if (!opts->name)
|
| 1207 | return -ENOMEM;
|
| 1208 |
|
| 1209 | continue;
|
| 1210 | }
|
| 1211 |
|
| 1212 | for_each_subsys(ss, i) {
|
| 1213 | if (strcmp(token, ss->name))
|
| 1214 | continue;
|
| 1215 | if (ss->disabled)
|
| 1216 | continue;
|
| 1217 |
|
| 1218 |
|
| 1219 | if (all_ss)
|
| 1220 | return -EINVAL;
|
| 1221 | set_bit(i, &opts->subsys_mask);
|
| 1222 | one_ss = true;
|
| 1223 |
|
| 1224 | break;
|
| 1225 | }
|
| 1226 | if (i == CGROUP_SUBSYS_COUNT)
|
| 1227 | return -ENOENT;
|
| 1228 | }
|
| 1229 |
|
| 1230 | |
| 1231 | * If the 'all' option was specified select all the subsystems,
|
| 1232 | * otherwise if 'none', 'name=' and a subsystem name options
|
| 1233 | * were not specified, let's default to 'all'
|
| 1234 |
|
| 1235 | if (all_ss || (!one_ss && !opts->none && !opts->name))
|
| 1236 | for_each_subsys(ss, i)
|
| 1237 | if (!ss->disabled)
|
| 1238 | set_bit(i, &opts->subsys_mask);
|
| 1239 |
|
| 1240 |
|
| 1241 |
|
| 1242 | if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) {
|
| 1243 | pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n");
|
| 1244 |
|
| 1245 | if (opts->flags & CGRP_ROOT_NOPREFIX) {
|
| 1246 | pr_err("cgroup: sane_behavior: noprefix is not allowed\n");
|
| 1247 | return -EINVAL;
|
| 1248 | }
|
| 1249 |
|
| 1250 | if (opts->cpuset_clone_children) {
|
| 1251 | pr_err("cgroup: sane_behavior: clone_children is not allowed\n");
|
| 1252 | return -EINVAL;
|
| 1253 | }
|
| 1254 | }
|
| 1255 |
|
| 1256 | |
| 1257 | * Option noprefix was introduced just for backward compatibility
|
| 1258 | * with the old cpuset, so we allow noprefix only if mounting just
|
| 1259 | * the cpuset subsystem.
|
| 1260 |
|
| 1261 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
|
| 1262 | return -EINVAL;
|
| 1263 |
|
| 1264 |
|
| 1265 |
|
| 1266 | if (opts->subsys_mask && opts->none)
|
| 1267 | return -EINVAL;
|
| 1268 |
|
| 1269 | |
| 1270 | * We either have to specify by name or by subsystems. (So all
|
| 1271 | * empty hierarchies must have a name).
|
| 1272 |
|
| 1273 | if (!opts->subsys_mask && !opts->name)
|
| 1274 | return -EINVAL;
|
| 1275 |
|
| 1276 | return 0;
|
| 1277 | }
|
| 1278 |
|
| 1279 | static int cgroup_remount(struct super_block *sb, int *flags, char *data)
|
| 1280 | {
|
| 1281 | int ret = 0;
|
| 1282 | struct cgroupfs_root *root = sb->s_fs_info;
|
| 1283 | struct cgroup *cgrp = &root->top_cgroup;
|
| 1284 | struct cgroup_sb_opts opts;
|
| 1285 | unsigned long added_mask, removed_mask;
|
| 1286 |
|
| 1287 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) {
|
| 1288 | pr_err("cgroup: sane_behavior: remount is not allowed\n");
|
| 1289 | return -EINVAL;
|
| 1290 | }
|
| 1291 |
|
| 1292 | mutex_lock(&cgrp->dentry->d_inode->i_mutex);
|
| 1293 | mutex_lock(&cgroup_mutex);
|
| 1294 | mutex_lock(&cgroup_root_mutex);
|
| 1295 |
|
| 1296 |
|
| 1297 | ret = parse_cgroupfs_options(data, &opts);
|
| 1298 | if (ret)
|
| 1299 | goto out_unlock;
|
| 1300 |
|
| 1301 | if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
|
| 1302 | pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
|
| 1303 | task_tgid_nr(current), current->comm);
|
| 1304 |
|
| 1305 | added_mask = opts.subsys_mask & ~root->subsys_mask;
|
| 1306 | removed_mask = root->subsys_mask & ~opts.subsys_mask;
|
| 1307 |
|
| 1308 |
|
| 1309 | if (((opts.flags ^ root->flags) & CGRP_ROOT_OPTION_MASK) ||
|
| 1310 | (opts.name && strcmp(opts.name, root->name))) {
|
| 1311 | pr_err("cgroup: option or name mismatch, new: 0x%lx \"%s\", old: 0x%lx \"%s\"\n",
|
| 1312 | opts.flags & CGRP_ROOT_OPTION_MASK, opts.name ?: "",
|
| 1313 | root->flags & CGRP_ROOT_OPTION_MASK, root->name);
|
| 1314 | ret = -EINVAL;
|
| 1315 | goto out_unlock;
|
| 1316 | }
|
| 1317 |
|
| 1318 |
|
| 1319 | if (root->number_of_cgroups > 1) {
|
| 1320 | ret = -EBUSY;
|
| 1321 | goto out_unlock;
|
| 1322 | }
|
| 1323 |
|
| 1324 | ret = rebind_subsystems(root, added_mask, removed_mask);
|
| 1325 | if (ret)
|
| 1326 | goto out_unlock;
|
| 1327 |
|
| 1328 | if (opts.release_agent)
|
| 1329 | strcpy(root->release_agent_path, opts.release_agent);
|
| 1330 | out_unlock:
|
| 1331 | kfree(opts.release_agent);
|
| 1332 | kfree(opts.name);
|
| 1333 | mutex_unlock(&cgroup_root_mutex);
|
| 1334 | mutex_unlock(&cgroup_mutex);
|
| 1335 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
|
| 1336 | return ret;
|
| 1337 | }
|
| 1338 |
|
| 1339 | static const struct super_operations cgroup_ops = {
|
| 1340 | .statfs = simple_statfs,
|
| 1341 | .drop_inode = generic_delete_inode,
|
| 1342 | .show_options = cgroup_show_options,
|
| 1343 | .remount_fs = cgroup_remount,
|
| 1344 | };
|
| 1345 |
|
| 1346 | static void init_cgroup_housekeeping(struct cgroup *cgrp)
|
| 1347 | {
|
| 1348 | INIT_LIST_HEAD(&cgrp->sibling);
|
| 1349 | INIT_LIST_HEAD(&cgrp->children);
|
| 1350 | INIT_LIST_HEAD(&cgrp->files);
|
| 1351 | INIT_LIST_HEAD(&cgrp->cset_links);
|
| 1352 | INIT_LIST_HEAD(&cgrp->release_list);
|
| 1353 | INIT_LIST_HEAD(&cgrp->pidlists);
|
| 1354 | mutex_init(&cgrp->pidlist_mutex);
|
| 1355 | cgrp->dummy_css.cgroup = cgrp;
|
| 1356 | simple_xattrs_init(&cgrp->xattrs);
|
| 1357 | }
|
| 1358 |
|
| 1359 | static void init_cgroup_root(struct cgroupfs_root *root)
|
| 1360 | {
|
| 1361 | struct cgroup *cgrp = &root->top_cgroup;
|
| 1362 |
|
| 1363 | INIT_LIST_HEAD(&root->root_list);
|
| 1364 | root->number_of_cgroups = 1;
|
| 1365 | cgrp->root = root;
|
| 1366 | RCU_INIT_POINTER(cgrp->name, &root_cgroup_name);
|
| 1367 | init_cgroup_housekeeping(cgrp);
|
| 1368 | idr_init(&root->cgroup_idr);
|
| 1369 | }
|
| 1370 |
|
| 1371 | static int cgroup_init_root_id(struct cgroupfs_root *root, int start, int end)
|
| 1372 | {
|
| 1373 | int id;
|
| 1374 |
|
| 1375 | lockdep_assert_held(&cgroup_mutex);
|
| 1376 | lockdep_assert_held(&cgroup_root_mutex);
|
| 1377 |
|
| 1378 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, start, end,
|
| 1379 | GFP_KERNEL);
|
| 1380 | if (id < 0)
|
| 1381 | return id;
|
| 1382 |
|
| 1383 | root->hierarchy_id = id;
|
| 1384 | return 0;
|
| 1385 | }
|
| 1386 |
|
| 1387 | static void cgroup_exit_root_id(struct cgroupfs_root *root)
|
| 1388 | {
|
| 1389 | lockdep_assert_held(&cgroup_mutex);
|
| 1390 | lockdep_assert_held(&cgroup_root_mutex);
|
| 1391 |
|
| 1392 | if (root->hierarchy_id) {
|
| 1393 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
|
| 1394 | root->hierarchy_id = 0;
|
| 1395 | }
|
| 1396 | }
|
| 1397 |
|
| 1398 | static int cgroup_test_super(struct super_block *sb, void *data)
|
| 1399 | {
|
| 1400 | struct cgroup_sb_opts *opts = data;
|
| 1401 | struct cgroupfs_root *root = sb->s_fs_info;
|
| 1402 |
|
| 1403 |
|
| 1404 | if (opts->name && strcmp(opts->name, root->name))
|
| 1405 | return 0;
|
| 1406 |
|
| 1407 | |
| 1408 | * If we asked for subsystems (or explicitly for no
|
| 1409 | * subsystems) then they must match
|
| 1410 |
|
| 1411 | if ((opts->subsys_mask || opts->none)
|
| 1412 | && (opts->subsys_mask != root->subsys_mask))
|
| 1413 | return 0;
|
| 1414 |
|
| 1415 | return 1;
|
| 1416 | }
|
| 1417 |
|
| 1418 | static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
|
| 1419 | {
|
| 1420 | struct cgroupfs_root *root;
|
| 1421 |
|
| 1422 | if (!opts->subsys_mask && !opts->none)
|
| 1423 | return NULL;
|
| 1424 |
|
| 1425 | root = kzalloc(sizeof(*root), GFP_KERNEL);
|
| 1426 | if (!root)
|
| 1427 | return ERR_PTR(-ENOMEM);
|
| 1428 |
|
| 1429 | init_cgroup_root(root);
|
| 1430 |
|
| 1431 | |
| 1432 | * We need to set @root->subsys_mask now so that @root can be
|
| 1433 | * matched by cgroup_test_super() before it finishes
|
| 1434 | * initialization; otherwise, competing mounts with the same
|
| 1435 | * options may try to bind the same subsystems instead of waiting
|
| 1436 | * for the first one leading to unexpected mount errors.
|
| 1437 | * SUBSYS_BOUND will be set once actual binding is complete.
|
| 1438 |
|
| 1439 | root->subsys_mask = opts->subsys_mask;
|
| 1440 | root->flags = opts->flags;
|
| 1441 | if (opts->release_agent)
|
| 1442 | strcpy(root->release_agent_path, opts->release_agent);
|
| 1443 | if (opts->name)
|
| 1444 | strcpy(root->name, opts->name);
|
| 1445 | if (opts->cpuset_clone_children)
|
| 1446 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags);
|
| 1447 | return root;
|
| 1448 | }
|
| 1449 |
|
| 1450 | static void cgroup_free_root(struct cgroupfs_root *root)
|
| 1451 | {
|
| 1452 | if (root) {
|
| 1453 |
|
| 1454 | WARN_ON_ONCE(root->hierarchy_id);
|
| 1455 |
|
| 1456 | idr_destroy(&root->cgroup_idr);
|
| 1457 | kfree(root);
|
| 1458 | }
|
| 1459 | }
|
| 1460 |
|
| 1461 | static int cgroup_set_super(struct super_block *sb, void *data)
|
| 1462 | {
|
| 1463 | int ret;
|
| 1464 | struct cgroup_sb_opts *opts = data;
|
| 1465 |
|
| 1466 |
|
| 1467 | if (!opts->new_root)
|
| 1468 | return -EINVAL;
|
| 1469 |
|
| 1470 | BUG_ON(!opts->subsys_mask && !opts->none);
|
| 1471 |
|
| 1472 | ret = set_anon_super(sb, NULL);
|
| 1473 | if (ret)
|
| 1474 | return ret;
|
| 1475 |
|
| 1476 | sb->s_fs_info = opts->new_root;
|
| 1477 | opts->new_root->sb = sb;
|
| 1478 |
|
| 1479 | sb->s_blocksize = PAGE_CACHE_SIZE;
|
| 1480 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
|
| 1481 | sb->s_magic = CGROUP_SUPER_MAGIC;
|
| 1482 | sb->s_op = &cgroup_ops;
|
| 1483 |
|
| 1484 | return 0;
|
| 1485 | }
|
| 1486 |
|
| 1487 | static int cgroup_get_rootdir(struct super_block *sb)
|
| 1488 | {
|
| 1489 | static const struct dentry_operations cgroup_dops = {
|
| 1490 | .d_iput = cgroup_diput,
|
| 1491 | .d_delete = always_delete_dentry,
|
| 1492 | };
|
| 1493 |
|
| 1494 | struct inode *inode =
|
| 1495 | cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb);
|
| 1496 |
|
| 1497 | if (!inode)
|
| 1498 | return -ENOMEM;
|
| 1499 |
|
| 1500 | inode->i_fop = &simple_dir_operations;
|
| 1501 | inode->i_op = &cgroup_dir_inode_operations;
|
| 1502 |
|
| 1503 | inc_nlink(inode);
|
| 1504 | sb->s_root = d_make_root(inode);
|
| 1505 | if (!sb->s_root)
|
| 1506 | return -ENOMEM;
|
| 1507 |
|
| 1508 | sb->s_d_op = &cgroup_dops;
|
| 1509 | return 0;
|
| 1510 | }
|
| 1511 |
|
| 1512 | static struct dentry *cgroup_mount(struct file_system_type *fs_type,
|
| 1513 | int flags, const char *unused_dev_name,
|
| 1514 | void *data)
|
| 1515 | {
|
| 1516 | struct cgroup_sb_opts opts;
|
| 1517 | struct cgroupfs_root *root;
|
| 1518 | int ret = 0;
|
| 1519 | struct super_block *sb;
|
| 1520 | struct cgroupfs_root *new_root;
|
| 1521 | struct list_head tmp_links;
|
| 1522 | struct inode *inode;
|
| 1523 | const struct cred *cred;
|
| 1524 |
|
| 1525 |
|
| 1526 | mutex_lock(&cgroup_mutex);
|
| 1527 | ret = parse_cgroupfs_options(data, &opts);
|
| 1528 | mutex_unlock(&cgroup_mutex);
|
| 1529 | if (ret)
|
| 1530 | goto out_err;
|
| 1531 |
|
| 1532 | |
| 1533 | * Allocate a new cgroup root. We may not need it if we're
|
| 1534 | * reusing an existing hierarchy.
|
| 1535 |
|
| 1536 | new_root = cgroup_root_from_opts(&opts);
|
| 1537 | if (IS_ERR(new_root)) {
|
| 1538 | ret = PTR_ERR(new_root);
|
| 1539 | goto out_err;
|
| 1540 | }
|
| 1541 | opts.new_root = new_root;
|
| 1542 |
|
| 1543 |
|
| 1544 | sb = sget(fs_type, cgroup_test_super, cgroup_set_super, 0, &opts);
|
| 1545 | if (IS_ERR(sb)) {
|
| 1546 | ret = PTR_ERR(sb);
|
| 1547 | cgroup_free_root(opts.new_root);
|
| 1548 | goto out_err;
|
| 1549 | }
|
| 1550 |
|
| 1551 | root = sb->s_fs_info;
|
| 1552 | BUG_ON(!root);
|
| 1553 | if (root == opts.new_root) {
|
| 1554 |
|
| 1555 | struct cgroup *root_cgrp = &root->top_cgroup;
|
| 1556 | struct cgroupfs_root *existing_root;
|
| 1557 | int i;
|
| 1558 | struct css_set *cset;
|
| 1559 |
|
| 1560 | BUG_ON(sb->s_root != NULL);
|
| 1561 |
|
| 1562 | ret = cgroup_get_rootdir(sb);
|
| 1563 | if (ret)
|
| 1564 | goto drop_new_super;
|
| 1565 | inode = sb->s_root->d_inode;
|
| 1566 |
|
| 1567 | mutex_lock(&inode->i_mutex);
|
| 1568 | mutex_lock(&cgroup_mutex);
|
| 1569 | mutex_lock(&cgroup_root_mutex);
|
| 1570 |
|
| 1571 | ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL);
|
| 1572 | if (ret < 0)
|
| 1573 | goto unlock_drop;
|
| 1574 | root_cgrp->id = ret;
|
| 1575 |
|
| 1576 |
|
| 1577 | ret = -EBUSY;
|
| 1578 | if (strlen(root->name))
|
| 1579 | for_each_active_root(existing_root)
|
| 1580 | if (!strcmp(existing_root->name, root->name))
|
| 1581 | goto unlock_drop;
|
| 1582 |
|
| 1583 | |
| 1584 | * We're accessing css_set_count without locking
|
| 1585 | * css_set_lock here, but that's OK - it can only be
|
| 1586 | * increased by someone holding cgroup_lock, and
|
| 1587 | * that's us. The worst that can happen is that we
|
| 1588 | * have some link structures left over
|
| 1589 |
|
| 1590 | ret = allocate_cgrp_cset_links(css_set_count, &tmp_links);
|
| 1591 | if (ret)
|
| 1592 | goto unlock_drop;
|
| 1593 |
|
| 1594 |
|
| 1595 | ret = cgroup_init_root_id(root, 2, 0);
|
| 1596 | if (ret)
|
| 1597 | goto unlock_drop;
|
| 1598 |
|
| 1599 | sb->s_root->d_fsdata = root_cgrp;
|
| 1600 | root_cgrp->dentry = sb->s_root;
|
| 1601 |
|
| 1602 | |
| 1603 | * We're inside get_sb() and will call lookup_one_len() to
|
| 1604 | * create the root files, which doesn't work if SELinux is
|
| 1605 | * in use. The following cred dancing somehow works around
|
| 1606 | * it. See 2ce9738ba ("cgroupfs: use init_cred when
|
| 1607 | * populating new cgroupfs mount") for more details.
|
| 1608 |
|
| 1609 | cred = override_creds(&init_cred);
|
| 1610 |
|
| 1611 | ret = cgroup_addrm_files(root_cgrp, cgroup_base_files, true);
|
| 1612 | if (ret)
|
| 1613 | goto rm_base_files;
|
| 1614 |
|
| 1615 | ret = rebind_subsystems(root, root->subsys_mask, 0);
|
| 1616 | if (ret)
|
| 1617 | goto rm_base_files;
|
| 1618 |
|
| 1619 | revert_creds(cred);
|
| 1620 |
|
| 1621 | |
| 1622 | * There must be no failure case after here, since rebinding
|
| 1623 | * takes care of subsystems' refcounts, which are explicitly
|
| 1624 | * dropped in the failure exit path.
|
| 1625 |
|
| 1626 |
|
| 1627 | list_add(&root->root_list, &cgroup_roots);
|
| 1628 | cgroup_root_count++;
|
| 1629 |
|
| 1630 | |
| 1631 | * the css_set objects
|
| 1632 | write_lock(&css_set_lock);
|
| 1633 | hash_for_each(css_set_table, i, cset, hlist)
|
| 1634 | link_css_set(&tmp_links, cset, root_cgrp);
|
| 1635 | write_unlock(&css_set_lock);
|
| 1636 |
|
| 1637 | free_cgrp_cset_links(&tmp_links);
|
| 1638 |
|
| 1639 | BUG_ON(!list_empty(&root_cgrp->children));
|
| 1640 | BUG_ON(root->number_of_cgroups != 1);
|
| 1641 |
|
| 1642 | mutex_unlock(&cgroup_root_mutex);
|
| 1643 | mutex_unlock(&cgroup_mutex);
|
| 1644 | mutex_unlock(&inode->i_mutex);
|
| 1645 | } else {
|
| 1646 | |
| 1647 | * We re-used an existing hierarchy - the new root (if
|
| 1648 | * any) is not needed
|
| 1649 |
|
| 1650 | cgroup_free_root(opts.new_root);
|
| 1651 |
|
| 1652 | if ((root->flags ^ opts.flags) & CGRP_ROOT_OPTION_MASK) {
|
| 1653 | if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) {
|
| 1654 | pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n");
|
| 1655 | ret = -EINVAL;
|
| 1656 | goto drop_new_super;
|
| 1657 | } else {
|
| 1658 | pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n");
|
| 1659 | }
|
| 1660 | }
|
| 1661 | }
|
| 1662 |
|
| 1663 | kfree(opts.release_agent);
|
| 1664 | kfree(opts.name);
|
| 1665 | return dget(sb->s_root);
|
| 1666 |
|
| 1667 | rm_base_files:
|
| 1668 | free_cgrp_cset_links(&tmp_links);
|
| 1669 | cgroup_addrm_files(&root->top_cgroup, cgroup_base_files, false);
|
| 1670 | revert_creds(cred);
|
| 1671 | unlock_drop:
|
| 1672 | cgroup_exit_root_id(root);
|
| 1673 | mutex_unlock(&cgroup_root_mutex);
|
| 1674 | mutex_unlock(&cgroup_mutex);
|
| 1675 | mutex_unlock(&inode->i_mutex);
|
| 1676 | drop_new_super:
|
| 1677 | deactivate_locked_super(sb);
|
| 1678 | out_err:
|
| 1679 | kfree(opts.release_agent);
|
| 1680 | kfree(opts.name);
|
| 1681 | return ERR_PTR(ret);
|
| 1682 | }
|
| 1683 |
|
| 1684 | static void cgroup_kill_sb(struct super_block *sb)
|
| 1685 | {
|
| 1686 | struct cgroupfs_root *root = sb->s_fs_info;
|
| 1687 | struct cgroup *cgrp = &root->top_cgroup;
|
| 1688 | struct cgrp_cset_link *link, *tmp_link;
|
| 1689 | int ret;
|
| 1690 |
|
| 1691 | BUG_ON(!root);
|
| 1692 |
|
| 1693 | BUG_ON(root->number_of_cgroups != 1);
|
| 1694 | BUG_ON(!list_empty(&cgrp->children));
|
| 1695 |
|
| 1696 | mutex_lock(&cgrp->dentry->d_inode->i_mutex);
|
| 1697 | mutex_lock(&cgroup_mutex);
|
| 1698 | mutex_lock(&cgroup_root_mutex);
|
| 1699 |
|
| 1700 |
|
| 1701 | if (root->flags & CGRP_ROOT_SUBSYS_BOUND) {
|
| 1702 | ret = rebind_subsystems(root, 0, root->subsys_mask);
|
| 1703 |
|
| 1704 | BUG_ON(ret);
|
| 1705 | }
|
| 1706 |
|
| 1707 | |
| 1708 | * Release all the links from cset_links to this hierarchy's
|
| 1709 | * root cgroup
|
| 1710 |
|
| 1711 | write_lock(&css_set_lock);
|
| 1712 |
|
| 1713 | list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
|
| 1714 | list_del(&link->cset_link);
|
| 1715 | list_del(&link->cgrp_link);
|
| 1716 | kfree(link);
|
| 1717 | }
|
| 1718 | write_unlock(&css_set_lock);
|
| 1719 |
|
| 1720 | if (!list_empty(&root->root_list)) {
|
| 1721 | list_del(&root->root_list);
|
| 1722 | cgroup_root_count--;
|
| 1723 | }
|
| 1724 |
|
| 1725 | cgroup_exit_root_id(root);
|
| 1726 |
|
| 1727 | mutex_unlock(&cgroup_root_mutex);
|
| 1728 | mutex_unlock(&cgroup_mutex);
|
| 1729 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
|
| 1730 |
|
| 1731 | simple_xattrs_free(&cgrp->xattrs);
|
| 1732 |
|
| 1733 | kill_litter_super(sb);
|
| 1734 | cgroup_free_root(root);
|
| 1735 | }
|
| 1736 |
|
| 1737 | static struct file_system_type cgroup_fs_type = {
|
| 1738 | .name = "cgroup",
|
| 1739 | .mount = cgroup_mount,
|
| 1740 | .kill_sb = cgroup_kill_sb,
|
| 1741 | };
|
| 1742 |
|
| 1743 | static struct kobject *cgroup_kobj;
|
| 1744 |
|
| 1745 | |
| 1746 | * cgroup_path - generate the path of a cgroup
|
| 1747 | * @cgrp: the cgroup in question
|
| 1748 | * @buf: the buffer to write the path into
|
| 1749 | * @buflen: the length of the buffer
|
| 1750 | *
|
| 1751 | * Writes path of cgroup into buf. Returns 0 on success, -errno on error.
