| 1 | |
| 2 | * Generic process-grouping system.
|
| 3 | *
|
| 4 | * Based originally on the cpuset system, extracted by Paul Menage
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| 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.
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| 15 | *
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| 16 | * Portions derived from Patrick Mochel's sysfs code.
|
| 17 | * sysfs is Copyright (c) 2001-3 Patrick Mochel
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| 18 | *
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| 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 | *
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| 24 | * This file is subject to the terms and conditions of the GNU General Public
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| 25 | * License. See the file COPYING in the main directory of the Linux
|
| 26 | * distribution for more details.
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| 27 |
|
| 28 |
|
| 29 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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| 30 |
|
| 31 | #include <linux/cgroup.h>
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| 32 | #include <linux/cred.h>
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| 33 | #include <linux/ctype.h>
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| 34 | #include <linux/errno.h>
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| 35 | #include <linux/init_task.h>
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| 36 | #include <linux/kernel.h>
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| 37 | #include <linux/list.h>
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| 38 | #include <linux/magic.h>
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| 39 | #include <linux/mm.h>
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| 40 | #include <linux/mutex.h>
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| 41 | #include <linux/mount.h>
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| 42 | #include <linux/pagemap.h>
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| 43 | #include <linux/proc_fs.h>
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| 44 | #include <linux/rcupdate.h>
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| 45 | #include <linux/sched.h>
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| 46 | #include <linux/slab.h>
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| 47 | #include <linux/spinlock.h>
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| 48 | #include <linux/rwsem.h>
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| 49 | #include <linux/string.h>
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| 50 | #include <linux/sort.h>
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| 51 | #include <linux/kmod.h>
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| 52 | #include <linux/delayacct.h>
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| 53 | #include <linux/cgroupstats.h>
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| 54 | #include <linux/hashtable.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/kthread.h>
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| 59 | #include <linux/delay.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 |
|
| 71 | #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
|
| 72 | MAX_CFTYPE_NAME + 2)
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| 73 |
|
| 74 | |
| 75 | * cgroup_mutex is the master lock. Any modification to cgroup or its
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| 76 | * hierarchy must be performed while holding it.
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| 77 | *
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| 78 | * css_set_rwsem protects task->cgroups pointer, the list of css_set
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| 79 | * objects, and the chain of tasks off each css_set.
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| 80 | *
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| 81 | * These locks are exported if CONFIG_PROVE_RCU so that accessors in
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| 82 | * cgroup.h can use them for lockdep annotations.
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| 83 |
|
| 84 | #ifdef CONFIG_PROVE_RCU
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| 85 | DEFINE_MUTEX(cgroup_mutex);
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| 86 | DECLARE_RWSEM(css_set_rwsem);
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| 87 | EXPORT_SYMBOL_GPL(cgroup_mutex);
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| 88 | EXPORT_SYMBOL_GPL(css_set_rwsem);
|
| 89 | #else
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| 90 | static DEFINE_MUTEX(cgroup_mutex);
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| 91 | static DECLARE_RWSEM(css_set_rwsem);
|
| 92 | #endif
|
| 93 |
|
| 94 | |
| 95 | * Protects cgroup_idr and css_idr so that IDs can be released without
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| 96 | * grabbing cgroup_mutex.
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| 97 |
|
| 98 | static DEFINE_SPINLOCK(cgroup_idr_lock);
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| 99 |
|
| 100 | |
| 101 | * Protects cgroup_subsys->release_agent_path. Modifying it also requires
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| 102 | * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
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| 103 |
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| 104 | static DEFINE_SPINLOCK(release_agent_path_lock);
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| 105 |
|
| 106 | #define cgroup_assert_mutex_or_rcu_locked() \
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| 107 | rcu_lockdep_assert(rcu_read_lock_held() || \
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| 108 | lockdep_is_held(&cgroup_mutex), \
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| 109 | "cgroup_mutex or RCU read lock required");
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| 110 |
|
| 111 | |
| 112 | * cgroup destruction makes heavy use of work items and there can be a lot
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| 113 | * of concurrent destructions. Use a separate workqueue so that cgroup
|
| 114 | * destruction work items don't end up filling up max_active of system_wq
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| 115 | * which may lead to deadlock.
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| 116 |
|
| 117 | static struct workqueue_struct *cgroup_destroy_wq;
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| 118 |
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| 119 | |
| 120 | * pidlist destructions need to be flushed on cgroup destruction. Use a
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| 121 | * separate workqueue as flush domain.
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| 122 |
|
| 123 | static struct workqueue_struct *cgroup_pidlist_destroy_wq;
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| 124 |
|
| 125 |
|
| 126 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
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| 127 | static struct cgroup_subsys *cgroup_subsys[] = {
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| 128 | #include <linux/cgroup_subsys.h>
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| 129 | };
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| 130 | #undef SUBSYS
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| 131 |
|
| 132 |
|
| 133 | #define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
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| 134 | static const char *cgroup_subsys_name[] = {
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| 135 | #include <linux/cgroup_subsys.h>
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| 136 | };
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| 137 | #undef SUBSYS
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| 138 |
|
| 139 | |
| 140 | * The default hierarchy, reserved for the subsystems that are otherwise
|
| 141 | * unattached - it never has more than a single cgroup, and all tasks are
|
| 142 | * part of that cgroup.
|
| 143 |
|
| 144 | struct cgroup_root cgrp_dfl_root;
|
| 145 |
|
| 146 | |
| 147 | * The default hierarchy always exists but is hidden until mounted for the
|
| 148 | * first time. This is for backward compatibility.
|
| 149 |
|
| 150 | static bool cgrp_dfl_root_visible;
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| 151 |
|
| 152 | |
| 153 | * Set by the boot param of the same name and makes subsystems with NULL
|
| 154 | * ->dfl_files to use ->legacy_files on the default hierarchy.
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| 155 |
|
| 156 | static bool cgroup_legacy_files_on_dfl;
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| 157 |
|
| 158 |
|
| 159 | static unsigned int cgrp_dfl_root_inhibit_ss_mask;
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| 160 |
|
| 161 |
|
| 162 |
|
| 163 | static LIST_HEAD(cgroup_roots);
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| 164 | static int cgroup_root_count;
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| 165 |
|
| 166 |
|
| 167 | static DEFINE_IDR(cgroup_hierarchy_idr);
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| 168 |
|
| 169 | |
| 170 | * Assign a monotonically increasing serial number to csses. It guarantees
|
| 171 | * cgroups with bigger numbers are newer than those with smaller numbers.
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| 172 | * Also, as csses are always appended to the parent's ->children list, it
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| 173 | * guarantees that sibling csses are always sorted in the ascending serial
|
| 174 | * number order on the list. Protected by cgroup_mutex.
|
| 175 |
|
| 176 | static u64 css_serial_nr_next = 1;
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| 177 |
|
| 178 | |
| 179 | * check for fork/exit handlers to call. This avoids us having to do
|
| 180 | * extra work in the fork/exit path if none of the subsystems need to
|
| 181 | * be called.
|
| 182 |
|
| 183 | static int need_forkexit_callback __read_mostly;
|
| 184 |
|
| 185 | static struct cftype cgroup_dfl_base_files[];
|
| 186 | static struct cftype cgroup_legacy_base_files[];
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| 187 |
|
| 188 | static int rebind_subsystems(struct cgroup_root *dst_root,
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| 189 | unsigned int ss_mask);
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| 190 | static int cgroup_destroy_locked(struct cgroup *cgrp);
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| 191 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
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| 192 | bool visible);
|
| 193 | static void css_release(struct percpu_ref *ref);
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| 194 | static void kill_css(struct cgroup_subsys_state *css);
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| 195 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
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| 196 | bool is_add);
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| 197 |
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| 198 |
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| 199 | static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end,
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| 200 | gfp_t gfp_mask)
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| 201 | {
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| 202 | int ret;
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| 203 |
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| 204 | idr_preload(gfp_mask);
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| 205 | spin_lock_bh(&cgroup_idr_lock);
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| 206 | ret = idr_alloc(idr, ptr, start, end, gfp_mask);
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| 207 | spin_unlock_bh(&cgroup_idr_lock);
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| 208 | idr_preload_end();
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| 209 | return ret;
|
| 210 | }
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| 211 |
|
| 212 | static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id)
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| 213 | {
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| 214 | void *ret;
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| 215 |
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| 216 | spin_lock_bh(&cgroup_idr_lock);
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| 217 | ret = idr_replace(idr, ptr, id);
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| 218 | spin_unlock_bh(&cgroup_idr_lock);
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| 219 | return ret;
|
| 220 | }
|
| 221 |
|
| 222 | static void cgroup_idr_remove(struct idr *idr, int id)
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| 223 | {
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| 224 | spin_lock_bh(&cgroup_idr_lock);
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| 225 | idr_remove(idr, id);
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| 226 | spin_unlock_bh(&cgroup_idr_lock);
|
| 227 | }
|
| 228 |
|
| 229 | static struct cgroup *cgroup_parent(struct cgroup *cgrp)
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| 230 | {
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| 231 | struct cgroup_subsys_state *parent_css = cgrp->self.parent;
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| 232 |
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| 233 | if (parent_css)
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| 234 | return container_of(parent_css, struct cgroup, self);
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| 235 | return NULL;
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| 236 | }
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| 237 |
|
| 238 | |
| 239 | * cgroup_css - obtain a cgroup's css for the specified subsystem
|
| 240 | * @cgrp: the cgroup of interest
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| 241 | * @ss: the subsystem of interest (%NULL returns @cgrp->self)
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| 242 | *
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| 243 | * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
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| 244 | * function must be called either under cgroup_mutex or rcu_read_lock() and
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| 245 | * the caller is responsible for pinning the returned css if it wants to
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| 246 | * keep accessing it outside the said locks. This function may return
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| 247 | * %NULL if @cgrp doesn't have @subsys_id enabled.
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| 248 |
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| 249 | static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
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| 250 | struct cgroup_subsys *ss)
|
| 251 | {
|
| 252 | if (ss)
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| 253 | return rcu_dereference_check(cgrp->subsys[ss->id],
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| 254 | lockdep_is_held(&cgroup_mutex));
|
| 255 | else
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| 256 | return &cgrp->self;
|
| 257 | }
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| 258 |
|
| 259 | |
| 260 | * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
|
| 261 | * @cgrp: the cgroup of interest
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| 262 | * @ss: the subsystem of interest (%NULL returns @cgrp->self)
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| 263 | *
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| 264 | * Similar to cgroup_css() but returns the effctive css, which is defined
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| 265 | * as the matching css of the nearest ancestor including self which has @ss
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| 266 | * enabled. If @ss is associated with the hierarchy @cgrp is on, this
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| 267 | * function is guaranteed to return non-NULL css.
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| 268 |
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| 269 | static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
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| 270 | struct cgroup_subsys *ss)
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| 271 | {
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| 272 | lockdep_assert_held(&cgroup_mutex);
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| 273 |
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| 274 | if (!ss)
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| 275 | return &cgrp->self;
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| 276 |
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| 277 | if (!(cgrp->root->subsys_mask & (1 << ss->id)))
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| 278 | return NULL;
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| 279 |
|
| 280 | |
| 281 | * This function is used while updating css associations and thus
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| 282 | * can't test the csses directly. Use ->child_subsys_mask.
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| 283 |
|
| 284 | while (cgroup_parent(cgrp) &&
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| 285 | !(cgroup_parent(cgrp)->child_subsys_mask & (1 << ss->id)))
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| 286 | cgrp = cgroup_parent(cgrp);
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| 287 |
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| 288 | return cgroup_css(cgrp, ss);
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| 289 | }
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| 290 |
|
| 291 | |
| 292 | * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
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| 293 | * @cgrp: the cgroup of interest
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| 294 | * @ss: the subsystem of interest
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| 295 | *
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| 296 | * Find and get the effective css of @cgrp for @ss. The effective css is
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| 297 | * defined as the matching css of the nearest ancestor including self which
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| 298 | * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
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| 299 | * the root css is returned, so this function always returns a valid css.
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| 300 | * The returned css must be put using css_put().
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| 301 |
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| 302 | struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
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| 303 | struct cgroup_subsys *ss)
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| 304 | {
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| 305 | struct cgroup_subsys_state *css;
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| 306 |
|
| 307 | rcu_read_lock();
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| 308 |
|
| 309 | do {
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| 310 | css = cgroup_css(cgrp, ss);
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| 311 |
|
| 312 | if (css && css_tryget_online(css))
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| 313 | goto out_unlock;
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| 314 | cgrp = cgroup_parent(cgrp);
|
| 315 | } while (cgrp);
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| 316 |
|
| 317 | css = init_css_set.subsys[ss->id];
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| 318 | css_get(css);
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| 319 | out_unlock:
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| 320 | rcu_read_unlock();
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| 321 | return css;
|
| 322 | }
|
| 323 |
|
| 324 |
|
| 325 | static inline bool cgroup_is_dead(const struct cgroup *cgrp)
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| 326 | {
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| 327 | return !(cgrp->self.flags & CSS_ONLINE);
|
| 328 | }
|
| 329 |
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| 330 | struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
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| 331 | {
|
| 332 | struct cgroup *cgrp = of->kn->parent->priv;
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| 333 | struct cftype *cft = of_cft(of);
|
| 334 |
|
| 335 | |
| 336 | * This is open and unprotected implementation of cgroup_css().
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| 337 | * seq_css() is only called from a kernfs file operation which has
|
| 338 | * an active reference on the file. Because all the subsystem
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| 339 | * files are drained before a css is disassociated with a cgroup,
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| 340 | * the matching css from the cgroup's subsys table is guaranteed to
|
| 341 | * be and stay valid until the enclosing operation is complete.
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| 342 |
|
| 343 | if (cft->ss)
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| 344 | return rcu_dereference_raw(cgrp->subsys[cft->ss->id]);
|
| 345 | else
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| 346 | return &cgrp->self;
|
| 347 | }
|
| 348 | EXPORT_SYMBOL_GPL(of_css);
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| 349 |
|
| 350 | |
| 351 | * cgroup_is_descendant - test ancestry
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| 352 | * @cgrp: the cgroup to be tested
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| 353 | * @ancestor: possible ancestor of @cgrp
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| 354 | *
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| 355 | * Test whether @cgrp is a descendant of @ancestor. It also returns %true
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| 356 | * if @cgrp == @ancestor. This function is safe to call as long as @cgrp
|
| 357 | * and @ancestor are accessible.
|
| 358 |
|
| 359 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor)
|
| 360 | {
|
| 361 | while (cgrp) {
|
| 362 | if (cgrp == ancestor)
|
| 363 | return true;
|
| 364 | cgrp = cgroup_parent(cgrp);
|
| 365 | }
|
| 366 | return false;
|
| 367 | }
|
| 368 |
|
| 369 | static int notify_on_release(const struct cgroup *cgrp)
|
| 370 | {
|
| 371 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
|
| 372 | }
|
| 373 |
|
| 374 | |
| 375 | * for_each_css - iterate all css's of a cgroup
|
| 376 | * @css: the iteration cursor
|
| 377 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
|
| 378 | * @cgrp: the target cgroup to iterate css's of
|
| 379 | *
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| 380 | * Should be called under cgroup_[tree_]mutex.
|
| 381 |
|
| 382 | #define for_each_css(css, ssid, cgrp) \
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| 383 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
|
| 384 | if (!((css) = rcu_dereference_check( \
|
| 385 | (cgrp)->subsys[(ssid)], \
|
| 386 | lockdep_is_held(&cgroup_mutex)))) { } \
|
| 387 | else
|
| 388 |
|
| 389 | |
| 390 | * for_each_e_css - iterate all effective css's of a cgroup
|
| 391 | * @css: the iteration cursor
|
| 392 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
|
| 393 | * @cgrp: the target cgroup to iterate css's of
|
| 394 | *
|
| 395 | * Should be called under cgroup_[tree_]mutex.
|
| 396 |
|
| 397 | #define for_each_e_css(css, ssid, cgrp) \
|
| 398 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
|
| 399 | if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \
|
| 400 | ; \
|
| 401 | else
|
| 402 |
|
| 403 | |
| 404 | * for_each_subsys - iterate all enabled cgroup subsystems
|
| 405 | * @ss: the iteration cursor
|
| 406 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
|
| 407 |
|
| 408 | #define for_each_subsys(ss, ssid) \
|
| 409 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
|
| 410 | (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
|
| 411 |
|
| 412 |
|
| 413 | #define for_each_root(root) \
|
| 414 | list_for_each_entry((root), &cgroup_roots, root_list)
|
| 415 |
|
| 416 |
|
| 417 | #define cgroup_for_each_live_child(child, cgrp) \
|
| 418 | list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
|
| 419 | if (({ lockdep_assert_held(&cgroup_mutex); \
|
| 420 | cgroup_is_dead(child); })) \
|
| 421 | ; \
|
| 422 | else
|
| 423 |
|
| 424 | static void cgroup_release_agent(struct work_struct *work);
|
| 425 | static void check_for_release(struct cgroup *cgrp);
|
| 426 |
|
| 427 | |
| 428 | * A cgroup can be associated with multiple css_sets as different tasks may
|
| 429 | * belong to different cgroups on different hierarchies. In the other
|
| 430 | * direction, a css_set is naturally associated with multiple cgroups.
|
| 431 | * This M:N relationship is represented by the following link structure
|
| 432 | * which exists for each association and allows traversing the associations
|
| 433 | * from both sides.
|
| 434 |
|
| 435 | struct cgrp_cset_link {
|
| 436 |
|
| 437 | struct cgroup *cgrp;
|
| 438 | struct css_set *cset;
|
| 439 |
|
| 440 |
|
| 441 | struct list_head cset_link;
|
| 442 |
|
| 443 |
|
| 444 | struct list_head cgrp_link;
|
| 445 | };
|
| 446 |
|
| 447 | |
| 448 | * The default css_set - used by init and its children prior to any
|
| 449 | * hierarchies being mounted. It contains a pointer to the root state
|
| 450 | * for each subsystem. Also used to anchor the list of css_sets. Not
|
| 451 | * reference-counted, to improve performance when child cgroups
|
| 452 | * haven't been created.
|
| 453 |
|
| 454 | struct css_set init_css_set = {
|
| 455 | .refcount = ATOMIC_INIT(1),
|
| 456 | .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links),
|
| 457 | .tasks = LIST_HEAD_INIT(init_css_set.tasks),
|
| 458 | .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks),
|
| 459 | .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node),
|
| 460 | .mg_node = LIST_HEAD_INIT(init_css_set.mg_node),
|
| 461 | };
|
| 462 |
|
| 463 | static int css_set_count = 1;
|
| 464 |
|
| 465 | |
| 466 | * cgroup_update_populated - updated populated count of a cgroup
|
| 467 | * @cgrp: the target cgroup
|
| 468 | * @populated: inc or dec populated count
|
| 469 | *
|
| 470 | * @cgrp is either getting the first task (css_set) or losing the last.
|
| 471 | * Update @cgrp->populated_cnt accordingly. The count is propagated
|
| 472 | * towards root so that a given cgroup's populated_cnt is zero iff the
|
| 473 | * cgroup and all its descendants are empty.
|
| 474 | *
|
| 475 | * @cgrp's interface file "cgroup.populated" is zero if
|
| 476 | * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt
|
| 477 | * changes from or to zero, userland is notified that the content of the
|
| 478 | * interface file has changed. This can be used to detect when @cgrp and
|
| 479 | * its descendants become populated or empty.
|
| 480 |
|
| 481 | static void cgroup_update_populated(struct cgroup *cgrp, bool populated)
|
| 482 | {
|
| 483 | lockdep_assert_held(&css_set_rwsem);
|
| 484 |
|
| 485 | do {
|
| 486 | bool trigger;
|
| 487 |
|
| 488 | if (populated)
|
| 489 | trigger = !cgrp->populated_cnt++;
|
| 490 | else
|
| 491 | trigger = !--cgrp->populated_cnt;
|
| 492 |
|
| 493 | if (!trigger)
|
| 494 | break;
|
| 495 |
|
| 496 | if (cgrp->populated_kn)
|
| 497 | kernfs_notify(cgrp->populated_kn);
|
| 498 | cgrp = cgroup_parent(cgrp);
|
| 499 | } while (cgrp);
|
| 500 | }
|
| 501 |
|
| 502 | |
| 503 | * hash table for cgroup groups. This improves the performance to find
|
| 504 | * an existing css_set. This hash doesn't (currently) take into
|
| 505 | * account cgroups in empty hierarchies.