|
| 1752 | *
|
| 1753 | * We can't generate cgroup path using dentry->d_name, as accessing
|
| 1754 | * dentry->name must be protected by irq-unsafe dentry->d_lock or parent
|
| 1755 | * inode's i_mutex, while on the other hand cgroup_path() can be called
|
| 1756 | * with some irq-safe spinlocks held.
|
| 1757 |
|
| 1758 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
|
| 1759 | {
|
| 1760 | int ret = -ENAMETOOLONG;
|
| 1761 | char *start;
|
| 1762 |
|
| 1763 | if (!cgrp->parent) {
|
| 1764 | if (strlcpy(buf, "/", buflen) >= buflen)
|
| 1765 | return -ENAMETOOLONG;
|
| 1766 | return 0;
|
| 1767 | }
|
| 1768 |
|
| 1769 | start = buf + buflen - 1;
|
| 1770 | *start = '\0';
|
| 1771 |
|
| 1772 | rcu_read_lock();
|
| 1773 | do {
|
| 1774 | const char *name = cgroup_name(cgrp);
|
| 1775 | int len;
|
| 1776 |
|
| 1777 | len = strlen(name);
|
| 1778 | if ((start -= len) < buf)
|
| 1779 | goto out;
|
| 1780 | memcpy(start, name, len);
|
| 1781 |
|
| 1782 | if (--start < buf)
|
| 1783 | goto out;
|
| 1784 | *start = '/';
|
| 1785 |
|
| 1786 | cgrp = cgrp->parent;
|
| 1787 | } while (cgrp->parent);
|
| 1788 | ret = 0;
|
| 1789 | memmove(buf, start, buf + buflen - start);
|
| 1790 | out:
|
| 1791 | rcu_read_unlock();
|
| 1792 | return ret;
|
| 1793 | }
|
| 1794 | EXPORT_SYMBOL_GPL(cgroup_path);
|
| 1795 |
|
| 1796 | |
| 1797 | * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
|
| 1798 | * @task: target task
|
| 1799 | * @buf: the buffer to write the path into
|
| 1800 | * @buflen: the length of the buffer
|
| 1801 | *
|
| 1802 | * Determine @task's cgroup on the first (the one with the lowest non-zero
|
| 1803 | * hierarchy_id) cgroup hierarchy and copy its path into @buf. This
|
| 1804 | * function grabs cgroup_mutex and shouldn't be used inside locks used by
|
| 1805 | * cgroup controller callbacks.
|
| 1806 | *
|
| 1807 | * Returns 0 on success, fails with -%ENAMETOOLONG if @buflen is too short.
|
| 1808 |
|
| 1809 | int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
|
| 1810 | {
|
| 1811 | struct cgroupfs_root *root;
|
| 1812 | struct cgroup *cgrp;
|
| 1813 | int hierarchy_id = 1, ret = 0;
|
| 1814 |
|
| 1815 | if (buflen < 2)
|
| 1816 | return -ENAMETOOLONG;
|
| 1817 |
|
| 1818 | mutex_lock(&cgroup_mutex);
|
| 1819 |
|
| 1820 | root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
|
| 1821 |
|
| 1822 | if (root) {
|
| 1823 | cgrp = task_cgroup_from_root(task, root);
|
| 1824 | ret = cgroup_path(cgrp, buf, buflen);
|
| 1825 | } else {
|
| 1826 |
|
| 1827 | memcpy(buf, "/", 2);
|
| 1828 | }
|
| 1829 |
|
| 1830 | mutex_unlock(&cgroup_mutex);
|
| 1831 | return ret;
|
| 1832 | }
|
| 1833 | EXPORT_SYMBOL_GPL(task_cgroup_path);
|
| 1834 |
|
| 1835 | |
| 1836 | * Control Group taskset
|
| 1837 |
|
| 1838 | struct task_and_cgroup {
|
| 1839 | struct task_struct *task;
|
| 1840 | struct cgroup *cgrp;
|
| 1841 | struct css_set *cset;
|
| 1842 | };
|
| 1843 |
|
| 1844 | struct cgroup_taskset {
|
| 1845 | struct task_and_cgroup single;
|
| 1846 | struct flex_array *tc_array;
|
| 1847 | int tc_array_len;
|
| 1848 | int idx;
|
| 1849 | struct cgroup *cur_cgrp;
|
| 1850 | };
|
| 1851 |
|
| 1852 | |
| 1853 | * cgroup_taskset_first - reset taskset and return the first task
|
| 1854 | * @tset: taskset of interest
|
| 1855 | *
|
| 1856 | * @tset iteration is initialized and the first task is returned.
|
| 1857 |
|
| 1858 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset)
|
| 1859 | {
|
| 1860 | if (tset->tc_array) {
|
| 1861 | tset->idx = 0;
|
| 1862 | return cgroup_taskset_next(tset);
|
| 1863 | } else {
|
| 1864 | tset->cur_cgrp = tset->single.cgrp;
|
| 1865 | return tset->single.task;
|
| 1866 | }
|
| 1867 | }
|
| 1868 | EXPORT_SYMBOL_GPL(cgroup_taskset_first);
|
| 1869 |
|
| 1870 | |
| 1871 | * cgroup_taskset_next - iterate to the next task in taskset
|
| 1872 | * @tset: taskset of interest
|
| 1873 | *
|
| 1874 | * Return the next task in @tset. Iteration must have been initialized
|
| 1875 | * with cgroup_taskset_first().
|
| 1876 |
|
| 1877 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset)
|
| 1878 | {
|
| 1879 | struct task_and_cgroup *tc;
|
| 1880 |
|
| 1881 | if (!tset->tc_array || tset->idx >= tset->tc_array_len)
|
| 1882 | return NULL;
|
| 1883 |
|
| 1884 | tc = flex_array_get(tset->tc_array, tset->idx++);
|
| 1885 | tset->cur_cgrp = tc->cgrp;
|
| 1886 | return tc->task;
|
| 1887 | }
|
| 1888 | EXPORT_SYMBOL_GPL(cgroup_taskset_next);
|
| 1889 |
|
| 1890 | |
| 1891 | * cgroup_taskset_cur_css - return the matching css for the current task
|
| 1892 | * @tset: taskset of interest
|
| 1893 | * @subsys_id: the ID of the target subsystem
|
| 1894 | *
|
| 1895 | * Return the css for the current (last returned) task of @tset for
|
| 1896 | * subsystem specified by @subsys_id. This function must be preceded by
|
| 1897 | * either cgroup_taskset_first() or cgroup_taskset_next().
|
| 1898 |
|
| 1899 | struct cgroup_subsys_state *cgroup_taskset_cur_css(struct cgroup_taskset *tset,
|
| 1900 | int subsys_id)
|
| 1901 | {
|
| 1902 | return cgroup_css(tset->cur_cgrp, cgroup_subsys[subsys_id]);
|
| 1903 | }
|
| 1904 | EXPORT_SYMBOL_GPL(cgroup_taskset_cur_css);
|
| 1905 |
|
| 1906 | |
| 1907 | * cgroup_taskset_size - return the number of tasks in taskset
|
| 1908 | * @tset: taskset of interest
|
| 1909 |
|
| 1910 | int cgroup_taskset_size(struct cgroup_taskset *tset)
|
| 1911 | {
|
| 1912 | return tset->tc_array ? tset->tc_array_len : 1;
|
| 1913 | }
|
| 1914 | EXPORT_SYMBOL_GPL(cgroup_taskset_size);
|
| 1915 |
|
| 1916 |
|
| 1917 | |
| 1918 | * cgroup_task_migrate - move a task from one cgroup to another.
|
| 1919 | *
|
| 1920 | * Must be called with cgroup_mutex and threadgroup locked.
|
| 1921 |
|
| 1922 | static void cgroup_task_migrate(struct cgroup *old_cgrp,
|
| 1923 | struct task_struct *tsk,
|
| 1924 | struct css_set *new_cset)
|
| 1925 | {
|
| 1926 | struct css_set *old_cset;
|
| 1927 |
|
| 1928 | |
| 1929 | * We are synchronized through threadgroup_lock() against PF_EXITING
|
| 1930 | * setting such that we can't race against cgroup_exit() changing the
|
| 1931 | * css_set to init_css_set and dropping the old one.
|
| 1932 |
|
| 1933 | WARN_ON_ONCE(tsk->flags & PF_EXITING);
|
| 1934 | old_cset = task_css_set(tsk);
|
| 1935 |
|
| 1936 | task_lock(tsk);
|
| 1937 | rcu_assign_pointer(tsk->cgroups, new_cset);
|
| 1938 | task_unlock(tsk);
|
| 1939 |
|
| 1940 |
|
| 1941 | write_lock(&css_set_lock);
|
| 1942 | if (!list_empty(&tsk->cg_list))
|
| 1943 | list_move(&tsk->cg_list, &new_cset->tasks);
|
| 1944 | write_unlock(&css_set_lock);
|
| 1945 |
|
| 1946 | |
| 1947 | * We just gained a reference on old_cset by taking it from the
|
| 1948 | * task. As trading it for new_cset is protected by cgroup_mutex,
|
| 1949 | * we're safe to drop it here; it will be freed under RCU.
|
| 1950 |
|
| 1951 | set_bit(CGRP_RELEASABLE, &old_cgrp->flags);
|
| 1952 | put_css_set(old_cset);
|
| 1953 | }
|
| 1954 |
|
| 1955 | |
| 1956 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
|
| 1957 | * @cgrp: the cgroup to attach to
|
| 1958 | * @tsk: the task or the leader of the threadgroup to be attached
|
| 1959 | * @threadgroup: attach the whole threadgroup?
|
| 1960 | *
|
| 1961 | * Call holding cgroup_mutex and the group_rwsem of the leader. Will take
|
| 1962 | * task_lock of @tsk or each thread in the threadgroup individually in turn.
|
| 1963 |
|
| 1964 | static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk,
|
| 1965 | bool threadgroup)
|
| 1966 | {
|
| 1967 | int retval, i, group_size;
|
| 1968 | struct cgroupfs_root *root = cgrp->root;
|
| 1969 | struct cgroup_subsys_state *css, *failed_css = NULL;
|
| 1970 |
|
| 1971 | struct task_struct *leader = tsk;
|
| 1972 | struct task_and_cgroup *tc;
|
| 1973 | struct flex_array *group;
|
| 1974 | struct cgroup_taskset tset = { };
|
| 1975 |
|
| 1976 | |
| 1977 | * step 0: in order to do expensive, possibly blocking operations for
|
| 1978 | * every thread, we cannot iterate the thread group list, since it needs
|
| 1979 | * rcu or tasklist locked. instead, build an array of all threads in the
|
| 1980 | * group - group_rwsem prevents new threads from appearing, and if
|
| 1981 | * threads exit, this will just be an over-estimate.
|
| 1982 |
|
| 1983 | if (threadgroup)
|
| 1984 | group_size = get_nr_threads(tsk);
|
| 1985 | else
|
| 1986 | group_size = 1;
|
| 1987 |
|
| 1988 | group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL);
|
| 1989 | if (!group)
|
| 1990 | return -ENOMEM;
|
| 1991 |
|
| 1992 | retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL);
|
| 1993 | if (retval)
|
| 1994 | goto out_free_group_list;
|
| 1995 |
|
| 1996 | i = 0;
|
| 1997 | |
| 1998 | * Prevent freeing of tasks while we take a snapshot. Tasks that are
|
| 1999 | * already PF_EXITING could be freed from underneath us unless we
|
| 2000 | * take an rcu_read_lock.
|
| 2001 |
|
| 2002 | rcu_read_lock();
|
| 2003 | do {
|
| 2004 | struct task_and_cgroup ent;
|
| 2005 |
|
| 2006 |
|
| 2007 | if (tsk->flags & PF_EXITING)
|
| 2008 | goto next;
|
| 2009 |
|
| 2010 |
|
| 2011 | BUG_ON(i >= group_size);
|
| 2012 | ent.task = tsk;
|
| 2013 | ent.cgrp = task_cgroup_from_root(tsk, root);
|
| 2014 |
|
| 2015 | if (ent.cgrp == cgrp)
|
| 2016 | goto next;
|
| 2017 | |
| 2018 | * saying GFP_ATOMIC has no effect here because we did prealloc
|
| 2019 | * earlier, but it's good form to communicate our expectations.
|
| 2020 |
|
| 2021 | retval = flex_array_put(group, i, &ent, GFP_ATOMIC);
|
| 2022 | BUG_ON(retval != 0);
|
| 2023 | i++;
|
| 2024 | next:
|
| 2025 | if (!threadgroup)
|
| 2026 | break;
|
| 2027 | } while_each_thread(leader, tsk);
|
| 2028 | rcu_read_unlock();
|
| 2029 |
|
| 2030 | group_size = i;
|
| 2031 | tset.tc_array = group;
|
| 2032 | tset.tc_array_len = group_size;
|
| 2033 |
|
| 2034 |
|
| 2035 | retval = 0;
|
| 2036 | if (!group_size)
|
| 2037 | goto out_free_group_list;
|
| 2038 |
|
| 2039 | |
| 2040 | * step 1: check that we can legitimately attach to the cgroup.
|
| 2041 |
|
| 2042 | for_each_css(css, i, cgrp) {
|
| 2043 | if (css->ss->can_attach) {
|
| 2044 | retval = css->ss->can_attach(css, &tset);
|
| 2045 | if (retval) {
|
| 2046 | failed_css = css;
|
| 2047 | goto out_cancel_attach;
|
| 2048 | }
|
| 2049 | }
|
| 2050 | }
|
| 2051 |
|
| 2052 | |
| 2053 | * step 2: make sure css_sets exist for all threads to be migrated.
|
| 2054 | * we use find_css_set, which allocates a new one if necessary.
|
| 2055 |
|
| 2056 | for (i = 0; i < group_size; i++) {
|
| 2057 | struct css_set *old_cset;
|
| 2058 |
|
| 2059 | tc = flex_array_get(group, i);
|
| 2060 | old_cset = task_css_set(tc->task);
|
| 2061 | tc->cset = find_css_set(old_cset, cgrp);
|
| 2062 | if (!tc->cset) {
|
| 2063 | retval = -ENOMEM;
|
| 2064 | goto out_put_css_set_refs;
|
| 2065 | }
|
| 2066 | }
|
| 2067 |
|
| 2068 | |
| 2069 | * step 3: now that we're guaranteed success wrt the css_sets,
|
| 2070 | * proceed to move all tasks to the new cgroup. There are no
|
| 2071 | * failure cases after here, so this is the commit point.
|
| 2072 |
|
| 2073 | for (i = 0; i < group_size; i++) {
|
| 2074 | tc = flex_array_get(group, i);
|
| 2075 | cgroup_task_migrate(tc->cgrp, tc->task, tc->cset);
|
| 2076 | }
|
| 2077 |
|
| 2078 |
|
| 2079 | |
| 2080 | * step 4: do subsystem attach callbacks.
|
| 2081 |
|
| 2082 | for_each_css(css, i, cgrp)
|
| 2083 | if (css->ss->attach)
|
| 2084 | css->ss->attach(css, &tset);
|
| 2085 |
|
| 2086 | |
| 2087 | * step 5: success! and cleanup
|
| 2088 |
|
| 2089 | retval = 0;
|
| 2090 | out_put_css_set_refs:
|
| 2091 | if (retval) {
|
| 2092 | for (i = 0; i < group_size; i++) {
|
| 2093 | tc = flex_array_get(group, i);
|
| 2094 | if (!tc->cset)
|
| 2095 | break;
|
| 2096 | put_css_set(tc->cset);
|
| 2097 | }
|
| 2098 | }
|
| 2099 | out_cancel_attach:
|
| 2100 | if (retval) {
|
| 2101 | for_each_css(css, i, cgrp) {
|
| 2102 | if (css == failed_css)
|
| 2103 | break;
|
| 2104 | if (css->ss->cancel_attach)
|
| 2105 | css->ss->cancel_attach(css, &tset);
|
| 2106 | }
|
| 2107 | }
|
| 2108 | out_free_group_list:
|
| 2109 | flex_array_free(group);
|
| 2110 | return retval;
|
| 2111 | }
|
| 2112 |
|
| 2113 | |
| 2114 | * Find the task_struct of the task to attach by vpid and pass it along to the
|
| 2115 | * function to attach either it or all tasks in its threadgroup. Will lock
|
| 2116 | * cgroup_mutex and threadgroup; may take task_lock of task.
|
| 2117 |
|
| 2118 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup)
|
| 2119 | {
|
| 2120 | struct task_struct *tsk;
|
| 2121 | const struct cred *cred = current_cred(), *tcred;
|
| 2122 | int ret;
|
| 2123 |
|
| 2124 | if (!cgroup_lock_live_group(cgrp))
|
| 2125 | return -ENODEV;
|
| 2126 |
|
| 2127 | retry_find_task:
|
| 2128 | rcu_read_lock();
|
| 2129 | if (pid) {
|
| 2130 | tsk = find_task_by_vpid(pid);
|
| 2131 | if (!tsk) {
|
| 2132 | rcu_read_unlock();
|
| 2133 | ret = -ESRCH;
|
| 2134 | goto out_unlock_cgroup;
|
| 2135 | }
|
| 2136 | |
| 2137 | * even if we're attaching all tasks in the thread group, we
|
| 2138 | * only need to check permissions on one of them.
|
| 2139 |
|
| 2140 | tcred = __task_cred(tsk);
|
| 2141 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
|
| 2142 | !uid_eq(cred->euid, tcred->uid) &&
|
| 2143 | !uid_eq(cred->euid, tcred->suid)) {
|
| 2144 | rcu_read_unlock();
|
| 2145 | ret = -EACCES;
|
| 2146 | goto out_unlock_cgroup;
|
| 2147 | }
|
| 2148 | } else
|
| 2149 | tsk = current;
|
| 2150 |
|
| 2151 | if (threadgroup)
|
| 2152 | tsk = tsk->group_leader;
|
| 2153 |
|
| 2154 | |
| 2155 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become
|
| 2156 | * trapped in a cpuset, or RT worker may be born in a cgroup
|
| 2157 | * with no rt_runtime allocated. Just say no.
|
| 2158 |
|
| 2159 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) {
|
| 2160 | ret = -EINVAL;
|
| 2161 | rcu_read_unlock();
|
| 2162 | goto out_unlock_cgroup;
|
| 2163 | }
|
| 2164 |
|
| 2165 | get_task_struct(tsk);
|
| 2166 | rcu_read_unlock();
|
| 2167 |
|
| 2168 | threadgroup_lock(tsk);
|
| 2169 | if (threadgroup) {
|
| 2170 | if (!thread_group_leader(tsk)) {
|
| 2171 | |
| 2172 | * a race with de_thread from another thread's exec()
|
| 2173 | * may strip us of our leadership, if this happens,
|
| 2174 | * there is no choice but to throw this task away and
|
| 2175 | * try again; this is
|
| 2176 | * "double-double-toil-and-trouble-check locking".
|
| 2177 |
|
| 2178 | threadgroup_unlock(tsk);
|
| 2179 | put_task_struct(tsk);
|
| 2180 | goto retry_find_task;
|
| 2181 | }
|
| 2182 | }
|
| 2183 |
|
| 2184 | ret = cgroup_attach_task(cgrp, tsk, threadgroup);
|
| 2185 |
|
| 2186 | threadgroup_unlock(tsk);
|
| 2187 |
|
| 2188 | put_task_struct(tsk);
|
| 2189 | out_unlock_cgroup:
|
| 2190 | mutex_unlock(&cgroup_mutex);
|
| 2191 | return ret;
|
| 2192 | }
|
| 2193 |
|
| 2194 | |
| 2195 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
|
| 2196 | * @from: attach to all cgroups of a given task
|
| 2197 | * @tsk: the task to be attached
|
| 2198 |
|
| 2199 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
|
| 2200 | {
|
| 2201 | struct cgroupfs_root *root;
|
| 2202 | int retval = 0;
|
| 2203 |
|
| 2204 | mutex_lock(&cgroup_mutex);
|
| 2205 | for_each_active_root(root) {
|
| 2206 | struct cgroup *from_cgrp = task_cgroup_from_root(from, root);
|
| 2207 |
|
| 2208 | retval = cgroup_attach_task(from_cgrp, tsk, false);
|
| 2209 | if (retval)
|
| 2210 | break;
|
| 2211 | }
|
| 2212 | mutex_unlock(&cgroup_mutex);
|
| 2213 |
|
| 2214 | return retval;
|
| 2215 | }
|
| 2216 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
|
| 2217 |
|
| 2218 | static int cgroup_tasks_write(struct cgroup_subsys_state *css,
|
| 2219 | struct cftype *cft, u64 pid)
|
| 2220 | {
|
| 2221 | return attach_task_by_pid(css->cgroup, pid, false);
|
| 2222 | }
|
| 2223 |
|
| 2224 | static int cgroup_procs_write(struct cgroup_subsys_state *css,
|
| 2225 | struct cftype *cft, u64 tgid)
|
| 2226 | {
|
| 2227 | return attach_task_by_pid(css->cgroup, tgid, true);
|
| 2228 | }
|
| 2229 |
|
| 2230 | static int cgroup_release_agent_write(struct cgroup_subsys_state *css,
|
| 2231 | struct cftype *cft, const char *buffer)
|
| 2232 | {
|
| 2233 | BUILD_BUG_ON(sizeof(css->cgroup->root->release_agent_path) < PATH_MAX);
|
| 2234 | if (strlen(buffer) >= PATH_MAX)
|
| 2235 | return -EINVAL;
|
| 2236 | if (!cgroup_lock_live_group(css->cgroup))
|
| 2237 | return -ENODEV;
|
| 2238 | mutex_lock(&cgroup_root_mutex);
|
| 2239 | strcpy(css->cgroup->root->release_agent_path, buffer);
|
| 2240 | mutex_unlock(&cgroup_root_mutex);
|
| 2241 | mutex_unlock(&cgroup_mutex);
|
| 2242 | return 0;
|
| 2243 | }
|
| 2244 |
|
| 2245 | static int cgroup_release_agent_show(struct seq_file *seq, void *v)
|
| 2246 | {
|
| 2247 | struct cgroup *cgrp = seq_css(seq)->cgroup;
|
| 2248 |
|
| 2249 | if (!cgroup_lock_live_group(cgrp))
|
| 2250 | return -ENODEV;
|
| 2251 | seq_puts(seq, cgrp->root->release_agent_path);
|
| 2252 | seq_putc(seq, '\n');
|
| 2253 | mutex_unlock(&cgroup_mutex);
|
| 2254 | return 0;
|
| 2255 | }
|
| 2256 |
|
| 2257 | static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
|
| 2258 | {
|
| 2259 | struct cgroup *cgrp = seq_css(seq)->cgroup;
|
| 2260 |
|
| 2261 | seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp));
|
| 2262 | return 0;
|
| 2263 | }
|
| 2264 |
|
| 2265 |
|
| 2266 | #define CGROUP_LOCAL_BUFFER_SIZE 64
|
| 2267 |
|
| 2268 | static ssize_t cgroup_file_write(struct file *file, const char __user *userbuf,
|
| 2269 | size_t nbytes, loff_t *ppos)
|
| 2270 | {
|
| 2271 | struct cfent *cfe = __d_cfe(file->f_dentry);
|
| 2272 | struct cftype *cft = __d_cft(file->f_dentry);
|
| 2273 | struct cgroup_subsys_state *css = cfe->css;
|
| 2274 | size_t max_bytes = cft->max_write_len ?: CGROUP_LOCAL_BUFFER_SIZE - 1;
|
| 2275 | char *buf;
|
| 2276 | int ret;
|
| 2277 |
|
| 2278 | if (nbytes >= max_bytes)
|
| 2279 | return -E2BIG;
|
| 2280 |
|
| 2281 | buf = kmalloc(nbytes + 1, GFP_KERNEL);
|
| 2282 | if (!buf)
|
| 2283 | return -ENOMEM;
|
| 2284 |
|
| 2285 | if (copy_from_user(buf, userbuf, nbytes)) {
|
| 2286 | ret = -EFAULT;
|
| 2287 | goto out_free;
|
| 2288 | }
|
| 2289 |
|
| 2290 | buf[nbytes] = '\0';
|
| 2291 |
|
| 2292 | if (cft->write_string) {
|
| 2293 | ret = cft->write_string(css, cft, strstrip(buf));
|
| 2294 | } else if (cft->write_u64) {
|
| 2295 | unsigned long long v;
|
| 2296 | ret = kstrtoull(buf, 0, &v);
|
| 2297 | if (!ret)
|
| 2298 | ret = cft->write_u64(css, cft, v);
|
| 2299 | } else if (cft->write_s64) {
|
| 2300 | long long v;
|
| 2301 | ret = kstrtoll(buf, 0, &v);
|
| 2302 | if (!ret)
|
| 2303 | ret = cft->write_s64(css, cft, v);
|
| 2304 | } else if (cft->trigger) {
|
| 2305 | ret = cft->trigger(css, (unsigned int)cft->private);
|
| 2306 | } else {
|
| 2307 | ret = -EINVAL;
|
| 2308 | }
|
| 2309 | out_free:
|
| 2310 | kfree(buf);
|
| 2311 | return ret ?: nbytes;
|
| 2312 | }
|
| 2313 |
|
| 2314 | |
| 2315 | * seqfile ops/methods for returning structured data. Currently just
|
| 2316 | * supports string->u64 maps, but can be extended in future.