|
| 506 |
|
| 507 | #define CSS_SET_HASH_BITS 7
|
| 508 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
|
| 509 |
|
| 510 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
|
| 511 | {
|
| 512 | unsigned long key = 0UL;
|
| 513 | struct cgroup_subsys *ss;
|
| 514 | int i;
|
| 515 |
|
| 516 | for_each_subsys(ss, i)
|
| 517 | key += (unsigned long)css[i];
|
| 518 | key = (key >> 16) ^ key;
|
| 519 |
|
| 520 | return key;
|
| 521 | }
|
| 522 |
|
| 523 | static void put_css_set_locked(struct css_set *cset)
|
| 524 | {
|
| 525 | struct cgrp_cset_link *link, *tmp_link;
|
| 526 | struct cgroup_subsys *ss;
|
| 527 | int ssid;
|
| 528 |
|
| 529 | lockdep_assert_held(&css_set_rwsem);
|
| 530 |
|
| 531 | if (!atomic_dec_and_test(&cset->refcount))
|
| 532 | return;
|
| 533 |
|
| 534 |
|
| 535 | for_each_subsys(ss, ssid)
|
| 536 | list_del(&cset->e_cset_node[ssid]);
|
| 537 | hash_del(&cset->hlist);
|
| 538 | css_set_count--;
|
| 539 |
|
| 540 | list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) {
|
| 541 | struct cgroup *cgrp = link->cgrp;
|
| 542 |
|
| 543 | list_del(&link->cset_link);
|
| 544 | list_del(&link->cgrp_link);
|
| 545 |
|
| 546 |
|
| 547 | if (list_empty(&cgrp->cset_links)) {
|
| 548 | cgroup_update_populated(cgrp, false);
|
| 549 | check_for_release(cgrp);
|
| 550 | }
|
| 551 |
|
| 552 | kfree(link);
|
| 553 | }
|
| 554 |
|
| 555 | kfree_rcu(cset, rcu_head);
|
| 556 | }
|
| 557 |
|
| 558 | static void put_css_set(struct css_set *cset)
|
| 559 | {
|
| 560 | |
| 561 | * Ensure that the refcount doesn't hit zero while any readers
|
| 562 | * can see it. Similar to atomic_dec_and_lock(), but for an
|
| 563 | * rwlock
|
| 564 |
|
| 565 | if (atomic_add_unless(&cset->refcount, -1, 1))
|
| 566 | return;
|
| 567 |
|
| 568 | down_write(&css_set_rwsem);
|
| 569 | put_css_set_locked(cset);
|
| 570 | up_write(&css_set_rwsem);
|
| 571 | }
|
| 572 |
|
| 573 | |
| 574 | * refcounted get/put for css_set objects
|
| 575 |
|
| 576 | static inline void get_css_set(struct css_set *cset)
|
| 577 | {
|
| 578 | atomic_inc(&cset->refcount);
|
| 579 | }
|
| 580 |
|
| 581 | |
| 582 | * compare_css_sets - helper function for find_existing_css_set().
|
| 583 | * @cset: candidate css_set being tested
|
| 584 | * @old_cset: existing css_set for a task
|
| 585 | * @new_cgrp: cgroup that's being entered by the task
|
| 586 | * @template: desired set of css pointers in css_set (pre-calculated)
|
| 587 | *
|
| 588 | * Returns true if "cset" matches "old_cset" except for the hierarchy
|
| 589 | * which "new_cgrp" belongs to, for which it should match "new_cgrp".
|
| 590 |
|
| 591 | static bool compare_css_sets(struct css_set *cset,
|
| 592 | struct css_set *old_cset,
|
| 593 | struct cgroup *new_cgrp,
|
| 594 | struct cgroup_subsys_state *template[])
|
| 595 | {
|
| 596 | struct list_head *l1, *l2;
|
| 597 |
|
| 598 | |
| 599 | * On the default hierarchy, there can be csets which are
|
| 600 | * associated with the same set of cgroups but different csses.
|
| 601 | * Let's first ensure that csses match.
|
| 602 |
|
| 603 | if (memcmp(template, cset->subsys, sizeof(cset->subsys)))
|
| 604 | return false;
|
| 605 |
|
| 606 | |
| 607 | * Compare cgroup pointers in order to distinguish between
|
| 608 | * different cgroups in hierarchies. As different cgroups may
|
| 609 | * share the same effective css, this comparison is always
|
| 610 | * necessary.
|
| 611 |
|
| 612 | l1 = &cset->cgrp_links;
|
| 613 | l2 = &old_cset->cgrp_links;
|
| 614 | while (1) {
|
| 615 | struct cgrp_cset_link *link1, *link2;
|
| 616 | struct cgroup *cgrp1, *cgrp2;
|
| 617 |
|
| 618 | l1 = l1->next;
|
| 619 | l2 = l2->next;
|
| 620 |
|
| 621 | if (l1 == &cset->cgrp_links) {
|
| 622 | BUG_ON(l2 != &old_cset->cgrp_links);
|
| 623 | break;
|
| 624 | } else {
|
| 625 | BUG_ON(l2 == &old_cset->cgrp_links);
|
| 626 | }
|
| 627 |
|
| 628 | link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link);
|
| 629 | link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link);
|
| 630 | cgrp1 = link1->cgrp;
|
| 631 | cgrp2 = link2->cgrp;
|
| 632 |
|
| 633 | BUG_ON(cgrp1->root != cgrp2->root);
|
| 634 |
|
| 635 | |
| 636 | * If this hierarchy is the hierarchy of the cgroup
|
| 637 | * that's changing, then we need to check that this
|
| 638 | * css_set points to the new cgroup; if it's any other
|
| 639 | * hierarchy, then this css_set should point to the
|
| 640 | * same cgroup as the old css_set.
|
| 641 |
|
| 642 | if (cgrp1->root == new_cgrp->root) {
|
| 643 | if (cgrp1 != new_cgrp)
|
| 644 | return false;
|
| 645 | } else {
|
| 646 | if (cgrp1 != cgrp2)
|
| 647 | return false;
|
| 648 | }
|
| 649 | }
|
| 650 | return true;
|
| 651 | }
|
| 652 |
|
| 653 | |
| 654 | * find_existing_css_set - init css array and find the matching css_set
|
| 655 | * @old_cset: the css_set that we're using before the cgroup transition
|
| 656 | * @cgrp: the cgroup that we're moving into
|
| 657 | * @template: out param for the new set of csses, should be clear on entry
|
| 658 |
|
| 659 | static struct css_set *find_existing_css_set(struct css_set *old_cset,
|
| 660 | struct cgroup *cgrp,
|
| 661 | struct cgroup_subsys_state *template[])
|
| 662 | {
|
| 663 | struct cgroup_root *root = cgrp->root;
|
| 664 | struct cgroup_subsys *ss;
|
| 665 | struct css_set *cset;
|
| 666 | unsigned long key;
|
| 667 | int i;
|
| 668 |
|
| 669 | |
| 670 | * Build the set of subsystem state objects that we want to see in the
|
| 671 | * new css_set. while subsystems can change globally, the entries here
|
| 672 | * won't change, so no need for locking.
|
| 673 |
|
| 674 | for_each_subsys(ss, i) {
|
| 675 | if (root->subsys_mask & (1UL << i)) {
|
| 676 | |
| 677 | * @ss is in this hierarchy, so we want the
|
| 678 | * effective css from @cgrp.
|
| 679 |
|
| 680 | template[i] = cgroup_e_css(cgrp, ss);
|
| 681 | } else {
|
| 682 | |
| 683 | * @ss is not in this hierarchy, so we don't want
|
| 684 | * to change the css.
|
| 685 |
|
| 686 | template[i] = old_cset->subsys[i];
|
| 687 | }
|
| 688 | }
|
| 689 |
|
| 690 | key = css_set_hash(template);
|
| 691 | hash_for_each_possible(css_set_table, cset, hlist, key) {
|
| 692 | if (!compare_css_sets(cset, old_cset, cgrp, template))
|
| 693 | continue;
|
| 694 |
|
| 695 |
|
| 696 | return cset;
|
| 697 | }
|
| 698 |
|
| 699 |
|
| 700 | return NULL;
|
| 701 | }
|
| 702 |
|
| 703 | static void free_cgrp_cset_links(struct list_head *links_to_free)
|
| 704 | {
|
| 705 | struct cgrp_cset_link *link, *tmp_link;
|
| 706 |
|
| 707 | list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) {
|
| 708 | list_del(&link->cset_link);
|
| 709 | kfree(link);
|
| 710 | }
|
| 711 | }
|
| 712 |
|
| 713 | |
| 714 | * allocate_cgrp_cset_links - allocate cgrp_cset_links
|
| 715 | * @count: the number of links to allocate
|
| 716 | * @tmp_links: list_head the allocated links are put on
|
| 717 | *
|
| 718 | * Allocate @count cgrp_cset_link structures and chain them on @tmp_links
|
| 719 | * through ->cset_link. Returns 0 on success or -errno.
|
| 720 |
|
| 721 | static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links)
|
| 722 | {
|
| 723 | struct cgrp_cset_link *link;
|
| 724 | int i;
|
| 725 |
|
| 726 | INIT_LIST_HEAD(tmp_links);
|
| 727 |
|
| 728 | for (i = 0; i < count; i++) {
|
| 729 | link = kzalloc(sizeof(*link), GFP_KERNEL);
|
| 730 | if (!link) {
|
| 731 | free_cgrp_cset_links(tmp_links);
|
| 732 | return -ENOMEM;
|
| 733 | }
|
| 734 | list_add(&link->cset_link, tmp_links);
|
| 735 | }
|
| 736 | return 0;
|
| 737 | }
|
| 738 |
|
| 739 | |
| 740 | * link_css_set - a helper function to link a css_set to a cgroup
|
| 741 | * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
|
| 742 | * @cset: the css_set to be linked
|
| 743 | * @cgrp: the destination cgroup
|
| 744 |
|
| 745 | static void link_css_set(struct list_head *tmp_links, struct css_set *cset,
|
| 746 | struct cgroup *cgrp)
|
| 747 | {
|
| 748 | struct cgrp_cset_link *link;
|
| 749 |
|
| 750 | BUG_ON(list_empty(tmp_links));
|
| 751 |
|
| 752 | if (cgroup_on_dfl(cgrp))
|
| 753 | cset->dfl_cgrp = cgrp;
|
| 754 |
|
| 755 | link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link);
|
| 756 | link->cset = cset;
|
| 757 | link->cgrp = cgrp;
|
| 758 |
|
| 759 | if (list_empty(&cgrp->cset_links))
|
| 760 | cgroup_update_populated(cgrp, true);
|
| 761 | list_move(&link->cset_link, &cgrp->cset_links);
|
| 762 |
|
| 763 | |
| 764 | * Always add links to the tail of the list so that the list
|
| 765 | * is sorted by order of hierarchy creation
|
| 766 |
|
| 767 | list_add_tail(&link->cgrp_link, &cset->cgrp_links);
|
| 768 | }
|
| 769 |
|
| 770 | |
| 771 | * find_css_set - return a new css_set with one cgroup updated
|
| 772 | * @old_cset: the baseline css_set
|
| 773 | * @cgrp: the cgroup to be updated
|
| 774 | *
|
| 775 | * Return a new css_set that's equivalent to @old_cset, but with @cgrp
|
| 776 | * substituted into the appropriate hierarchy.
|
| 777 |
|
| 778 | static struct css_set *find_css_set(struct css_set *old_cset,
|
| 779 | struct cgroup *cgrp)
|
| 780 | {
|
| 781 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { };
|
| 782 | struct css_set *cset;
|
| 783 | struct list_head tmp_links;
|
| 784 | struct cgrp_cset_link *link;
|
| 785 | struct cgroup_subsys *ss;
|
| 786 | unsigned long key;
|
| 787 | int ssid;
|
| 788 |
|
| 789 | lockdep_assert_held(&cgroup_mutex);
|
| 790 |
|
| 791 | |
| 792 | * the desired set
|
| 793 | down_read(&css_set_rwsem);
|
| 794 | cset = find_existing_css_set(old_cset, cgrp, template);
|
| 795 | if (cset)
|
| 796 | get_css_set(cset);
|
| 797 | up_read(&css_set_rwsem);
|
| 798 |
|
| 799 | if (cset)
|
| 800 | return cset;
|
| 801 |
|
| 802 | cset = kzalloc(sizeof(*cset), GFP_KERNEL);
|
| 803 | if (!cset)
|
| 804 | return NULL;
|
| 805 |
|
| 806 |
|
| 807 | if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) {
|
| 808 | kfree(cset);
|
| 809 | return NULL;
|
| 810 | }
|
| 811 |
|
| 812 | atomic_set(&cset->refcount, 1);
|
| 813 | INIT_LIST_HEAD(&cset->cgrp_links);
|
| 814 | INIT_LIST_HEAD(&cset->tasks);
|
| 815 | INIT_LIST_HEAD(&cset->mg_tasks);
|
| 816 | INIT_LIST_HEAD(&cset->mg_preload_node);
|
| 817 | INIT_LIST_HEAD(&cset->mg_node);
|
| 818 | INIT_HLIST_NODE(&cset->hlist);
|
| 819 |
|
| 820 | |
| 821 | * find_existing_css_set()
|
| 822 | memcpy(cset->subsys, template, sizeof(cset->subsys));
|
| 823 |
|
| 824 | down_write(&css_set_rwsem);
|
| 825 |
|
| 826 | list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) {
|
| 827 | struct cgroup *c = link->cgrp;
|
| 828 |
|
| 829 | if (c->root == cgrp->root)
|
| 830 | c = cgrp;
|
| 831 | link_css_set(&tmp_links, cset, c);
|
| 832 | }
|
| 833 |
|
| 834 | BUG_ON(!list_empty(&tmp_links));
|
| 835 |
|
| 836 | css_set_count++;
|
| 837 |
|
| 838 |
|
| 839 | key = css_set_hash(cset->subsys);
|
| 840 | hash_add(css_set_table, &cset->hlist, key);
|
| 841 |
|
| 842 | for_each_subsys(ss, ssid)
|
| 843 | list_add_tail(&cset->e_cset_node[ssid],
|
| 844 | &cset->subsys[ssid]->cgroup->e_csets[ssid]);
|
| 845 |
|
| 846 | up_write(&css_set_rwsem);
|
| 847 |
|
| 848 | return cset;
|
| 849 | }
|
| 850 |
|
| 851 | static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
|
| 852 | {
|
| 853 | struct cgroup *root_cgrp = kf_root->kn->priv;
|
| 854 |
|
| 855 | return root_cgrp->root;
|
| 856 | }
|
| 857 |
|
| 858 | static int cgroup_init_root_id(struct cgroup_root *root)
|
| 859 | {
|
| 860 | int id;
|
| 861 |
|
| 862 | lockdep_assert_held(&cgroup_mutex);
|
| 863 |
|
| 864 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL);
|
| 865 | if (id < 0)
|
| 866 | return id;
|
| 867 |
|
| 868 | root->hierarchy_id = id;
|
| 869 | return 0;
|
| 870 | }
|
| 871 |
|
| 872 | static void cgroup_exit_root_id(struct cgroup_root *root)
|
| 873 | {
|
| 874 | lockdep_assert_held(&cgroup_mutex);
|
| 875 |
|
| 876 | if (root->hierarchy_id) {
|
| 877 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
|
| 878 | root->hierarchy_id = 0;
|
| 879 | }
|
| 880 | }
|
| 881 |
|
| 882 | static void cgroup_free_root(struct cgroup_root *root)
|
| 883 | {
|
| 884 | if (root) {
|
| 885 |
|
| 886 | WARN_ON_ONCE(root->hierarchy_id);
|
| 887 |
|
| 888 | idr_destroy(&root->cgroup_idr);
|
| 889 | kfree(root);
|
| 890 | }
|
| 891 | }
|
| 892 |
|
| 893 | static void cgroup_destroy_root(struct cgroup_root *root)
|
| 894 | {
|
| 895 | struct cgroup *cgrp = &root->cgrp;
|
| 896 | struct cgrp_cset_link *link, *tmp_link;
|
| 897 |
|
| 898 | mutex_lock(&cgroup_mutex);
|
| 899 |
|
| 900 | BUG_ON(atomic_read(&root->nr_cgrps));
|
| 901 | BUG_ON(!list_empty(&cgrp->self.children));
|
| 902 |
|
| 903 |
|
| 904 | rebind_subsystems(&cgrp_dfl_root, root->subsys_mask);
|
| 905 |
|
| 906 | |
| 907 | * Release all the links from cset_links to this hierarchy's
|
| 908 | * root cgroup
|
| 909 |
|
| 910 | down_write(&css_set_rwsem);
|
| 911 |
|
| 912 | list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
|
| 913 | list_del(&link->cset_link);
|
| 914 | list_del(&link->cgrp_link);
|
| 915 | kfree(link);
|
| 916 | }
|
| 917 | up_write(&css_set_rwsem);
|
| 918 |
|
| 919 | if (!list_empty(&root->root_list)) {
|
| 920 | list_del(&root->root_list);
|
| 921 | cgroup_root_count--;
|
| 922 | }
|
| 923 |
|
| 924 | cgroup_exit_root_id(root);
|
| 925 |
|
| 926 | mutex_unlock(&cgroup_mutex);
|
| 927 |
|
| 928 | kernfs_destroy_root(root->kf_root);
|
| 929 | cgroup_free_root(root);
|
| 930 | }
|
| 931 |
|
| 932 |
|
| 933 | static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
|
| 934 | struct cgroup_root *root)
|
| 935 | {
|
| 936 | struct cgroup *res = NULL;
|
| 937 |
|
| 938 | lockdep_assert_held(&cgroup_mutex);
|
| 939 | lockdep_assert_held(&css_set_rwsem);
|
| 940 |
|
| 941 | if (cset == &init_css_set) {
|
| 942 | res = &root->cgrp;
|
| 943 | } else {
|
| 944 | struct cgrp_cset_link *link;
|
| 945 |
|
| 946 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
|
| 947 | struct cgroup *c = link->cgrp;
|
| 948 |
|
| 949 | if (c->root == root) {
|
| 950 | res = c;
|
| 951 | break;
|
| 952 | }
|
| 953 | }
|
| 954 | }
|
| 955 |
|
| 956 | BUG_ON(!res);
|
| 957 | return res;
|
| 958 | }
|
| 959 |
|
| 960 | |
| 961 | * Return the cgroup for "task" from the given hierarchy. Must be
|
| 962 | * called with cgroup_mutex and css_set_rwsem held.
|
| 963 |
|
| 964 | static struct cgroup *task_cgroup_from_root(struct task_struct *task,
|
| 965 | struct cgroup_root *root)
|
| 966 | {
|
| 967 | |
| 968 | * No need to lock the task - since we hold cgroup_mutex the
|
| 969 | * task can't change groups, so the only thing that can happen
|
| 970 | * is that it exits and its css is set back to init_css_set.
|
| 971 |
|
| 972 | return cset_cgroup_from_root(task_css_set(task), root);
|
| 973 | }
|
| 974 |
|
| 975 | |
| 976 | * A task must hold cgroup_mutex to modify cgroups.
|
| 977 | *
|
| 978 | * Any task can increment and decrement the count field without lock.
|
| 979 | * So in general, code holding cgroup_mutex can't rely on the count
|
| 980 | * field not changing. However, if the count goes to zero, then only
|
| 981 | * cgroup_attach_task() can increment it again. Because a count of zero
|
| 982 | * means that no tasks are currently attached, therefore there is no
|
| 983 | * way a task attached to that cgroup can fork (the other way to
|
| 984 | * increment the count). So code holding cgroup_mutex can safely
|
| 985 | * assume that if the count is zero, it will stay zero. Similarly, if
|
| 986 | * a task holds cgroup_mutex on a cgroup with zero count, it
|
| 987 | * knows that the cgroup won't be removed, as cgroup_rmdir()
|
| 988 | * needs that mutex.
|
| 989 | *
|
| 990 | * A cgroup can only be deleted if both its 'count' of using tasks
|
| 991 | * is zero, and its list of 'children' cgroups is empty. Since all
|
| 992 | * tasks in the system use _some_ cgroup, and since there is always at
|
| 993 | * least one task in the system (init, pid == 1), therefore, root cgroup
|
| 994 | * always has either children cgroups and/or using tasks. So we don't
|
| 995 | * need a special hack to ensure that root cgroup cannot be deleted.