|
| 2317 |
|
| 2318 |
|
| 2319 | static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos)
|
| 2320 | {
|
| 2321 | struct cftype *cft = seq_cft(seq);
|
| 2322 |
|
| 2323 | if (cft->seq_start) {
|
| 2324 | return cft->seq_start(seq, ppos);
|
| 2325 | } else {
|
| 2326 | |
| 2327 | * The same behavior and code as single_open(). Returns
|
| 2328 | * !NULL if pos is at the beginning; otherwise, NULL.
|
| 2329 |
|
| 2330 | return NULL + !*ppos;
|
| 2331 | }
|
| 2332 | }
|
| 2333 |
|
| 2334 | static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos)
|
| 2335 | {
|
| 2336 | struct cftype *cft = seq_cft(seq);
|
| 2337 |
|
| 2338 | if (cft->seq_next) {
|
| 2339 | return cft->seq_next(seq, v, ppos);
|
| 2340 | } else {
|
| 2341 | |
| 2342 | * The same behavior and code as single_open(), always
|
| 2343 | * terminate after the initial read.
|
| 2344 |
|
| 2345 | ++*ppos;
|
| 2346 | return NULL;
|
| 2347 | }
|
| 2348 | }
|
| 2349 |
|
| 2350 | static void cgroup_seqfile_stop(struct seq_file *seq, void *v)
|
| 2351 | {
|
| 2352 | struct cftype *cft = seq_cft(seq);
|
| 2353 |
|
| 2354 | if (cft->seq_stop)
|
| 2355 | cft->seq_stop(seq, v);
|
| 2356 | }
|
| 2357 |
|
| 2358 | static int cgroup_seqfile_show(struct seq_file *m, void *arg)
|
| 2359 | {
|
| 2360 | struct cftype *cft = seq_cft(m);
|
| 2361 | struct cgroup_subsys_state *css = seq_css(m);
|
| 2362 |
|
| 2363 | if (cft->seq_show)
|
| 2364 | return cft->seq_show(m, arg);
|
| 2365 |
|
| 2366 | if (cft->read_u64)
|
| 2367 | seq_printf(m, "%llu\n", cft->read_u64(css, cft));
|
| 2368 | else if (cft->read_s64)
|
| 2369 | seq_printf(m, "%lld\n", cft->read_s64(css, cft));
|
| 2370 | else
|
| 2371 | return -EINVAL;
|
| 2372 | return 0;
|
| 2373 | }
|
| 2374 |
|
| 2375 | static struct seq_operations cgroup_seq_operations = {
|
| 2376 | .start = cgroup_seqfile_start,
|
| 2377 | .next = cgroup_seqfile_next,
|
| 2378 | .stop = cgroup_seqfile_stop,
|
| 2379 | .show = cgroup_seqfile_show,
|
| 2380 | };
|
| 2381 |
|
| 2382 | static int cgroup_file_open(struct inode *inode, struct file *file)
|
| 2383 | {
|
| 2384 | struct cfent *cfe = __d_cfe(file->f_dentry);
|
| 2385 | struct cftype *cft = __d_cft(file->f_dentry);
|
| 2386 | struct cgroup *cgrp = __d_cgrp(cfe->dentry->d_parent);
|
| 2387 | struct cgroup_subsys_state *css;
|
| 2388 | struct cgroup_open_file *of;
|
| 2389 | int err;
|
| 2390 |
|
| 2391 | err = generic_file_open(inode, file);
|
| 2392 | if (err)
|
| 2393 | return err;
|
| 2394 |
|
| 2395 | |
| 2396 | * If the file belongs to a subsystem, pin the css. Will be
|
| 2397 | * unpinned either on open failure or release. This ensures that
|
| 2398 | * @css stays alive for all file operations.
|
| 2399 |
|
| 2400 | rcu_read_lock();
|
| 2401 | css = cgroup_css(cgrp, cft->ss);
|
| 2402 | if (cft->ss && !css_tryget(css))
|
| 2403 | css = NULL;
|
| 2404 | rcu_read_unlock();
|
| 2405 |
|
| 2406 | if (!css)
|
| 2407 | return -ENODEV;
|
| 2408 |
|
| 2409 | |
| 2410 | * @cfe->css is used by read/write/close to determine the
|
| 2411 | * associated css. @file->private_data would be a better place but
|
| 2412 | * that's already used by seqfile. Multiple accessors may use it
|
| 2413 | * simultaneously which is okay as the association never changes.
|
| 2414 |
|
| 2415 | WARN_ON_ONCE(cfe->css && cfe->css != css);
|
| 2416 | cfe->css = css;
|
| 2417 |
|
| 2418 | of = __seq_open_private(file, &cgroup_seq_operations,
|
| 2419 | sizeof(struct cgroup_open_file));
|
| 2420 | if (of) {
|
| 2421 | of->cfe = cfe;
|
| 2422 | return 0;
|
| 2423 | }
|
| 2424 |
|
| 2425 | if (css->ss)
|
| 2426 | css_put(css);
|
| 2427 | return -ENOMEM;
|
| 2428 | }
|
| 2429 |
|
| 2430 | static int cgroup_file_release(struct inode *inode, struct file *file)
|
| 2431 | {
|
| 2432 | struct cfent *cfe = __d_cfe(file->f_dentry);
|
| 2433 | struct cgroup_subsys_state *css = cfe->css;
|
| 2434 |
|
| 2435 | if (css->ss)
|
| 2436 | css_put(css);
|
| 2437 | return seq_release_private(inode, file);
|
| 2438 | }
|
| 2439 |
|
| 2440 | |
| 2441 | * cgroup_rename - Only allow simple rename of directories in place.
|
| 2442 |
|
| 2443 | static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry,
|
| 2444 | struct inode *new_dir, struct dentry *new_dentry)
|
| 2445 | {
|
| 2446 | int ret;
|
| 2447 | struct cgroup_name *name, *old_name;
|
| 2448 | struct cgroup *cgrp;
|
| 2449 |
|
| 2450 | |
| 2451 | * It's convinient to use parent dir's i_mutex to protected
|
| 2452 | * cgrp->name.
|
| 2453 |
|
| 2454 | lockdep_assert_held(&old_dir->i_mutex);
|
| 2455 |
|
| 2456 | if (!S_ISDIR(old_dentry->d_inode->i_mode))
|
| 2457 | return -ENOTDIR;
|
| 2458 | if (new_dentry->d_inode)
|
| 2459 | return -EEXIST;
|
| 2460 | if (old_dir != new_dir)
|
| 2461 | return -EIO;
|
| 2462 |
|
| 2463 | cgrp = __d_cgrp(old_dentry);
|
| 2464 |
|
| 2465 | |
| 2466 | * This isn't a proper migration and its usefulness is very
|
| 2467 | * limited. Disallow if sane_behavior.
|
| 2468 |
|
| 2469 | if (cgroup_sane_behavior(cgrp))
|
| 2470 | return -EPERM;
|
| 2471 |
|
| 2472 | name = cgroup_alloc_name(new_dentry);
|
| 2473 | if (!name)
|
| 2474 | return -ENOMEM;
|
| 2475 |
|
| 2476 | ret = simple_rename(old_dir, old_dentry, new_dir, new_dentry);
|
| 2477 | if (ret) {
|
| 2478 | kfree(name);
|
| 2479 | return ret;
|
| 2480 | }
|
| 2481 |
|
| 2482 | old_name = rcu_dereference_protected(cgrp->name, true);
|
| 2483 | rcu_assign_pointer(cgrp->name, name);
|
| 2484 |
|
| 2485 | kfree_rcu(old_name, rcu_head);
|
| 2486 | return 0;
|
| 2487 | }
|
| 2488 |
|
| 2489 | static struct simple_xattrs *__d_xattrs(struct dentry *dentry)
|
| 2490 | {
|
| 2491 | if (S_ISDIR(dentry->d_inode->i_mode))
|
| 2492 | return &__d_cgrp(dentry)->xattrs;
|
| 2493 | else
|
| 2494 | return &__d_cfe(dentry)->xattrs;
|
| 2495 | }
|
| 2496 |
|
| 2497 | static inline int xattr_enabled(struct dentry *dentry)
|
| 2498 | {
|
| 2499 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
|
| 2500 | return root->flags & CGRP_ROOT_XATTR;
|
| 2501 | }
|
| 2502 |
|
| 2503 | static bool is_valid_xattr(const char *name)
|
| 2504 | {
|
| 2505 | if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
|
| 2506 | !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN))
|
| 2507 | return true;
|
| 2508 | return false;
|
| 2509 | }
|
| 2510 |
|
| 2511 | static int cgroup_setxattr(struct dentry *dentry, const char *name,
|
| 2512 | const void *val, size_t size, int flags)
|
| 2513 | {
|
| 2514 | if (!xattr_enabled(dentry))
|
| 2515 | return -EOPNOTSUPP;
|
| 2516 | if (!is_valid_xattr(name))
|
| 2517 | return -EINVAL;
|
| 2518 | return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags);
|
| 2519 | }
|
| 2520 |
|
| 2521 | static int cgroup_removexattr(struct dentry *dentry, const char *name)
|
| 2522 | {
|
| 2523 | if (!xattr_enabled(dentry))
|
| 2524 | return -EOPNOTSUPP;
|
| 2525 | if (!is_valid_xattr(name))
|
| 2526 | return -EINVAL;
|
| 2527 | return simple_xattr_remove(__d_xattrs(dentry), name);
|
| 2528 | }
|
| 2529 |
|
| 2530 | static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name,
|
| 2531 | void *buf, size_t size)
|
| 2532 | {
|
| 2533 | if (!xattr_enabled(dentry))
|
| 2534 | return -EOPNOTSUPP;
|
| 2535 | if (!is_valid_xattr(name))
|
| 2536 | return -EINVAL;
|
| 2537 | return simple_xattr_get(__d_xattrs(dentry), name, buf, size);
|
| 2538 | }
|
| 2539 |
|
| 2540 | static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size)
|
| 2541 | {
|
| 2542 | if (!xattr_enabled(dentry))
|
| 2543 | return -EOPNOTSUPP;
|
| 2544 | return simple_xattr_list(__d_xattrs(dentry), buf, size);
|
| 2545 | }
|
| 2546 |
|
| 2547 | static const struct file_operations cgroup_file_operations = {
|
| 2548 | .read = seq_read,
|
| 2549 | .write = cgroup_file_write,
|
| 2550 | .llseek = generic_file_llseek,
|
| 2551 | .open = cgroup_file_open,
|
| 2552 | .release = cgroup_file_release,
|
| 2553 | };
|
| 2554 |
|
| 2555 | static const struct inode_operations cgroup_file_inode_operations = {
|
| 2556 | .setxattr = cgroup_setxattr,
|
| 2557 | .getxattr = cgroup_getxattr,
|
| 2558 | .listxattr = cgroup_listxattr,
|
| 2559 | .removexattr = cgroup_removexattr,
|
| 2560 | };
|
| 2561 |
|
| 2562 | static const struct inode_operations cgroup_dir_inode_operations = {
|
| 2563 | .lookup = simple_lookup,
|
| 2564 | .mkdir = cgroup_mkdir,
|
| 2565 | .rmdir = cgroup_rmdir,
|
| 2566 | .rename = cgroup_rename,
|
| 2567 | .setxattr = cgroup_setxattr,
|
| 2568 | .getxattr = cgroup_getxattr,
|
| 2569 | .listxattr = cgroup_listxattr,
|
| 2570 | .removexattr = cgroup_removexattr,
|
| 2571 | };
|
| 2572 |
|
| 2573 | static int cgroup_create_file(struct dentry *dentry, umode_t mode,
|
| 2574 | struct super_block *sb)
|
| 2575 | {
|
| 2576 | struct inode *inode;
|
| 2577 |
|
| 2578 | if (!dentry)
|
| 2579 | return -ENOENT;
|
| 2580 | if (dentry->d_inode)
|
| 2581 | return -EEXIST;
|
| 2582 |
|
| 2583 | inode = cgroup_new_inode(mode, sb);
|
| 2584 | if (!inode)
|
| 2585 | return -ENOMEM;
|
| 2586 |
|
| 2587 | if (S_ISDIR(mode)) {
|
| 2588 | inode->i_op = &cgroup_dir_inode_operations;
|
| 2589 | inode->i_fop = &simple_dir_operations;
|
| 2590 |
|
| 2591 |
|
| 2592 | inc_nlink(inode);
|
| 2593 | inc_nlink(dentry->d_parent->d_inode);
|
| 2594 |
|
| 2595 | |
| 2596 | * Control reaches here with cgroup_mutex held.
|
| 2597 | * @inode->i_mutex should nest outside cgroup_mutex but we
|
| 2598 | * want to populate it immediately without releasing
|
| 2599 | * cgroup_mutex. As @inode isn't visible to anyone else
|
| 2600 | * yet, trylock will always succeed without affecting
|
| 2601 | * lockdep checks.
|
| 2602 |
|
| 2603 | WARN_ON_ONCE(!mutex_trylock(&inode->i_mutex));
|
| 2604 | } else if (S_ISREG(mode)) {
|
| 2605 | inode->i_size = 0;
|
| 2606 | inode->i_fop = &cgroup_file_operations;
|
| 2607 | inode->i_op = &cgroup_file_inode_operations;
|
| 2608 | }
|
| 2609 | d_instantiate(dentry, inode);
|
| 2610 | dget(dentry);
|
| 2611 | return 0;
|
| 2612 | }
|
| 2613 |
|
| 2614 | |
| 2615 | * cgroup_file_mode - deduce file mode of a control file
|
| 2616 | * @cft: the control file in question
|
| 2617 | *
|
| 2618 | * returns cft->mode if ->mode is not 0
|
| 2619 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler
|
| 2620 | * returns S_IRUGO if it has only a read handler
|
| 2621 | * returns S_IWUSR if it has only a write hander
|
| 2622 |
|
| 2623 | static umode_t cgroup_file_mode(const struct cftype *cft)
|
| 2624 | {
|
| 2625 | umode_t mode = 0;
|
| 2626 |
|
| 2627 | if (cft->mode)
|
| 2628 | return cft->mode;
|
| 2629 |
|
| 2630 | if (cft->read_u64 || cft->read_s64 || cft->seq_show)
|
| 2631 | mode |= S_IRUGO;
|
| 2632 |
|
| 2633 | if (cft->write_u64 || cft->write_s64 || cft->write_string ||
|
| 2634 | cft->trigger)
|
| 2635 | mode |= S_IWUSR;
|
| 2636 |
|
| 2637 | return mode;
|
| 2638 | }
|
| 2639 |
|
| 2640 | static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft)
|
| 2641 | {
|
| 2642 | struct dentry *dir = cgrp->dentry;
|
| 2643 | struct cgroup *parent = __d_cgrp(dir);
|
| 2644 | struct dentry *dentry;
|
| 2645 | struct cfent *cfe;
|
| 2646 | int error;
|
| 2647 | umode_t mode;
|
| 2648 | char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
|
| 2649 |
|
| 2650 | if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
|
| 2651 | !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) {
|
| 2652 | strcpy(name, cft->ss->name);
|
| 2653 | strcat(name, ".");
|
| 2654 | }
|
| 2655 | strcat(name, cft->name);
|
| 2656 |
|
| 2657 | BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex));
|
| 2658 |
|
| 2659 | cfe = kzalloc(sizeof(*cfe), GFP_KERNEL);
|
| 2660 | if (!cfe)
|
| 2661 | return -ENOMEM;
|
| 2662 |
|
| 2663 | dentry = lookup_one_len(name, dir, strlen(name));
|
| 2664 | if (IS_ERR(dentry)) {
|
| 2665 | error = PTR_ERR(dentry);
|
| 2666 | goto out;
|
| 2667 | }
|
| 2668 |
|
| 2669 | cfe->type = (void *)cft;
|
| 2670 | cfe->dentry = dentry;
|
| 2671 | dentry->d_fsdata = cfe;
|
| 2672 | simple_xattrs_init(&cfe->xattrs);
|
| 2673 |
|
| 2674 | mode = cgroup_file_mode(cft);
|
| 2675 | error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb);
|
| 2676 | if (!error) {
|
| 2677 | list_add_tail(&cfe->node, &parent->files);
|
| 2678 | cfe = NULL;
|
| 2679 | }
|
| 2680 | dput(dentry);
|
| 2681 | out:
|
| 2682 | kfree(cfe);
|
| 2683 | return error;
|
| 2684 | }
|
| 2685 |
|
| 2686 | |
| 2687 | * cgroup_addrm_files - add or remove files to a cgroup directory
|
| 2688 | * @cgrp: the target cgroup
|
| 2689 | * @cfts: array of cftypes to be added
|
| 2690 | * @is_add: whether to add or remove
|
| 2691 | *
|
| 2692 | * Depending on @is_add, add or remove files defined by @cfts on @cgrp.
|
| 2693 | * For removals, this function never fails. If addition fails, this
|
| 2694 | * function doesn't remove files already added. The caller is responsible
|
| 2695 | * for cleaning up.
|
| 2696 |
|
| 2697 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
|
| 2698 | bool is_add)
|
| 2699 | {
|
| 2700 | struct cftype *cft;
|
| 2701 | int ret;
|
| 2702 |
|
| 2703 | lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
|
| 2704 | lockdep_assert_held(&cgroup_mutex);
|
| 2705 |
|
| 2706 | for (cft = cfts; cft->name[0] != '\0'; cft++) {
|
| 2707 |
|
| 2708 | if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp))
|
| 2709 | continue;
|
| 2710 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent)
|
| 2711 | continue;
|
| 2712 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent)
|
| 2713 | continue;
|
| 2714 |
|
| 2715 | if (is_add) {
|
| 2716 | ret = cgroup_add_file(cgrp, cft);
|
| 2717 | if (ret) {
|
| 2718 | pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n",
|
| 2719 | cft->name, ret);
|
| 2720 | return ret;
|
| 2721 | }
|
| 2722 | } else {
|
| 2723 | cgroup_rm_file(cgrp, cft);
|
| 2724 | }
|
| 2725 | }
|
| 2726 | return 0;
|
| 2727 | }
|
| 2728 |
|
| 2729 | static void cgroup_cfts_prepare(void)
|
| 2730 | __acquires(&cgroup_mutex)
|
| 2731 | {
|
| 2732 | |
| 2733 | * Thanks to the entanglement with vfs inode locking, we can't walk
|
| 2734 | * the existing cgroups under cgroup_mutex and create files.
|
| 2735 | * Instead, we use css_for_each_descendant_pre() and drop RCU read
|
| 2736 | * lock before calling cgroup_addrm_files().
|
| 2737 |
|
| 2738 | mutex_lock(&cgroup_mutex);
|
| 2739 | }
|
| 2740 |
|
| 2741 | static int cgroup_cfts_commit(struct cftype *cfts, bool is_add)
|
| 2742 | __releases(&cgroup_mutex)
|
| 2743 | {
|
| 2744 | LIST_HEAD(pending);
|
| 2745 | struct cgroup_subsys *ss = cfts[0].ss;
|
| 2746 | struct cgroup *root = &ss->root->top_cgroup;
|
| 2747 | struct super_block *sb = ss->root->sb;
|
| 2748 | struct dentry *prev = NULL;
|
| 2749 | struct inode *inode;
|
| 2750 | struct cgroup_subsys_state *css;
|
| 2751 | u64 update_before;
|
| 2752 | int ret = 0;
|
| 2753 |
|
| 2754 |
|
| 2755 | if (!cfts || ss->root == &cgroup_dummy_root ||
|
| 2756 | !atomic_inc_not_zero(&sb->s_active)) {
|
| 2757 | mutex_unlock(&cgroup_mutex);
|
| 2758 | return 0;
|
| 2759 | }
|
| 2760 |
|
| 2761 | |
| 2762 | * All cgroups which are created after we drop cgroup_mutex will
|
| 2763 | * have the updated set of files, so we only need to update the
|
| 2764 | * cgroups created before the current @cgroup_serial_nr_next.
|
| 2765 |
|
| 2766 | update_before = cgroup_serial_nr_next;
|
| 2767 |
|
| 2768 |
|
| 2769 | css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
|
| 2770 | struct cgroup *cgrp = css->cgroup;
|
| 2771 |
|
| 2772 | if (cgroup_is_dead(cgrp))
|
| 2773 | continue;
|
| 2774 |
|
| 2775 | inode = cgrp->dentry->d_inode;
|
| 2776 | dget(cgrp->dentry);
|
| 2777 | dput(prev);
|
| 2778 | prev = cgrp->dentry;
|
| 2779 |
|
| 2780 | mutex_unlock(&cgroup_mutex);
|
| 2781 | mutex_lock(&inode->i_mutex);
|
| 2782 | mutex_lock(&cgroup_mutex);
|
| 2783 | if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp))
|
| 2784 | ret = cgroup_addrm_files(cgrp, cfts, is_add);
|
| 2785 | mutex_unlock(&inode->i_mutex);
|
| 2786 | if (ret)
|
| 2787 | break;
|
| 2788 | }
|
| 2789 | mutex_unlock(&cgroup_mutex);
|
| 2790 | dput(prev);
|
| 2791 | deactivate_super(sb);
|
| 2792 | return ret;
|
| 2793 | }
|
| 2794 |
|
| 2795 | |
| 2796 | * cgroup_add_cftypes - add an array of cftypes to a subsystem
|
| 2797 | * @ss: target cgroup subsystem
|
| 2798 | * @cfts: zero-length name terminated array of cftypes
|
| 2799 | *
|
| 2800 | * Register @cfts to @ss. Files described by @cfts are created for all
|
| 2801 | * existing cgroups to which @ss is attached and all future cgroups will
|
| 2802 | * have them too. This function can be called anytime whether @ss is
|
| 2803 | * attached or not.