|
| 996 | *
|
| 997 | * P.S. One more locking exception. RCU is used to guard the
|
| 998 | * update of a tasks cgroup pointer by cgroup_attach_task()
|
| 999 |
|
| 1000 |
|
| 1001 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned int subsys_mask);
|
| 1002 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
|
| 1003 | static const struct file_operations proc_cgroupstats_operations;
|
| 1004 |
|
| 1005 | static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
|
| 1006 | char *buf)
|
| 1007 | {
|
| 1008 | if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
|
| 1009 | !(cgrp->root->flags & CGRP_ROOT_NOPREFIX))
|
| 1010 | snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s",
|
| 1011 | cft->ss->name, cft->name);
|
| 1012 | else
|
| 1013 | strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
|
| 1014 | return buf;
|
| 1015 | }
|
| 1016 |
|
| 1017 | |
| 1018 | * cgroup_file_mode - deduce file mode of a control file
|
| 1019 | * @cft: the control file in question
|
| 1020 | *
|
| 1021 | * returns cft->mode if ->mode is not 0
|
| 1022 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler
|
| 1023 | * returns S_IRUGO if it has only a read handler
|
| 1024 | * returns S_IWUSR if it has only a write hander
|
| 1025 |
|
| 1026 | static umode_t cgroup_file_mode(const struct cftype *cft)
|
| 1027 | {
|
| 1028 | umode_t mode = 0;
|
| 1029 |
|
| 1030 | if (cft->mode)
|
| 1031 | return cft->mode;
|
| 1032 |
|
| 1033 | if (cft->read_u64 || cft->read_s64 || cft->seq_show)
|
| 1034 | mode |= S_IRUGO;
|
| 1035 |
|
| 1036 | if (cft->write_u64 || cft->write_s64 || cft->write)
|
| 1037 | mode |= S_IWUSR;
|
| 1038 |
|
| 1039 | return mode;
|
| 1040 | }
|
| 1041 |
|
| 1042 | static void cgroup_get(struct cgroup *cgrp)
|
| 1043 | {
|
| 1044 | WARN_ON_ONCE(cgroup_is_dead(cgrp));
|
| 1045 | css_get(&cgrp->self);
|
| 1046 | }
|
| 1047 |
|
| 1048 | static bool cgroup_tryget(struct cgroup *cgrp)
|
| 1049 | {
|
| 1050 | return css_tryget(&cgrp->self);
|
| 1051 | }
|
| 1052 |
|
| 1053 | static void cgroup_put(struct cgroup *cgrp)
|
| 1054 | {
|
| 1055 | css_put(&cgrp->self);
|
| 1056 | }
|
| 1057 |
|
| 1058 | |
| 1059 | * cgroup_calc_child_subsys_mask - calculate child_subsys_mask
|
| 1060 | * @cgrp: the target cgroup
|
| 1061 | * @subtree_control: the new subtree_control mask to consider
|
| 1062 | *
|
| 1063 | * On the default hierarchy, a subsystem may request other subsystems to be
|
| 1064 | * enabled together through its ->depends_on mask. In such cases, more
|
| 1065 | * subsystems than specified in "cgroup.subtree_control" may be enabled.
|
| 1066 | *
|
| 1067 | * This function calculates which subsystems need to be enabled if
|
| 1068 | * @subtree_control is to be applied to @cgrp. The returned mask is always
|
| 1069 | * a superset of @subtree_control and follows the usual hierarchy rules.
|
| 1070 |
|
| 1071 | static unsigned int cgroup_calc_child_subsys_mask(struct cgroup *cgrp,
|
| 1072 | unsigned int subtree_control)
|
| 1073 | {
|
| 1074 | struct cgroup *parent = cgroup_parent(cgrp);
|
| 1075 | unsigned int cur_ss_mask = subtree_control;
|
| 1076 | struct cgroup_subsys *ss;
|
| 1077 | int ssid;
|
| 1078 |
|
| 1079 | lockdep_assert_held(&cgroup_mutex);
|
| 1080 |
|
| 1081 | if (!cgroup_on_dfl(cgrp))
|
| 1082 | return cur_ss_mask;
|
| 1083 |
|
| 1084 | while (true) {
|
| 1085 | unsigned int new_ss_mask = cur_ss_mask;
|
| 1086 |
|
| 1087 | for_each_subsys(ss, ssid)
|
| 1088 | if (cur_ss_mask & (1 << ssid))
|
| 1089 | new_ss_mask |= ss->depends_on;
|
| 1090 |
|
| 1091 | |
| 1092 | * Mask out subsystems which aren't available. This can
|
| 1093 | * happen only if some depended-upon subsystems were bound
|
| 1094 | * to non-default hierarchies.
|
| 1095 |
|
| 1096 | if (parent)
|
| 1097 | new_ss_mask &= parent->child_subsys_mask;
|
| 1098 | else
|
| 1099 | new_ss_mask &= cgrp->root->subsys_mask;
|
| 1100 |
|
| 1101 | if (new_ss_mask == cur_ss_mask)
|
| 1102 | break;
|
| 1103 | cur_ss_mask = new_ss_mask;
|
| 1104 | }
|
| 1105 |
|
| 1106 | return cur_ss_mask;
|
| 1107 | }
|
| 1108 |
|
| 1109 | |
| 1110 | * cgroup_refresh_child_subsys_mask - update child_subsys_mask
|
| 1111 | * @cgrp: the target cgroup
|
| 1112 | *
|
| 1113 | * Update @cgrp->child_subsys_mask according to the current
|
| 1114 | * @cgrp->subtree_control using cgroup_calc_child_subsys_mask().
|
| 1115 |
|
| 1116 | static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp)
|
| 1117 | {
|
| 1118 | cgrp->child_subsys_mask =
|
| 1119 | cgroup_calc_child_subsys_mask(cgrp, cgrp->subtree_control);
|
| 1120 | }
|
| 1121 |
|
| 1122 | |
| 1123 | * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
|
| 1124 | * @kn: the kernfs_node being serviced
|
| 1125 | *
|
| 1126 | * This helper undoes cgroup_kn_lock_live() and should be invoked before
|
| 1127 | * the method finishes if locking succeeded. Note that once this function
|
| 1128 | * returns the cgroup returned by cgroup_kn_lock_live() may become
|
| 1129 | * inaccessible any time. If the caller intends to continue to access the
|
| 1130 | * cgroup, it should pin it before invoking this function.
|
| 1131 |
|
| 1132 | static void cgroup_kn_unlock(struct kernfs_node *kn)
|
| 1133 | {
|
| 1134 | struct cgroup *cgrp;
|
| 1135 |
|
| 1136 | if (kernfs_type(kn) == KERNFS_DIR)
|
| 1137 | cgrp = kn->priv;
|
| 1138 | else
|
| 1139 | cgrp = kn->parent->priv;
|
| 1140 |
|
| 1141 | mutex_unlock(&cgroup_mutex);
|
| 1142 |
|
| 1143 | kernfs_unbreak_active_protection(kn);
|
| 1144 | cgroup_put(cgrp);
|
| 1145 | }
|
| 1146 |
|
| 1147 | |
| 1148 | * cgroup_kn_lock_live - locking helper for cgroup kernfs methods
|
| 1149 | * @kn: the kernfs_node being serviced
|
| 1150 | *
|
| 1151 | * This helper is to be used by a cgroup kernfs method currently servicing
|
| 1152 | * @kn. It breaks the active protection, performs cgroup locking and
|
| 1153 | * verifies that the associated cgroup is alive. Returns the cgroup if
|
| 1154 | * alive; otherwise, %NULL. A successful return should be undone by a
|
| 1155 | * matching cgroup_kn_unlock() invocation.
|
| 1156 | *
|
| 1157 | * Any cgroup kernfs method implementation which requires locking the
|
| 1158 | * associated cgroup should use this helper. It avoids nesting cgroup
|
| 1159 | * locking under kernfs active protection and allows all kernfs operations
|
| 1160 | * including self-removal.
|
| 1161 |
|
| 1162 | static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn)
|
| 1163 | {
|
| 1164 | struct cgroup *cgrp;
|
| 1165 |
|
| 1166 | if (kernfs_type(kn) == KERNFS_DIR)
|
| 1167 | cgrp = kn->priv;
|
| 1168 | else
|
| 1169 | cgrp = kn->parent->priv;
|
| 1170 |
|
| 1171 | |
| 1172 | * We're gonna grab cgroup_mutex which nests outside kernfs
|
| 1173 | * active_ref. cgroup liveliness check alone provides enough
|
| 1174 | * protection against removal. Ensure @cgrp stays accessible and
|
| 1175 | * break the active_ref protection.
|
| 1176 |
|
| 1177 | if (!cgroup_tryget(cgrp))
|
| 1178 | return NULL;
|
| 1179 | kernfs_break_active_protection(kn);
|
| 1180 |
|
| 1181 | mutex_lock(&cgroup_mutex);
|
| 1182 |
|
| 1183 | if (!cgroup_is_dead(cgrp))
|
| 1184 | return cgrp;
|
| 1185 |
|
| 1186 | cgroup_kn_unlock(kn);
|
| 1187 | return NULL;
|
| 1188 | }
|
| 1189 |
|
| 1190 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
|
| 1191 | {
|
| 1192 | char name[CGROUP_FILE_NAME_MAX];
|
| 1193 |
|
| 1194 | lockdep_assert_held(&cgroup_mutex);
|
| 1195 | kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
|
| 1196 | }
|
| 1197 |
|
| 1198 | |
| 1199 | * cgroup_clear_dir - remove subsys files in a cgroup directory
|
| 1200 | * @cgrp: target cgroup
|
| 1201 | * @subsys_mask: mask of the subsystem ids whose files should be removed
|
| 1202 |
|
| 1203 | static void cgroup_clear_dir(struct cgroup *cgrp, unsigned int subsys_mask)
|
| 1204 | {
|
| 1205 | struct cgroup_subsys *ss;
|
| 1206 | int i;
|
| 1207 |
|
| 1208 | for_each_subsys(ss, i) {
|
| 1209 | struct cftype *cfts;
|
| 1210 |
|
| 1211 | if (!(subsys_mask & (1 << i)))
|
| 1212 | continue;
|
| 1213 | list_for_each_entry(cfts, &ss->cfts, node)
|
| 1214 | cgroup_addrm_files(cgrp, cfts, false);
|
| 1215 | }
|
| 1216 | }
|
| 1217 |
|
| 1218 | static int rebind_subsystems(struct cgroup_root *dst_root, unsigned int ss_mask)
|
| 1219 | {
|
| 1220 | struct cgroup_subsys *ss;
|
| 1221 | unsigned int tmp_ss_mask;
|
| 1222 | int ssid, i, ret;
|
| 1223 |
|
| 1224 | lockdep_assert_held(&cgroup_mutex);
|
| 1225 |
|
| 1226 | for_each_subsys(ss, ssid) {
|
| 1227 | if (!(ss_mask & (1 << ssid)))
|
| 1228 | continue;
|
| 1229 |
|
| 1230 |
|
| 1231 | if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss)))
|
| 1232 | return -EBUSY;
|
| 1233 |
|
| 1234 |
|
| 1235 | if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root)
|
| 1236 | return -EBUSY;
|
| 1237 | }
|
| 1238 |
|
| 1239 |
|
| 1240 | tmp_ss_mask = ss_mask;
|
| 1241 | if (dst_root == &cgrp_dfl_root)
|
| 1242 | tmp_ss_mask &= ~cgrp_dfl_root_inhibit_ss_mask;
|
| 1243 |
|
| 1244 | ret = cgroup_populate_dir(&dst_root->cgrp, tmp_ss_mask);
|
| 1245 | if (ret) {
|
| 1246 | if (dst_root != &cgrp_dfl_root)
|
| 1247 | return ret;
|
| 1248 |
|
| 1249 | |
| 1250 | * Rebinding back to the default root is not allowed to
|
| 1251 | * fail. Using both default and non-default roots should
|
| 1252 | * be rare. Moving subsystems back and forth even more so.
|
| 1253 | * Just warn about it and continue.
|
| 1254 |
|
| 1255 | if (cgrp_dfl_root_visible) {
|
| 1256 | pr_warn("failed to create files (%d) while rebinding 0x%x to default root\n",
|
| 1257 | ret, ss_mask);
|
| 1258 | pr_warn("you may retry by moving them to a different hierarchy and unbinding\n");
|
| 1259 | }
|
| 1260 | }
|
| 1261 |
|
| 1262 | |
| 1263 | * Nothing can fail from this point on. Remove files for the
|
| 1264 | * removed subsystems and rebind each subsystem.
|
| 1265 |
|
| 1266 | for_each_subsys(ss, ssid)
|
| 1267 | if (ss_mask & (1 << ssid))
|
| 1268 | cgroup_clear_dir(&ss->root->cgrp, 1 << ssid);
|
| 1269 |
|
| 1270 | for_each_subsys(ss, ssid) {
|
| 1271 | struct cgroup_root *src_root;
|
| 1272 | struct cgroup_subsys_state *css;
|
| 1273 | struct css_set *cset;
|
| 1274 |
|
| 1275 | if (!(ss_mask & (1 << ssid)))
|
| 1276 | continue;
|
| 1277 |
|
| 1278 | src_root = ss->root;
|
| 1279 | css = cgroup_css(&src_root->cgrp, ss);
|
| 1280 |
|
| 1281 | WARN_ON(!css || cgroup_css(&dst_root->cgrp, ss));
|
| 1282 |
|
| 1283 | RCU_INIT_POINTER(src_root->cgrp.subsys[ssid], NULL);
|
| 1284 | rcu_assign_pointer(dst_root->cgrp.subsys[ssid], css);
|
| 1285 | ss->root = dst_root;
|
| 1286 | css->cgroup = &dst_root->cgrp;
|
| 1287 |
|
| 1288 | down_write(&css_set_rwsem);
|
| 1289 | hash_for_each(css_set_table, i, cset, hlist)
|
| 1290 | list_move_tail(&cset->e_cset_node[ss->id],
|
| 1291 | &dst_root->cgrp.e_csets[ss->id]);
|
| 1292 | up_write(&css_set_rwsem);
|
| 1293 |
|
| 1294 | src_root->subsys_mask &= ~(1 << ssid);
|
| 1295 | src_root->cgrp.subtree_control &= ~(1 << ssid);
|
| 1296 | cgroup_refresh_child_subsys_mask(&src_root->cgrp);
|
| 1297 |
|
| 1298 |
|
| 1299 | dst_root->subsys_mask |= 1 << ssid;
|
| 1300 | if (dst_root != &cgrp_dfl_root) {
|
| 1301 | dst_root->cgrp.subtree_control |= 1 << ssid;
|
| 1302 | cgroup_refresh_child_subsys_mask(&dst_root->cgrp);
|
| 1303 | }
|
| 1304 |
|
| 1305 | if (ss->bind)
|
| 1306 | ss->bind(css);
|
| 1307 | }
|
| 1308 |
|
| 1309 | kernfs_activate(dst_root->cgrp.kn);
|
| 1310 | return 0;
|
| 1311 | }
|
| 1312 |
|
| 1313 | static int cgroup_show_options(struct seq_file *seq,
|
| 1314 | struct kernfs_root *kf_root)
|
| 1315 | {
|
| 1316 | struct cgroup_root *root = cgroup_root_from_kf(kf_root);
|
| 1317 | struct cgroup_subsys *ss;
|
| 1318 | int ssid;
|
| 1319 |
|
| 1320 | for_each_subsys(ss, ssid)
|
| 1321 | if (root->subsys_mask & (1 << ssid))
|
| 1322 | seq_printf(seq, ",%s", ss->name);
|
| 1323 | if (root->flags & CGRP_ROOT_NOPREFIX)
|
| 1324 | seq_puts(seq, ",noprefix");
|
| 1325 | if (root->flags & CGRP_ROOT_XATTR)
|
| 1326 | seq_puts(seq, ",xattr");
|
| 1327 |
|
| 1328 | spin_lock(&release_agent_path_lock);
|
| 1329 | if (strlen(root->release_agent_path))
|
| 1330 | seq_printf(seq, ",release_agent=%s", root->release_agent_path);
|
| 1331 | spin_unlock(&release_agent_path_lock);
|
| 1332 |
|
| 1333 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
|
| 1334 | seq_puts(seq, ",clone_children");
|
| 1335 | if (strlen(root->name))
|
| 1336 | seq_printf(seq, ",name=%s", root->name);
|
| 1337 | return 0;
|
| 1338 | }
|
| 1339 |
|
| 1340 | struct cgroup_sb_opts {
|
| 1341 | unsigned int subsys_mask;
|
| 1342 | unsigned int flags;
|
| 1343 | char *release_agent;
|
| 1344 | bool cpuset_clone_children;
|
| 1345 | char *name;
|
| 1346 |
|
| 1347 | bool none;
|
| 1348 | };
|
| 1349 |
|
| 1350 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
|
| 1351 | {
|
| 1352 | char *token, *o = data;
|
| 1353 | bool all_ss = false, one_ss = false;
|
| 1354 | unsigned int mask = -1U;
|
| 1355 | struct cgroup_subsys *ss;
|
| 1356 | int nr_opts = 0;
|
| 1357 | int i;
|
| 1358 |
|
| 1359 | #ifdef CONFIG_CPUSETS
|
| 1360 | mask = ~(1U << cpuset_cgrp_id);
|
| 1361 | #endif
|
| 1362 |
|
| 1363 | memset(opts, 0, sizeof(*opts));
|
| 1364 |
|
| 1365 | while ((token = strsep(&o, ",")) != NULL) {
|
| 1366 | nr_opts++;
|
| 1367 |
|
| 1368 | if (!*token)
|
| 1369 | return -EINVAL;
|
| 1370 | if (!strcmp(token, "none")) {
|
| 1371 |
|
| 1372 | opts->none = true;
|
| 1373 | continue;
|
| 1374 | }
|
| 1375 | if (!strcmp(token, "all")) {
|
| 1376 |
|
| 1377 | if (one_ss)
|
| 1378 | return -EINVAL;
|
| 1379 | all_ss = true;
|
| 1380 | continue;
|
| 1381 | }
|
| 1382 | if (!strcmp(token, "__DEVEL__sane_behavior")) {
|
| 1383 | opts->flags |= CGRP_ROOT_SANE_BEHAVIOR;
|
| 1384 | continue;
|
| 1385 | }
|
| 1386 | if (!strcmp(token, "noprefix")) {
|
| 1387 | opts->flags |= CGRP_ROOT_NOPREFIX;
|
| 1388 | continue;
|
| 1389 | }
|
| 1390 | if (!strcmp(token, "clone_children")) {
|
| 1391 | opts->cpuset_clone_children = true;
|
| 1392 | continue;
|
| 1393 | }
|
| 1394 | if (!strcmp(token, "xattr")) {
|
| 1395 | opts->flags |= CGRP_ROOT_XATTR;
|
| 1396 | continue;
|
| 1397 | }
|
| 1398 | if (!strncmp(token, "release_agent=", 14)) {
|
| 1399 |
|
| 1400 | if (opts->release_agent)
|
| 1401 | return -EINVAL;
|
| 1402 | opts->release_agent =
|
| 1403 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
|
| 1404 | if (!opts->release_agent)
|
| 1405 | return -ENOMEM;
|
| 1406 | continue;
|
| 1407 | }
|
| 1408 | if (!strncmp(token, "name=", 5)) {
|
| 1409 | const char *name = token + 5;
|
| 1410 |
|
| 1411 | if (!strlen(name))
|
| 1412 | return -EINVAL;
|
| 1413 |
|
| 1414 | for (i = 0; i < strlen(name); i++) {
|
| 1415 | char c = name[i];
|
| 1416 | if (isalnum(c))
|
| 1417 | continue;
|
| 1418 | if ((c == '.') || (c == '-') || (c == '_'))
|
| 1419 | continue;
|
| 1420 | return -EINVAL;
|
| 1421 | }
|
| 1422 |
|
| 1423 | if (opts->name)
|
| 1424 | return -EINVAL;
|
| 1425 | opts->name = kstrndup(name,
|
| 1426 | MAX_CGROUP_ROOT_NAMELEN - 1,
|
| 1427 | GFP_KERNEL);
|
| 1428 | if (!opts->name)
|
| 1429 | return -ENOMEM;
|
| 1430 |
|
| 1431 | continue;
|
| 1432 | }
|
| 1433 |
|
| 1434 | for_each_subsys(ss, i) {
|
| 1435 | if (strcmp(token, ss->name))
|
| 1436 | continue;
|
| 1437 | if (ss->disabled)
|
| 1438 | continue;
|
| 1439 |
|
| 1440 |
|
| 1441 | if (all_ss)
|
| 1442 | return -EINVAL;
|
| 1443 | opts->subsys_mask |= (1 << i);
|
| 1444 | one_ss = true;
|
| 1445 |
|
| 1446 | break;
|
| 1447 | }
|
| 1448 | if (i == CGROUP_SUBSYS_COUNT)
|
| 1449 | return -ENOENT;
|
| 1450 | }
|
| 1451 |
|
| 1452 | if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) {
|
| 1453 | pr_warn("sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n");
|
| 1454 | if (nr_opts != 1) {
|
| 1455 | pr_err("sane_behavior: no other mount options allowed\n");
|
| 1456 | return -EINVAL;
|
| 1457 | }
|
| 1458 | return 0;
|
| 1459 | }
|
| 1460 |
|
| 1461 | |
| 1462 | * If the 'all' option was specified select all the subsystems,
|
| 1463 | * otherwise if 'none', 'name=' and a subsystem name options were
|
| 1464 | * not specified, let's default to 'all'
|
| 1465 |
|
| 1466 | if (all_ss || (!one_ss && !opts->none && !opts->name))
|
| 1467 | for_each_subsys(ss, i)
|
| 1468 | if (!ss->disabled)
|
| 1469 | opts->subsys_mask |= (1 << i);
|
| 1470 |
|
| 1471 | |
| 1472 | * We either have to specify by name or by subsystems. (So all
|
| 1473 | * empty hierarchies must have a name).
|
| 1474 |
|
| 1475 | if (!opts->subsys_mask && !opts->name)
|
| 1476 | return -EINVAL;
|
| 1477 |
|
| 1478 | |
| 1479 | * Option noprefix was introduced just for backward compatibility
|
| 1480 | * with the old cpuset, so we allow noprefix only if mounting just
|
| 1481 | * the cpuset subsystem.
|
| 1482 |
|
| 1483 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
|
| 1484 | return -EINVAL;
|
| 1485 |
|
| 1486 |
|
| 1487 | if (opts->subsys_mask && opts->none)
|
| 1488 | return -EINVAL;
|
| 1489 |
|
| 1490 | return 0;
|
| 1491 | }
|
| 1492 |
|
| 1493 | static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
|
| 1494 | {
|
| 1495 | int ret = 0;
|
| 1496 | struct cgroup_root *root = cgroup_root_from_kf(kf_root);
|
| 1497 | struct cgroup_sb_opts opts;
|
| 1498 | unsigned int added_mask, removed_mask;
|
| 1499 |
|
| 1500 | if (root == &cgrp_dfl_root) {
|
| 1501 | pr_err("remount is not allowed\n");
|
| 1502 | return -EINVAL;
|
| 1503 | }
|
| 1504 |
|
| 1505 | mutex_lock(&cgroup_mutex);
|
| 1506 |
|
| 1507 |
|
| 1508 | ret = parse_cgroupfs_options(data, &opts);
|
| 1509 | if (ret)
|
| 1510 | goto out_unlock;
|
| 1511 |
|
| 1512 | if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
|
| 1513 | pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
|
| 1514 | task_tgid_nr(current), current->comm);
|
| 1515 |
|
| 1516 | added_mask = opts.subsys_mask & ~root->subsys_mask;
|
| 1517 | removed_mask = root->subsys_mask & ~opts.subsys_mask;
|
| 1518 |
|
| 1519 |
|
| 1520 | if ((opts.flags ^ root->flags) ||
|
| 1521 | (opts.name && strcmp(opts.name, root->name))) {
|
| 1522 | pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
|
| 1523 | opts.flags, opts.name ?: "", root->flags, root->name);
|
| 1524 | ret = -EINVAL;
|
| 1525 | goto out_unlock;
|
| 1526 | }
|
| 1527 |
|
| 1528 |
|
| 1529 | if (!list_empty(&root->cgrp.self.children)) {
|
| 1530 | ret = -EBUSY;
|
| 1531 | goto out_unlock;
|
| 1532 | }
|
| 1533 |
|
| 1534 | ret = rebind_subsystems(root, added_mask);
|
| 1535 | if (ret)
|
| 1536 | goto out_unlock;
|
| 1537 |
|
| 1538 | rebind_subsystems(&cgrp_dfl_root, removed_mask);
|
| 1539 |
|
| 1540 | if (opts.release_agent) {
|
| 1541 | spin_lock(&release_agent_path_lock);
|
| 1542 | strcpy(root->release_agent_path, opts.release_agent);
|
| 1543 | spin_unlock(&release_agent_path_lock);
|
| 1544 | }
|
| 1545 | out_unlock:
|
| 1546 | kfree(opts.release_agent);
|
| 1547 | kfree(opts.name);
|
| 1548 | mutex_unlock(&cgroup_mutex);
|
| 1549 | return ret;
|
| 1550 | }
|
| 1551 |
|
| 1552 | |
| 1553 | * To reduce the fork() overhead for systems that are not actually using
|
| 1554 | * their cgroups capability, we don't maintain the lists running through
|
| 1555 | * each css_set to its tasks until we see the list actually used - in other
|
| 1556 | * words after the first mount.
|
| 1557 |
|
| 1558 | static bool use_task_css_set_links __read_mostly;
|
| 1559 |
|
| 1560 | static void cgroup_enable_task_cg_lists(void)
|
| 1561 | {
|
| 1562 | struct task_struct *p, *g;
|
| 1563 |
|
| 1564 | down_write(&css_set_rwsem);
|
| 1565 |
|
| 1566 | if (use_task_css_set_links)
|
| 1567 | goto out_unlock;
|
| 1568 |
|
| 1569 | use_task_css_set_links = true;
|
| 1570 |
|
| 1571 | |
| 1572 | * We need tasklist_lock because RCU is not safe against
|
| 1573 | * while_each_thread(). Besides, a forking task that has passed
|
| 1574 | * cgroup_post_fork() without seeing use_task_css_set_links = 1
|
| 1575 | * is not guaranteed to have its child immediately visible in the
|
| 1576 | * tasklist if we walk through it with RCU.
|
| 1577 |
|
| 1578 | read_lock(&tasklist_lock);
|
| 1579 | do_each_thread(g, p) {
|
| 1580 | WARN_ON_ONCE(!list_empty(&p->cg_list) ||
|
| 1581 | task_css_set(p) != &init_css_set);
|
| 1582 |
|
| 1583 | |
| 1584 | * We should check if the process is exiting, otherwise
|
| 1585 | * it will race with cgroup_exit() in that the list
|
| 1586 | * entry won't be deleted though the process has exited.
|
| 1587 | * Do it while holding siglock so that we don't end up
|
| 1588 | * racing against cgroup_exit().
|
| 1589 |
|
| 1590 | spin_lock_irq(&p->sighand->siglock);
|
| 1591 | if (!(p->flags & PF_EXITING)) {
|
| 1592 | struct css_set *cset = task_css_set(p);
|
| 1593 |
|
| 1594 | list_add(&p->cg_list, &cset->tasks);
|
| 1595 | get_css_set(cset);
|
| 1596 | }
|
| 1597 | spin_unlock_irq(&p->sighand->siglock);
|
| 1598 | } while_each_thread(g, p);
|
| 1599 | read_unlock(&tasklist_lock);
|
| 1600 | out_unlock:
|
| 1601 | up_write(&css_set_rwsem);
|
| 1602 | }
|
| 1603 |
|
| 1604 | static void init_cgroup_housekeeping(struct cgroup *cgrp)
|
| 1605 | {
|
| 1606 | struct cgroup_subsys *ss;
|
| 1607 | int ssid;
|
| 1608 |
|
| 1609 | INIT_LIST_HEAD(&cgrp->self.sibling);
|
| 1610 | INIT_LIST_HEAD(&cgrp->self.children);
|
| 1611 | INIT_LIST_HEAD(&cgrp->cset_links);
|
| 1612 | INIT_LIST_HEAD(&cgrp->pidlists);
|
| 1613 | mutex_init(&cgrp->pidlist_mutex);
|
| 1614 | cgrp->self.cgroup = cgrp;
|
| 1615 | cgrp->self.flags |= CSS_ONLINE;
|
| 1616 |
|
| 1617 | for_each_subsys(ss, ssid)
|
| 1618 | INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
|
| 1619 |
|
| 1620 | init_waitqueue_head(&cgrp->offline_waitq);
|
| 1621 | INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent);
|
| 1622 | }
|
| 1623 |
|
| 1624 | static void init_cgroup_root(struct cgroup_root *root,
|
| 1625 | struct cgroup_sb_opts *opts)
|
| 1626 | {
|
| 1627 | struct cgroup *cgrp = &root->cgrp;
|
| 1628 |
|
| 1629 | INIT_LIST_HEAD(&root->root_list);
|
| 1630 | atomic_set(&root->nr_cgrps, 1);
|
| 1631 | cgrp->root = root;
|
| 1632 | init_cgroup_housekeeping(cgrp);
|
| 1633 | idr_init(&root->cgroup_idr);
|
| 1634 |
|
| 1635 | root->flags = opts->flags;
|
| 1636 | if (opts->release_agent)
|
| 1637 | strcpy(root->release_agent_path, opts->release_agent);
|
| 1638 | if (opts->name)
|
| 1639 | strcpy(root->name, opts->name);
|
| 1640 | if (opts->cpuset_clone_children)
|
| 1641 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
|
| 1642 | }
|
| 1643 |
|
| 1644 | static int cgroup_setup_root(struct cgroup_root *root, unsigned int ss_mask)
|
| 1645 | {
|
| 1646 | LIST_HEAD(tmp_links);
|
| 1647 | struct cgroup *root_cgrp = &root->cgrp;
|
| 1648 | struct cftype *base_files;
|
| 1649 | struct css_set *cset;
|
| 1650 | int i, ret;
|
| 1651 |
|
| 1652 | lockdep_assert_held(&cgroup_mutex);
|
| 1653 |
|
| 1654 | ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_NOWAIT);
|
| 1655 | if (ret < 0)
|
| 1656 | goto out;
|
| 1657 | root_cgrp->id = ret;
|
| 1658 |
|
| 1659 | ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, 0,
|
| 1660 | GFP_KERNEL);
|
| 1661 | if (ret)
|
| 1662 | goto out;
|
| 1663 |
|
| 1664 | |
| 1665 | * We're accessing css_set_count without locking css_set_rwsem here,
|
| 1666 | * but that's OK - it can only be increased by someone holding
|
| 1667 | * cgroup_lock, and that's us. The worst that can happen is that we
|
| 1668 | * have some link structures left over
|
| 1669 |
|
| 1670 | ret = allocate_cgrp_cset_links(css_set_count, &tmp_links);
|
| 1671 | if (ret)
|
| 1672 | goto cancel_ref;
|
| 1673 |
|
| 1674 | ret = cgroup_init_root_id(root);
|
| 1675 | if (ret)
|
| 1676 | goto cancel_ref;
|
| 1677 |
|
| 1678 | root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops,
|
| 1679 | KERNFS_ROOT_CREATE_DEACTIVATED,
|
| 1680 | root_cgrp);
|
| 1681 | if (IS_ERR(root->kf_root)) {
|
| 1682 | ret = PTR_ERR(root->kf_root);
|
| 1683 | goto exit_root_id;
|
| 1684 | }
|
| 1685 | root_cgrp->kn = root->kf_root->kn;
|
| 1686 |
|
| 1687 | if (root == &cgrp_dfl_root)
|
| 1688 | base_files = cgroup_dfl_base_files;
|
| 1689 | else
|
| 1690 | base_files = cgroup_legacy_base_files;
|
| 1691 |
|
| 1692 | ret = cgroup_addrm_files(root_cgrp, base_files, true);
|
| 1693 | if (ret)
|
| 1694 | goto destroy_root;
|
| 1695 |
|
| 1696 | ret = rebind_subsystems(root, ss_mask);
|
| 1697 | if (ret)
|
| 1698 | goto destroy_root;
|
| 1699 |
|
| 1700 | |
| 1701 | * There must be no failure case after here, since rebinding takes
|
| 1702 | * care of subsystems' refcounts, which are explicitly dropped in
|
| 1703 | * the failure exit path.
|
| 1704 |
|
| 1705 | list_add(&root->root_list, &cgroup_roots);
|
| 1706 | cgroup_root_count++;
|
| 1707 |
|
| 1708 | |
| 1709 | * Link the root cgroup in this hierarchy into all the css_set
|
| 1710 | * objects.
|
| 1711 |
|
| 1712 | down_write(&css_set_rwsem);
|
| 1713 | hash_for_each(css_set_table, i, cset, hlist)
|
| 1714 | link_css_set(&tmp_links, cset, root_cgrp);
|
| 1715 | up_write(&css_set_rwsem);
|
| 1716 |
|
| 1717 | BUG_ON(!list_empty(&root_cgrp->self.children));
|
| 1718 | BUG_ON(atomic_read(&root->nr_cgrps) != 1);
|
| 1719 |
|
| 1720 | kernfs_activate(root_cgrp->kn);
|
| 1721 | ret = 0;
|
| 1722 | goto out;
|
| 1723 |
|
| 1724 | destroy_root:
|
| 1725 | kernfs_destroy_root(root->kf_root);
|
| 1726 | root->kf_root = NULL;
|
| 1727 | exit_root_id:
|
| 1728 | cgroup_exit_root_id(root);
|
| 1729 | cancel_ref:
|
| 1730 | percpu_ref_exit(&root_cgrp->self.refcnt);
|
| 1731 | out:
|
| 1732 | free_cgrp_cset_links(&tmp_links);
|
| 1733 | return ret;
|
| 1734 | }
|
| 1735 |
|
| 1736 | static struct dentry *cgroup_mount(struct file_system_type *fs_type,
|
| 1737 | int flags, const char *unused_dev_name,
|
| 1738 | void *data)
|
| 1739 | {
|
| 1740 | struct super_block *pinned_sb = NULL;
|
| 1741 | struct cgroup_subsys *ss;
|
| 1742 | struct cgroup_root *root;
|
| 1743 | struct cgroup_sb_opts opts;
|
| 1744 | struct dentry *dentry;
|
| 1745 | int ret;
|
| 1746 | int i;
|
| 1747 | bool new_sb;
|
| 1748 |
|
| 1749 | |
| 1750 | * The first time anyone tries to mount a cgroup, enable the list
|
| 1751 | * linking each css_set to its tasks and fix up all existing tasks.
|
| 1752 |
|
| 1753 | if (!use_task_css_set_links)
|
| 1754 | cgroup_enable_task_cg_lists();
|
| 1755 |
|
| 1756 | mutex_lock(&cgroup_mutex);
|
| 1757 |
|
| 1758 |
|
| 1759 | ret = parse_cgroupfs_options(data, &opts);
|
| 1760 | if (ret)
|
| 1761 | goto out_unlock;
|
| 1762 |
|
| 1763 |
|
| 1764 | if (opts.flags & CGRP_ROOT_SANE_BEHAVIOR) {
|
| 1765 | cgrp_dfl_root_visible = true;
|
| 1766 | root = &cgrp_dfl_root;
|
| 1767 | cgroup_get(&root->cgrp);
|
| 1768 | ret = 0;
|
| 1769 | goto out_unlock;
|
| 1770 | }
|
| 1771 |
|
| 1772 | |
| 1773 | * Destruction of cgroup root is asynchronous, so subsystems may
|
| 1774 | * still be dying after the previous unmount. Let's drain the
|
| 1775 | * dying subsystems. We just need to ensure that the ones
|
| 1776 | * unmounted previously finish dying and don't care about new ones
|
| 1777 | * starting. Testing ref liveliness is good enough.
|
| 1778 |
|
| 1779 | for_each_subsys(ss, i) {
|
| 1780 | if (!(opts.subsys_mask & (1 << i)) ||
|
| 1781 | ss->root == &cgrp_dfl_root)
|
| 1782 | continue;
|
| 1783 |
|
| 1784 | if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
|
| 1785 | mutex_unlock(&cgroup_mutex);
|
| 1786 | msleep(10);
|
| 1787 | ret = restart_syscall();
|
| 1788 | goto out_free;
|
| 1789 | }
|
| 1790 | cgroup_put(&ss->root->cgrp);
|
| 1791 | }
|
| 1792 |
|
| 1793 | for_each_root(root) {
|
| 1794 | bool name_match = false;
|
| 1795 |
|
| 1796 | if (root == &cgrp_dfl_root)
|
| 1797 | continue;
|
| 1798 |
|
| 1799 | |
| 1800 | * If we asked for a name then it must match. Also, if
|
| 1801 | * name matches but sybsys_mask doesn't, we should fail.
|
| 1802 | * Remember whether name matched.
|
| 1803 |
|
| 1804 | if (opts.name) {
|
| 1805 | if (strcmp(opts.name, root->name))
|
| 1806 | continue;
|
| 1807 | name_match = true;
|
| 1808 | }
|
| 1809 |
|
| 1810 | |
| 1811 | * If we asked for subsystems (or explicitly for no
|
| 1812 | * subsystems) then they must match.
|
| 1813 |
|
| 1814 | if ((opts.subsys_mask || opts.none) &&
|
| 1815 | (opts.subsys_mask != root->subsys_mask)) {
|
| 1816 | if (!name_match)
|
| 1817 | continue;
|
| 1818 | ret = -EBUSY;
|
| 1819 | goto out_unlock;
|
| 1820 | }
|
| 1821 |
|
| 1822 | if (root->flags ^ opts.flags)
|
| 1823 | pr_warn("new mount options do not match the existing superblock, will be ignored\n");
|
| 1824 |
|
| 1825 | |
| 1826 | * We want to reuse @root whose lifetime is governed by its
|
| 1827 | * ->cgrp. Let's check whether @root is alive and keep it
|
| 1828 | * that way. As cgroup_kill_sb() can happen anytime, we
|
| 1829 | * want to block it by pinning the sb so that @root doesn't
|
| 1830 | * get killed before mount is complete.
|
| 1831 | *
|
| 1832 | * With the sb pinned, tryget_live can reliably indicate
|
| 1833 | * whether @root can be reused. If it's being killed,
|
| 1834 | * drain it. We can use wait_queue for the wait but this
|
| 1835 | * path is super cold. Let's just sleep a bit and retry.
|
| 1836 |
|
| 1837 | pinned_sb = kernfs_pin_sb(root->kf_root, NULL);
|
| 1838 | if (IS_ERR(pinned_sb) ||
|
| 1839 | !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
|
| 1840 | mutex_unlock(&cgroup_mutex);
|
| 1841 | if (!IS_ERR_OR_NULL(pinned_sb))
|
| 1842 | deactivate_super(pinned_sb);
|
| 1843 | msleep(10);
|
| 1844 | ret = restart_syscall();
|
| 1845 | goto out_free;
|
| 1846 | }
|
| 1847 |
|
| 1848 | ret = 0;
|
| 1849 | goto out_unlock;
|
| 1850 | }
|
| 1851 |
|
| 1852 | |
| 1853 | * No such thing, create a new one. name= matching without subsys
|
| 1854 | * specification is allowed for already existing hierarchies but we
|
| 1855 | * can't create new one without subsys specification.
|
| 1856 |
|
| 1857 | if (!opts.subsys_mask && !opts.none) {
|
| 1858 | ret = -EINVAL;
|
| 1859 | goto out_unlock;
|
| 1860 | }
|
| 1861 |
|
| 1862 | root = kzalloc(sizeof(*root), GFP_KERNEL);
|
| 1863 | if (!root) {
|
| 1864 | ret = -ENOMEM;
|
| 1865 | goto out_unlock;
|
| 1866 | }
|
| 1867 |
|
| 1868 | init_cgroup_root(root, &opts);
|
| 1869 |
|
| 1870 | ret = cgroup_setup_root(root, opts.subsys_mask);
|
| 1871 | if (ret)
|
| 1872 | cgroup_free_root(root);
|
| 1873 |
|
| 1874 | out_unlock:
|
| 1875 | mutex_unlock(&cgroup_mutex);
|
| 1876 | out_free:
|
| 1877 | kfree(opts.release_agent);
|
| 1878 | kfree(opts.name);
|
| 1879 |
|
| 1880 | if (ret)
|
| 1881 | return ERR_PTR(ret);
|
| 1882 |
|
| 1883 | dentry = kernfs_mount(fs_type, flags, root->kf_root,
|
| 1884 | CGROUP_SUPER_MAGIC, &new_sb);
|
| 1885 | if (IS_ERR(dentry) || !new_sb)
|
| 1886 | cgroup_put(&root->cgrp);
|
| 1887 |
|
| 1888 | |
| 1889 | * If @pinned_sb, we're reusing an existing root and holding an
|
| 1890 | * extra ref on its sb. Mount is complete. Put the extra ref.
|
| 1891 |
|
| 1892 | if (pinned_sb) {
|
| 1893 | WARN_ON(new_sb);
|
| 1894 | deactivate_super(pinned_sb);
|
| 1895 | }
|
| 1896 |
|
| 1897 | return dentry;
|
| 1898 | }
|
| 1899 |
|
| 1900 | static void cgroup_kill_sb(struct super_block *sb)
|
| 1901 | {
|
| 1902 | struct kernfs_root *kf_root = kernfs_root_from_sb(sb);
|
| 1903 | struct cgroup_root *root = cgroup_root_from_kf(kf_root);
|
| 1904 |
|
| 1905 | |
| 1906 | * If @root doesn't have any mounts or children, start killing it.
|
| 1907 | * This prevents new mounts by disabling percpu_ref_tryget_live().
|
| 1908 | * cgroup_mount() may wait for @root's release.
|
| 1909 | *
|
| 1910 | * And don't kill the default root.
|
| 1911 |
|
| 1912 | if (!list_empty(&root->cgrp.self.children) ||
|
| 1913 | root == &cgrp_dfl_root)
|
| 1914 | cgroup_put(&root->cgrp);
|
| 1915 | else
|
| 1916 | percpu_ref_kill(&root->cgrp.self.refcnt);
|
| 1917 |
|
| 1918 | kernfs_kill_sb(sb);
|
| 1919 | }
|
| 1920 |
|
| 1921 | static struct file_system_type cgroup_fs_type = {
|
| 1922 | .name = "cgroup",
|
| 1923 | .mount = cgroup_mount,
|
| 1924 | .kill_sb = cgroup_kill_sb,
|
| 1925 | };
|
| 1926 |
|
| 1927 | static struct kobject *cgroup_kobj;
|
| 1928 |
|
| 1929 | |
| 1930 | * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
|
| 1931 | * @task: target task
|
| 1932 | * @buf: the buffer to write the path into
|
| 1933 | * @buflen: the length of the buffer
|
| 1934 | *
|
| 1935 | * Determine @task's cgroup on the first (the one with the lowest non-zero
|
| 1936 | * hierarchy_id) cgroup hierarchy and copy its path into @buf. This
|
| 1937 | * function grabs cgroup_mutex and shouldn't be used inside locks used by
|
| 1938 | * cgroup controller callbacks.
|
| 1939 | *
|
| 1940 | * Return value is the same as kernfs_path().