|
| 2804 | *
|
| 2805 | * Returns 0 on successful registration, -errno on failure. Note that this
|
| 2806 | * function currently returns 0 as long as @cfts registration is successful
|
| 2807 | * even if some file creation attempts on existing cgroups fail.
|
| 2808 |
|
| 2809 | int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
| 2810 | {
|
| 2811 | struct cftype_set *set;
|
| 2812 | struct cftype *cft;
|
| 2813 | int ret;
|
| 2814 |
|
| 2815 | set = kzalloc(sizeof(*set), GFP_KERNEL);
|
| 2816 | if (!set)
|
| 2817 | return -ENOMEM;
|
| 2818 |
|
| 2819 | for (cft = cfts; cft->name[0] != '\0'; cft++)
|
| 2820 | cft->ss = ss;
|
| 2821 |
|
| 2822 | cgroup_cfts_prepare();
|
| 2823 | set->cfts = cfts;
|
| 2824 | list_add_tail(&set->node, &ss->cftsets);
|
| 2825 | ret = cgroup_cfts_commit(cfts, true);
|
| 2826 | if (ret)
|
| 2827 | cgroup_rm_cftypes(cfts);
|
| 2828 | return ret;
|
| 2829 | }
|
| 2830 | EXPORT_SYMBOL_GPL(cgroup_add_cftypes);
|
| 2831 |
|
| 2832 | |
| 2833 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
|
| 2834 | * @cfts: zero-length name terminated array of cftypes
|
| 2835 | *
|
| 2836 | * Unregister @cfts. Files described by @cfts are removed from all
|
| 2837 | * existing cgroups and all future cgroups won't have them either. This
|
| 2838 | * function can be called anytime whether @cfts' subsys is attached or not.
|
| 2839 | *
|
| 2840 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not
|
| 2841 | * registered.
|
| 2842 |
|
| 2843 | int cgroup_rm_cftypes(struct cftype *cfts)
|
| 2844 | {
|
| 2845 | struct cftype_set *set;
|
| 2846 |
|
| 2847 | if (!cfts || !cfts[0].ss)
|
| 2848 | return -ENOENT;
|
| 2849 |
|
| 2850 | cgroup_cfts_prepare();
|
| 2851 |
|
| 2852 | list_for_each_entry(set, &cfts[0].ss->cftsets, node) {
|
| 2853 | if (set->cfts == cfts) {
|
| 2854 | list_del(&set->node);
|
| 2855 | kfree(set);
|
| 2856 | cgroup_cfts_commit(cfts, false);
|
| 2857 | return 0;
|
| 2858 | }
|
| 2859 | }
|
| 2860 |
|
| 2861 | cgroup_cfts_commit(NULL, false);
|
| 2862 | return -ENOENT;
|
| 2863 | }
|
| 2864 |
|
| 2865 | |
| 2866 | * cgroup_task_count - count the number of tasks in a cgroup.
|
| 2867 | * @cgrp: the cgroup in question
|
| 2868 | *
|
| 2869 | * Return the number of tasks in the cgroup.
|
| 2870 |
|
| 2871 | int cgroup_task_count(const struct cgroup *cgrp)
|
| 2872 | {
|
| 2873 | int count = 0;
|
| 2874 | struct cgrp_cset_link *link;
|
| 2875 |
|
| 2876 | read_lock(&css_set_lock);
|
| 2877 | list_for_each_entry(link, &cgrp->cset_links, cset_link)
|
| 2878 | count += atomic_read(&link->cset->refcount);
|
| 2879 | read_unlock(&css_set_lock);
|
| 2880 | return count;
|
| 2881 | }
|
| 2882 |
|
| 2883 | |
| 2884 | * To reduce the fork() overhead for systems that are not actually using
|
| 2885 | * their cgroups capability, we don't maintain the lists running through
|
| 2886 | * each css_set to its tasks until we see the list actually used - in other
|
| 2887 | * words after the first call to css_task_iter_start().
|
| 2888 |
|
| 2889 | static void cgroup_enable_task_cg_lists(void)
|
| 2890 | {
|
| 2891 | struct task_struct *p, *g;
|
| 2892 | write_lock(&css_set_lock);
|
| 2893 | use_task_css_set_links = 1;
|
| 2894 | |
| 2895 | * We need tasklist_lock because RCU is not safe against
|
| 2896 | * while_each_thread(). Besides, a forking task that has passed
|
| 2897 | * cgroup_post_fork() without seeing use_task_css_set_links = 1
|
| 2898 | * is not guaranteed to have its child immediately visible in the
|
| 2899 | * tasklist if we walk through it with RCU.
|
| 2900 |
|
| 2901 | read_lock(&tasklist_lock);
|
| 2902 | do_each_thread(g, p) {
|
| 2903 | task_lock(p);
|
| 2904 | |
| 2905 | * We should check if the process is exiting, otherwise
|
| 2906 | * it will race with cgroup_exit() in that the list
|
| 2907 | * entry won't be deleted though the process has exited.
|
| 2908 | * Do it while holding siglock so that we don't end up
|
| 2909 | * racing against cgroup_exit().
|
| 2910 |
|
| 2911 | spin_lock_irq(&p->sighand->siglock);
|
| 2912 | if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list))
|
| 2913 | list_add(&p->cg_list, &task_css_set(p)->tasks);
|
| 2914 | spin_unlock_irq(&p->sighand->siglock);
|
| 2915 |
|
| 2916 | task_unlock(p);
|
| 2917 | } while_each_thread(g, p);
|
| 2918 | read_unlock(&tasklist_lock);
|
| 2919 | write_unlock(&css_set_lock);
|
| 2920 | }
|
| 2921 |
|
| 2922 | |
| 2923 | * css_next_child - find the next child of a given css
|
| 2924 | * @pos_css: the current position (%NULL to initiate traversal)
|
| 2925 | * @parent_css: css whose children to walk
|
| 2926 | *
|
| 2927 | * This function returns the next child of @parent_css and should be called
|
| 2928 | * under either cgroup_mutex or RCU read lock. The only requirement is
|
| 2929 | * that @parent_css and @pos_css are accessible. The next sibling is
|
| 2930 | * guaranteed to be returned regardless of their states.
|
| 2931 |
|
| 2932 | struct cgroup_subsys_state *
|
| 2933 | css_next_child(struct cgroup_subsys_state *pos_css,
|
| 2934 | struct cgroup_subsys_state *parent_css)
|
| 2935 | {
|
| 2936 | struct cgroup *pos = pos_css ? pos_css->cgroup : NULL;
|
| 2937 | struct cgroup *cgrp = parent_css->cgroup;
|
| 2938 | struct cgroup *next;
|
| 2939 |
|
| 2940 | cgroup_assert_mutex_or_rcu_locked();
|
| 2941 |
|
| 2942 | |
| 2943 | * @pos could already have been removed. Once a cgroup is removed,
|
| 2944 | * its ->sibling.next is no longer updated when its next sibling
|
| 2945 | * changes. As CGRP_DEAD assertion is serialized and happens
|
| 2946 | * before the cgroup is taken off the ->sibling list, if we see it
|
| 2947 | * unasserted, it's guaranteed that the next sibling hasn't
|
| 2948 | * finished its grace period even if it's already removed, and thus
|
| 2949 | * safe to dereference from this RCU critical section. If
|
| 2950 | * ->sibling.next is inaccessible, cgroup_is_dead() is guaranteed
|
| 2951 | * to be visible as %true here.
|
| 2952 | *
|
| 2953 | * If @pos is dead, its next pointer can't be dereferenced;
|
| 2954 | * however, as each cgroup is given a monotonically increasing
|
| 2955 | * unique serial number and always appended to the sibling list,
|
| 2956 | * the next one can be found by walking the parent's children until
|
| 2957 | * we see a cgroup with higher serial number than @pos's. While
|
| 2958 | * this path can be slower, it's taken only when either the current
|
| 2959 | * cgroup is removed or iteration and removal race.
|
| 2960 |
|
| 2961 | if (!pos) {
|
| 2962 | next = list_entry_rcu(cgrp->children.next, struct cgroup, sibling);
|
| 2963 | } else if (likely(!cgroup_is_dead(pos))) {
|
| 2964 | next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling);
|
| 2965 | } else {
|
| 2966 | list_for_each_entry_rcu(next, &cgrp->children, sibling)
|
| 2967 | if (next->serial_nr > pos->serial_nr)
|
| 2968 | break;
|
| 2969 | }
|
| 2970 |
|
| 2971 | if (&next->sibling == &cgrp->children)
|
| 2972 | return NULL;
|
| 2973 |
|
| 2974 | return cgroup_css(next, parent_css->ss);
|
| 2975 | }
|
| 2976 | EXPORT_SYMBOL_GPL(css_next_child);
|
| 2977 |
|
| 2978 | |
| 2979 | * css_next_descendant_pre - find the next descendant for pre-order walk
|
| 2980 | * @pos: the current position (%NULL to initiate traversal)
|
| 2981 | * @root: css whose descendants to walk
|
| 2982 | *
|
| 2983 | * To be used by css_for_each_descendant_pre(). Find the next descendant
|
| 2984 | * to visit for pre-order traversal of @root's descendants. @root is
|
| 2985 | * included in the iteration and the first node to be visited.
|
| 2986 | *
|
| 2987 | * While this function requires cgroup_mutex or RCU read locking, it
|
| 2988 | * doesn't require the whole traversal to be contained in a single critical
|
| 2989 | * section. This function will return the correct next descendant as long
|
| 2990 | * as both @pos and @root are accessible and @pos is a descendant of @root.
|
| 2991 |
|
| 2992 | struct cgroup_subsys_state *
|
| 2993 | css_next_descendant_pre(struct cgroup_subsys_state *pos,
|
| 2994 | struct cgroup_subsys_state *root)
|
| 2995 | {
|
| 2996 | struct cgroup_subsys_state *next;
|
| 2997 |
|
| 2998 | cgroup_assert_mutex_or_rcu_locked();
|
| 2999 |
|
| 3000 |
|
| 3001 | if (!pos)
|
| 3002 | return root;
|
| 3003 |
|
| 3004 |
|
| 3005 | next = css_next_child(NULL, pos);
|
| 3006 | if (next)
|
| 3007 | return next;
|
| 3008 |
|
| 3009 |
|
| 3010 | while (pos != root) {
|
| 3011 | next = css_next_child(pos, css_parent(pos));
|
| 3012 | if (next)
|
| 3013 | return next;
|
| 3014 | pos = css_parent(pos);
|
| 3015 | }
|
| 3016 |
|
| 3017 | return NULL;
|
| 3018 | }
|
| 3019 | EXPORT_SYMBOL_GPL(css_next_descendant_pre);
|
| 3020 |
|
| 3021 | |
| 3022 | * css_rightmost_descendant - return the rightmost descendant of a css
|
| 3023 | * @pos: css of interest
|
| 3024 | *
|
| 3025 | * Return the rightmost descendant of @pos. If there's no descendant, @pos
|
| 3026 | * is returned. This can be used during pre-order traversal to skip
|
| 3027 | * subtree of @pos.
|
| 3028 | *
|
| 3029 | * While this function requires cgroup_mutex or RCU read locking, it
|
| 3030 | * doesn't require the whole traversal to be contained in a single critical
|
| 3031 | * section. This function will return the correct rightmost descendant as
|
| 3032 | * long as @pos is accessible.
|
| 3033 |
|
| 3034 | struct cgroup_subsys_state *
|
| 3035 | css_rightmost_descendant(struct cgroup_subsys_state *pos)
|
| 3036 | {
|
| 3037 | struct cgroup_subsys_state *last, *tmp;
|
| 3038 |
|
| 3039 | cgroup_assert_mutex_or_rcu_locked();
|
| 3040 |
|
| 3041 | do {
|
| 3042 | last = pos;
|
| 3043 |
|
| 3044 | pos = NULL;
|
| 3045 | css_for_each_child(tmp, last)
|
| 3046 | pos = tmp;
|
| 3047 | } while (pos);
|
| 3048 |
|
| 3049 | return last;
|
| 3050 | }
|
| 3051 | EXPORT_SYMBOL_GPL(css_rightmost_descendant);
|
| 3052 |
|
| 3053 | static struct cgroup_subsys_state *
|
| 3054 | css_leftmost_descendant(struct cgroup_subsys_state *pos)
|
| 3055 | {
|
| 3056 | struct cgroup_subsys_state *last;
|
| 3057 |
|
| 3058 | do {
|
| 3059 | last = pos;
|
| 3060 | pos = css_next_child(NULL, pos);
|
| 3061 | } while (pos);
|
| 3062 |
|
| 3063 | return last;
|
| 3064 | }
|
| 3065 |
|
| 3066 | |
| 3067 | * css_next_descendant_post - find the next descendant for post-order walk
|
| 3068 | * @pos: the current position (%NULL to initiate traversal)
|
| 3069 | * @root: css whose descendants to walk
|
| 3070 | *
|
| 3071 | * To be used by css_for_each_descendant_post(). Find the next descendant
|
| 3072 | * to visit for post-order traversal of @root's descendants. @root is
|
| 3073 | * included in the iteration and the last node to be visited.
|
| 3074 | *
|
| 3075 | * While this function requires cgroup_mutex or RCU read locking, it
|
| 3076 | * doesn't require the whole traversal to be contained in a single critical
|
| 3077 | * section. This function will return the correct next descendant as long
|
| 3078 | * as both @pos and @cgroup are accessible and @pos is a descendant of
|
| 3079 | * @cgroup.
|
| 3080 |
|
| 3081 | struct cgroup_subsys_state *
|
| 3082 | css_next_descendant_post(struct cgroup_subsys_state *pos,
|
| 3083 | struct cgroup_subsys_state *root)
|
| 3084 | {
|
| 3085 | struct cgroup_subsys_state *next;
|
| 3086 |
|
| 3087 | cgroup_assert_mutex_or_rcu_locked();
|
| 3088 |
|
| 3089 |
|
| 3090 | if (!pos)
|
| 3091 | return css_leftmost_descendant(root);
|
| 3092 |
|
| 3093 |
|
| 3094 | if (pos == root)
|
| 3095 | return NULL;
|
| 3096 |
|
| 3097 |
|
| 3098 | next = css_next_child(pos, css_parent(pos));
|
| 3099 | if (next)
|
| 3100 | return css_leftmost_descendant(next);
|
| 3101 |
|
| 3102 |
|
| 3103 | return css_parent(pos);
|
| 3104 | }
|
| 3105 | EXPORT_SYMBOL_GPL(css_next_descendant_post);
|
| 3106 |
|
| 3107 | |
| 3108 | * css_advance_task_iter - advance a task itererator to the next css_set
|
| 3109 | * @it: the iterator to advance
|
| 3110 | *
|
| 3111 | * Advance @it to the next css_set to walk.
|
| 3112 |
|
| 3113 | static void css_advance_task_iter(struct css_task_iter *it)
|
| 3114 | {
|
| 3115 | struct list_head *l = it->cset_link;
|
| 3116 | struct cgrp_cset_link *link;
|
| 3117 | struct css_set *cset;
|
| 3118 |
|
| 3119 |
|
| 3120 | do {
|
| 3121 | l = l->next;
|
| 3122 | if (l == &it->origin_css->cgroup->cset_links) {
|
| 3123 | it->cset_link = NULL;
|
| 3124 | return;
|
| 3125 | }
|
| 3126 | link = list_entry(l, struct cgrp_cset_link, cset_link);
|
| 3127 | cset = link->cset;
|
| 3128 | } while (list_empty(&cset->tasks));
|
| 3129 | it->cset_link = l;
|
| 3130 | it->task = cset->tasks.next;
|
| 3131 | }
|
| 3132 |
|
| 3133 | |
| 3134 | * css_task_iter_start - initiate task iteration
|
| 3135 | * @css: the css to walk tasks of
|
| 3136 | * @it: the task iterator to use
|
| 3137 | *
|
| 3138 | * Initiate iteration through the tasks of @css. The caller can call
|
| 3139 | * css_task_iter_next() to walk through the tasks until the function
|
| 3140 | * returns NULL. On completion of iteration, css_task_iter_end() must be
|
| 3141 | * called.
|
| 3142 | *
|
| 3143 | * Note that this function acquires a lock which is released when the
|
| 3144 | * iteration finishes. The caller can't sleep while iteration is in
|
| 3145 | * progress.
|
| 3146 |
|
| 3147 | void css_task_iter_start(struct cgroup_subsys_state *css,
|
| 3148 | struct css_task_iter *it)
|
| 3149 | __acquires(css_set_lock)
|
| 3150 | {
|
| 3151 | |
| 3152 | * The first time anyone tries to iterate across a css, we need to
|
| 3153 | * enable the list linking each css_set to its tasks, and fix up
|
| 3154 | * all existing tasks.
|
| 3155 |
|
| 3156 | if (!use_task_css_set_links)
|
| 3157 | cgroup_enable_task_cg_lists();
|
| 3158 |
|
| 3159 | read_lock(&css_set_lock);
|
| 3160 |
|
| 3161 | it->origin_css = css;
|
| 3162 | it->cset_link = &css->cgroup->cset_links;
|
| 3163 |
|
| 3164 | css_advance_task_iter(it);
|
| 3165 | }
|
| 3166 |
|
| 3167 | |
| 3168 | * css_task_iter_next - return the next task for the iterator
|
| 3169 | * @it: the task iterator being iterated
|
| 3170 | *
|
| 3171 | * The "next" function for task iteration. @it should have been
|
| 3172 | * initialized via css_task_iter_start(). Returns NULL when the iteration
|
| 3173 | * reaches the end.
|
| 3174 |
|
| 3175 | struct task_struct *css_task_iter_next(struct css_task_iter *it)
|
| 3176 | {
|
| 3177 | struct task_struct *res;
|
| 3178 | struct list_head *l = it->task;
|
| 3179 | struct cgrp_cset_link *link;
|
| 3180 |
|
| 3181 |
|
| 3182 | if (!it->cset_link)
|
| 3183 | return NULL;
|
| 3184 | res = list_entry(l, struct task_struct, cg_list);
|
| 3185 |
|
| 3186 | l = l->next;
|
| 3187 | link = list_entry(it->cset_link, struct cgrp_cset_link, cset_link);
|
| 3188 | if (l == &link->cset->tasks) {
|
| 3189 | |
| 3190 | * We reached the end of this task list - move on to the
|
| 3191 | * next cgrp_cset_link.
|
| 3192 |
|
| 3193 | css_advance_task_iter(it);
|
| 3194 | } else {
|
| 3195 | it->task = l;
|
| 3196 | }
|
| 3197 | return res;
|
| 3198 | }
|
| 3199 |
|
| 3200 | |
| 3201 | * css_task_iter_end - finish task iteration
|
| 3202 | * @it: the task iterator to finish
|
| 3203 | *
|
| 3204 | * Finish task iteration started by css_task_iter_start().
|
| 3205 |
|
| 3206 | void css_task_iter_end(struct css_task_iter *it)
|
| 3207 | __releases(css_set_lock)
|
| 3208 | {
|
| 3209 | read_unlock(&css_set_lock);
|
| 3210 | }
|
| 3211 |
|
| 3212 | static inline int started_after_time(struct task_struct *t1,
|
| 3213 | struct timespec *time,
|
| 3214 | struct task_struct *t2)
|
| 3215 | {
|
| 3216 | int start_diff = timespec_compare(&t1->start_time, time);
|
| 3217 | if (start_diff > 0) {
|
| 3218 | return 1;
|
| 3219 | } else if (start_diff < 0) {
|
| 3220 | return 0;
|
| 3221 | } else {
|
| 3222 | |
| 3223 | * Arbitrarily, if two processes started at the same
|
| 3224 | * time, we'll say that the lower pointer value
|
| 3225 | * started first. Note that t2 may have exited by now
|
| 3226 | * so this may not be a valid pointer any longer, but
|
| 3227 | * that's fine - it still serves to distinguish
|
| 3228 | * between two tasks started (effectively) simultaneously.
|
| 3229 |
|
| 3230 | return t1 > t2;
|
| 3231 | }
|
| 3232 | }
|
| 3233 |
|
| 3234 | |
| 3235 | * This function is a callback from heap_insert() and is used to order
|
| 3236 | * the heap.
|
| 3237 | * In this case we order the heap in descending task start time.
|
| 3238 |
|
| 3239 | static inline int started_after(void *p1, void *p2)
|
| 3240 | {
|
| 3241 | struct task_struct *t1 = p1;
|
| 3242 | struct task_struct *t2 = p2;
|
| 3243 | return started_after_time(t1, &t2->start_time, t2);
|
| 3244 | }
|
| 3245 |
|
| 3246 | |
| 3247 | * css_scan_tasks - iterate though all the tasks in a css
|
| 3248 | * @css: the css to iterate tasks of
|
| 3249 | * @test: optional test callback
|
| 3250 | * @process: process callback
|
| 3251 | * @data: data passed to @test and @process
|
| 3252 | * @heap: optional pre-allocated heap used for task iteration
|
| 3253 | *
|
| 3254 | * Iterate through all the tasks in @css, calling @test for each, and if it
|
| 3255 | * returns %true, call @process for it also.
|
| 3256 | *
|
| 3257 | * @test may be NULL, meaning always true (select all tasks), which
|
| 3258 | * effectively duplicates css_task_iter_{start,next,end}() but does not
|
| 3259 | * lock css_set_lock for the call to @process.
|
| 3260 | *
|
| 3261 | * It is guaranteed that @process will act on every task that is a member
|
| 3262 | * of @css for the duration of this call. This function may or may not
|
| 3263 | * call @process for tasks that exit or move to a different css during the
|
| 3264 | * call, or are forked or move into the css during the call.
|
| 3265 | *
|
| 3266 | * Note that @test may be called with locks held, and may in some
|
| 3267 | * situations be called multiple times for the same task, so it should be
|
| 3268 | * cheap.
|
| 3269 | *
|
| 3270 | * If @heap is non-NULL, a heap has been pre-allocated and will be used for
|
| 3271 | * heap operations (and its "gt" member will be overwritten), else a
|
| 3272 | * temporary heap will be used (allocation of which may cause this function
|
| 3273 | * to fail).
|
| 3274 |
|
| 3275 | int css_scan_tasks(struct cgroup_subsys_state *css,
|
| 3276 | bool (*test)(struct task_struct *, void *),
|
| 3277 | void (*process)(struct task_struct *, void *),
|
| 3278 | void *data, struct ptr_heap *heap)
|
| 3279 | {
|
| 3280 | int retval, i;
|
| 3281 | struct css_task_iter it;
|
| 3282 | struct task_struct *p, *dropped;
|
| 3283 |
|
| 3284 | struct task_struct *latest_task = NULL;
|
| 3285 | struct ptr_heap tmp_heap;
|
| 3286 | struct timespec latest_time = { 0, 0 };
|
| 3287 |
|
| 3288 | if (heap) {
|
| 3289 |
|
| 3290 | heap->gt = &started_after;
|
| 3291 | } else {
|
| 3292 |
|
| 3293 | heap = &tmp_heap;
|
| 3294 | retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after);
|
| 3295 | if (retval)
|
| 3296 |
|
| 3297 | return retval;
|
| 3298 | }
|
| 3299 |
|
| 3300 | again:
|
| 3301 | |
| 3302 | * Scan tasks in the css, using the @test callback to determine
|
| 3303 | * which are of interest, and invoking @process callback on the
|
| 3304 | * ones which need an update. Since we don't want to hold any
|
| 3305 | * locks during the task updates, gather tasks to be processed in a
|
| 3306 | * heap structure. The heap is sorted by descending task start
|
| 3307 | * time. If the statically-sized heap fills up, we overflow tasks
|
| 3308 | * that started later, and in future iterations only consider tasks
|
| 3309 | * that started after the latest task in the previous pass. This
|
| 3310 | * guarantees forward progress and that we don't miss any tasks.