|
| 1941 |
|
| 1942 | char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
|
| 1943 | {
|
| 1944 | struct cgroup_root *root;
|
| 1945 | struct cgroup *cgrp;
|
| 1946 | int hierarchy_id = 1;
|
| 1947 | char *path = NULL;
|
| 1948 |
|
| 1949 | mutex_lock(&cgroup_mutex);
|
| 1950 | down_read(&css_set_rwsem);
|
| 1951 |
|
| 1952 | root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
|
| 1953 |
|
| 1954 | if (root) {
|
| 1955 | cgrp = task_cgroup_from_root(task, root);
|
| 1956 | path = cgroup_path(cgrp, buf, buflen);
|
| 1957 | } else {
|
| 1958 |
|
| 1959 | if (strlcpy(buf, "/", buflen) < buflen)
|
| 1960 | path = buf;
|
| 1961 | }
|
| 1962 |
|
| 1963 | up_read(&css_set_rwsem);
|
| 1964 | mutex_unlock(&cgroup_mutex);
|
| 1965 | return path;
|
| 1966 | }
|
| 1967 | EXPORT_SYMBOL_GPL(task_cgroup_path);
|
| 1968 |
|
| 1969 |
|
| 1970 | struct cgroup_taskset {
|
| 1971 |
|
| 1972 | struct list_head src_csets;
|
| 1973 | struct list_head dst_csets;
|
| 1974 |
|
| 1975 | |
| 1976 | * Fields for cgroup_taskset_*() iteration.
|
| 1977 | *
|
| 1978 | * Before migration is committed, the target migration tasks are on
|
| 1979 | * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of
|
| 1980 | * the csets on ->dst_csets. ->csets point to either ->src_csets
|
| 1981 | * or ->dst_csets depending on whether migration is committed.
|
| 1982 | *
|
| 1983 | * ->cur_csets and ->cur_task point to the current task position
|
| 1984 | * during iteration.
|
| 1985 |
|
| 1986 | struct list_head *csets;
|
| 1987 | struct css_set *cur_cset;
|
| 1988 | struct task_struct *cur_task;
|
| 1989 | };
|
| 1990 |
|
| 1991 | |
| 1992 | * cgroup_taskset_first - reset taskset and return the first task
|
| 1993 | * @tset: taskset of interest
|
| 1994 | *
|
| 1995 | * @tset iteration is initialized and the first task is returned.
|
| 1996 |
|
| 1997 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset)
|
| 1998 | {
|
| 1999 | tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node);
|
| 2000 | tset->cur_task = NULL;
|
| 2001 |
|
| 2002 | return cgroup_taskset_next(tset);
|
| 2003 | }
|
| 2004 |
|
| 2005 | |
| 2006 | * cgroup_taskset_next - iterate to the next task in taskset
|
| 2007 | * @tset: taskset of interest
|
| 2008 | *
|
| 2009 | * Return the next task in @tset. Iteration must have been initialized
|
| 2010 | * with cgroup_taskset_first().
|
| 2011 |
|
| 2012 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset)
|
| 2013 | {
|
| 2014 | struct css_set *cset = tset->cur_cset;
|
| 2015 | struct task_struct *task = tset->cur_task;
|
| 2016 |
|
| 2017 | while (&cset->mg_node != tset->csets) {
|
| 2018 | if (!task)
|
| 2019 | task = list_first_entry(&cset->mg_tasks,
|
| 2020 | struct task_struct, cg_list);
|
| 2021 | else
|
| 2022 | task = list_next_entry(task, cg_list);
|
| 2023 |
|
| 2024 | if (&task->cg_list != &cset->mg_tasks) {
|
| 2025 | tset->cur_cset = cset;
|
| 2026 | tset->cur_task = task;
|
| 2027 | return task;
|
| 2028 | }
|
| 2029 |
|
| 2030 | cset = list_next_entry(cset, mg_node);
|
| 2031 | task = NULL;
|
| 2032 | }
|
| 2033 |
|
| 2034 | return NULL;
|
| 2035 | }
|
| 2036 |
|
| 2037 | |
| 2038 | * cgroup_task_migrate - move a task from one cgroup to another.
|
| 2039 | * @old_cgrp: the cgroup @tsk is being migrated from
|
| 2040 | * @tsk: the task being migrated
|
| 2041 | * @new_cset: the new css_set @tsk is being attached to
|
| 2042 | *
|
| 2043 | * Must be called with cgroup_mutex, threadgroup and css_set_rwsem locked.
|
| 2044 |
|
| 2045 | static void cgroup_task_migrate(struct cgroup *old_cgrp,
|
| 2046 | struct task_struct *tsk,
|
| 2047 | struct css_set *new_cset)
|
| 2048 | {
|
| 2049 | struct css_set *old_cset;
|
| 2050 |
|
| 2051 | lockdep_assert_held(&cgroup_mutex);
|
| 2052 | lockdep_assert_held(&css_set_rwsem);
|
| 2053 |
|
| 2054 | |
| 2055 | * We are synchronized through threadgroup_lock() against PF_EXITING
|
| 2056 | * setting such that we can't race against cgroup_exit() changing the
|
| 2057 | * css_set to init_css_set and dropping the old one.
|
| 2058 |
|
| 2059 | WARN_ON_ONCE(tsk->flags & PF_EXITING);
|
| 2060 | old_cset = task_css_set(tsk);
|
| 2061 |
|
| 2062 | get_css_set(new_cset);
|
| 2063 | rcu_assign_pointer(tsk->cgroups, new_cset);
|
| 2064 |
|
| 2065 | |
| 2066 | * Use move_tail so that cgroup_taskset_first() still returns the
|
| 2067 | * leader after migration. This works because cgroup_migrate()
|
| 2068 | * ensures that the dst_cset of the leader is the first on the
|
| 2069 | * tset's dst_csets list.
|
| 2070 |
|
| 2071 | list_move_tail(&tsk->cg_list, &new_cset->mg_tasks);
|
| 2072 |
|
| 2073 | |
| 2074 | * We just gained a reference on old_cset by taking it from the
|
| 2075 | * task. As trading it for new_cset is protected by cgroup_mutex,
|
| 2076 | * we're safe to drop it here; it will be freed under RCU.
|
| 2077 |
|
| 2078 | put_css_set_locked(old_cset);
|
| 2079 | }
|
| 2080 |
|
| 2081 | |
| 2082 | * cgroup_migrate_finish - cleanup after attach
|
| 2083 | * @preloaded_csets: list of preloaded css_sets
|
| 2084 | *
|
| 2085 | * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
|
| 2086 | * those functions for details.
|
| 2087 |
|
| 2088 | static void cgroup_migrate_finish(struct list_head *preloaded_csets)
|
| 2089 | {
|
| 2090 | struct css_set *cset, *tmp_cset;
|
| 2091 |
|
| 2092 | lockdep_assert_held(&cgroup_mutex);
|
| 2093 |
|
| 2094 | down_write(&css_set_rwsem);
|
| 2095 | list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) {
|
| 2096 | cset->mg_src_cgrp = NULL;
|
| 2097 | cset->mg_dst_cset = NULL;
|
| 2098 | list_del_init(&cset->mg_preload_node);
|
| 2099 | put_css_set_locked(cset);
|
| 2100 | }
|
| 2101 | up_write(&css_set_rwsem);
|
| 2102 | }
|
| 2103 |
|
| 2104 | |
| 2105 | * cgroup_migrate_add_src - add a migration source css_set
|
| 2106 | * @src_cset: the source css_set to add
|
| 2107 | * @dst_cgrp: the destination cgroup
|
| 2108 | * @preloaded_csets: list of preloaded css_sets
|
| 2109 | *
|
| 2110 | * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
|
| 2111 | * @src_cset and add it to @preloaded_csets, which should later be cleaned
|
| 2112 | * up by cgroup_migrate_finish().
|
| 2113 | *
|
| 2114 | * This function may be called without holding threadgroup_lock even if the
|
| 2115 | * target is a process. Threads may be created and destroyed but as long
|
| 2116 | * as cgroup_mutex is not dropped, no new css_set can be put into play and
|
| 2117 | * the preloaded css_sets are guaranteed to cover all migrations.
|
| 2118 |
|
| 2119 | static void cgroup_migrate_add_src(struct css_set *src_cset,
|
| 2120 | struct cgroup *dst_cgrp,
|
| 2121 | struct list_head *preloaded_csets)
|
| 2122 | {
|
| 2123 | struct cgroup *src_cgrp;
|
| 2124 |
|
| 2125 | lockdep_assert_held(&cgroup_mutex);
|
| 2126 | lockdep_assert_held(&css_set_rwsem);
|
| 2127 |
|
| 2128 | src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
|
| 2129 |
|
| 2130 | if (!list_empty(&src_cset->mg_preload_node))
|
| 2131 | return;
|
| 2132 |
|
| 2133 | WARN_ON(src_cset->mg_src_cgrp);
|
| 2134 | WARN_ON(!list_empty(&src_cset->mg_tasks));
|
| 2135 | WARN_ON(!list_empty(&src_cset->mg_node));
|
| 2136 |
|
| 2137 | src_cset->mg_src_cgrp = src_cgrp;
|
| 2138 | get_css_set(src_cset);
|
| 2139 | list_add(&src_cset->mg_preload_node, preloaded_csets);
|
| 2140 | }
|
| 2141 |
|
| 2142 | |
| 2143 | * cgroup_migrate_prepare_dst - prepare destination css_sets for migration
|
| 2144 | * @dst_cgrp: the destination cgroup (may be %NULL)
|
| 2145 | * @preloaded_csets: list of preloaded source css_sets
|
| 2146 | *
|
| 2147 | * Tasks are about to be moved to @dst_cgrp and all the source css_sets
|
| 2148 | * have been preloaded to @preloaded_csets. This function looks up and
|
| 2149 | * pins all destination css_sets, links each to its source, and append them
|
| 2150 | * to @preloaded_csets. If @dst_cgrp is %NULL, the destination of each
|
| 2151 | * source css_set is assumed to be its cgroup on the default hierarchy.
|
| 2152 | *
|
| 2153 | * This function must be called after cgroup_migrate_add_src() has been
|
| 2154 | * called on each migration source css_set. After migration is performed
|
| 2155 | * using cgroup_migrate(), cgroup_migrate_finish() must be called on
|
| 2156 | * @preloaded_csets.
|
| 2157 |
|
| 2158 | static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp,
|
| 2159 | struct list_head *preloaded_csets)
|
| 2160 | {
|
| 2161 | LIST_HEAD(csets);
|
| 2162 | struct css_set *src_cset, *tmp_cset;
|
| 2163 |
|
| 2164 | lockdep_assert_held(&cgroup_mutex);
|
| 2165 |
|
| 2166 | |
| 2167 | * Except for the root, child_subsys_mask must be zero for a cgroup
|
| 2168 | * with tasks so that child cgroups don't compete against tasks.
|
| 2169 |
|
| 2170 | if (dst_cgrp && cgroup_on_dfl(dst_cgrp) && cgroup_parent(dst_cgrp) &&
|
| 2171 | dst_cgrp->child_subsys_mask)
|
| 2172 | return -EBUSY;
|
| 2173 |
|
| 2174 |
|
| 2175 | list_for_each_entry_safe(src_cset, tmp_cset, preloaded_csets, mg_preload_node) {
|
| 2176 | struct css_set *dst_cset;
|
| 2177 |
|
| 2178 | dst_cset = find_css_set(src_cset,
|
| 2179 | dst_cgrp ?: src_cset->dfl_cgrp);
|
| 2180 | if (!dst_cset)
|
| 2181 | goto err;
|
| 2182 |
|
| 2183 | WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset);
|
| 2184 |
|
| 2185 | |
| 2186 | * If src cset equals dst, it's noop. Drop the src.
|
| 2187 | * cgroup_migrate() will skip the cset too. Note that we
|
| 2188 | * can't handle src == dst as some nodes are used by both.
|
| 2189 |
|
| 2190 | if (src_cset == dst_cset) {
|
| 2191 | src_cset->mg_src_cgrp = NULL;
|
| 2192 | list_del_init(&src_cset->mg_preload_node);
|
| 2193 | put_css_set(src_cset);
|
| 2194 | put_css_set(dst_cset);
|
| 2195 | continue;
|
| 2196 | }
|
| 2197 |
|
| 2198 | src_cset->mg_dst_cset = dst_cset;
|
| 2199 |
|
| 2200 | if (list_empty(&dst_cset->mg_preload_node))
|
| 2201 | list_add(&dst_cset->mg_preload_node, &csets);
|
| 2202 | else
|
| 2203 | put_css_set(dst_cset);
|
| 2204 | }
|
| 2205 |
|
| 2206 | list_splice_tail(&csets, preloaded_csets);
|
| 2207 | return 0;
|
| 2208 | err:
|
| 2209 | cgroup_migrate_finish(&csets);
|
| 2210 | return -ENOMEM;
|
| 2211 | }
|
| 2212 |
|
| 2213 | |
| 2214 | * cgroup_migrate - migrate a process or task to a cgroup
|
| 2215 | * @cgrp: the destination cgroup
|
| 2216 | * @leader: the leader of the process or the task to migrate
|
| 2217 | * @threadgroup: whether @leader points to the whole process or a single task
|
| 2218 | *
|
| 2219 | * Migrate a process or task denoted by @leader to @cgrp. If migrating a
|
| 2220 | * process, the caller must be holding threadgroup_lock of @leader. The
|
| 2221 | * caller is also responsible for invoking cgroup_migrate_add_src() and
|
| 2222 | * cgroup_migrate_prepare_dst() on the targets before invoking this
|
| 2223 | * function and following up with cgroup_migrate_finish().
|
| 2224 | *
|
| 2225 | * As long as a controller's ->can_attach() doesn't fail, this function is
|
| 2226 | * guaranteed to succeed. This means that, excluding ->can_attach()
|
| 2227 | * failure, when migrating multiple targets, the success or failure can be
|
| 2228 | * decided for all targets by invoking group_migrate_prepare_dst() before
|
| 2229 | * actually starting migrating.
|
| 2230 |
|
| 2231 | static int cgroup_migrate(struct cgroup *cgrp, struct task_struct *leader,
|
| 2232 | bool threadgroup)
|
| 2233 | {
|
| 2234 | struct cgroup_taskset tset = {
|
| 2235 | .src_csets = LIST_HEAD_INIT(tset.src_csets),
|
| 2236 | .dst_csets = LIST_HEAD_INIT(tset.dst_csets),
|
| 2237 | .csets = &tset.src_csets,
|
| 2238 | };
|
| 2239 | struct cgroup_subsys_state *css, *failed_css = NULL;
|
| 2240 | struct css_set *cset, *tmp_cset;
|
| 2241 | struct task_struct *task, *tmp_task;
|
| 2242 | int i, ret;
|
| 2243 |
|
| 2244 | |
| 2245 | * Prevent freeing of tasks while we take a snapshot. Tasks that are
|
| 2246 | * already PF_EXITING could be freed from underneath us unless we
|
| 2247 | * take an rcu_read_lock.
|
| 2248 |
|
| 2249 | down_write(&css_set_rwsem);
|
| 2250 | rcu_read_lock();
|
| 2251 | task = leader;
|
| 2252 | do {
|
| 2253 |
|
| 2254 | if (task->flags & PF_EXITING)
|
| 2255 | goto next;
|
| 2256 |
|
| 2257 |
|
| 2258 | if (list_empty(&task->cg_list))
|
| 2259 | goto next;
|
| 2260 |
|
| 2261 | cset = task_css_set(task);
|
| 2262 | if (!cset->mg_src_cgrp)
|
| 2263 | goto next;
|
| 2264 |
|
| 2265 | |
| 2266 | * cgroup_taskset_first() must always return the leader.
|
| 2267 | * Take care to avoid disturbing the ordering.
|
| 2268 |
|
| 2269 | list_move_tail(&task->cg_list, &cset->mg_tasks);
|
| 2270 | if (list_empty(&cset->mg_node))
|
| 2271 | list_add_tail(&cset->mg_node, &tset.src_csets);
|
| 2272 | if (list_empty(&cset->mg_dst_cset->mg_node))
|
| 2273 | list_move_tail(&cset->mg_dst_cset->mg_node,
|
| 2274 | &tset.dst_csets);
|
| 2275 | next:
|
| 2276 | if (!threadgroup)
|
| 2277 | break;
|
| 2278 | } while_each_thread(leader, task);
|
| 2279 | rcu_read_unlock();
|
| 2280 | up_write(&css_set_rwsem);
|
| 2281 |
|
| 2282 |
|
| 2283 | if (list_empty(&tset.src_csets))
|
| 2284 | return 0;
|
| 2285 |
|
| 2286 |
|
| 2287 | for_each_e_css(css, i, cgrp) {
|
| 2288 | if (css->ss->can_attach) {
|
| 2289 | ret = css->ss->can_attach(css, &tset);
|
| 2290 | if (ret) {
|
| 2291 | failed_css = css;
|
| 2292 | goto out_cancel_attach;
|
| 2293 | }
|
| 2294 | }
|
| 2295 | }
|
| 2296 |
|
| 2297 | |
| 2298 | * Now that we're guaranteed success, proceed to move all tasks to
|
| 2299 | * the new cgroup. There are no failure cases after here, so this
|
| 2300 | * is the commit point.
|
| 2301 |
|
| 2302 | down_write(&css_set_rwsem);
|
| 2303 | list_for_each_entry(cset, &tset.src_csets, mg_node) {
|
| 2304 | list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list)
|
| 2305 | cgroup_task_migrate(cset->mg_src_cgrp, task,
|
| 2306 | cset->mg_dst_cset);
|
| 2307 | }
|
| 2308 | up_write(&css_set_rwsem);
|
| 2309 |
|
| 2310 | |
| 2311 | * Migration is committed, all target tasks are now on dst_csets.
|
| 2312 | * Nothing is sensitive to fork() after this point. Notify
|
| 2313 | * controllers that migration is complete.
|
| 2314 |
|
| 2315 | tset.csets = &tset.dst_csets;
|
| 2316 |
|
| 2317 | for_each_e_css(css, i, cgrp)
|
| 2318 | if (css->ss->attach)
|
| 2319 | css->ss->attach(css, &tset);
|
| 2320 |
|
| 2321 | ret = 0;
|
| 2322 | goto out_release_tset;
|
| 2323 |
|
| 2324 | out_cancel_attach:
|
| 2325 | for_each_e_css(css, i, cgrp) {
|
| 2326 | if (css == failed_css)
|
| 2327 | break;
|
| 2328 | if (css->ss->cancel_attach)
|
| 2329 | css->ss->cancel_attach(css, &tset);
|
| 2330 | }
|
| 2331 | out_release_tset:
|
| 2332 | down_write(&css_set_rwsem);
|
| 2333 | list_splice_init(&tset.dst_csets, &tset.src_csets);
|
| 2334 | list_for_each_entry_safe(cset, tmp_cset, &tset.src_csets, mg_node) {
|
| 2335 | list_splice_tail_init(&cset->mg_tasks, &cset->tasks);
|
| 2336 | list_del_init(&cset->mg_node);
|
| 2337 | }
|
| 2338 | up_write(&css_set_rwsem);
|
| 2339 | return ret;
|
| 2340 | }
|
| 2341 |
|
| 2342 | |
| 2343 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
|
| 2344 | * @dst_cgrp: the cgroup to attach to
|
| 2345 | * @leader: the task or the leader of the threadgroup to be attached
|
| 2346 | * @threadgroup: attach the whole threadgroup?
|
| 2347 | *
|
| 2348 | * Call holding cgroup_mutex and threadgroup_lock of @leader.
|
| 2349 |
|
| 2350 | static int cgroup_attach_task(struct cgroup *dst_cgrp,
|
| 2351 | struct task_struct *leader, bool threadgroup)
|
| 2352 | {
|
| 2353 | LIST_HEAD(preloaded_csets);
|
| 2354 | struct task_struct *task;
|
| 2355 | int ret;
|
| 2356 |
|
| 2357 |
|
| 2358 | down_read(&css_set_rwsem);
|
| 2359 | rcu_read_lock();
|
| 2360 | task = leader;
|
| 2361 | do {
|
| 2362 | cgroup_migrate_add_src(task_css_set(task), dst_cgrp,
|
| 2363 | &preloaded_csets);
|
| 2364 | if (!threadgroup)
|
| 2365 | break;
|
| 2366 | } while_each_thread(leader, task);
|
| 2367 | rcu_read_unlock();
|
| 2368 | up_read(&css_set_rwsem);
|
| 2369 |
|
| 2370 |
|
| 2371 | ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets);
|
| 2372 | if (!ret)
|
| 2373 | ret = cgroup_migrate(dst_cgrp, leader, threadgroup);
|
| 2374 |
|
| 2375 | cgroup_migrate_finish(&preloaded_csets);
|
| 2376 | return ret;
|
| 2377 | }
|
| 2378 |
|
| 2379 | |
| 2380 | * Find the task_struct of the task to attach by vpid and pass it along to the
|
| 2381 | * function to attach either it or all tasks in its threadgroup. Will lock
|
| 2382 | * cgroup_mutex and threadgroup.