|
| 3311 |
|
| 3312 | heap->size = 0;
|
| 3313 | css_task_iter_start(css, &it);
|
| 3314 | while ((p = css_task_iter_next(&it))) {
|
| 3315 | |
| 3316 | * Only affect tasks that qualify per the caller's callback,
|
| 3317 | * if he provided one
|
| 3318 |
|
| 3319 | if (test && !test(p, data))
|
| 3320 | continue;
|
| 3321 | |
| 3322 | * Only process tasks that started after the last task
|
| 3323 | * we processed
|
| 3324 |
|
| 3325 | if (!started_after_time(p, &latest_time, latest_task))
|
| 3326 | continue;
|
| 3327 | dropped = heap_insert(heap, p);
|
| 3328 | if (dropped == NULL) {
|
| 3329 | |
| 3330 | * The new task was inserted; the heap wasn't
|
| 3331 | * previously full
|
| 3332 |
|
| 3333 | get_task_struct(p);
|
| 3334 | } else if (dropped != p) {
|
| 3335 | |
| 3336 | * The new task was inserted, and pushed out a
|
| 3337 | * different task
|
| 3338 |
|
| 3339 | get_task_struct(p);
|
| 3340 | put_task_struct(dropped);
|
| 3341 | }
|
| 3342 | |
| 3343 | * Else the new task was newer than anything already in
|
| 3344 | * the heap and wasn't inserted
|
| 3345 |
|
| 3346 | }
|
| 3347 | css_task_iter_end(&it);
|
| 3348 |
|
| 3349 | if (heap->size) {
|
| 3350 | for (i = 0; i < heap->size; i++) {
|
| 3351 | struct task_struct *q = heap->ptrs[i];
|
| 3352 | if (i == 0) {
|
| 3353 | latest_time = q->start_time;
|
| 3354 | latest_task = q;
|
| 3355 | }
|
| 3356 |
|
| 3357 | process(q, data);
|
| 3358 | put_task_struct(q);
|
| 3359 | }
|
| 3360 | |
| 3361 | * If we had to process any tasks at all, scan again
|
| 3362 | * in case some of them were in the middle of forking
|
| 3363 | * children that didn't get processed.
|
| 3364 | * Not the most efficient way to do it, but it avoids
|
| 3365 | * having to take callback_mutex in the fork path
|
| 3366 |
|
| 3367 | goto again;
|
| 3368 | }
|
| 3369 | if (heap == &tmp_heap)
|
| 3370 | heap_free(&tmp_heap);
|
| 3371 | return 0;
|
| 3372 | }
|
| 3373 |
|
| 3374 | static void cgroup_transfer_one_task(struct task_struct *task, void *data)
|
| 3375 | {
|
| 3376 | struct cgroup *new_cgroup = data;
|
| 3377 |
|
| 3378 | mutex_lock(&cgroup_mutex);
|
| 3379 | cgroup_attach_task(new_cgroup, task, false);
|
| 3380 | mutex_unlock(&cgroup_mutex);
|
| 3381 | }
|
| 3382 |
|
| 3383 | |
| 3384 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
|
| 3385 | * @to: cgroup to which the tasks will be moved
|
| 3386 | * @from: cgroup in which the tasks currently reside
|
| 3387 |
|
| 3388 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
|
| 3389 | {
|
| 3390 | return css_scan_tasks(&from->dummy_css, NULL, cgroup_transfer_one_task,
|
| 3391 | to, NULL);
|
| 3392 | }
|
| 3393 |
|
| 3394 | |
| 3395 | * Stuff for reading the 'tasks'/'procs' files.
|
| 3396 | *
|
| 3397 | * Reading this file can return large amounts of data if a cgroup has
|
| 3398 | * *lots* of attached tasks. So it may need several calls to read(),
|
| 3399 | * but we cannot guarantee that the information we produce is correct
|
| 3400 | * unless we produce it entirely atomically.
|
| 3401 | *
|
| 3402 |
|
| 3403 |
|
| 3404 |
|
| 3405 | enum cgroup_filetype {
|
| 3406 | CGROUP_FILE_PROCS,
|
| 3407 | CGROUP_FILE_TASKS,
|
| 3408 | };
|
| 3409 |
|
| 3410 | |
| 3411 | * A pidlist is a list of pids that virtually represents the contents of one
|
| 3412 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
|
| 3413 | * a pair (one each for procs, tasks) for each pid namespace that's relevant
|
| 3414 | * to the cgroup.
|
| 3415 |
|
| 3416 | struct cgroup_pidlist {
|
| 3417 | |
| 3418 | * used to find which pidlist is wanted. doesn't change as long as
|
| 3419 | * this particular list stays in the list.
|
| 3420 |
|
| 3421 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
|
| 3422 |
|
| 3423 | pid_t *list;
|
| 3424 |
|
| 3425 | int length;
|
| 3426 |
|
| 3427 | struct list_head links;
|
| 3428 |
|
| 3429 | struct cgroup *owner;
|
| 3430 |
|
| 3431 | struct delayed_work destroy_dwork;
|
| 3432 | };
|
| 3433 |
|
| 3434 | |
| 3435 | * The following two functions "fix" the issue where there are more pids
|
| 3436 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
|
| 3437 | * TODO: replace with a kernel-wide solution to this problem
|
| 3438 |
|
| 3439 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
|
| 3440 | static void *pidlist_allocate(int count)
|
| 3441 | {
|
| 3442 | if (PIDLIST_TOO_LARGE(count))
|
| 3443 | return vmalloc(count * sizeof(pid_t));
|
| 3444 | else
|
| 3445 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
|
| 3446 | }
|
| 3447 |
|
| 3448 | static void pidlist_free(void *p)
|
| 3449 | {
|
| 3450 | if (is_vmalloc_addr(p))
|
| 3451 | vfree(p);
|
| 3452 | else
|
| 3453 | kfree(p);
|
| 3454 | }
|
| 3455 |
|
| 3456 | |
| 3457 | * Used to destroy all pidlists lingering waiting for destroy timer. None
|
| 3458 | * should be left afterwards.
|
| 3459 |
|
| 3460 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp)
|
| 3461 | {
|
| 3462 | struct cgroup_pidlist *l, *tmp_l;
|
| 3463 |
|
| 3464 | mutex_lock(&cgrp->pidlist_mutex);
|
| 3465 | list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
|
| 3466 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
|
| 3467 | mutex_unlock(&cgrp->pidlist_mutex);
|
| 3468 |
|
| 3469 | flush_workqueue(cgroup_pidlist_destroy_wq);
|
| 3470 | BUG_ON(!list_empty(&cgrp->pidlists));
|
| 3471 | }
|
| 3472 |
|
| 3473 | static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
|
| 3474 | {
|
| 3475 | struct delayed_work *dwork = to_delayed_work(work);
|
| 3476 | struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
|
| 3477 | destroy_dwork);
|
| 3478 | struct cgroup_pidlist *tofree = NULL;
|
| 3479 |
|
| 3480 | mutex_lock(&l->owner->pidlist_mutex);
|
| 3481 |
|
| 3482 | |
| 3483 | * Destroy iff we didn't get queued again. The state won't change
|
| 3484 | * as destroy_dwork can only be queued while locked.
|
| 3485 |
|
| 3486 | if (!delayed_work_pending(dwork)) {
|
| 3487 | list_del(&l->links);
|
| 3488 | pidlist_free(l->list);
|
| 3489 | put_pid_ns(l->key.ns);
|
| 3490 | tofree = l;
|
| 3491 | }
|
| 3492 |
|
| 3493 | mutex_unlock(&l->owner->pidlist_mutex);
|
| 3494 | kfree(tofree);
|
| 3495 | }
|
| 3496 |
|
| 3497 | |
| 3498 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
|
| 3499 | * Returns the number of unique elements.
|
| 3500 |
|
| 3501 | static int pidlist_uniq(pid_t *list, int length)
|
| 3502 | {
|
| 3503 | int src, dest = 1;
|
| 3504 |
|
| 3505 | |
| 3506 | * we presume the 0th element is unique, so i starts at 1. trivial
|
| 3507 | * edge cases first; no work needs to be done for either
|
| 3508 |
|
| 3509 | if (length == 0 || length == 1)
|
| 3510 | return length;
|
| 3511 |
|
| 3512 | for (src = 1; src < length; src++) {
|
| 3513 |
|
| 3514 | while (list[src] == list[src-1]) {
|
| 3515 | src++;
|
| 3516 | if (src == length)
|
| 3517 | goto after;
|
| 3518 | }
|
| 3519 |
|
| 3520 | list[dest] = list[src];
|
| 3521 | dest++;
|
| 3522 | }
|
| 3523 | after:
|
| 3524 | return dest;
|
| 3525 | }
|
| 3526 |
|
| 3527 | |
| 3528 | * The two pid files - task and cgroup.procs - guaranteed that the result
|
| 3529 | * is sorted, which forced this whole pidlist fiasco. As pid order is
|
| 3530 | * different per namespace, each namespace needs differently sorted list,
|
| 3531 | * making it impossible to use, for example, single rbtree of member tasks
|
| 3532 | * sorted by task pointer. As pidlists can be fairly large, allocating one
|
| 3533 | * per open file is dangerous, so cgroup had to implement shared pool of
|
| 3534 | * pidlists keyed by cgroup and namespace.
|
| 3535 | *
|
| 3536 | * All this extra complexity was caused by the original implementation
|
| 3537 | * committing to an entirely unnecessary property. In the long term, we
|
| 3538 | * want to do away with it. Explicitly scramble sort order if
|
| 3539 | * sane_behavior so that no such expectation exists in the new interface.
|
| 3540 | *
|
| 3541 | * Scrambling is done by swapping every two consecutive bits, which is
|
| 3542 | * non-identity one-to-one mapping which disturbs sort order sufficiently.
|
| 3543 |
|
| 3544 | static pid_t pid_fry(pid_t pid)
|
| 3545 | {
|
| 3546 | unsigned a = pid & 0x55555555;
|
| 3547 | unsigned b = pid & 0xAAAAAAAA;
|
| 3548 |
|
| 3549 | return (a << 1) | (b >> 1);
|
| 3550 | }
|
| 3551 |
|
| 3552 | static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid)
|
| 3553 | {
|
| 3554 | if (cgroup_sane_behavior(cgrp))
|
| 3555 | return pid_fry(pid);
|
| 3556 | else
|
| 3557 | return pid;
|
| 3558 | }
|
| 3559 |
|
| 3560 | static int cmppid(const void *a, const void *b)
|
| 3561 | {
|
| 3562 | return *(pid_t *)a - *(pid_t *)b;
|
| 3563 | }
|
| 3564 |
|
| 3565 | static int fried_cmppid(const void *a, const void *b)
|
| 3566 | {
|
| 3567 | return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b);
|
| 3568 | }
|
| 3569 |
|
| 3570 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
|
| 3571 | enum cgroup_filetype type)
|
| 3572 | {
|
| 3573 | struct cgroup_pidlist *l;
|
| 3574 |
|
| 3575 | struct pid_namespace *ns = task_active_pid_ns(current);
|
| 3576 |
|
| 3577 | lockdep_assert_held(&cgrp->pidlist_mutex);
|
| 3578 |
|
| 3579 | list_for_each_entry(l, &cgrp->pidlists, links)
|
| 3580 | if (l->key.type == type && l->key.ns == ns)
|
| 3581 | return l;
|
| 3582 | return NULL;
|
| 3583 | }
|
| 3584 |
|
| 3585 | |
| 3586 | * find the appropriate pidlist for our purpose (given procs vs tasks)
|
| 3587 | * returns with the lock on that pidlist already held, and takes care
|
| 3588 | * of the use count, or returns NULL with no locks held if we're out of
|
| 3589 | * memory.
|
| 3590 |
|
| 3591 | static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
|
| 3592 | enum cgroup_filetype type)
|
| 3593 | {
|
| 3594 | struct cgroup_pidlist *l;
|
| 3595 |
|
| 3596 | lockdep_assert_held(&cgrp->pidlist_mutex);
|
| 3597 |
|
| 3598 | l = cgroup_pidlist_find(cgrp, type);
|
| 3599 | if (l)
|
| 3600 | return l;
|
| 3601 |
|
| 3602 |
|
| 3603 | l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
|
| 3604 | if (!l)
|
| 3605 | return l;
|
| 3606 |
|
| 3607 | INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
|
| 3608 | l->key.type = type;
|
| 3609 |
|
| 3610 | l->key.ns = get_pid_ns(task_active_pid_ns(current));
|
| 3611 | l->owner = cgrp;
|
| 3612 | list_add(&l->links, &cgrp->pidlists);
|
| 3613 | return l;
|
| 3614 | }
|
| 3615 |
|
| 3616 | |
| 3617 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids
|
| 3618 |
|
| 3619 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
|
| 3620 | struct cgroup_pidlist **lp)
|
| 3621 | {
|
| 3622 | pid_t *array;
|
| 3623 | int length;
|
| 3624 | int pid, n = 0;
|
| 3625 | struct css_task_iter it;
|
| 3626 | struct task_struct *tsk;
|
| 3627 | struct cgroup_pidlist *l;
|
| 3628 |
|
| 3629 | lockdep_assert_held(&cgrp->pidlist_mutex);
|
| 3630 |
|
| 3631 | |
| 3632 | * If cgroup gets more users after we read count, we won't have
|
| 3633 | * enough space - tough. This race is indistinguishable to the
|
| 3634 | * caller from the case that the additional cgroup users didn't
|
| 3635 | * show up until sometime later on.
|
| 3636 |
|
| 3637 | length = cgroup_task_count(cgrp);
|
| 3638 | array = pidlist_allocate(length);
|
| 3639 | if (!array)
|
| 3640 | return -ENOMEM;
|
| 3641 |
|
| 3642 | css_task_iter_start(&cgrp->dummy_css, &it);
|
| 3643 | while ((tsk = css_task_iter_next(&it))) {
|
| 3644 | if (unlikely(n == length))
|
| 3645 | break;
|
| 3646 |
|
| 3647 | if (type == CGROUP_FILE_PROCS)
|
| 3648 | pid = task_tgid_vnr(tsk);
|
| 3649 | else
|
| 3650 | pid = task_pid_vnr(tsk);
|
| 3651 | if (pid > 0)
|
| 3652 | array[n++] = pid;
|
| 3653 | }
|
| 3654 | css_task_iter_end(&it);
|
| 3655 | length = n;
|
| 3656 |
|
| 3657 | if (cgroup_sane_behavior(cgrp))
|
| 3658 | sort(array, length, sizeof(pid_t), fried_cmppid, NULL);
|
| 3659 | else
|
| 3660 | sort(array, length, sizeof(pid_t), cmppid, NULL);
|
| 3661 | if (type == CGROUP_FILE_PROCS)
|
| 3662 | length = pidlist_uniq(array, length);
|
| 3663 |
|
| 3664 | l = cgroup_pidlist_find_create(cgrp, type);
|
| 3665 | if (!l) {
|
| 3666 | mutex_unlock(&cgrp->pidlist_mutex);
|
| 3667 | pidlist_free(array);
|
| 3668 | return -ENOMEM;
|
| 3669 | }
|
| 3670 |
|
| 3671 |
|
| 3672 | pidlist_free(l->list);
|
| 3673 | l->list = array;
|
| 3674 | l->length = length;
|
| 3675 | *lp = l;
|
| 3676 | return 0;
|
| 3677 | }
|
| 3678 |
|
| 3679 | |
| 3680 | * cgroupstats_build - build and fill cgroupstats
|
| 3681 | * @stats: cgroupstats to fill information into
|
| 3682 | * @dentry: A dentry entry belonging to the cgroup for which stats have
|
| 3683 | * been requested.
|
| 3684 | *
|
| 3685 | * Build and fill cgroupstats so that taskstats can export it to user
|
| 3686 | * space.
|
| 3687 |
|
| 3688 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
|
| 3689 | {
|
| 3690 | int ret = -EINVAL;
|
| 3691 | struct cgroup *cgrp;
|
| 3692 | struct css_task_iter it;
|
| 3693 | struct task_struct *tsk;
|
| 3694 |
|
| 3695 | |
| 3696 | * Validate dentry by checking the superblock operations,
|
| 3697 | * and make sure it's a directory.
|
| 3698 |
|
| 3699 | if (dentry->d_sb->s_op != &cgroup_ops ||
|
| 3700 | !S_ISDIR(dentry->d_inode->i_mode))
|
| 3701 | goto err;
|
| 3702 |
|
| 3703 | ret = 0;
|
| 3704 | cgrp = dentry->d_fsdata;
|
| 3705 |
|
| 3706 | css_task_iter_start(&cgrp->dummy_css, &it);
|
| 3707 | while ((tsk = css_task_iter_next(&it))) {
|
| 3708 | switch (tsk->state) {
|
| 3709 | case TASK_RUNNING:
|
| 3710 | stats->nr_running++;
|
| 3711 | break;
|
| 3712 | case TASK_INTERRUPTIBLE:
|
| 3713 | stats->nr_sleeping++;
|
| 3714 | break;
|
| 3715 | case TASK_UNINTERRUPTIBLE:
|
| 3716 | stats->nr_uninterruptible++;
|
| 3717 | break;
|
| 3718 | case TASK_STOPPED:
|
| 3719 | stats->nr_stopped++;
|
| 3720 | break;
|
| 3721 | default:
|
| 3722 | if (delayacct_is_task_waiting_on_io(tsk))
|
| 3723 | stats->nr_io_wait++;
|
| 3724 | break;
|
| 3725 | }
|
| 3726 | }
|
| 3727 | css_task_iter_end(&it);
|
| 3728 |
|
| 3729 | err:
|
| 3730 | return ret;
|
| 3731 | }
|
| 3732 |
|
| 3733 |
|
| 3734 | |
| 3735 | * seq_file methods for the tasks/procs files. The seq_file position is the
|
| 3736 | * next pid to display; the seq_file iterator is a pointer to the pid
|
| 3737 | * in the cgroup->l->list array.
|
| 3738 |
|
| 3739 |
|
| 3740 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
|
| 3741 | {
|
| 3742 | |
| 3743 | * Initially we receive a position value that corresponds to
|
| 3744 | * one more than the last pid shown (or 0 on the first call or
|
| 3745 | * after a seek to the start). Use a binary-search to find the
|
| 3746 | * next pid to display, if any
|
| 3747 |
|
| 3748 | struct cgroup_open_file *of = s->private;
|
| 3749 | struct cgroup *cgrp = seq_css(s)->cgroup;
|
| 3750 | struct cgroup_pidlist *l;
|
| 3751 | enum cgroup_filetype type = seq_cft(s)->private;
|
| 3752 | int index = 0, pid = *pos;
|
| 3753 | int *iter, ret;
|
| 3754 |
|
| 3755 | mutex_lock(&cgrp->pidlist_mutex);
|
| 3756 |
|
| 3757 | |
| 3758 | * !NULL @of->priv indicates that this isn't the first start()
|
| 3759 | * after open. If the matching pidlist is around, we can use that.
|
| 3760 | * Look for it. Note that @of->priv can't be used directly. It
|
| 3761 | * could already have been destroyed.
|
| 3762 |
|
| 3763 | if (of->priv)
|
| 3764 | of->priv = cgroup_pidlist_find(cgrp, type);
|
| 3765 |
|
| 3766 | |
| 3767 | * Either this is the first start() after open or the matching
|
| 3768 | * pidlist has been destroyed inbetween. Create a new one.
|
| 3769 |
|
| 3770 | if (!of->priv) {
|
| 3771 | ret = pidlist_array_load(cgrp, type,
|
| 3772 | (struct cgroup_pidlist **)&of->priv);
|
| 3773 | if (ret)
|
| 3774 | return ERR_PTR(ret);
|
| 3775 | }
|
| 3776 | l = of->priv;
|
| 3777 |
|
| 3778 | if (pid) {
|
| 3779 | int end = l->length;
|
| 3780 |
|
| 3781 | while (index < end) {
|
| 3782 | int mid = (index + end) / 2;
|
| 3783 | if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) {
|
| 3784 | index = mid;
|
| 3785 | break;
|
| 3786 | } else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid)
|
| 3787 | index = mid + 1;
|
| 3788 | else
|
| 3789 | end = mid;
|
| 3790 | }
|
| 3791 | }
|
| 3792 |
|
| 3793 | if (index >= l->length)
|
| 3794 | return NULL;
|
| 3795 |
|
| 3796 | iter = l->list + index;
|
| 3797 | *pos = cgroup_pid_fry(cgrp, *iter);
|
| 3798 | return iter;
|
| 3799 | }
|
| 3800 |
|
| 3801 | static void cgroup_pidlist_stop(struct seq_file *s, void *v)
|
| 3802 | {
|
| 3803 | struct cgroup_open_file *of = s->private;
|
| 3804 | struct cgroup_pidlist *l = of->priv;
|
| 3805 |
|
| 3806 | if (l)
|
| 3807 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
|
| 3808 | CGROUP_PIDLIST_DESTROY_DELAY);
|
| 3809 | mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
|
| 3810 | }
|
| 3811 |
|
| 3812 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
|
| 3813 | {
|
| 3814 | struct cgroup_open_file *of = s->private;
|
| 3815 | struct cgroup_pidlist *l = of->priv;
|
| 3816 | pid_t *p = v;
|
| 3817 | pid_t *end = l->list + l->length;
|
| 3818 | |
| 3819 | * Advance to the next pid in the array. If this goes off the
|
| 3820 | * end, we're done
|
| 3821 |
|
| 3822 | p++;
|
| 3823 | if (p >= end) {
|
| 3824 | return NULL;
|
| 3825 | } else {
|
| 3826 | *pos = cgroup_pid_fry(seq_css(s)->cgroup, *p);
|
| 3827 | return p;
|
| 3828 | }
|
| 3829 | }
|
| 3830 |
|
| 3831 | static int cgroup_pidlist_show(struct seq_file *s, void *v)
|
| 3832 | {
|
| 3833 | return seq_printf(s, "%d\n", *(int *)v);
|
| 3834 | }
|
| 3835 |
|
| 3836 | |
| 3837 | * seq_operations functions for iterating on pidlists through seq_file -
|
| 3838 | * independent of whether it's tasks or procs
|
| 3839 |
|
| 3840 | static const struct seq_operations cgroup_pidlist_seq_operations = {
|
| 3841 | .start = cgroup_pidlist_start,
|
| 3842 | .stop = cgroup_pidlist_stop,
|
| 3843 | .next = cgroup_pidlist_next,
|
| 3844 | .show = cgroup_pidlist_show,
|
| 3845 | };
|
| 3846 |
|
| 3847 | static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
|
| 3848 | struct cftype *cft)
|
| 3849 | {
|
| 3850 | return notify_on_release(css->cgroup);
|
| 3851 | }
|
| 3852 |
|
| 3853 | static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
|
| 3854 | struct cftype *cft, u64 val)
|
| 3855 | {
|
| 3856 | clear_bit(CGRP_RELEASABLE, &css->cgroup->flags);
|
| 3857 | if (val)
|
| 3858 | set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
|
| 3859 | else
|
| 3860 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
|
| 3861 | return 0;
|
| 3862 | }
|
| 3863 |
|
| 3864 | |
| 3865 | * When dput() is called asynchronously, if umount has been done and
|
| 3866 | * then deactivate_super() in cgroup_free_fn() kills the superblock,
|
| 3867 | * there's a small window that vfs will see the root dentry with non-zero
|
| 3868 | * refcnt and trigger BUG().
|
| 3869 | *
|
| 3870 | * That's why we hold a reference before dput() and drop it right after.