|
| 2383 |
|
| 2384 | static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
|
| 2385 | size_t nbytes, loff_t off, bool threadgroup)
|
| 2386 | {
|
| 2387 | struct task_struct *tsk;
|
| 2388 | const struct cred *cred = current_cred(), *tcred;
|
| 2389 | struct cgroup *cgrp;
|
| 2390 | pid_t pid;
|
| 2391 | int ret;
|
| 2392 |
|
| 2393 | if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
|
| 2394 | return -EINVAL;
|
| 2395 |
|
| 2396 | cgrp = cgroup_kn_lock_live(of->kn);
|
| 2397 | if (!cgrp)
|
| 2398 | return -ENODEV;
|
| 2399 |
|
| 2400 | retry_find_task:
|
| 2401 | rcu_read_lock();
|
| 2402 | if (pid) {
|
| 2403 | tsk = find_task_by_vpid(pid);
|
| 2404 | if (!tsk) {
|
| 2405 | rcu_read_unlock();
|
| 2406 | ret = -ESRCH;
|
| 2407 | goto out_unlock_cgroup;
|
| 2408 | }
|
| 2409 | |
| 2410 | * even if we're attaching all tasks in the thread group, we
|
| 2411 | * only need to check permissions on one of them.
|
| 2412 |
|
| 2413 | tcred = __task_cred(tsk);
|
| 2414 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
|
| 2415 | !uid_eq(cred->euid, tcred->uid) &&
|
| 2416 | !uid_eq(cred->euid, tcred->suid)) {
|
| 2417 | rcu_read_unlock();
|
| 2418 | ret = -EACCES;
|
| 2419 | goto out_unlock_cgroup;
|
| 2420 | }
|
| 2421 | } else
|
| 2422 | tsk = current;
|
| 2423 |
|
| 2424 | if (threadgroup)
|
| 2425 | tsk = tsk->group_leader;
|
| 2426 |
|
| 2427 | |
| 2428 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become
|
| 2429 | * trapped in a cpuset, or RT worker may be born in a cgroup
|
| 2430 | * with no rt_runtime allocated. Just say no.
|
| 2431 |
|
| 2432 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) {
|
| 2433 | ret = -EINVAL;
|
| 2434 | rcu_read_unlock();
|
| 2435 | goto out_unlock_cgroup;
|
| 2436 | }
|
| 2437 |
|
| 2438 | get_task_struct(tsk);
|
| 2439 | rcu_read_unlock();
|
| 2440 |
|
| 2441 | threadgroup_lock(tsk);
|
| 2442 | if (threadgroup) {
|
| 2443 | if (!thread_group_leader(tsk)) {
|
| 2444 | |
| 2445 | * a race with de_thread from another thread's exec()
|
| 2446 | * may strip us of our leadership, if this happens,
|
| 2447 | * there is no choice but to throw this task away and
|
| 2448 | * try again; this is
|
| 2449 | * "double-double-toil-and-trouble-check locking".
|
| 2450 |
|
| 2451 | threadgroup_unlock(tsk);
|
| 2452 | put_task_struct(tsk);
|
| 2453 | goto retry_find_task;
|
| 2454 | }
|
| 2455 | }
|
| 2456 |
|
| 2457 | ret = cgroup_attach_task(cgrp, tsk, threadgroup);
|
| 2458 |
|
| 2459 | threadgroup_unlock(tsk);
|
| 2460 |
|
| 2461 | put_task_struct(tsk);
|
| 2462 | out_unlock_cgroup:
|
| 2463 | cgroup_kn_unlock(of->kn);
|
| 2464 | return ret ?: nbytes;
|
| 2465 | }
|
| 2466 |
|
| 2467 | |
| 2468 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
|
| 2469 | * @from: attach to all cgroups of a given task
|
| 2470 | * @tsk: the task to be attached
|
| 2471 |
|
| 2472 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
|
| 2473 | {
|
| 2474 | struct cgroup_root *root;
|
| 2475 | int retval = 0;
|
| 2476 |
|
| 2477 | mutex_lock(&cgroup_mutex);
|
| 2478 | for_each_root(root) {
|
| 2479 | struct cgroup *from_cgrp;
|
| 2480 |
|
| 2481 | if (root == &cgrp_dfl_root)
|
| 2482 | continue;
|
| 2483 |
|
| 2484 | down_read(&css_set_rwsem);
|
| 2485 | from_cgrp = task_cgroup_from_root(from, root);
|
| 2486 | up_read(&css_set_rwsem);
|
| 2487 |
|
| 2488 | retval = cgroup_attach_task(from_cgrp, tsk, false);
|
| 2489 | if (retval)
|
| 2490 | break;
|
| 2491 | }
|
| 2492 | mutex_unlock(&cgroup_mutex);
|
| 2493 |
|
| 2494 | return retval;
|
| 2495 | }
|
| 2496 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
|
| 2497 |
|
| 2498 | static ssize_t cgroup_tasks_write(struct kernfs_open_file *of,
|
| 2499 | char *buf, size_t nbytes, loff_t off)
|
| 2500 | {
|
| 2501 | return __cgroup_procs_write(of, buf, nbytes, off, false);
|
| 2502 | }
|
| 2503 |
|
| 2504 | static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
|
| 2505 | char *buf, size_t nbytes, loff_t off)
|
| 2506 | {
|
| 2507 | return __cgroup_procs_write(of, buf, nbytes, off, true);
|
| 2508 | }
|
| 2509 |
|
| 2510 | static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
|
| 2511 | char *buf, size_t nbytes, loff_t off)
|
| 2512 | {
|
| 2513 | struct cgroup *cgrp;
|
| 2514 |
|
| 2515 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
|
| 2516 |
|
| 2517 | cgrp = cgroup_kn_lock_live(of->kn);
|
| 2518 | if (!cgrp)
|
| 2519 | return -ENODEV;
|
| 2520 | spin_lock(&release_agent_path_lock);
|
| 2521 | strlcpy(cgrp->root->release_agent_path, strstrip(buf),
|
| 2522 | sizeof(cgrp->root->release_agent_path));
|
| 2523 | spin_unlock(&release_agent_path_lock);
|
| 2524 | cgroup_kn_unlock(of->kn);
|
| 2525 | return nbytes;
|
| 2526 | }
|
| 2527 |
|
| 2528 | static int cgroup_release_agent_show(struct seq_file *seq, void *v)
|
| 2529 | {
|
| 2530 | struct cgroup *cgrp = seq_css(seq)->cgroup;
|
| 2531 |
|
| 2532 | spin_lock(&release_agent_path_lock);
|
| 2533 | seq_puts(seq, cgrp->root->release_agent_path);
|
| 2534 | spin_unlock(&release_agent_path_lock);
|
| 2535 | seq_putc(seq, '\n');
|
| 2536 | return 0;
|
| 2537 | }
|
| 2538 |
|
| 2539 | static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
|
| 2540 | {
|
| 2541 | seq_puts(seq, "0\n");
|
| 2542 | return 0;
|
| 2543 | }
|
| 2544 |
|
| 2545 | static void cgroup_print_ss_mask(struct seq_file *seq, unsigned int ss_mask)
|
| 2546 | {
|
| 2547 | struct cgroup_subsys *ss;
|
| 2548 | bool printed = false;
|
| 2549 | int ssid;
|
| 2550 |
|
| 2551 | for_each_subsys(ss, ssid) {
|
| 2552 | if (ss_mask & (1 << ssid)) {
|
| 2553 | if (printed)
|
| 2554 | seq_putc(seq, ' ');
|
| 2555 | seq_printf(seq, "%s", ss->name);
|
| 2556 | printed = true;
|
| 2557 | }
|
| 2558 | }
|
| 2559 | if (printed)
|
| 2560 | seq_putc(seq, '\n');
|
| 2561 | }
|
| 2562 |
|
| 2563 |
|
| 2564 | static int cgroup_root_controllers_show(struct seq_file *seq, void *v)
|
| 2565 | {
|
| 2566 | struct cgroup *cgrp = seq_css(seq)->cgroup;
|
| 2567 |
|
| 2568 | cgroup_print_ss_mask(seq, cgrp->root->subsys_mask &
|
| 2569 | ~cgrp_dfl_root_inhibit_ss_mask);
|
| 2570 | return 0;
|
| 2571 | }
|
| 2572 |
|
| 2573 |
|
| 2574 | static int cgroup_controllers_show(struct seq_file *seq, void *v)
|
| 2575 | {
|
| 2576 | struct cgroup *cgrp = seq_css(seq)->cgroup;
|
| 2577 |
|
| 2578 | cgroup_print_ss_mask(seq, cgroup_parent(cgrp)->subtree_control);
|
| 2579 | return 0;
|
| 2580 | }
|
| 2581 |
|
| 2582 |
|
| 2583 | static int cgroup_subtree_control_show(struct seq_file *seq, void *v)
|
| 2584 | {
|
| 2585 | struct cgroup *cgrp = seq_css(seq)->cgroup;
|
| 2586 |
|
| 2587 | cgroup_print_ss_mask(seq, cgrp->subtree_control);
|
| 2588 | return 0;
|
| 2589 | }
|
| 2590 |
|
| 2591 | |
| 2592 | * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy
|
| 2593 | * @cgrp: root of the subtree to update csses for
|
| 2594 | *
|
| 2595 | * @cgrp's child_subsys_mask has changed and its subtree's (self excluded)
|
| 2596 | * css associations need to be updated accordingly. This function looks up
|
| 2597 | * all css_sets which are attached to the subtree, creates the matching
|
| 2598 | * updated css_sets and migrates the tasks to the new ones.
|
| 2599 |
|
| 2600 | static int cgroup_update_dfl_csses(struct cgroup *cgrp)
|
| 2601 | {
|
| 2602 | LIST_HEAD(preloaded_csets);
|
| 2603 | struct cgroup_subsys_state *css;
|
| 2604 | struct css_set *src_cset;
|
| 2605 | int ret;
|
| 2606 |
|
| 2607 | lockdep_assert_held(&cgroup_mutex);
|
| 2608 |
|
| 2609 |
|
| 2610 | down_read(&css_set_rwsem);
|
| 2611 | css_for_each_descendant_pre(css, cgroup_css(cgrp, NULL)) {
|
| 2612 | struct cgrp_cset_link *link;
|
| 2613 |
|
| 2614 |
|
| 2615 | if (css->cgroup == cgrp)
|
| 2616 | continue;
|
| 2617 |
|
| 2618 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link)
|
| 2619 | cgroup_migrate_add_src(link->cset, cgrp,
|
| 2620 | &preloaded_csets);
|
| 2621 | }
|
| 2622 | up_read(&css_set_rwsem);
|
| 2623 |
|
| 2624 |
|
| 2625 | ret = cgroup_migrate_prepare_dst(NULL, &preloaded_csets);
|
| 2626 | if (ret)
|
| 2627 | goto out_finish;
|
| 2628 |
|
| 2629 | list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) {
|
| 2630 | struct task_struct *last_task = NULL, *task;
|
| 2631 |
|
| 2632 |
|
| 2633 | if (!src_cset->mg_src_cgrp)
|
| 2634 | break;
|
| 2635 |
|
| 2636 | |
| 2637 | * All tasks in src_cset need to be migrated to the
|
| 2638 | * matching dst_cset. Empty it process by process. We
|
| 2639 | * walk tasks but migrate processes. The leader might even
|
| 2640 | * belong to a different cset but such src_cset would also
|
| 2641 | * be among the target src_csets because the default
|
| 2642 | * hierarchy enforces per-process membership.
|
| 2643 |
|
| 2644 | while (true) {
|
| 2645 | down_read(&css_set_rwsem);
|
| 2646 | task = list_first_entry_or_null(&src_cset->tasks,
|
| 2647 | struct task_struct, cg_list);
|
| 2648 | if (task) {
|
| 2649 | task = task->group_leader;
|
| 2650 | WARN_ON_ONCE(!task_css_set(task)->mg_src_cgrp);
|
| 2651 | get_task_struct(task);
|
| 2652 | }
|
| 2653 | up_read(&css_set_rwsem);
|
| 2654 |
|
| 2655 | if (!task)
|
| 2656 | break;
|
| 2657 |
|
| 2658 |
|
| 2659 | if (WARN(last_task == task,
|
| 2660 | "cgroup: update_dfl_csses failed to make progress, aborting in inconsistent state\n"))
|
| 2661 | goto out_finish;
|
| 2662 | last_task = task;
|
| 2663 |
|
| 2664 | threadgroup_lock(task);
|
| 2665 |
|
| 2666 | if (!thread_group_leader(task)) {
|
| 2667 | threadgroup_unlock(task);
|
| 2668 | put_task_struct(task);
|
| 2669 | continue;
|
| 2670 | }
|
| 2671 |
|
| 2672 | ret = cgroup_migrate(src_cset->dfl_cgrp, task, true);
|
| 2673 |
|
| 2674 | threadgroup_unlock(task);
|
| 2675 | put_task_struct(task);
|
| 2676 |
|
| 2677 | if (WARN(ret, "cgroup: failed to update controllers for the default hierarchy (%d), further operations may crash or hang\n", ret))
|
| 2678 | goto out_finish;
|
| 2679 | }
|
| 2680 | }
|
| 2681 |
|
| 2682 | out_finish:
|
| 2683 | cgroup_migrate_finish(&preloaded_csets);
|
| 2684 | return ret;
|
| 2685 | }
|
| 2686 |
|
| 2687 |
|
| 2688 | static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
|
| 2689 | char *buf, size_t nbytes,
|
| 2690 | loff_t off)
|
| 2691 | {
|
| 2692 | unsigned int enable = 0, disable = 0;
|
| 2693 | unsigned int css_enable, css_disable, old_sc, new_sc, old_ss, new_ss;
|
| 2694 | struct cgroup *cgrp, *child;
|
| 2695 | struct cgroup_subsys *ss;
|
| 2696 | char *tok;
|
| 2697 | int ssid, ret;
|
| 2698 |
|
| 2699 | |
| 2700 | * Parse input - space separated list of subsystem names prefixed
|
| 2701 | * with either + or -.
|
| 2702 |
|
| 2703 | buf = strstrip(buf);
|
| 2704 | while ((tok = strsep(&buf, " "))) {
|
| 2705 | if (tok[0] == '\0')
|
| 2706 | continue;
|
| 2707 | for_each_subsys(ss, ssid) {
|
| 2708 | if (ss->disabled || strcmp(tok + 1, ss->name) ||
|
| 2709 | ((1 << ss->id) & cgrp_dfl_root_inhibit_ss_mask))
|
| 2710 | continue;
|
| 2711 |
|
| 2712 | if (*tok == '+') {
|
| 2713 | enable |= 1 << ssid;
|
| 2714 | disable &= ~(1 << ssid);
|
| 2715 | } else if (*tok == '-') {
|
| 2716 | disable |= 1 << ssid;
|
| 2717 | enable &= ~(1 << ssid);
|
| 2718 | } else {
|
| 2719 | return -EINVAL;
|
| 2720 | }
|
| 2721 | break;
|
| 2722 | }
|
| 2723 | if (ssid == CGROUP_SUBSYS_COUNT)
|
| 2724 | return -EINVAL;
|
| 2725 | }
|
| 2726 |
|
| 2727 | cgrp = cgroup_kn_lock_live(of->kn);
|
| 2728 | if (!cgrp)
|
| 2729 | return -ENODEV;
|
| 2730 |
|
| 2731 | for_each_subsys(ss, ssid) {
|
| 2732 | if (enable & (1 << ssid)) {
|
| 2733 | if (cgrp->subtree_control & (1 << ssid)) {
|
| 2734 | enable &= ~(1 << ssid);
|
| 2735 | continue;
|
| 2736 | }
|
| 2737 |
|
| 2738 |
|
| 2739 | if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) ||
|
| 2740 | (cgroup_parent(cgrp) &&
|
| 2741 | !(cgroup_parent(cgrp)->subtree_control & (1 << ssid)))) {
|
| 2742 | ret = -ENOENT;
|
| 2743 | goto out_unlock;
|
| 2744 | }
|
| 2745 | } else if (disable & (1 << ssid)) {
|
| 2746 | if (!(cgrp->subtree_control & (1 << ssid))) {
|
| 2747 | disable &= ~(1 << ssid);
|
| 2748 | continue;
|
| 2749 | }
|
| 2750 |
|
| 2751 |
|
| 2752 | cgroup_for_each_live_child(child, cgrp) {
|
| 2753 | if (child->subtree_control & (1 << ssid)) {
|
| 2754 | ret = -EBUSY;
|
| 2755 | goto out_unlock;
|
| 2756 | }
|
| 2757 | }
|
| 2758 | }
|
| 2759 | }
|
| 2760 |
|
| 2761 | if (!enable && !disable) {
|
| 2762 | ret = 0;
|
| 2763 | goto out_unlock;
|
| 2764 | }
|
| 2765 |
|
| 2766 | |
| 2767 | * Except for the root, subtree_control must be zero for a cgroup
|
| 2768 | * with tasks so that child cgroups don't compete against tasks.
|
| 2769 |
|
| 2770 | if (enable && cgroup_parent(cgrp) && !list_empty(&cgrp->cset_links)) {
|
| 2771 | ret = -EBUSY;
|
| 2772 | goto out_unlock;
|
| 2773 | }
|
| 2774 |
|
| 2775 | |
| 2776 | * Update subsys masks and calculate what needs to be done. More
|
| 2777 | * subsystems than specified may need to be enabled or disabled
|
| 2778 | * depending on subsystem dependencies.
|
| 2779 |
|
| 2780 | old_sc = cgrp->subtree_control;
|
| 2781 | old_ss = cgrp->child_subsys_mask;
|
| 2782 | new_sc = (old_sc | enable) & ~disable;
|
| 2783 | new_ss = cgroup_calc_child_subsys_mask(cgrp, new_sc);
|
| 2784 |
|
| 2785 | css_enable = ~old_ss & new_ss;
|
| 2786 | css_disable = old_ss & ~new_ss;
|
| 2787 | enable |= css_enable;
|
| 2788 | disable |= css_disable;
|
| 2789 |
|
| 2790 | |
| 2791 | * Because css offlining is asynchronous, userland might try to
|
| 2792 | * re-enable the same controller while the previous instance is
|
| 2793 | * still around. In such cases, wait till it's gone using
|
| 2794 | * offline_waitq.
|
| 2795 |
|
| 2796 | for_each_subsys(ss, ssid) {
|
| 2797 | if (!(css_enable & (1 << ssid)))
|
| 2798 | continue;
|
| 2799 |
|
| 2800 | cgroup_for_each_live_child(child, cgrp) {
|
| 2801 | DEFINE_WAIT(wait);
|
| 2802 |
|
| 2803 | if (!cgroup_css(child, ss))
|
| 2804 | continue;
|
| 2805 |
|
| 2806 | cgroup_get(child);
|
| 2807 | prepare_to_wait(&child->offline_waitq, &wait,
|
| 2808 | TASK_UNINTERRUPTIBLE);
|
| 2809 | cgroup_kn_unlock(of->kn);
|
| 2810 | schedule();
|
| 2811 | finish_wait(&child->offline_waitq, &wait);
|
| 2812 | cgroup_put(child);
|
| 2813 |
|
| 2814 | return restart_syscall();
|
| 2815 | }
|
| 2816 | }
|
| 2817 |
|
| 2818 | cgrp->subtree_control = new_sc;
|
| 2819 | cgrp->child_subsys_mask = new_ss;
|
| 2820 |
|
| 2821 | |
| 2822 | * Create new csses or make the existing ones visible. A css is
|
| 2823 | * created invisible if it's being implicitly enabled through
|
| 2824 | * dependency. An invisible css is made visible when the userland
|
| 2825 | * explicitly enables it.
|
| 2826 |
|
| 2827 | for_each_subsys(ss, ssid) {
|
| 2828 | if (!(enable & (1 << ssid)))
|
| 2829 | continue;
|
| 2830 |
|
| 2831 | cgroup_for_each_live_child(child, cgrp) {
|
| 2832 | if (css_enable & (1 << ssid))
|
| 2833 | ret = create_css(child, ss,
|
| 2834 | cgrp->subtree_control & (1 << ssid));
|
| 2835 | else
|
| 2836 | ret = cgroup_populate_dir(child, 1 << ssid);
|
| 2837 | if (ret)
|
| 2838 | goto err_undo_css;
|
| 2839 | }
|
| 2840 | }
|
| 2841 |
|
| 2842 | |
| 2843 | * At this point, cgroup_e_css() results reflect the new csses
|
| 2844 | * making the following cgroup_update_dfl_csses() properly update
|
| 2845 | * css associations of all tasks in the subtree.
|
| 2846 |
|
| 2847 | ret = cgroup_update_dfl_csses(cgrp);
|
| 2848 | if (ret)
|
| 2849 | goto err_undo_css;
|
| 2850 |
|
| 2851 | |
| 2852 | * All tasks are migrated out of disabled csses. Kill or hide
|
| 2853 | * them. A css is hidden when the userland requests it to be
|
| 2854 | * disabled while other subsystems are still depending on it. The
|
| 2855 | * css must not actively control resources and be in the vanilla
|
| 2856 | * state if it's made visible again later. Controllers which may
|
| 2857 | * be depended upon should provide ->css_reset() for this purpose.