|
| 3871 |
|
| 3872 | static void cgroup_dput(struct cgroup *cgrp)
|
| 3873 | {
|
| 3874 | struct super_block *sb = cgrp->root->sb;
|
| 3875 |
|
| 3876 | atomic_inc(&sb->s_active);
|
| 3877 | dput(cgrp->dentry);
|
| 3878 | deactivate_super(sb);
|
| 3879 | }
|
| 3880 |
|
| 3881 | static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
|
| 3882 | struct cftype *cft)
|
| 3883 | {
|
| 3884 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
| 3885 | }
|
| 3886 |
|
| 3887 | static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
|
| 3888 | struct cftype *cft, u64 val)
|
| 3889 | {
|
| 3890 | if (val)
|
| 3891 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
| 3892 | else
|
| 3893 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
| 3894 | return 0;
|
| 3895 | }
|
| 3896 |
|
| 3897 | static struct cftype cgroup_base_files[] = {
|
| 3898 | {
|
| 3899 | .name = "cgroup.procs",
|
| 3900 | .seq_start = cgroup_pidlist_start,
|
| 3901 | .seq_next = cgroup_pidlist_next,
|
| 3902 | .seq_stop = cgroup_pidlist_stop,
|
| 3903 | .seq_show = cgroup_pidlist_show,
|
| 3904 | .private = CGROUP_FILE_PROCS,
|
| 3905 | .write_u64 = cgroup_procs_write,
|
| 3906 | .mode = S_IRUGO | S_IWUSR,
|
| 3907 | },
|
| 3908 | {
|
| 3909 | .name = "cgroup.clone_children",
|
| 3910 | .flags = CFTYPE_INSANE,
|
| 3911 | .read_u64 = cgroup_clone_children_read,
|
| 3912 | .write_u64 = cgroup_clone_children_write,
|
| 3913 | },
|
| 3914 | {
|
| 3915 | .name = "cgroup.sane_behavior",
|
| 3916 | .flags = CFTYPE_ONLY_ON_ROOT,
|
| 3917 | .seq_show = cgroup_sane_behavior_show,
|
| 3918 | },
|
| 3919 |
|
| 3920 | |
| 3921 | * Historical crazy stuff. These don't have "cgroup." prefix and
|
| 3922 | * don't exist if sane_behavior. If you're depending on these, be
|
| 3923 | * prepared to be burned.
|
| 3924 |
|
| 3925 | {
|
| 3926 | .name = "tasks",
|
| 3927 | .flags = CFTYPE_INSANE,
|
| 3928 | .seq_start = cgroup_pidlist_start,
|
| 3929 | .seq_next = cgroup_pidlist_next,
|
| 3930 | .seq_stop = cgroup_pidlist_stop,
|
| 3931 | .seq_show = cgroup_pidlist_show,
|
| 3932 | .private = CGROUP_FILE_TASKS,
|
| 3933 | .write_u64 = cgroup_tasks_write,
|
| 3934 | .mode = S_IRUGO | S_IWUSR,
|
| 3935 | },
|
| 3936 | {
|
| 3937 | .name = "notify_on_release",
|
| 3938 | .flags = CFTYPE_INSANE,
|
| 3939 | .read_u64 = cgroup_read_notify_on_release,
|
| 3940 | .write_u64 = cgroup_write_notify_on_release,
|
| 3941 | },
|
| 3942 | {
|
| 3943 | .name = "release_agent",
|
| 3944 | .flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT,
|
| 3945 | .seq_show = cgroup_release_agent_show,
|
| 3946 | .write_string = cgroup_release_agent_write,
|
| 3947 | .max_write_len = PATH_MAX,
|
| 3948 | },
|
| 3949 | { }
|
| 3950 | };
|
| 3951 |
|
| 3952 | |
| 3953 | * cgroup_populate_dir - create subsys files in a cgroup directory
|
| 3954 | * @cgrp: target cgroup
|
| 3955 | * @subsys_mask: mask of the subsystem ids whose files should be added
|
| 3956 | *
|
| 3957 | * On failure, no file is added.
|
| 3958 |
|
| 3959 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask)
|
| 3960 | {
|
| 3961 | struct cgroup_subsys *ss;
|
| 3962 | int i, ret = 0;
|
| 3963 |
|
| 3964 |
|
| 3965 | for_each_subsys(ss, i) {
|
| 3966 | struct cftype_set *set;
|
| 3967 |
|
| 3968 | if (!test_bit(i, &subsys_mask))
|
| 3969 | continue;
|
| 3970 |
|
| 3971 | list_for_each_entry(set, &ss->cftsets, node) {
|
| 3972 | ret = cgroup_addrm_files(cgrp, set->cfts, true);
|
| 3973 | if (ret < 0)
|
| 3974 | goto err;
|
| 3975 | }
|
| 3976 | }
|
| 3977 | return 0;
|
| 3978 | err:
|
| 3979 | cgroup_clear_dir(cgrp, subsys_mask);
|
| 3980 | return ret;
|
| 3981 | }
|
| 3982 |
|
| 3983 | |
| 3984 | * css destruction is four-stage process.
|
| 3985 | *
|
| 3986 | * 1. Destruction starts. Killing of the percpu_ref is initiated.
|
| 3987 | * Implemented in kill_css().
|
| 3988 | *
|
| 3989 | * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
|
| 3990 | * and thus css_tryget() is guaranteed to fail, the css can be offlined
|
| 3991 | * by invoking offline_css(). After offlining, the base ref is put.
|
| 3992 | * Implemented in css_killed_work_fn().
|
| 3993 | *
|
| 3994 | * 3. When the percpu_ref reaches zero, the only possible remaining
|
| 3995 | * accessors are inside RCU read sections. css_release() schedules the
|
| 3996 | * RCU callback.
|
| 3997 | *
|
| 3998 | * 4. After the grace period, the css can be freed. Implemented in
|
| 3999 | * css_free_work_fn().
|
| 4000 | *
|
| 4001 | * It is actually hairier because both step 2 and 4 require process context
|
| 4002 | * and thus involve punting to css->destroy_work adding two additional
|
| 4003 | * steps to the already complex sequence.
|
| 4004 |
|
| 4005 | static void css_free_work_fn(struct work_struct *work)
|
| 4006 | {
|
| 4007 | struct cgroup_subsys_state *css =
|
| 4008 | container_of(work, struct cgroup_subsys_state, destroy_work);
|
| 4009 | struct cgroup *cgrp = css->cgroup;
|
| 4010 |
|
| 4011 | if (css->parent)
|
| 4012 | css_put(css->parent);
|
| 4013 |
|
| 4014 | css->ss->css_free(css);
|
| 4015 | cgroup_dput(cgrp);
|
| 4016 | }
|
| 4017 |
|
| 4018 | static void css_free_rcu_fn(struct rcu_head *rcu_head)
|
| 4019 | {
|
| 4020 | struct cgroup_subsys_state *css =
|
| 4021 | container_of(rcu_head, struct cgroup_subsys_state, rcu_head);
|
| 4022 |
|
| 4023 | |
| 4024 | * css holds an extra ref to @cgrp->dentry which is put on the last
|
| 4025 | * css_put(). dput() requires process context which we don't have.
|
| 4026 |
|
| 4027 | INIT_WORK(&css->destroy_work, css_free_work_fn);
|
| 4028 | queue_work(cgroup_destroy_wq, &css->destroy_work);
|
| 4029 | }
|
| 4030 |
|
| 4031 | static void css_release(struct percpu_ref *ref)
|
| 4032 | {
|
| 4033 | struct cgroup_subsys_state *css =
|
| 4034 | container_of(ref, struct cgroup_subsys_state, refcnt);
|
| 4035 |
|
| 4036 | rcu_assign_pointer(css->cgroup->subsys[css->ss->subsys_id], NULL);
|
| 4037 | call_rcu(&css->rcu_head, css_free_rcu_fn);
|
| 4038 | }
|
| 4039 |
|
| 4040 | static void init_css(struct cgroup_subsys_state *css, struct cgroup_subsys *ss,
|
| 4041 | struct cgroup *cgrp)
|
| 4042 | {
|
| 4043 | css->cgroup = cgrp;
|
| 4044 | css->ss = ss;
|
| 4045 | css->flags = 0;
|
| 4046 |
|
| 4047 | if (cgrp->parent)
|
| 4048 | css->parent = cgroup_css(cgrp->parent, ss);
|
| 4049 | else
|
| 4050 | css->flags |= CSS_ROOT;
|
| 4051 |
|
| 4052 | BUG_ON(cgroup_css(cgrp, ss));
|
| 4053 | }
|
| 4054 |
|
| 4055 |
|
| 4056 | static int online_css(struct cgroup_subsys_state *css)
|
| 4057 | {
|
| 4058 | struct cgroup_subsys *ss = css->ss;
|
| 4059 | int ret = 0;
|
| 4060 |
|
| 4061 | lockdep_assert_held(&cgroup_mutex);
|
| 4062 |
|
| 4063 | if (ss->css_online)
|
| 4064 | ret = ss->css_online(css);
|
| 4065 | if (!ret) {
|
| 4066 | css->flags |= CSS_ONLINE;
|
| 4067 | css->cgroup->nr_css++;
|
| 4068 | rcu_assign_pointer(css->cgroup->subsys[ss->subsys_id], css);
|
| 4069 | }
|
| 4070 | return ret;
|
| 4071 | }
|
| 4072 |
|
| 4073 |
|
| 4074 | static void offline_css(struct cgroup_subsys_state *css)
|
| 4075 | {
|
| 4076 | struct cgroup_subsys *ss = css->ss;
|
| 4077 |
|
| 4078 | lockdep_assert_held(&cgroup_mutex);
|
| 4079 |
|
| 4080 | if (!(css->flags & CSS_ONLINE))
|
| 4081 | return;
|
| 4082 |
|
| 4083 | if (ss->css_offline)
|
| 4084 | ss->css_offline(css);
|
| 4085 |
|
| 4086 | css->flags &= ~CSS_ONLINE;
|
| 4087 | css->cgroup->nr_css--;
|
| 4088 | RCU_INIT_POINTER(css->cgroup->subsys[ss->subsys_id], css);
|
| 4089 | }
|
| 4090 |
|
| 4091 | |
| 4092 | * create_css - create a cgroup_subsys_state
|
| 4093 | * @cgrp: the cgroup new css will be associated with
|
| 4094 | * @ss: the subsys of new css
|
| 4095 | *
|
| 4096 | * Create a new css associated with @cgrp - @ss pair. On success, the new
|
| 4097 | * css is online and installed in @cgrp with all interface files created.
|
| 4098 | * Returns 0 on success, -errno on failure.
|
| 4099 |
|
| 4100 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss)
|
| 4101 | {
|
| 4102 | struct cgroup *parent = cgrp->parent;
|
| 4103 | struct cgroup_subsys_state *css;
|
| 4104 | int err;
|
| 4105 |
|
| 4106 | lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
|
| 4107 | lockdep_assert_held(&cgroup_mutex);
|
| 4108 |
|
| 4109 | css = ss->css_alloc(cgroup_css(parent, ss));
|
| 4110 | if (IS_ERR(css))
|
| 4111 | return PTR_ERR(css);
|
| 4112 |
|
| 4113 | err = percpu_ref_init(&css->refcnt, css_release);
|
| 4114 | if (err)
|
| 4115 | goto err_free;
|
| 4116 |
|
| 4117 | init_css(css, ss, cgrp);
|
| 4118 |
|
| 4119 | err = cgroup_populate_dir(cgrp, 1 << ss->subsys_id);
|
| 4120 | if (err)
|
| 4121 | goto err_free;
|
| 4122 |
|
| 4123 | err = online_css(css);
|
| 4124 | if (err)
|
| 4125 | goto err_free;
|
| 4126 |
|
| 4127 | dget(cgrp->dentry);
|
| 4128 | css_get(css->parent);
|
| 4129 |
|
| 4130 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
|
| 4131 | parent->parent) {
|
| 4132 | pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
|
| 4133 | current->comm, current->pid, ss->name);
|
| 4134 | if (!strcmp(ss->name, "memory"))
|
| 4135 | pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
|
| 4136 | ss->warned_broken_hierarchy = true;
|
| 4137 | }
|
| 4138 |
|
| 4139 | return 0;
|
| 4140 |
|
| 4141 | err_free:
|
| 4142 | percpu_ref_cancel_init(&css->refcnt);
|
| 4143 | ss->css_free(css);
|
| 4144 | return err;
|
| 4145 | }
|
| 4146 |
|
| 4147 | |
| 4148 | * cgroup_create - create a cgroup
|
| 4149 | * @parent: cgroup that will be parent of the new cgroup
|
| 4150 | * @dentry: dentry of the new cgroup
|
| 4151 | * @mode: mode to set on new inode
|
| 4152 | *
|
| 4153 | * Must be called with the mutex on the parent inode held
|
| 4154 |
|
| 4155 | static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
|
| 4156 | umode_t mode)
|
| 4157 | {
|
| 4158 | struct cgroup *cgrp;
|
| 4159 | struct cgroup_name *name;
|
| 4160 | struct cgroupfs_root *root = parent->root;
|
| 4161 | int ssid, err;
|
| 4162 | struct cgroup_subsys *ss;
|
| 4163 | struct super_block *sb = root->sb;
|
| 4164 |
|
| 4165 |
|
| 4166 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
|
| 4167 | if (!cgrp)
|
| 4168 | return -ENOMEM;
|
| 4169 |
|
| 4170 | name = cgroup_alloc_name(dentry);
|
| 4171 | if (!name) {
|
| 4172 | err = -ENOMEM;
|
| 4173 | goto err_free_cgrp;
|
| 4174 | }
|
| 4175 | rcu_assign_pointer(cgrp->name, name);
|
| 4176 |
|
| 4177 | |
| 4178 | * Only live parents can have children. Note that the liveliness
|
| 4179 | * check isn't strictly necessary because cgroup_mkdir() and
|
| 4180 | * cgroup_rmdir() are fully synchronized by i_mutex; however, do it
|
| 4181 | * anyway so that locking is contained inside cgroup proper and we
|
| 4182 | * don't get nasty surprises if we ever grow another caller.
|
| 4183 |
|
| 4184 | if (!cgroup_lock_live_group(parent)) {
|
| 4185 | err = -ENODEV;
|
| 4186 | goto err_free_name;
|
| 4187 | }
|
| 4188 |
|
| 4189 | |
| 4190 | * Temporarily set the pointer to NULL, so idr_find() won't return
|
| 4191 | * a half-baked cgroup.
|
| 4192 |
|
| 4193 | cgrp->id = idr_alloc(&root->cgroup_idr, NULL, 1, 0, GFP_KERNEL);
|
| 4194 | if (cgrp->id < 0) {
|
| 4195 | err = -ENOMEM;
|
| 4196 | goto err_unlock;
|
| 4197 | }
|
| 4198 |
|
| 4199 | |
| 4200 | * get deleted on unmount if there are child cgroups. This
|
| 4201 | * can be done outside cgroup_mutex, since the sb can't
|
| 4202 | * disappear while someone has an open control file on the
|
| 4203 | * fs
|
| 4204 | atomic_inc(&sb->s_active);
|
| 4205 |
|
| 4206 | init_cgroup_housekeeping(cgrp);
|
| 4207 |
|
| 4208 | dentry->d_fsdata = cgrp;
|
| 4209 | cgrp->dentry = dentry;
|
| 4210 |
|
| 4211 | cgrp->parent = parent;
|
| 4212 | cgrp->dummy_css.parent = &parent->dummy_css;
|
| 4213 | cgrp->root = parent->root;
|
| 4214 |
|
| 4215 | if (notify_on_release(parent))
|
| 4216 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
|
| 4217 |
|
| 4218 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags))
|
| 4219 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
|
| 4220 |
|
| 4221 | |
| 4222 | * Create directory. cgroup_create_file() returns with the new
|
| 4223 | * directory locked on success so that it can be populated without
|
| 4224 | * dropping cgroup_mutex.
|
| 4225 |
|
| 4226 | err = cgroup_create_file(dentry, S_IFDIR | mode, sb);
|
| 4227 | if (err < 0)
|
| 4228 | goto err_free_id;
|
| 4229 | lockdep_assert_held(&dentry->d_inode->i_mutex);
|
| 4230 |
|
| 4231 | cgrp->serial_nr = cgroup_serial_nr_next++;
|
| 4232 |
|
| 4233 |
|
| 4234 | list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
|
| 4235 | root->number_of_cgroups++;
|
| 4236 |
|
| 4237 |
|
| 4238 | dget(parent->dentry);
|
| 4239 |
|
| 4240 | |
| 4241 | * @cgrp is now fully operational. If something fails after this
|
| 4242 | * point, it'll be released via the normal destruction path.
|
| 4243 |
|
| 4244 | idr_replace(&root->cgroup_idr, cgrp, cgrp->id);
|
| 4245 |
|
| 4246 | err = cgroup_addrm_files(cgrp, cgroup_base_files, true);
|
| 4247 | if (err)
|
| 4248 | goto err_destroy;
|
| 4249 |
|
| 4250 |
|
| 4251 | for_each_subsys(ss, ssid) {
|
| 4252 | if (root->subsys_mask & (1 << ssid)) {
|
| 4253 | err = create_css(cgrp, ss);
|
| 4254 | if (err)
|
| 4255 | goto err_destroy;
|
| 4256 | }
|
| 4257 | }
|
| 4258 |
|
| 4259 | mutex_unlock(&cgroup_mutex);
|
| 4260 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
|
| 4261 |
|
| 4262 | return 0;
|
| 4263 |
|
| 4264 | err_free_id:
|
| 4265 | idr_remove(&root->cgroup_idr, cgrp->id);
|
| 4266 |
|
| 4267 | deactivate_super(sb);
|
| 4268 | err_unlock:
|
| 4269 | mutex_unlock(&cgroup_mutex);
|
| 4270 | err_free_name:
|
| 4271 | kfree(rcu_dereference_raw(cgrp->name));
|
| 4272 | err_free_cgrp:
|
| 4273 | kfree(cgrp);
|
| 4274 | return err;
|
| 4275 |
|
| 4276 | err_destroy:
|
| 4277 | cgroup_destroy_locked(cgrp);
|
| 4278 | mutex_unlock(&cgroup_mutex);
|
| 4279 | mutex_unlock(&dentry->d_inode->i_mutex);
|
| 4280 | return err;
|
| 4281 | }
|
| 4282 |
|
| 4283 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
|
| 4284 | {
|
| 4285 | struct cgroup *c_parent = dentry->d_parent->d_fsdata;
|
| 4286 |
|
| 4287 |
|
| 4288 | return cgroup_create(c_parent, dentry, mode | S_IFDIR);
|
| 4289 | }
|
| 4290 |
|
| 4291 | |
| 4292 | * This is called when the refcnt of a css is confirmed to be killed.
|
| 4293 | * css_tryget() is now guaranteed to fail.
|
| 4294 |
|
| 4295 | static void css_killed_work_fn(struct work_struct *work)
|
| 4296 | {
|
| 4297 | struct cgroup_subsys_state *css =
|
| 4298 | container_of(work, struct cgroup_subsys_state, destroy_work);
|
| 4299 | struct cgroup *cgrp = css->cgroup;
|
| 4300 |
|
| 4301 | mutex_lock(&cgroup_mutex);
|
| 4302 |
|
| 4303 | |
| 4304 | * css_tryget() is guaranteed to fail now. Tell subsystems to
|
| 4305 | * initate destruction.
|
| 4306 |
|
| 4307 | offline_css(css);
|
| 4308 |
|
| 4309 | |
| 4310 | * If @cgrp is marked dead, it's waiting for refs of all css's to
|
| 4311 | * be disabled before proceeding to the second phase of cgroup
|
| 4312 | * destruction. If we are the last one, kick it off.
|
| 4313 |
|
| 4314 | if (!cgrp->nr_css && cgroup_is_dead(cgrp))
|
| 4315 | cgroup_destroy_css_killed(cgrp);
|
| 4316 |
|
| 4317 | mutex_unlock(&cgroup_mutex);
|
| 4318 |
|
| 4319 | |
| 4320 | * Put the css refs from kill_css(). Each css holds an extra
|
| 4321 | * reference to the cgroup's dentry and cgroup removal proceeds
|
| 4322 | * regardless of css refs. On the last put of each css, whenever
|
| 4323 | * that may be, the extra dentry ref is put so that dentry
|
| 4324 | * destruction happens only after all css's are released.
|
| 4325 |
|
| 4326 | css_put(css);
|
| 4327 | }
|
| 4328 |
|
| 4329 |
|
| 4330 | static void css_killed_ref_fn(struct percpu_ref *ref)
|
| 4331 | {
|
| 4332 | struct cgroup_subsys_state *css =
|
| 4333 | container_of(ref, struct cgroup_subsys_state, refcnt);
|
| 4334 |
|
| 4335 | INIT_WORK(&css->destroy_work, css_killed_work_fn);
|
| 4336 | queue_work(cgroup_destroy_wq, &css->destroy_work);
|
| 4337 | }
|
| 4338 |
|
| 4339 | |
| 4340 | * kill_css - destroy a css
|
| 4341 | * @css: css to destroy
|
| 4342 | *
|
| 4343 | * This function initiates destruction of @css by removing cgroup interface
|
| 4344 | * files and putting its base reference. ->css_offline() will be invoked
|
| 4345 | * asynchronously once css_tryget() is guaranteed to fail and when the
|
| 4346 | * reference count reaches zero, @css will be released.
|
| 4347 |
|
| 4348 | static void kill_css(struct cgroup_subsys_state *css)
|
| 4349 | {
|
| 4350 | cgroup_clear_dir(css->cgroup, 1 << css->ss->subsys_id);
|
| 4351 |
|
| 4352 | |
| 4353 | * Killing would put the base ref, but we need to keep it alive
|
| 4354 | * until after ->css_offline().
|
| 4355 |
|
| 4356 | css_get(css);
|
| 4357 |
|
| 4358 | |
| 4359 | * cgroup core guarantees that, by the time ->css_offline() is
|
| 4360 | * invoked, no new css reference will be given out via
|
| 4361 | * css_tryget(). We can't simply call percpu_ref_kill() and
|
| 4362 | * proceed to offlining css's because percpu_ref_kill() doesn't
|
| 4363 | * guarantee that the ref is seen as killed on all CPUs on return.
|
| 4364 | *
|
| 4365 | * Use percpu_ref_kill_and_confirm() to get notifications as each
|
| 4366 | * css is confirmed to be seen as killed on all CPUs.
|
| 4367 |
|
| 4368 | percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);
|
| 4369 | }
|
| 4370 |
|
| 4371 | |
| 4372 | * cgroup_destroy_locked - the first stage of cgroup destruction
|
| 4373 | * @cgrp: cgroup to be destroyed
|
| 4374 | *
|
| 4375 | * css's make use of percpu refcnts whose killing latency shouldn't be
|
| 4376 | * exposed to userland and are RCU protected. Also, cgroup core needs to
|
| 4377 | * guarantee that css_tryget() won't succeed by the time ->css_offline() is
|
| 4378 | * invoked. To satisfy all the requirements, destruction is implemented in
|
| 4379 | * the following two steps.
|
| 4380 | *
|
| 4381 | * s1. Verify @cgrp can be destroyed and mark it dying. Remove all
|
| 4382 | * userland visible parts and start killing the percpu refcnts of
|
| 4383 | * css's. Set up so that the next stage will be kicked off once all
|
| 4384 | * the percpu refcnts are confirmed to be killed.
|
| 4385 | *
|
| 4386 | * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
|
| 4387 | * rest of destruction. Once all cgroup references are gone, the
|
| 4388 | * cgroup is RCU-freed.
|
| 4389 | *
|
| 4390 | * This function implements s1. After this step, @cgrp is gone as far as
|
| 4391 | * the userland is concerned and a new cgroup with the same name may be
|
| 4392 | * created. As cgroup doesn't care about the names internally, this
|
| 4393 | * doesn't cause any problem.