|
| 2858 |
|
| 2859 | for_each_subsys(ss, ssid) {
|
| 2860 | if (!(disable & (1 << ssid)))
|
| 2861 | continue;
|
| 2862 |
|
| 2863 | cgroup_for_each_live_child(child, cgrp) {
|
| 2864 | struct cgroup_subsys_state *css = cgroup_css(child, ss);
|
| 2865 |
|
| 2866 | if (css_disable & (1 << ssid)) {
|
| 2867 | kill_css(css);
|
| 2868 | } else {
|
| 2869 | cgroup_clear_dir(child, 1 << ssid);
|
| 2870 | if (ss->css_reset)
|
| 2871 | ss->css_reset(css);
|
| 2872 | }
|
| 2873 | }
|
| 2874 | }
|
| 2875 |
|
| 2876 | |
| 2877 | * The effective csses of all the descendants (excluding @cgrp) may
|
| 2878 | * have changed. Subsystems can optionally subscribe to this event
|
| 2879 | * by implementing ->css_e_css_changed() which is invoked if any of
|
| 2880 | * the effective csses seen from the css's cgroup may have changed.
|
| 2881 |
|
| 2882 | for_each_subsys(ss, ssid) {
|
| 2883 | struct cgroup_subsys_state *this_css = cgroup_css(cgrp, ss);
|
| 2884 | struct cgroup_subsys_state *css;
|
| 2885 |
|
| 2886 | if (!ss->css_e_css_changed || !this_css)
|
| 2887 | continue;
|
| 2888 |
|
| 2889 | css_for_each_descendant_pre(css, this_css)
|
| 2890 | if (css != this_css)
|
| 2891 | ss->css_e_css_changed(css);
|
| 2892 | }
|
| 2893 |
|
| 2894 | kernfs_activate(cgrp->kn);
|
| 2895 | ret = 0;
|
| 2896 | out_unlock:
|
| 2897 | cgroup_kn_unlock(of->kn);
|
| 2898 | return ret ?: nbytes;
|
| 2899 |
|
| 2900 | err_undo_css:
|
| 2901 | cgrp->subtree_control = old_sc;
|
| 2902 | cgrp->child_subsys_mask = old_ss;
|
| 2903 |
|
| 2904 | for_each_subsys(ss, ssid) {
|
| 2905 | if (!(enable & (1 << ssid)))
|
| 2906 | continue;
|
| 2907 |
|
| 2908 | cgroup_for_each_live_child(child, cgrp) {
|
| 2909 | struct cgroup_subsys_state *css = cgroup_css(child, ss);
|
| 2910 |
|
| 2911 | if (!css)
|
| 2912 | continue;
|
| 2913 |
|
| 2914 | if (css_enable & (1 << ssid))
|
| 2915 | kill_css(css);
|
| 2916 | else
|
| 2917 | cgroup_clear_dir(child, 1 << ssid);
|
| 2918 | }
|
| 2919 | }
|
| 2920 | goto out_unlock;
|
| 2921 | }
|
| 2922 |
|
| 2923 | static int cgroup_populated_show(struct seq_file *seq, void *v)
|
| 2924 | {
|
| 2925 | seq_printf(seq, "%d\n", (bool)seq_css(seq)->cgroup->populated_cnt);
|
| 2926 | return 0;
|
| 2927 | }
|
| 2928 |
|
| 2929 | static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf,
|
| 2930 | size_t nbytes, loff_t off)
|
| 2931 | {
|
| 2932 | struct cgroup *cgrp = of->kn->parent->priv;
|
| 2933 | struct cftype *cft = of->kn->priv;
|
| 2934 | struct cgroup_subsys_state *css;
|
| 2935 | int ret;
|
| 2936 |
|
| 2937 | if (cft->write)
|
| 2938 | return cft->write(of, buf, nbytes, off);
|
| 2939 |
|
| 2940 | |
| 2941 | * kernfs guarantees that a file isn't deleted with operations in
|
| 2942 | * flight, which means that the matching css is and stays alive and
|
| 2943 | * doesn't need to be pinned. The RCU locking is not necessary
|
| 2944 | * either. It's just for the convenience of using cgroup_css().
|
| 2945 |
|
| 2946 | rcu_read_lock();
|
| 2947 | css = cgroup_css(cgrp, cft->ss);
|
| 2948 | rcu_read_unlock();
|
| 2949 |
|
| 2950 | if (cft->write_u64) {
|
| 2951 | unsigned long long v;
|
| 2952 | ret = kstrtoull(buf, 0, &v);
|
| 2953 | if (!ret)
|
| 2954 | ret = cft->write_u64(css, cft, v);
|
| 2955 | } else if (cft->write_s64) {
|
| 2956 | long long v;
|
| 2957 | ret = kstrtoll(buf, 0, &v);
|
| 2958 | if (!ret)
|
| 2959 | ret = cft->write_s64(css, cft, v);
|
| 2960 | } else {
|
| 2961 | ret = -EINVAL;
|
| 2962 | }
|
| 2963 |
|
| 2964 | return ret ?: nbytes;
|
| 2965 | }
|
| 2966 |
|
| 2967 | static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos)
|
| 2968 | {
|
| 2969 | return seq_cft(seq)->seq_start(seq, ppos);
|
| 2970 | }
|
| 2971 |
|
| 2972 | static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos)
|
| 2973 | {
|
| 2974 | return seq_cft(seq)->seq_next(seq, v, ppos);
|
| 2975 | }
|
| 2976 |
|
| 2977 | static void cgroup_seqfile_stop(struct seq_file *seq, void *v)
|
| 2978 | {
|
| 2979 | seq_cft(seq)->seq_stop(seq, v);
|
| 2980 | }
|
| 2981 |
|
| 2982 | static int cgroup_seqfile_show(struct seq_file *m, void *arg)
|
| 2983 | {
|
| 2984 | struct cftype *cft = seq_cft(m);
|
| 2985 | struct cgroup_subsys_state *css = seq_css(m);
|
| 2986 |
|
| 2987 | if (cft->seq_show)
|
| 2988 | return cft->seq_show(m, arg);
|
| 2989 |
|
| 2990 | if (cft->read_u64)
|
| 2991 | seq_printf(m, "%llu\n", cft->read_u64(css, cft));
|
| 2992 | else if (cft->read_s64)
|
| 2993 | seq_printf(m, "%lld\n", cft->read_s64(css, cft));
|
| 2994 | else
|
| 2995 | return -EINVAL;
|
| 2996 | return 0;
|
| 2997 | }
|
| 2998 |
|
| 2999 | static struct kernfs_ops cgroup_kf_single_ops = {
|
| 3000 | .atomic_write_len = PAGE_SIZE,
|
| 3001 | .write = cgroup_file_write,
|
| 3002 | .seq_show = cgroup_seqfile_show,
|
| 3003 | };
|
| 3004 |
|
| 3005 | static struct kernfs_ops cgroup_kf_ops = {
|
| 3006 | .atomic_write_len = PAGE_SIZE,
|
| 3007 | .write = cgroup_file_write,
|
| 3008 | .seq_start = cgroup_seqfile_start,
|
| 3009 | .seq_next = cgroup_seqfile_next,
|
| 3010 | .seq_stop = cgroup_seqfile_stop,
|
| 3011 | .seq_show = cgroup_seqfile_show,
|
| 3012 | };
|
| 3013 |
|
| 3014 | |
| 3015 | * cgroup_rename - Only allow simple rename of directories in place.
|
| 3016 |
|
| 3017 | static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
|
| 3018 | const char *new_name_str)
|
| 3019 | {
|
| 3020 | struct cgroup *cgrp = kn->priv;
|
| 3021 | int ret;
|
| 3022 |
|
| 3023 | if (kernfs_type(kn) != KERNFS_DIR)
|
| 3024 | return -ENOTDIR;
|
| 3025 | if (kn->parent != new_parent)
|
| 3026 | return -EIO;
|
| 3027 |
|
| 3028 | |
| 3029 | * This isn't a proper migration and its usefulness is very
|
| 3030 | * limited. Disallow on the default hierarchy.
|
| 3031 |
|
| 3032 | if (cgroup_on_dfl(cgrp))
|
| 3033 | return -EPERM;
|
| 3034 |
|
| 3035 | |
| 3036 | * We're gonna grab cgroup_mutex which nests outside kernfs
|
| 3037 | * active_ref. kernfs_rename() doesn't require active_ref
|
| 3038 | * protection. Break them before grabbing cgroup_mutex.
|
| 3039 |
|
| 3040 | kernfs_break_active_protection(new_parent);
|
| 3041 | kernfs_break_active_protection(kn);
|
| 3042 |
|
| 3043 | mutex_lock(&cgroup_mutex);
|
| 3044 |
|
| 3045 | ret = kernfs_rename(kn, new_parent, new_name_str);
|
| 3046 |
|
| 3047 | mutex_unlock(&cgroup_mutex);
|
| 3048 |
|
| 3049 | kernfs_unbreak_active_protection(kn);
|
| 3050 | kernfs_unbreak_active_protection(new_parent);
|
| 3051 | return ret;
|
| 3052 | }
|
| 3053 |
|
| 3054 |
|
| 3055 | static int cgroup_kn_set_ugid(struct kernfs_node *kn)
|
| 3056 | {
|
| 3057 | struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
|
| 3058 | .ia_uid = current_fsuid(),
|
| 3059 | .ia_gid = current_fsgid(), };
|
| 3060 |
|
| 3061 | if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
|
| 3062 | gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
|
| 3063 | return 0;
|
| 3064 |
|
| 3065 | return kernfs_setattr(kn, &iattr);
|
| 3066 | }
|
| 3067 |
|
| 3068 | static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft)
|
| 3069 | {
|
| 3070 | char name[CGROUP_FILE_NAME_MAX];
|
| 3071 | struct kernfs_node *kn;
|
| 3072 | struct lock_class_key *key = NULL;
|
| 3073 | int ret;
|
| 3074 |
|
| 3075 | #ifdef CONFIG_DEBUG_LOCK_ALLOC
|
| 3076 | key = &cft->lockdep_key;
|
| 3077 | #endif
|
| 3078 | kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
|
| 3079 | cgroup_file_mode(cft), 0, cft->kf_ops, cft,
|
| 3080 | NULL, key);
|
| 3081 | if (IS_ERR(kn))
|
| 3082 | return PTR_ERR(kn);
|
| 3083 |
|
| 3084 | ret = cgroup_kn_set_ugid(kn);
|
| 3085 | if (ret) {
|
| 3086 | kernfs_remove(kn);
|
| 3087 | return ret;
|
| 3088 | }
|
| 3089 |
|
| 3090 | if (cft->seq_show == cgroup_populated_show)
|
| 3091 | cgrp->populated_kn = kn;
|
| 3092 | return 0;
|
| 3093 | }
|
| 3094 |
|
| 3095 | |
| 3096 | * cgroup_addrm_files - add or remove files to a cgroup directory
|
| 3097 | * @cgrp: the target cgroup
|
| 3098 | * @cfts: array of cftypes to be added
|
| 3099 | * @is_add: whether to add or remove
|
| 3100 | *
|
| 3101 | * Depending on @is_add, add or remove files defined by @cfts on @cgrp.
|
| 3102 | * For removals, this function never fails. If addition fails, this
|
| 3103 | * function doesn't remove files already added. The caller is responsible
|
| 3104 | * for cleaning up.
|
| 3105 |
|
| 3106 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
|
| 3107 | bool is_add)
|
| 3108 | {
|
| 3109 | struct cftype *cft;
|
| 3110 | int ret;
|
| 3111 |
|
| 3112 | lockdep_assert_held(&cgroup_mutex);
|
| 3113 |
|
| 3114 | for (cft = cfts; cft->name[0] != '\0'; cft++) {
|
| 3115 |
|
| 3116 | if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
|
| 3117 | continue;
|
| 3118 | if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp))
|
| 3119 | continue;
|
| 3120 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp))
|
| 3121 | continue;
|
| 3122 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp))
|
| 3123 | continue;
|
| 3124 |
|
| 3125 | if (is_add) {
|
| 3126 | ret = cgroup_add_file(cgrp, cft);
|
| 3127 | if (ret) {
|
| 3128 | pr_warn("%s: failed to add %s, err=%d\n",
|
| 3129 | __func__, cft->name, ret);
|
| 3130 | return ret;
|
| 3131 | }
|
| 3132 | } else {
|
| 3133 | cgroup_rm_file(cgrp, cft);
|
| 3134 | }
|
| 3135 | }
|
| 3136 | return 0;
|
| 3137 | }
|
| 3138 |
|
| 3139 | static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add)
|
| 3140 | {
|
| 3141 | LIST_HEAD(pending);
|
| 3142 | struct cgroup_subsys *ss = cfts[0].ss;
|
| 3143 | struct cgroup *root = &ss->root->cgrp;
|
| 3144 | struct cgroup_subsys_state *css;
|
| 3145 | int ret = 0;
|
| 3146 |
|
| 3147 | lockdep_assert_held(&cgroup_mutex);
|
| 3148 |
|
| 3149 |
|
| 3150 | css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
|
| 3151 | struct cgroup *cgrp = css->cgroup;
|
| 3152 |
|
| 3153 | if (cgroup_is_dead(cgrp))
|
| 3154 | continue;
|
| 3155 |
|
| 3156 | ret = cgroup_addrm_files(cgrp, cfts, is_add);
|
| 3157 | if (ret)
|
| 3158 | break;
|
| 3159 | }
|
| 3160 |
|
| 3161 | if (is_add && !ret)
|
| 3162 | kernfs_activate(root->kn);
|
| 3163 | return ret;
|
| 3164 | }
|
| 3165 |
|
| 3166 | static void cgroup_exit_cftypes(struct cftype *cfts)
|
| 3167 | {
|
| 3168 | struct cftype *cft;
|
| 3169 |
|
| 3170 | for (cft = cfts; cft->name[0] != '\0'; cft++) {
|
| 3171 |
|
| 3172 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE)
|
| 3173 | kfree(cft->kf_ops);
|
| 3174 | cft->kf_ops = NULL;
|
| 3175 | cft->ss = NULL;
|
| 3176 |
|
| 3177 |
|
| 3178 | cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL);
|
| 3179 | }
|
| 3180 | }
|
| 3181 |
|
| 3182 | static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
| 3183 | {
|
| 3184 | struct cftype *cft;
|
| 3185 |
|
| 3186 | for (cft = cfts; cft->name[0] != '\0'; cft++) {
|
| 3187 | struct kernfs_ops *kf_ops;
|
| 3188 |
|
| 3189 | WARN_ON(cft->ss || cft->kf_ops);
|
| 3190 |
|
| 3191 | if (cft->seq_start)
|
| 3192 | kf_ops = &cgroup_kf_ops;
|
| 3193 | else
|
| 3194 | kf_ops = &cgroup_kf_single_ops;
|
| 3195 |
|
| 3196 | |
| 3197 | * Ugh... if @cft wants a custom max_write_len, we need to
|
| 3198 | * make a copy of kf_ops to set its atomic_write_len.
|
| 3199 |
|
| 3200 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) {
|
| 3201 | kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL);
|
| 3202 | if (!kf_ops) {
|
| 3203 | cgroup_exit_cftypes(cfts);
|
| 3204 | return -ENOMEM;
|
| 3205 | }
|
| 3206 | kf_ops->atomic_write_len = cft->max_write_len;
|
| 3207 | }
|
| 3208 |
|
| 3209 | cft->kf_ops = kf_ops;
|
| 3210 | cft->ss = ss;
|
| 3211 | }
|
| 3212 |
|
| 3213 | return 0;
|
| 3214 | }
|
| 3215 |
|
| 3216 | static int cgroup_rm_cftypes_locked(struct cftype *cfts)
|
| 3217 | {
|
| 3218 | lockdep_assert_held(&cgroup_mutex);
|
| 3219 |
|
| 3220 | if (!cfts || !cfts[0].ss)
|
| 3221 | return -ENOENT;
|
| 3222 |
|
| 3223 | list_del(&cfts->node);
|
| 3224 | cgroup_apply_cftypes(cfts, false);
|
| 3225 | cgroup_exit_cftypes(cfts);
|
| 3226 | return 0;
|
| 3227 | }
|
| 3228 |
|
| 3229 | |
| 3230 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
|
| 3231 | * @cfts: zero-length name terminated array of cftypes
|
| 3232 | *
|
| 3233 | * Unregister @cfts. Files described by @cfts are removed from all
|
| 3234 | * existing cgroups and all future cgroups won't have them either. This
|
| 3235 | * function can be called anytime whether @cfts' subsys is attached or not.
|
| 3236 | *
|
| 3237 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not
|
| 3238 | * registered.
|
| 3239 |
|
| 3240 | int cgroup_rm_cftypes(struct cftype *cfts)
|
| 3241 | {
|
| 3242 | int ret;
|
| 3243 |
|
| 3244 | mutex_lock(&cgroup_mutex);
|
| 3245 | ret = cgroup_rm_cftypes_locked(cfts);
|
| 3246 | mutex_unlock(&cgroup_mutex);
|
| 3247 | return ret;
|
| 3248 | }
|
| 3249 |
|
| 3250 | |
| 3251 | * cgroup_add_cftypes - add an array of cftypes to a subsystem
|
| 3252 | * @ss: target cgroup subsystem
|
| 3253 | * @cfts: zero-length name terminated array of cftypes
|
| 3254 | *
|
| 3255 | * Register @cfts to @ss. Files described by @cfts are created for all
|
| 3256 | * existing cgroups to which @ss is attached and all future cgroups will
|
| 3257 | * have them too. This function can be called anytime whether @ss is
|
| 3258 | * attached or not.
|
| 3259 | *
|
| 3260 | * Returns 0 on successful registration, -errno on failure. Note that this
|
| 3261 | * function currently returns 0 as long as @cfts registration is successful
|
| 3262 | * even if some file creation attempts on existing cgroups fail.
|
| 3263 |
|
| 3264 | static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
| 3265 | {
|
| 3266 | int ret;
|
| 3267 |
|
| 3268 | if (ss->disabled)
|
| 3269 | return 0;
|
| 3270 |
|
| 3271 | if (!cfts || cfts[0].name[0] == '\0')
|
| 3272 | return 0;
|
| 3273 |
|
| 3274 | ret = cgroup_init_cftypes(ss, cfts);
|
| 3275 | if (ret)
|
| 3276 | return ret;
|
| 3277 |
|
| 3278 | mutex_lock(&cgroup_mutex);
|
| 3279 |
|
| 3280 | list_add_tail(&cfts->node, &ss->cfts);
|
| 3281 | ret = cgroup_apply_cftypes(cfts, true);
|
| 3282 | if (ret)
|
| 3283 | cgroup_rm_cftypes_locked(cfts);
|
| 3284 |
|
| 3285 | mutex_unlock(&cgroup_mutex);
|
| 3286 | return ret;
|
| 3287 | }
|
| 3288 |
|
| 3289 | |
| 3290 | * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
|
| 3291 | * @ss: target cgroup subsystem
|
| 3292 | * @cfts: zero-length name terminated array of cftypes
|
| 3293 | *
|
| 3294 | * Similar to cgroup_add_cftypes() but the added files are only used for
|
| 3295 | * the default hierarchy.
|
| 3296 |
|
| 3297 | int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
| 3298 | {
|
| 3299 | struct cftype *cft;
|
| 3300 |
|
| 3301 | for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
|
| 3302 | cft->flags |= __CFTYPE_ONLY_ON_DFL;
|
| 3303 | return cgroup_add_cftypes(ss, cfts);
|
| 3304 | }
|
| 3305 |
|
| 3306 | |
| 3307 | * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
|
| 3308 | * @ss: target cgroup subsystem
|
| 3309 | * @cfts: zero-length name terminated array of cftypes
|
| 3310 | *
|
| 3311 | * Similar to cgroup_add_cftypes() but the added files are only used for
|
| 3312 | * the legacy hierarchies.
|
| 3313 |
|
| 3314 | int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
| 3315 | {
|
| 3316 | struct cftype *cft;
|
| 3317 |
|
| 3318 | |
| 3319 | * If legacy_flies_on_dfl, we want to show the legacy files on the
|
| 3320 | * dfl hierarchy but iff the target subsystem hasn't been updated
|
| 3321 | * for the dfl hierarchy yet.
|
| 3322 |
|
| 3323 | if (!cgroup_legacy_files_on_dfl ||
|
| 3324 | ss->dfl_cftypes != ss->legacy_cftypes) {
|
| 3325 | for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
|
| 3326 | cft->flags |= __CFTYPE_NOT_ON_DFL;
|
| 3327 | }
|
| 3328 |
|
| 3329 | return cgroup_add_cftypes(ss, cfts);
|
| 3330 | }
|
| 3331 |
|
| 3332 | |
| 3333 | * cgroup_task_count - count the number of tasks in a cgroup.
|
| 3334 | * @cgrp: the cgroup in question
|
| 3335 | *
|
| 3336 | * Return the number of tasks in the cgroup.