|
| 4394 |
|
| 4395 | static int cgroup_destroy_locked(struct cgroup *cgrp)
|
| 4396 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex)
|
| 4397 | {
|
| 4398 | struct dentry *d = cgrp->dentry;
|
| 4399 | struct cgroup_subsys_state *css;
|
| 4400 | struct cgroup *child;
|
| 4401 | bool empty;
|
| 4402 | int ssid;
|
| 4403 |
|
| 4404 | lockdep_assert_held(&d->d_inode->i_mutex);
|
| 4405 | lockdep_assert_held(&cgroup_mutex);
|
| 4406 |
|
| 4407 | |
| 4408 | * css_set_lock synchronizes access to ->cset_links and prevents
|
| 4409 | * @cgrp from being removed while __put_css_set() is in progress.
|
| 4410 |
|
| 4411 | read_lock(&css_set_lock);
|
| 4412 | empty = list_empty(&cgrp->cset_links);
|
| 4413 | read_unlock(&css_set_lock);
|
| 4414 | if (!empty)
|
| 4415 | return -EBUSY;
|
| 4416 |
|
| 4417 | |
| 4418 | * Make sure there's no live children. We can't test ->children
|
| 4419 | * emptiness as dead children linger on it while being destroyed;
|
| 4420 | * otherwise, "rmdir parent/child parent" may fail with -EBUSY.
|
| 4421 |
|
| 4422 | empty = true;
|
| 4423 | rcu_read_lock();
|
| 4424 | list_for_each_entry_rcu(child, &cgrp->children, sibling) {
|
| 4425 | empty = cgroup_is_dead(child);
|
| 4426 | if (!empty)
|
| 4427 | break;
|
| 4428 | }
|
| 4429 | rcu_read_unlock();
|
| 4430 | if (!empty)
|
| 4431 | return -EBUSY;
|
| 4432 |
|
| 4433 | |
| 4434 | * Initiate massacre of all css's. cgroup_destroy_css_killed()
|
| 4435 | * will be invoked to perform the rest of destruction once the
|
| 4436 | * percpu refs of all css's are confirmed to be killed.
|
| 4437 |
|
| 4438 | for_each_css(css, ssid, cgrp)
|
| 4439 | kill_css(css);
|
| 4440 |
|
| 4441 | |
| 4442 | * Mark @cgrp dead. This prevents further task migration and child
|
| 4443 | * creation by disabling cgroup_lock_live_group(). Note that
|
| 4444 | * CGRP_DEAD assertion is depended upon by css_next_child() to
|
| 4445 | * resume iteration after dropping RCU read lock. See
|
| 4446 | * css_next_child() for details.
|
| 4447 |
|
| 4448 | set_bit(CGRP_DEAD, &cgrp->flags);
|
| 4449 |
|
| 4450 |
|
| 4451 | raw_spin_lock(&release_list_lock);
|
| 4452 | if (!list_empty(&cgrp->release_list))
|
| 4453 | list_del_init(&cgrp->release_list);
|
| 4454 | raw_spin_unlock(&release_list_lock);
|
| 4455 |
|
| 4456 | |
| 4457 | * If @cgrp has css's attached, the second stage of cgroup
|
| 4458 | * destruction is kicked off from css_killed_work_fn() after the
|
| 4459 | * refs of all attached css's are killed. If @cgrp doesn't have
|
| 4460 | * any css, we kick it off here.
|
| 4461 |
|
| 4462 | if (!cgrp->nr_css)
|
| 4463 | cgroup_destroy_css_killed(cgrp);
|
| 4464 |
|
| 4465 | |
| 4466 | * Clear the base files and remove @cgrp directory. The removal
|
| 4467 | * puts the base ref but we aren't quite done with @cgrp yet, so
|
| 4468 | * hold onto it.
|
| 4469 |
|
| 4470 | cgroup_addrm_files(cgrp, cgroup_base_files, false);
|
| 4471 | dget(d);
|
| 4472 | cgroup_d_remove_dir(d);
|
| 4473 |
|
| 4474 | return 0;
|
| 4475 | };
|
| 4476 |
|
| 4477 | |
| 4478 | * cgroup_destroy_css_killed - the second step of cgroup destruction
|
| 4479 | * @work: cgroup->destroy_free_work
|
| 4480 | *
|
| 4481 | * This function is invoked from a work item for a cgroup which is being
|
| 4482 | * destroyed after all css's are offlined and performs the rest of
|
| 4483 | * destruction. This is the second step of destruction described in the
|
| 4484 | * comment above cgroup_destroy_locked().
|
| 4485 |
|
| 4486 | static void cgroup_destroy_css_killed(struct cgroup *cgrp)
|
| 4487 | {
|
| 4488 | struct cgroup *parent = cgrp->parent;
|
| 4489 | struct dentry *d = cgrp->dentry;
|
| 4490 |
|
| 4491 | lockdep_assert_held(&cgroup_mutex);
|
| 4492 |
|
| 4493 |
|
| 4494 | list_del_rcu(&cgrp->sibling);
|
| 4495 |
|
| 4496 | dput(d);
|
| 4497 |
|
| 4498 | set_bit(CGRP_RELEASABLE, &parent->flags);
|
| 4499 | check_for_release(parent);
|
| 4500 | }
|
| 4501 |
|
| 4502 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
|
| 4503 | {
|
| 4504 | int ret;
|
| 4505 |
|
| 4506 | mutex_lock(&cgroup_mutex);
|
| 4507 | ret = cgroup_destroy_locked(dentry->d_fsdata);
|
| 4508 | mutex_unlock(&cgroup_mutex);
|
| 4509 |
|
| 4510 | return ret;
|
| 4511 | }
|
| 4512 |
|
| 4513 | static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss)
|
| 4514 | {
|
| 4515 | INIT_LIST_HEAD(&ss->cftsets);
|
| 4516 |
|
| 4517 | |
| 4518 | * base_cftset is embedded in subsys itself, no need to worry about
|
| 4519 | * deregistration.
|
| 4520 |
|
| 4521 | if (ss->base_cftypes) {
|
| 4522 | struct cftype *cft;
|
| 4523 |
|
| 4524 | for (cft = ss->base_cftypes; cft->name[0] != '\0'; cft++)
|
| 4525 | cft->ss = ss;
|
| 4526 |
|
| 4527 | ss->base_cftset.cfts = ss->base_cftypes;
|
| 4528 | list_add_tail(&ss->base_cftset.node, &ss->cftsets);
|
| 4529 | }
|
| 4530 | }
|
| 4531 |
|
| 4532 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
|
| 4533 | {
|
| 4534 | struct cgroup_subsys_state *css;
|
| 4535 |
|
| 4536 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
|
| 4537 |
|
| 4538 | mutex_lock(&cgroup_mutex);
|
| 4539 |
|
| 4540 |
|
| 4541 | cgroup_init_cftsets(ss);
|
| 4542 |
|
| 4543 |
|
| 4544 | ss->root = &cgroup_dummy_root;
|
| 4545 | css = ss->css_alloc(cgroup_css(cgroup_dummy_top, ss));
|
| 4546 |
|
| 4547 | BUG_ON(IS_ERR(css));
|
| 4548 | init_css(css, ss, cgroup_dummy_top);
|
| 4549 |
|
| 4550 | |
| 4551 | * pointer to this state - since the subsystem is
|
| 4552 | * newly registered, all tasks and hence the
|
| 4553 | * init_css_set is in the subsystem's top cgroup.
|
| 4554 | init_css_set.subsys[ss->subsys_id] = css;
|
| 4555 |
|
| 4556 | need_forkexit_callback |= ss->fork || ss->exit;
|
| 4557 |
|
| 4558 | |
| 4559 | * registered, no tasks have been forked, so we don't
|
| 4560 | * need to invoke fork callbacks here.
|
| 4561 | BUG_ON(!list_empty(&init_task.tasks));
|
| 4562 |
|
| 4563 | BUG_ON(online_css(css));
|
| 4564 |
|
| 4565 | mutex_unlock(&cgroup_mutex);
|
| 4566 |
|
| 4567 | |
| 4568 | * need to register a subsys_id, among other things
|
| 4569 | BUG_ON(ss->module);
|
| 4570 | }
|
| 4571 |
|
| 4572 | |
| 4573 | * cgroup_load_subsys: load and register a modular subsystem at runtime
|
| 4574 | * @ss: the subsystem to load
|
| 4575 | *
|
| 4576 | * This function should be called in a modular subsystem's initcall. If the
|
| 4577 | * subsystem is built as a module, it will be assigned a new subsys_id and set
|
| 4578 | * up for use. If the subsystem is built-in anyway, work is delegated to the
|
| 4579 | * simpler cgroup_init_subsys.
|
| 4580 |
|
| 4581 | int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
|
| 4582 | {
|
| 4583 | struct cgroup_subsys_state *css;
|
| 4584 | int i, ret;
|
| 4585 | struct hlist_node *tmp;
|
| 4586 | struct css_set *cset;
|
| 4587 | unsigned long key;
|
| 4588 |
|
| 4589 |
|
| 4590 | if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN ||
|
| 4591 | ss->css_alloc == NULL || ss->css_free == NULL)
|
| 4592 | return -EINVAL;
|
| 4593 |
|
| 4594 | |
| 4595 | * we don't support callbacks in modular subsystems. this check is
|
| 4596 | * before the ss->module check for consistency; a subsystem that could
|
| 4597 | * be a module should still have no callbacks even if the user isn't
|
| 4598 | * compiling it as one.
|
| 4599 |
|
| 4600 | if (ss->fork || ss->exit)
|
| 4601 | return -EINVAL;
|
| 4602 |
|
| 4603 | |
| 4604 | * an optionally modular subsystem is built-in: we want to do nothing,
|
| 4605 | * since cgroup_init_subsys will have already taken care of it.
|
| 4606 |
|
| 4607 | if (ss->module == NULL) {
|
| 4608 |
|
| 4609 | BUG_ON(cgroup_subsys[ss->subsys_id] != ss);
|
| 4610 | return 0;
|
| 4611 | }
|
| 4612 |
|
| 4613 |
|
| 4614 | cgroup_init_cftsets(ss);
|
| 4615 |
|
| 4616 | mutex_lock(&cgroup_mutex);
|
| 4617 | mutex_lock(&cgroup_root_mutex);
|
| 4618 | cgroup_subsys[ss->subsys_id] = ss;
|
| 4619 |
|
| 4620 | |
| 4621 | * no ss->css_alloc seems to need anything important in the ss
|
| 4622 | * struct, so this can happen first (i.e. before the dummy root
|
| 4623 | * attachment).
|
| 4624 |
|
| 4625 | css = ss->css_alloc(cgroup_css(cgroup_dummy_top, ss));
|
| 4626 | if (IS_ERR(css)) {
|
| 4627 |
|
| 4628 | cgroup_subsys[ss->subsys_id] = NULL;
|
| 4629 | mutex_unlock(&cgroup_root_mutex);
|
| 4630 | mutex_unlock(&cgroup_mutex);
|
| 4631 | return PTR_ERR(css);
|
| 4632 | }
|
| 4633 |
|
| 4634 | ss->root = &cgroup_dummy_root;
|
| 4635 |
|
| 4636 |
|
| 4637 | init_css(css, ss, cgroup_dummy_top);
|
| 4638 |
|
| 4639 | |
| 4640 | * Now we need to entangle the css into the existing css_sets. unlike
|
| 4641 | * in cgroup_init_subsys, there are now multiple css_sets, so each one
|
| 4642 | * will need a new pointer to it; done by iterating the css_set_table.
|
| 4643 | * furthermore, modifying the existing css_sets will corrupt the hash
|
| 4644 | * table state, so each changed css_set will need its hash recomputed.
|
| 4645 | * this is all done under the css_set_lock.
|
| 4646 |
|
| 4647 | write_lock(&css_set_lock);
|
| 4648 | hash_for_each_safe(css_set_table, i, tmp, cset, hlist) {
|
| 4649 |
|
| 4650 | if (cset->subsys[ss->subsys_id])
|
| 4651 | continue;
|
| 4652 |
|
| 4653 | hash_del(&cset->hlist);
|
| 4654 |
|
| 4655 | cset->subsys[ss->subsys_id] = css;
|
| 4656 |
|
| 4657 | key = css_set_hash(cset->subsys);
|
| 4658 | hash_add(css_set_table, &cset->hlist, key);
|
| 4659 | }
|
| 4660 | write_unlock(&css_set_lock);
|
| 4661 |
|
| 4662 | ret = online_css(css);
|
| 4663 | if (ret) {
|
| 4664 | ss->css_free(css);
|
| 4665 | goto err_unload;
|
| 4666 | }
|
| 4667 |
|
| 4668 |
|
| 4669 | mutex_unlock(&cgroup_root_mutex);
|
| 4670 | mutex_unlock(&cgroup_mutex);
|
| 4671 | return 0;
|
| 4672 |
|
| 4673 | err_unload:
|
| 4674 | mutex_unlock(&cgroup_root_mutex);
|
| 4675 | mutex_unlock(&cgroup_mutex);
|
| 4676 |
|
| 4677 | cgroup_unload_subsys(ss);
|
| 4678 | return ret;
|
| 4679 | }
|
| 4680 | EXPORT_SYMBOL_GPL(cgroup_load_subsys);
|
| 4681 |
|
| 4682 | |
| 4683 | * cgroup_unload_subsys: unload a modular subsystem
|
| 4684 | * @ss: the subsystem to unload
|
| 4685 | *
|
| 4686 | * This function should be called in a modular subsystem's exitcall. When this
|
| 4687 | * function is invoked, the refcount on the subsystem's module will be 0, so
|
| 4688 | * the subsystem will not be attached to any hierarchy.
|
| 4689 |
|
| 4690 | void cgroup_unload_subsys(struct cgroup_subsys *ss)
|
| 4691 | {
|
| 4692 | struct cgrp_cset_link *link;
|
| 4693 | struct cgroup_subsys_state *css;
|
| 4694 |
|
| 4695 | BUG_ON(ss->module == NULL);
|
| 4696 |
|
| 4697 | |
| 4698 | * we shouldn't be called if the subsystem is in use, and the use of
|
| 4699 | * try_module_get() in rebind_subsystems() should ensure that it
|
| 4700 | * doesn't start being used while we're killing it off.
|
| 4701 |
|
| 4702 | BUG_ON(ss->root != &cgroup_dummy_root);
|
| 4703 |
|
| 4704 | mutex_lock(&cgroup_mutex);
|
| 4705 | mutex_lock(&cgroup_root_mutex);
|
| 4706 |
|
| 4707 | css = cgroup_css(cgroup_dummy_top, ss);
|
| 4708 | if (css)
|
| 4709 | offline_css(css);
|
| 4710 |
|
| 4711 |
|
| 4712 | cgroup_subsys[ss->subsys_id] = NULL;
|
| 4713 |
|
| 4714 | |
| 4715 | * disentangle the css from all css_sets attached to the dummy
|
| 4716 | * top. as in loading, we need to pay our respects to the hashtable
|
| 4717 | * gods.
|
| 4718 |
|
| 4719 | write_lock(&css_set_lock);
|
| 4720 | list_for_each_entry(link, &cgroup_dummy_top->cset_links, cset_link) {
|
| 4721 | struct css_set *cset = link->cset;
|
| 4722 | unsigned long key;
|
| 4723 |
|
| 4724 | hash_del(&cset->hlist);
|
| 4725 | cset->subsys[ss->subsys_id] = NULL;
|
| 4726 | key = css_set_hash(cset->subsys);
|
| 4727 | hash_add(css_set_table, &cset->hlist, key);
|
| 4728 | }
|
| 4729 | write_unlock(&css_set_lock);
|
| 4730 |
|
| 4731 | |
| 4732 | * remove subsystem's css from the cgroup_dummy_top and free it -
|
| 4733 | * need to free before marking as null because ss->css_free needs
|
| 4734 | * the cgrp->subsys pointer to find their state.
|
| 4735 |
|
| 4736 | if (css)
|
| 4737 | ss->css_free(css);
|
| 4738 | RCU_INIT_POINTER(cgroup_dummy_top->subsys[ss->subsys_id], NULL);
|
| 4739 |
|
| 4740 | mutex_unlock(&cgroup_root_mutex);
|
| 4741 | mutex_unlock(&cgroup_mutex);
|
| 4742 | }
|
| 4743 | EXPORT_SYMBOL_GPL(cgroup_unload_subsys);
|
| 4744 |
|
| 4745 | |
| 4746 | * cgroup_init_early - cgroup initialization at system boot
|
| 4747 | *
|
| 4748 | * Initialize cgroups at system boot, and initialize any
|
| 4749 | * subsystems that request early init.
|
| 4750 |
|
| 4751 | int __init cgroup_init_early(void)
|
| 4752 | {
|
| 4753 | struct cgroup_subsys *ss;
|
| 4754 | int i;
|
| 4755 |
|
| 4756 | atomic_set(&init_css_set.refcount, 1);
|
| 4757 | INIT_LIST_HEAD(&init_css_set.cgrp_links);
|
| 4758 | INIT_LIST_HEAD(&init_css_set.tasks);
|
| 4759 | INIT_HLIST_NODE(&init_css_set.hlist);
|
| 4760 | css_set_count = 1;
|
| 4761 | init_cgroup_root(&cgroup_dummy_root);
|
| 4762 | cgroup_root_count = 1;
|
| 4763 | RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
|
| 4764 |
|
| 4765 | init_cgrp_cset_link.cset = &init_css_set;
|
| 4766 | init_cgrp_cset_link.cgrp = cgroup_dummy_top;
|
| 4767 | list_add(&init_cgrp_cset_link.cset_link, &cgroup_dummy_top->cset_links);
|
| 4768 | list_add(&init_cgrp_cset_link.cgrp_link, &init_css_set.cgrp_links);
|
| 4769 |
|
| 4770 |
|
| 4771 | for_each_builtin_subsys(ss, i) {
|
| 4772 | BUG_ON(!ss->name);
|
| 4773 | BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
|
| 4774 | BUG_ON(!ss->css_alloc);
|
| 4775 | BUG_ON(!ss->css_free);
|
| 4776 | if (ss->subsys_id != i) {
|
| 4777 | printk(KERN_ERR "cgroup: Subsys %s id == %d\n",
|
| 4778 | ss->name, ss->subsys_id);
|
| 4779 | BUG();
|
| 4780 | }
|
| 4781 |
|
| 4782 | if (ss->early_init)
|
| 4783 | cgroup_init_subsys(ss);
|
| 4784 | }
|
| 4785 | return 0;
|
| 4786 | }
|
| 4787 |
|
| 4788 | |
| 4789 | * cgroup_init - cgroup initialization
|
| 4790 | *
|
| 4791 | * Register cgroup filesystem and /proc file, and initialize
|
| 4792 | * any subsystems that didn't request early init.
|
| 4793 |
|
| 4794 | int __init cgroup_init(void)
|
| 4795 | {
|
| 4796 | struct cgroup_subsys *ss;
|
| 4797 | unsigned long key;
|
| 4798 | int i, err;
|
| 4799 |
|
| 4800 | err = bdi_init(&cgroup_backing_dev_info);
|
| 4801 | if (err)
|
| 4802 | return err;
|
| 4803 |
|
| 4804 | for_each_builtin_subsys(ss, i) {
|
| 4805 | if (!ss->early_init)
|
| 4806 | cgroup_init_subsys(ss);
|
| 4807 | }
|
| 4808 |
|
| 4809 |
|
| 4810 | mutex_lock(&cgroup_mutex);
|
| 4811 | mutex_lock(&cgroup_root_mutex);
|
| 4812 |
|
| 4813 |
|
| 4814 | key = css_set_hash(init_css_set.subsys);
|
| 4815 | hash_add(css_set_table, &init_css_set.hlist, key);
|
| 4816 |
|
| 4817 | BUG_ON(cgroup_init_root_id(&cgroup_dummy_root, 0, 1));
|
| 4818 |
|
| 4819 | err = idr_alloc(&cgroup_dummy_root.cgroup_idr, cgroup_dummy_top,
|
| 4820 | 0, 1, GFP_KERNEL);
|
| 4821 | BUG_ON(err < 0);
|
| 4822 |
|
| 4823 | mutex_unlock(&cgroup_root_mutex);
|
| 4824 | mutex_unlock(&cgroup_mutex);
|
| 4825 |
|
| 4826 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);
|
| 4827 | if (!cgroup_kobj) {
|
| 4828 | err = -ENOMEM;
|
| 4829 | goto out;
|
| 4830 | }
|
| 4831 |
|
| 4832 | err = register_filesystem(&cgroup_fs_type);
|
| 4833 | if (err < 0) {
|
| 4834 | kobject_put(cgroup_kobj);
|
| 4835 | goto out;
|
| 4836 | }
|
| 4837 |
|
| 4838 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations);
|
| 4839 |
|
| 4840 | out:
|
| 4841 | if (err)
|
| 4842 | bdi_destroy(&cgroup_backing_dev_info);
|
| 4843 |
|
| 4844 | return err;
|
| 4845 | }
|
| 4846 |
|
| 4847 | static int __init cgroup_wq_init(void)
|
| 4848 | {
|
| 4849 | |
| 4850 | * There isn't much point in executing destruction path in
|
| 4851 | * parallel. Good chunk is serialized with cgroup_mutex anyway.
|
| 4852 | * Use 1 for @max_active.
|
| 4853 | *
|
| 4854 | * We would prefer to do this in cgroup_init() above, but that
|
| 4855 | * is called before init_workqueues(): so leave this until after.
|
| 4856 |
|
| 4857 | cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
|
| 4858 | BUG_ON(!cgroup_destroy_wq);
|
| 4859 |
|
| 4860 | |
| 4861 | * Used to destroy pidlists and separate to serve as flush domain.
|
| 4862 | * Cap @max_active to 1 too.
|
| 4863 |
|
| 4864 | cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
|
| 4865 | 0, 1);
|
| 4866 | BUG_ON(!cgroup_pidlist_destroy_wq);
|
| 4867 |
|
| 4868 | return 0;
|
| 4869 | }
|
| 4870 | core_initcall(cgroup_wq_init);
|
| 4871 |
|
| 4872 | |
| 4873 | * proc_cgroup_show()
|
| 4874 | * - Print task's cgroup paths into seq_file, one line for each hierarchy
|
| 4875 | * - Used for /proc/<pid>/cgroup.
|
| 4876 | * - No need to task_lock(tsk) on this tsk->cgroup reference, as it
|
| 4877 | * doesn't really matter if tsk->cgroup changes after we read it,
|
| 4878 | * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
|
| 4879 | * anyway. No need to check that tsk->cgroup != NULL, thanks to
|
| 4880 | * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
|
| 4881 | * cgroup to top_cgroup.
|
| 4882 |
|
| 4883 |
|
| 4884 |
|
| 4885 | int proc_cgroup_show(struct seq_file *m, void *v)
|
| 4886 | {
|
| 4887 | struct pid *pid;
|
| 4888 | struct task_struct *tsk;
|
| 4889 | char *buf;
|
| 4890 | int retval;
|
| 4891 | struct cgroupfs_root *root;
|
| 4892 |
|
| 4893 | retval = -ENOMEM;
|
| 4894 | buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
|
| 4895 | if (!buf)
|
| 4896 | goto out;
|
| 4897 |
|
| 4898 | retval = -ESRCH;
|
| 4899 | pid = m->private;
|
| 4900 | tsk = get_pid_task(pid, PIDTYPE_PID);
|
| 4901 | if (!tsk)
|
| 4902 | goto out_free;
|
| 4903 |
|
| 4904 | retval = 0;
|
| 4905 |
|
| 4906 | mutex_lock(&cgroup_mutex);
|
| 4907 |
|
| 4908 | for_each_active_root(root) {
|
| 4909 | struct cgroup_subsys *ss;
|
| 4910 | struct cgroup *cgrp;
|
| 4911 | int ssid, count = 0;
|
| 4912 |
|
| 4913 | seq_printf(m, "%d:", root->hierarchy_id);
|
| 4914 | for_each_subsys(ss, ssid)
|
| 4915 | if (root->subsys_mask & (1 << ssid))
|
| 4916 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
|
| 4917 | if (strlen(root->name))
|
| 4918 | seq_printf(m, "%sname=%s", count ? "," : "",
|
| 4919 | root->name);
|
| 4920 | seq_putc(m, ':');
|
| 4921 | cgrp = task_cgroup_from_root(tsk, root);
|
| 4922 | retval = cgroup_path(cgrp, buf, PAGE_SIZE);
|
| 4923 | if (retval < 0)
|
| 4924 | goto out_unlock;
|
| 4925 | seq_puts(m, buf);
|
| 4926 | seq_putc(m, '\n');
|
| 4927 | }
|
| 4928 |
|
| 4929 | out_unlock:
|
| 4930 | mutex_unlock(&cgroup_mutex);
|
| 4931 | put_task_struct(tsk);
|
| 4932 | out_free:
|
| 4933 | kfree(buf);
|
| 4934 | out:
|
| 4935 | return retval;
|
| 4936 | }
|
| 4937 |
|
| 4938 |
|
| 4939 | static int proc_cgroupstats_show(struct seq_file *m, void *v)
|
| 4940 | {
|
| 4941 | struct cgroup_subsys *ss;
|
| 4942 | int i;
|
| 4943 |
|
| 4944 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
|
| 4945 | |
| 4946 | * ideally we don't want subsystems moving around while we do this.
|
| 4947 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of
|
| 4948 | * subsys/hierarchy state.
|
| 4949 |
|
| 4950 | mutex_lock(&cgroup_mutex);
|
| 4951 |
|
| 4952 | for_each_subsys(ss, i)
|
| 4953 | seq_printf(m, "%s\t%d\t%d\t%d\n",
|
| 4954 | ss->name, ss->root->hierarchy_id,
|
| 4955 | ss->root->number_of_cgroups, !ss->disabled);
|
| 4956 |
|
| 4957 | mutex_unlock(&cgroup_mutex);
|
| 4958 | return 0;
|
| 4959 | }
|
| 4960 |
|
| 4961 | static int cgroupstats_open(struct inode *inode, struct file *file)
|
| 4962 | {
|
| 4963 | return single_open(file, proc_cgroupstats_show, NULL);
|
| 4964 | }
|
| 4965 |
|
| 4966 | static const struct file_operations proc_cgroupstats_operations = {
|
| 4967 | .open = cgroupstats_open,
|
| 4968 | .read = seq_read,
|
| 4969 | .llseek = seq_lseek,
|
| 4970 | .release = single_release,
|
| 4971 | };
|
| 4972 |
|
| 4973 | |
| 4974 | * cgroup_fork - attach newly forked task to its parents cgroup.
|
| 4975 | * @child: pointer to task_struct of forking parent process.
|
| 4976 | *
|
| 4977 | * Description: A task inherits its parent's cgroup at fork().
|
| 4978 | *
|
| 4979 | * A pointer to the shared css_set was automatically copied in
|
| 4980 | * fork.c by dup_task_struct(). However, we ignore that copy, since
|
| 4981 | * it was not made under the protection of RCU or cgroup_mutex, so
|
| 4982 | * might no longer be a valid cgroup pointer. cgroup_attach_task() might
|
| 4983 | * have already changed current->cgroups, allowing the previously
|
| 4984 | * referenced cgroup group to be removed and freed.
|
| 4985 | *
|
| 4986 | * At the point that cgroup_fork() is called, 'current' is the parent
|
| 4987 | * task, and the passed argument 'child' points to the child task.
|
| 4988 |
|
| 4989 | void cgroup_fork(struct task_struct *child)
|
| 4990 | {
|
| 4991 | task_lock(current);
|
| 4992 | get_css_set(task_css_set(current));
|
| 4993 | child->cgroups = current->cgroups;
|
| 4994 | task_unlock(current);
|
| 4995 | INIT_LIST_HEAD(&child->cg_list);
|
| 4996 | }
|
| 4997 |
|
| 4998 | |
| 4999 | * cgroup_post_fork - called on a new task after adding it to the task list
|
| 5000 | * @child: the task in question
|
| 5001 | *
|
| 5002 | * Adds the task to the list running through its css_set if necessary and
|
| 5003 | * call the subsystem fork() callbacks. Has to be after the task is
|
| 5004 | * visible on the task list in case we race with the first call to
|
| 5005 | * cgroup_task_iter_start() - to guarantee that the new task ends up on its
|
| 5006 | * list.
|
| 5007 |
|
| 5008 | void cgroup_post_fork(struct task_struct *child)
|
| 5009 | {
|
| 5010 | struct cgroup_subsys *ss;
|
| 5011 | int i;
|
| 5012 |
|
| 5013 | |
| 5014 | * use_task_css_set_links is set to 1 before we walk the tasklist
|
| 5015 | * under the tasklist_lock and we read it here after we added the child
|
| 5016 | * to the tasklist under the tasklist_lock as well. If the child wasn't
|
| 5017 | * yet in the tasklist when we walked through it from
|
| 5018 | * cgroup_enable_task_cg_lists(), then use_task_css_set_links value
|
| 5019 | * should be visible now due to the paired locking and barriers implied
|
| 5020 | * by LOCK/UNLOCK: it is written before the tasklist_lock unlock
|
| 5021 | * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock
|
| 5022 | * lock on fork.
|
| 5023 |
|
| 5024 | if (use_task_css_set_links) {
|
| 5025 | write_lock(&css_set_lock);
|
| 5026 | task_lock(child);
|
| 5027 | if (list_empty(&child->cg_list))
|
| 5028 | list_add(&child->cg_list, &task_css_set(child)->tasks);
|
| 5029 | task_unlock(child);
|
| 5030 | write_unlock(&css_set_lock);
|
| 5031 | }
|
| 5032 |
|
| 5033 | |
| 5034 | * Call ss->fork(). This must happen after @child is linked on
|
| 5035 | * css_set; otherwise, @child might change state between ->fork()
|
| 5036 | * and addition to css_set.
|
| 5037 |
|
| 5038 | if (need_forkexit_callback) {
|
| 5039 | |
| 5040 | * fork/exit callbacks are supported only for builtin
|
| 5041 | * subsystems, and the builtin section of the subsys
|
| 5042 | * array is immutable, so we don't need to lock the
|
| 5043 | * subsys array here. On the other hand, modular section
|
| 5044 | * of the array can be freed at module unload, so we
|
| 5045 | * can't touch that.
|
| 5046 |
|
| 5047 | for_each_builtin_subsys(ss, i)
|
| 5048 | if (ss->fork)
|
| 5049 | ss->fork(child);
|
| 5050 | }
|
| 5051 | }
|
| 5052 |
|
| 5053 | |
| 5054 | * cgroup_exit - detach cgroup from exiting task
|
| 5055 | * @tsk: pointer to task_struct of exiting process
|
| 5056 | * @run_callback: run exit callbacks?
|
| 5057 | *
|
| 5058 | * Description: Detach cgroup from @tsk and release it.
|
| 5059 | *
|
| 5060 | * Note that cgroups marked notify_on_release force every task in
|
| 5061 | * them to take the global cgroup_mutex mutex when exiting.
|
| 5062 | * This could impact scaling on very large systems. Be reluctant to
|
| 5063 | * use notify_on_release cgroups where very high task exit scaling
|
| 5064 | * is required on large systems.
|
| 5065 | *
|
| 5066 | * the_top_cgroup_hack:
|
| 5067 | *
|
| 5068 | * Set the exiting tasks cgroup to the root cgroup (top_cgroup).
|
| 5069 | *
|
| 5070 | * We call cgroup_exit() while the task is still competent to
|
| 5071 | * handle notify_on_release(), then leave the task attached to the
|
| 5072 | * root cgroup in each hierarchy for the remainder of its exit.
|
| 5073 | *
|
| 5074 | * To do this properly, we would increment the reference count on
|
| 5075 | * top_cgroup, and near the very end of the kernel/exit.c do_exit()
|
| 5076 | * code we would add a second cgroup function call, to drop that
|
| 5077 | * reference. This would just create an unnecessary hot spot on
|
| 5078 | * the top_cgroup reference count, to no avail.
|
| 5079 | *
|
| 5080 | * Normally, holding a reference to a cgroup without bumping its
|
| 5081 | * count is unsafe. The cgroup could go away, or someone could
|
| 5082 | * attach us to a different cgroup, decrementing the count on
|
| 5083 | * the first cgroup that we never incremented. But in this case,
|
| 5084 | * top_cgroup isn't going away, and either task has PF_EXITING set,
|
| 5085 | * which wards off any cgroup_attach_task() attempts, or task is a failed
|
| 5086 | * fork, never visible to cgroup_attach_task.
|
| 5087 |
|
| 5088 | void cgroup_exit(struct task_struct *tsk, int run_callbacks)
|
| 5089 | {
|
| 5090 | struct cgroup_subsys *ss;
|
| 5091 | struct css_set *cset;
|
| 5092 | int i;
|
| 5093 |
|
| 5094 | |
| 5095 | * Unlink from the css_set task list if necessary.
|
| 5096 | * Optimistically check cg_list before taking
|
| 5097 | * css_set_lock
|
| 5098 |
|
| 5099 | if (!list_empty(&tsk->cg_list)) {
|
| 5100 | write_lock(&css_set_lock);
|
| 5101 | if (!list_empty(&tsk->cg_list))
|
| 5102 | list_del_init(&tsk->cg_list);
|
| 5103 | write_unlock(&css_set_lock);
|
| 5104 | }
|
| 5105 |
|
| 5106 |
|
| 5107 | task_lock(tsk);
|
| 5108 | cset = task_css_set(tsk);
|
| 5109 | RCU_INIT_POINTER(tsk->cgroups, &init_css_set);
|
| 5110 |
|
| 5111 | if (run_callbacks && need_forkexit_callback) {
|
| 5112 | |
| 5113 | * fork/exit callbacks are supported only for builtin
|
| 5114 | * subsystems, see cgroup_post_fork() for details.
|
| 5115 |
|
| 5116 | for_each_builtin_subsys(ss, i) {
|
| 5117 | if (ss->exit) {
|
| 5118 | struct cgroup_subsys_state *old_css = cset->subsys[i];
|
| 5119 | struct cgroup_subsys_state *css = task_css(tsk, i);
|
| 5120 |
|
| 5121 | ss->exit(css, old_css, tsk);
|
| 5122 | }
|
| 5123 | }
|
| 5124 | }
|
| 5125 | task_unlock(tsk);
|
| 5126 |
|
| 5127 | put_css_set_taskexit(cset);
|
| 5128 | }
|
| 5129 |
|
| 5130 | static void check_for_release(struct cgroup *cgrp)
|
| 5131 | {
|
| 5132 | if (cgroup_is_releasable(cgrp) &&
|
| 5133 | list_empty(&cgrp->cset_links) && list_empty(&cgrp->children)) {
|
| 5134 | |
| 5135 | * Control Group is currently removeable. If it's not
|
| 5136 | * already queued for a userspace notification, queue
|
| 5137 | * it now
|
| 5138 |
|
| 5139 | int need_schedule_work = 0;
|
| 5140 |
|
| 5141 | raw_spin_lock(&release_list_lock);
|
| 5142 | if (!cgroup_is_dead(cgrp) &&
|
| 5143 | list_empty(&cgrp->release_list)) {
|
| 5144 | list_add(&cgrp->release_list, &release_list);
|
| 5145 | need_schedule_work = 1;
|
| 5146 | }
|
| 5147 | raw_spin_unlock(&release_list_lock);
|
| 5148 | if (need_schedule_work)
|
| 5149 | schedule_work(&release_agent_work);
|
| 5150 | }
|
| 5151 | }
|
| 5152 |
|
| 5153 | |
| 5154 | * Notify userspace when a cgroup is released, by running the
|
| 5155 | * configured release agent with the name of the cgroup (path
|
| 5156 | * relative to the root of cgroup file system) as the argument.
|
| 5157 | *
|
| 5158 | * Most likely, this user command will try to rmdir this cgroup.
|
| 5159 | *
|
| 5160 | * This races with the possibility that some other task will be
|
| 5161 | * attached to this cgroup before it is removed, or that some other
|
| 5162 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
|
| 5163 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer
|
| 5164 | * unused, and this cgroup will be reprieved from its death sentence,
|
| 5165 | * to continue to serve a useful existence. Next time it's released,
|
| 5166 | * we will get notified again, if it still has 'notify_on_release' set.
|
| 5167 | *
|
| 5168 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
|
| 5169 | * means only wait until the task is successfully execve()'d. The
|
| 5170 | * separate release agent task is forked by call_usermodehelper(),
|
| 5171 | * then control in this thread returns here, without waiting for the
|
| 5172 | * release agent task. We don't bother to wait because the caller of
|
| 5173 | * this routine has no use for the exit status of the release agent
|
| 5174 | * task, so no sense holding our caller up for that.
|
| 5175 |
|
| 5176 | static void cgroup_release_agent(struct work_struct *work)
|
| 5177 | {
|
| 5178 | BUG_ON(work != &release_agent_work);
|
| 5179 | mutex_lock(&cgroup_mutex);
|
| 5180 | raw_spin_lock(&release_list_lock);
|
| 5181 | while (!list_empty(&release_list)) {
|
| 5182 | char *argv[3], *envp[3];
|
| 5183 | int i;
|
| 5184 | char *pathbuf = NULL, *agentbuf = NULL;
|
| 5185 | struct cgroup *cgrp = list_entry(release_list.next,
|
| 5186 | struct cgroup,
|
| 5187 | release_list);
|
| 5188 | list_del_init(&cgrp->release_list);
|
| 5189 | raw_spin_unlock(&release_list_lock);
|
| 5190 | pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
|
| 5191 | if (!pathbuf)
|
| 5192 | goto continue_free;
|
| 5193 | if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0)
|
| 5194 | goto continue_free;
|
| 5195 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
|
| 5196 | if (!agentbuf)
|
| 5197 | goto continue_free;
|
| 5198 |
|
| 5199 | i = 0;
|
| 5200 | argv[i++] = agentbuf;
|
| 5201 | argv[i++] = pathbuf;
|
| 5202 | argv[i] = NULL;
|
| 5203 |
|
| 5204 | i = 0;
|
| 5205 |
|
| 5206 | envp[i++] = "HOME=/";
|
| 5207 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
|
| 5208 | envp[i] = NULL;
|
| 5209 |
|
| 5210 | |
| 5211 | * since the exec could involve hitting disk and hence
|
| 5212 | * be a slow process
|
| 5213 | mutex_unlock(&cgroup_mutex);
|
| 5214 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
|
| 5215 | mutex_lock(&cgroup_mutex);
|
| 5216 | continue_free:
|
| 5217 | kfree(pathbuf);
|
| 5218 | kfree(agentbuf);
|
| 5219 | raw_spin_lock(&release_list_lock);
|
| 5220 | }
|
| 5221 | raw_spin_unlock(&release_list_lock);
|
| 5222 | mutex_unlock(&cgroup_mutex);
|
| 5223 | }
|
| 5224 |
|
| 5225 | static int __init cgroup_disable(char *str)
|
| 5226 | {
|
| 5227 | struct cgroup_subsys *ss;
|
| 5228 | char *token;
|
| 5229 | int i;
|
| 5230 |
|
| 5231 | while ((token = strsep(&str, ",")) != NULL) {
|
| 5232 | if (!*token)
|
| 5233 | continue;
|
| 5234 |
|
| 5235 | |
| 5236 | * cgroup_disable, being at boot time, can't know about
|
| 5237 | * module subsystems, so we don't worry about them.
|
| 5238 |
|
| 5239 | for_each_builtin_subsys(ss, i) {
|
| 5240 | if (!strcmp(token, ss->name)) {
|
| 5241 | ss->disabled = 1;
|
| 5242 | printk(KERN_INFO "Disabling %s control group"
|
| 5243 | " subsystem\n", ss->name);
|
| 5244 | break;
|
| 5245 | }
|
| 5246 | }
|
| 5247 | }
|
| 5248 | return 1;
|
| 5249 | }
|
| 5250 | __setup("cgroup_disable=", cgroup_disable);
|
| 5251 |
|
| 5252 | |
| 5253 | * css_from_dir - get corresponding css from the dentry of a cgroup dir
|
| 5254 | * @dentry: directory dentry of interest
|
| 5255 | * @ss: subsystem of interest
|
| 5256 | *
|
| 5257 | * Must be called under cgroup_mutex or RCU read lock. The caller is
|
| 5258 | * responsible for pinning the returned css if it needs to be accessed
|
| 5259 | * outside the critical section.
|
| 5260 |
|
| 5261 | struct cgroup_subsys_state *css_from_dir(struct dentry *dentry,
|
| 5262 | struct cgroup_subsys *ss)
|
| 5263 | {
|
| 5264 | struct cgroup *cgrp;
|
| 5265 |
|
| 5266 | cgroup_assert_mutex_or_rcu_locked();
|
| 5267 |
|
| 5268 |
|
| 5269 | if (!dentry->d_inode ||
|
| 5270 | dentry->d_inode->i_op != &cgroup_dir_inode_operations)
|
| 5271 | return ERR_PTR(-EBADF);
|
| 5272 |
|
| 5273 | cgrp = __d_cgrp(dentry);
|
| 5274 | return cgroup_css(cgrp, ss) ?: ERR_PTR(-ENOENT);
|
| 5275 | }
|
| 5276 |
|
| 5277 | |
| 5278 | * css_from_id - lookup css by id
|
| 5279 | * @id: the cgroup id
|
| 5280 | * @ss: cgroup subsys to be looked into
|
| 5281 | *
|
| 5282 | * Returns the css if there's valid one with @id, otherwise returns NULL.
|
| 5283 | * Should be called under rcu_read_lock().
|
| 5284 |
|
| 5285 | struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
|
| 5286 | {
|
| 5287 | struct cgroup *cgrp;
|
| 5288 |
|
| 5289 | cgroup_assert_mutex_or_rcu_locked();
|
| 5290 |
|
| 5291 | cgrp = idr_find(&ss->root->cgroup_idr, id);
|
| 5292 | if (cgrp)
|
| 5293 | return cgroup_css(cgrp, ss);
|
| 5294 | return NULL;
|
| 5295 | }
|
| 5296 |
|
| 5297 | #ifdef CONFIG_CGROUP_DEBUG
|
| 5298 | static struct cgroup_subsys_state *
|
| 5299 | debug_css_alloc(struct cgroup_subsys_state *parent_css)
|
| 5300 | {
|
| 5301 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
|
| 5302 |
|
| 5303 | if (!css)
|
| 5304 | return ERR_PTR(-ENOMEM);
|
| 5305 |
|
| 5306 | return css;
|
| 5307 | }
|
| 5308 |
|
| 5309 | static void debug_css_free(struct cgroup_subsys_state *css)
|
| 5310 | {
|
| 5311 | kfree(css);
|
| 5312 | }
|
| 5313 |
|
| 5314 | static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
|
| 5315 | struct cftype *cft)
|
| 5316 | {
|
| 5317 | return cgroup_task_count(css->cgroup);
|
| 5318 | }
|
| 5319 |
|
| 5320 | static u64 current_css_set_read(struct cgroup_subsys_state *css,
|
| 5321 | struct cftype *cft)
|
| 5322 | {
|
| 5323 | return (u64)(unsigned long)current->cgroups;
|
| 5324 | }
|
| 5325 |
|
| 5326 | static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
|
| 5327 | struct cftype *cft)
|
| 5328 | {
|
| 5329 | u64 count;
|
| 5330 |
|
| 5331 | rcu_read_lock();
|
| 5332 | count = atomic_read(&task_css_set(current)->refcount);
|
| 5333 | rcu_read_unlock();
|
| 5334 | return count;
|
| 5335 | }
|
| 5336 |
|
| 5337 | static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
|
| 5338 | {
|
| 5339 | struct cgrp_cset_link *link;
|
| 5340 | struct css_set *cset;
|
| 5341 |
|
| 5342 | read_lock(&css_set_lock);
|
| 5343 | rcu_read_lock();
|
| 5344 | cset = rcu_dereference(current->cgroups);
|
| 5345 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
|
| 5346 | struct cgroup *c = link->cgrp;
|
| 5347 | const char *name;
|
| 5348 |
|
| 5349 | if (c->dentry)
|
| 5350 | name = c->dentry->d_name.name;
|
| 5351 | else
|
| 5352 | name = "?";
|
| 5353 | seq_printf(seq, "Root %d group %s\n",
|
| 5354 | c->root->hierarchy_id, name);
|
| 5355 | }
|
| 5356 | rcu_read_unlock();
|
| 5357 | read_unlock(&css_set_lock);
|
| 5358 | return 0;
|
| 5359 | }
|
| 5360 |
|
| 5361 | #define MAX_TASKS_SHOWN_PER_CSS 25
|
| 5362 | static int cgroup_css_links_read(struct seq_file *seq, void *v)
|
| 5363 | {
|
| 5364 | struct cgroup_subsys_state *css = seq_css(seq);
|
| 5365 | struct cgrp_cset_link *link;
|
| 5366 |
|
| 5367 | read_lock(&css_set_lock);
|
| 5368 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
|
| 5369 | struct css_set *cset = link->cset;
|
| 5370 | struct task_struct *task;
|
| 5371 | int count = 0;
|
| 5372 | seq_printf(seq, "css_set %p\n", cset);
|
| 5373 | list_for_each_entry(task, &cset->tasks, cg_list) {
|
| 5374 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) {
|
| 5375 | seq_puts(seq, " ...\n");
|
| 5376 | break;
|
| 5377 | } else {
|
| 5378 | seq_printf(seq, " task %d\n",
|
| 5379 | task_pid_vnr(task));
|
| 5380 | }
|
| 5381 | }
|
| 5382 | }
|
| 5383 | read_unlock(&css_set_lock);
|
| 5384 | return 0;
|
| 5385 | }
|
| 5386 |
|
| 5387 | static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
|
| 5388 | {
|
| 5389 | return test_bit(CGRP_RELEASABLE, &css->cgroup->flags);
|
| 5390 | }
|
| 5391 |
|
| 5392 | static struct cftype debug_files[] = {
|
| 5393 | {
|
| 5394 | .name = "taskcount",
|
| 5395 | .read_u64 = debug_taskcount_read,
|
| 5396 | },
|
| 5397 |
|
| 5398 | {
|
| 5399 | .name = "current_css_set",
|
| 5400 | .read_u64 = current_css_set_read,
|
| 5401 | },
|
| 5402 |
|
| 5403 | {
|
| 5404 | .name = "current_css_set_refcount",
|
| 5405 | .read_u64 = current_css_set_refcount_read,
|
| 5406 | },
|
| 5407 |
|
| 5408 | {
|
| 5409 | .name = "current_css_set_cg_links",
|
| 5410 | .seq_show = current_css_set_cg_links_read,
|
| 5411 | },
|
| 5412 |
|
| 5413 | {
|
| 5414 | .name = "cgroup_css_links",
|
| 5415 | .seq_show = cgroup_css_links_read,
|
| 5416 | },
|
| 5417 |
|
| 5418 | {
|
| 5419 | .name = "releasable",
|
| 5420 | .read_u64 = releasable_read,
|
| 5421 | },
|
| 5422 |
|
| 5423 | { }
|
| 5424 | };
|
| 5425 |
|
| 5426 | struct cgroup_subsys debug_subsys = {
|
| 5427 | .name = "debug",
|
| 5428 | .css_alloc = debug_css_alloc,
|
| 5429 | .css_free = debug_css_free,
|
| 5430 | .subsys_id = debug_subsys_id,
|
| 5431 | .base_cftypes = debug_files,
|
| 5432 | };
|
| 5433 | #endif
|