|
| 3337 |
|
| 3338 | static int cgroup_task_count(const struct cgroup *cgrp)
|
| 3339 | {
|
| 3340 | int count = 0;
|
| 3341 | struct cgrp_cset_link *link;
|
| 3342 |
|
| 3343 | down_read(&css_set_rwsem);
|
| 3344 | list_for_each_entry(link, &cgrp->cset_links, cset_link)
|
| 3345 | count += atomic_read(&link->cset->refcount);
|
| 3346 | up_read(&css_set_rwsem);
|
| 3347 | return count;
|
| 3348 | }
|
| 3349 |
|
| 3350 | |
| 3351 | * css_next_child - find the next child of a given css
|
| 3352 | * @pos: the current position (%NULL to initiate traversal)
|
| 3353 | * @parent: css whose children to walk
|
| 3354 | *
|
| 3355 | * This function returns the next child of @parent and should be called
|
| 3356 | * under either cgroup_mutex or RCU read lock. The only requirement is
|
| 3357 | * that @parent and @pos are accessible. The next sibling is guaranteed to
|
| 3358 | * be returned regardless of their states.
|
| 3359 | *
|
| 3360 | * If a subsystem synchronizes ->css_online() and the start of iteration, a
|
| 3361 | * css which finished ->css_online() is guaranteed to be visible in the
|
| 3362 | * future iterations and will stay visible until the last reference is put.
|
| 3363 | * A css which hasn't finished ->css_online() or already finished
|
| 3364 | * ->css_offline() may show up during traversal. It's each subsystem's
|
| 3365 | * responsibility to synchronize against on/offlining.
|
| 3366 |
|
| 3367 | struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
|
| 3368 | struct cgroup_subsys_state *parent)
|
| 3369 | {
|
| 3370 | struct cgroup_subsys_state *next;
|
| 3371 |
|
| 3372 | cgroup_assert_mutex_or_rcu_locked();
|
| 3373 |
|
| 3374 | |
| 3375 | * @pos could already have been unlinked from the sibling list.
|
| 3376 | * Once a cgroup is removed, its ->sibling.next is no longer
|
| 3377 | * updated when its next sibling changes. CSS_RELEASED is set when
|
| 3378 | * @pos is taken off list, at which time its next pointer is valid,
|
| 3379 | * and, as releases are serialized, the one pointed to by the next
|
| 3380 | * pointer is guaranteed to not have started release yet. This
|
| 3381 | * implies that if we observe !CSS_RELEASED on @pos in this RCU
|
| 3382 | * critical section, the one pointed to by its next pointer is
|
| 3383 | * guaranteed to not have finished its RCU grace period even if we
|
| 3384 | * have dropped rcu_read_lock() inbetween iterations.
|
| 3385 | *
|
| 3386 | * If @pos has CSS_RELEASED set, its next pointer can't be
|
| 3387 | * dereferenced; however, as each css is given a monotonically
|
| 3388 | * increasing unique serial number and always appended to the
|
| 3389 | * sibling list, the next one can be found by walking the parent's
|
| 3390 | * children until the first css with higher serial number than
|
| 3391 | * @pos's. While this path can be slower, it happens iff iteration
|
| 3392 | * races against release and the race window is very small.
|
| 3393 |
|
| 3394 | if (!pos) {
|
| 3395 | next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling);
|
| 3396 | } else if (likely(!(pos->flags & CSS_RELEASED))) {
|
| 3397 | next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling);
|
| 3398 | } else {
|
| 3399 | list_for_each_entry_rcu(next, &parent->children, sibling)
|
| 3400 | if (next->serial_nr > pos->serial_nr)
|
| 3401 | break;
|
| 3402 | }
|
| 3403 |
|
| 3404 | |
| 3405 | * @next, if not pointing to the head, can be dereferenced and is
|
| 3406 | * the next sibling.
|
| 3407 |
|
| 3408 | if (&next->sibling != &parent->children)
|
| 3409 | return next;
|
| 3410 | return NULL;
|
| 3411 | }
|
| 3412 |
|
| 3413 | |
| 3414 | * css_next_descendant_pre - find the next descendant for pre-order walk
|
| 3415 | * @pos: the current position (%NULL to initiate traversal)
|
| 3416 | * @root: css whose descendants to walk
|
| 3417 | *
|
| 3418 | * To be used by css_for_each_descendant_pre(). Find the next descendant
|
| 3419 | * to visit for pre-order traversal of @root's descendants. @root is
|
| 3420 | * included in the iteration and the first node to be visited.
|
| 3421 | *
|
| 3422 | * While this function requires cgroup_mutex or RCU read locking, it
|
| 3423 | * doesn't require the whole traversal to be contained in a single critical
|
| 3424 | * section. This function will return the correct next descendant as long
|
| 3425 | * as both @pos and @root are accessible and @pos is a descendant of @root.
|
| 3426 | *
|
| 3427 | * If a subsystem synchronizes ->css_online() and the start of iteration, a
|
| 3428 | * css which finished ->css_online() is guaranteed to be visible in the
|
| 3429 | * future iterations and will stay visible until the last reference is put.
|
| 3430 | * A css which hasn't finished ->css_online() or already finished
|
| 3431 | * ->css_offline() may show up during traversal. It's each subsystem's
|
| 3432 | * responsibility to synchronize against on/offlining.
|
| 3433 |
|
| 3434 | struct cgroup_subsys_state *
|
| 3435 | css_next_descendant_pre(struct cgroup_subsys_state *pos,
|
| 3436 | struct cgroup_subsys_state *root)
|
| 3437 | {
|
| 3438 | struct cgroup_subsys_state *next;
|
| 3439 |
|
| 3440 | cgroup_assert_mutex_or_rcu_locked();
|
| 3441 |
|
| 3442 |
|
| 3443 | if (!pos)
|
| 3444 | return root;
|
| 3445 |
|
| 3446 |
|
| 3447 | next = css_next_child(NULL, pos);
|
| 3448 | if (next)
|
| 3449 | return next;
|
| 3450 |
|
| 3451 |
|
| 3452 | while (pos != root) {
|
| 3453 | next = css_next_child(pos, pos->parent);
|
| 3454 | if (next)
|
| 3455 | return next;
|
| 3456 | pos = pos->parent;
|
| 3457 | }
|
| 3458 |
|
| 3459 | return NULL;
|
| 3460 | }
|
| 3461 |
|
| 3462 | |
| 3463 | * css_rightmost_descendant - return the rightmost descendant of a css
|
| 3464 | * @pos: css of interest
|
| 3465 | *
|
| 3466 | * Return the rightmost descendant of @pos. If there's no descendant, @pos
|
| 3467 | * is returned. This can be used during pre-order traversal to skip
|
| 3468 | * subtree of @pos.
|
| 3469 | *
|
| 3470 | * While this function requires cgroup_mutex or RCU read locking, it
|
| 3471 | * doesn't require the whole traversal to be contained in a single critical
|
| 3472 | * section. This function will return the correct rightmost descendant as
|
| 3473 | * long as @pos is accessible.
|
| 3474 |
|
| 3475 | struct cgroup_subsys_state *
|
| 3476 | css_rightmost_descendant(struct cgroup_subsys_state *pos)
|
| 3477 | {
|
| 3478 | struct cgroup_subsys_state *last, *tmp;
|
| 3479 |
|
| 3480 | cgroup_assert_mutex_or_rcu_locked();
|
| 3481 |
|
| 3482 | do {
|
| 3483 | last = pos;
|
| 3484 |
|
| 3485 | pos = NULL;
|
| 3486 | css_for_each_child(tmp, last)
|
| 3487 | pos = tmp;
|
| 3488 | } while (pos);
|
| 3489 |
|
| 3490 | return last;
|
| 3491 | }
|
| 3492 |
|
| 3493 | static struct cgroup_subsys_state *
|
| 3494 | css_leftmost_descendant(struct cgroup_subsys_state *pos)
|
| 3495 | {
|
| 3496 | struct cgroup_subsys_state *last;
|
| 3497 |
|
| 3498 | do {
|
| 3499 | last = pos;
|
| 3500 | pos = css_next_child(NULL, pos);
|
| 3501 | } while (pos);
|
| 3502 |
|
| 3503 | return last;
|
| 3504 | }
|
| 3505 |
|
| 3506 | |
| 3507 | * css_next_descendant_post - find the next descendant for post-order walk
|
| 3508 | * @pos: the current position (%NULL to initiate traversal)
|
| 3509 | * @root: css whose descendants to walk
|
| 3510 | *
|
| 3511 | * To be used by css_for_each_descendant_post(). Find the next descendant
|
| 3512 | * to visit for post-order traversal of @root's descendants. @root is
|
| 3513 | * included in the iteration and the last node to be visited.
|
| 3514 | *
|
| 3515 | * While this function requires cgroup_mutex or RCU read locking, it
|
| 3516 | * doesn't require the whole traversal to be contained in a single critical
|
| 3517 | * section. This function will return the correct next descendant as long
|
| 3518 | * as both @pos and @cgroup are accessible and @pos is a descendant of
|
| 3519 | * @cgroup.
|
| 3520 | *
|
| 3521 | * If a subsystem synchronizes ->css_online() and the start of iteration, a
|
| 3522 | * css which finished ->css_online() is guaranteed to be visible in the
|
| 3523 | * future iterations and will stay visible until the last reference is put.
|
| 3524 | * A css which hasn't finished ->css_online() or already finished
|
| 3525 | * ->css_offline() may show up during traversal. It's each subsystem's
|
| 3526 | * responsibility to synchronize against on/offlining.
|
| 3527 |
|
| 3528 | struct cgroup_subsys_state *
|
| 3529 | css_next_descendant_post(struct cgroup_subsys_state *pos,
|
| 3530 | struct cgroup_subsys_state *root)
|
| 3531 | {
|
| 3532 | struct cgroup_subsys_state *next;
|
| 3533 |
|
| 3534 | cgroup_assert_mutex_or_rcu_locked();
|
| 3535 |
|
| 3536 |
|
| 3537 | if (!pos)
|
| 3538 | return css_leftmost_descendant(root);
|
| 3539 |
|
| 3540 |
|
| 3541 | if (pos == root)
|
| 3542 | return NULL;
|
| 3543 |
|
| 3544 |
|
| 3545 | next = css_next_child(pos, pos->parent);
|
| 3546 | if (next)
|
| 3547 | return css_leftmost_descendant(next);
|
| 3548 |
|
| 3549 |
|
| 3550 | return pos->parent;
|
| 3551 | }
|
| 3552 |
|
| 3553 | |
| 3554 | * css_has_online_children - does a css have online children
|
| 3555 | * @css: the target css
|
| 3556 | *
|
| 3557 | * Returns %true if @css has any online children; otherwise, %false. This
|
| 3558 | * function can be called from any context but the caller is responsible
|
| 3559 | * for synchronizing against on/offlining as necessary.
|
| 3560 |
|
| 3561 | bool css_has_online_children(struct cgroup_subsys_state *css)
|
| 3562 | {
|
| 3563 | struct cgroup_subsys_state *child;
|
| 3564 | bool ret = false;
|
| 3565 |
|
| 3566 | rcu_read_lock();
|
| 3567 | css_for_each_child(child, css) {
|
| 3568 | if (child->flags & CSS_ONLINE) {
|
| 3569 | ret = true;
|
| 3570 | break;
|
| 3571 | }
|
| 3572 | }
|
| 3573 | rcu_read_unlock();
|
| 3574 | return ret;
|
| 3575 | }
|
| 3576 |
|
| 3577 | |
| 3578 | * css_advance_task_iter - advance a task itererator to the next css_set
|
| 3579 | * @it: the iterator to advance
|
| 3580 | *
|
| 3581 | * Advance @it to the next css_set to walk.
|
| 3582 |
|
| 3583 | static void css_advance_task_iter(struct css_task_iter *it)
|
| 3584 | {
|
| 3585 | struct list_head *l = it->cset_pos;
|
| 3586 | struct cgrp_cset_link *link;
|
| 3587 | struct css_set *cset;
|
| 3588 |
|
| 3589 |
|
| 3590 | do {
|
| 3591 | l = l->next;
|
| 3592 | if (l == it->cset_head) {
|
| 3593 | it->cset_pos = NULL;
|
| 3594 | return;
|
| 3595 | }
|
| 3596 |
|
| 3597 | if (it->ss) {
|
| 3598 | cset = container_of(l, struct css_set,
|
| 3599 | e_cset_node[it->ss->id]);
|
| 3600 | } else {
|
| 3601 | link = list_entry(l, struct cgrp_cset_link, cset_link);
|
| 3602 | cset = link->cset;
|
| 3603 | }
|
| 3604 | } while (list_empty(&cset->tasks) && list_empty(&cset->mg_tasks));
|
| 3605 |
|
| 3606 | it->cset_pos = l;
|
| 3607 |
|
| 3608 | if (!list_empty(&cset->tasks))
|
| 3609 | it->task_pos = cset->tasks.next;
|
| 3610 | else
|
| 3611 | it->task_pos = cset->mg_tasks.next;
|
| 3612 |
|
| 3613 | it->tasks_head = &cset->tasks;
|
| 3614 | it->mg_tasks_head = &cset->mg_tasks;
|
| 3615 | }
|
| 3616 |
|
| 3617 | |
| 3618 | * css_task_iter_start - initiate task iteration
|
| 3619 | * @css: the css to walk tasks of
|
| 3620 | * @it: the task iterator to use
|
| 3621 | *
|
| 3622 | * Initiate iteration through the tasks of @css. The caller can call
|
| 3623 | * css_task_iter_next() to walk through the tasks until the function
|
| 3624 | * returns NULL. On completion of iteration, css_task_iter_end() must be
|
| 3625 | * called.
|
| 3626 | *
|
| 3627 | * Note that this function acquires a lock which is released when the
|
| 3628 | * iteration finishes. The caller can't sleep while iteration is in
|
| 3629 | * progress.
|
| 3630 |
|
| 3631 | void css_task_iter_start(struct cgroup_subsys_state *css,
|
| 3632 | struct css_task_iter *it)
|
| 3633 | __acquires(css_set_rwsem)
|
| 3634 | {
|
| 3635 |
|
| 3636 | WARN_ON_ONCE(!use_task_css_set_links);
|
| 3637 |
|
| 3638 | down_read(&css_set_rwsem);
|
| 3639 |
|
| 3640 | it->ss = css->ss;
|
| 3641 |
|
| 3642 | if (it->ss)
|
| 3643 | it->cset_pos = &css->cgroup->e_csets[css->ss->id];
|
| 3644 | else
|
| 3645 | it->cset_pos = &css->cgroup->cset_links;
|
| 3646 |
|
| 3647 | it->cset_head = it->cset_pos;
|
| 3648 |
|
| 3649 | css_advance_task_iter(it);
|
| 3650 | }
|
| 3651 |
|
| 3652 | |
| 3653 | * css_task_iter_next - return the next task for the iterator
|
| 3654 | * @it: the task iterator being iterated
|
| 3655 | *
|
| 3656 | * The "next" function for task iteration. @it should have been
|
| 3657 | * initialized via css_task_iter_start(). Returns NULL when the iteration
|
| 3658 | * reaches the end.
|
| 3659 |
|
| 3660 | struct task_struct *css_task_iter_next(struct css_task_iter *it)
|
| 3661 | {
|
| 3662 | struct task_struct *res;
|
| 3663 | struct list_head *l = it->task_pos;
|
| 3664 |
|
| 3665 |
|
| 3666 | if (!it->cset_pos)
|
| 3667 | return NULL;
|
| 3668 | res = list_entry(l, struct task_struct, cg_list);
|
| 3669 |
|
| 3670 | |
| 3671 | * Advance iterator to find next entry. cset->tasks is consumed
|
| 3672 | * first and then ->mg_tasks. After ->mg_tasks, we move onto the
|
| 3673 | * next cset.
|
| 3674 |
|
| 3675 | l = l->next;
|
| 3676 |
|
| 3677 | if (l == it->tasks_head)
|
| 3678 | l = it->mg_tasks_head->next;
|
| 3679 |
|
| 3680 | if (l == it->mg_tasks_head)
|
| 3681 | css_advance_task_iter(it);
|
| 3682 | else
|
| 3683 | it->task_pos = l;
|
| 3684 |
|
| 3685 | return res;
|
| 3686 | }
|
| 3687 |
|
| 3688 | |
| 3689 | * css_task_iter_end - finish task iteration
|
| 3690 | * @it: the task iterator to finish
|
| 3691 | *
|
| 3692 | * Finish task iteration started by css_task_iter_start().
|
| 3693 |
|
| 3694 | void css_task_iter_end(struct css_task_iter *it)
|
| 3695 | __releases(css_set_rwsem)
|
| 3696 | {
|
| 3697 | up_read(&css_set_rwsem);
|
| 3698 | }
|
| 3699 |
|
| 3700 | |
| 3701 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
|
| 3702 | * @to: cgroup to which the tasks will be moved
|
| 3703 | * @from: cgroup in which the tasks currently reside
|
| 3704 | *
|
| 3705 | * Locking rules between cgroup_post_fork() and the migration path
|
| 3706 | * guarantee that, if a task is forking while being migrated, the new child
|
| 3707 | * is guaranteed to be either visible in the source cgroup after the
|
| 3708 | * parent's migration is complete or put into the target cgroup. No task
|
| 3709 | * can slip out of migration through forking.
|
| 3710 |
|
| 3711 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
|
| 3712 | {
|
| 3713 | LIST_HEAD(preloaded_csets);
|
| 3714 | struct cgrp_cset_link *link;
|
| 3715 | struct css_task_iter it;
|
| 3716 | struct task_struct *task;
|
| 3717 | int ret;
|
| 3718 |
|
| 3719 | mutex_lock(&cgroup_mutex);
|
| 3720 |
|
| 3721 |
|
| 3722 | down_read(&css_set_rwsem);
|
| 3723 | list_for_each_entry(link, &from->cset_links, cset_link)
|
| 3724 | cgroup_migrate_add_src(link->cset, to, &preloaded_csets);
|
| 3725 | up_read(&css_set_rwsem);
|
| 3726 |
|
| 3727 | ret = cgroup_migrate_prepare_dst(to, &preloaded_csets);
|
| 3728 | if (ret)
|
| 3729 | goto out_err;
|
| 3730 |
|
| 3731 | |
| 3732 | * Migrate tasks one-by-one until @form is empty. This fails iff
|
| 3733 | * ->can_attach() fails.
|
| 3734 |
|
| 3735 | do {
|
| 3736 | css_task_iter_start(&from->self, &it);
|
| 3737 | task = css_task_iter_next(&it);
|
| 3738 | if (task)
|
| 3739 | get_task_struct(task);
|
| 3740 | css_task_iter_end(&it);
|
| 3741 |
|
| 3742 | if (task) {
|
| 3743 | ret = cgroup_migrate(to, task, false);
|
| 3744 | put_task_struct(task);
|
| 3745 | }
|
| 3746 | } while (task && !ret);
|
| 3747 | out_err:
|
| 3748 | cgroup_migrate_finish(&preloaded_csets);
|
| 3749 | mutex_unlock(&cgroup_mutex);
|
| 3750 | return ret;
|
| 3751 | }
|
| 3752 |
|
| 3753 | |
| 3754 | * Stuff for reading the 'tasks'/'procs' files.
|
| 3755 | *
|
| 3756 | * Reading this file can return large amounts of data if a cgroup has
|
| 3757 | * *lots* of attached tasks. So it may need several calls to read(),
|
| 3758 | * but we cannot guarantee that the information we produce is correct
|
| 3759 | * unless we produce it entirely atomically.
|
| 3760 | *
|
| 3761 |
|
| 3762 |
|
| 3763 |
|
| 3764 | enum cgroup_filetype {
|
| 3765 | CGROUP_FILE_PROCS,
|
| 3766 | CGROUP_FILE_TASKS,
|
| 3767 | };
|
| 3768 |
|
| 3769 | |
| 3770 | * A pidlist is a list of pids that virtually represents the contents of one
|
| 3771 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
|
| 3772 | * a pair (one each for procs, tasks) for each pid namespace that's relevant
|
| 3773 | * to the cgroup.
|
| 3774 |
|
| 3775 | struct cgroup_pidlist {
|
| 3776 | |
| 3777 | * used to find which pidlist is wanted. doesn't change as long as
|
| 3778 | * this particular list stays in the list.
|
| 3779 |
|
| 3780 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
|
| 3781 |
|
| 3782 | pid_t *list;
|
| 3783 |
|
| 3784 | int length;
|
| 3785 |
|
| 3786 | struct list_head links;
|
| 3787 |
|
| 3788 | struct cgroup *owner;
|
| 3789 |
|
| 3790 | struct delayed_work destroy_dwork;
|
| 3791 | };
|
| 3792 |
|
| 3793 | |
| 3794 | * The following two functions "fix" the issue where there are more pids
|
| 3795 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
|
| 3796 | * TODO: replace with a kernel-wide solution to this problem
|
| 3797 |
|
| 3798 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
|
| 3799 | static void *pidlist_allocate(int count)
|
| 3800 | {
|
| 3801 | if (PIDLIST_TOO_LARGE(count))
|
| 3802 | return vmalloc(count * sizeof(pid_t));
|
| 3803 | else
|
| 3804 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
|
| 3805 | }
|
| 3806 |
|
| 3807 | static void pidlist_free(void *p)
|
| 3808 | {
|
| 3809 | if (is_vmalloc_addr(p))
|
| 3810 | vfree(p);
|
| 3811 | else
|
| 3812 | kfree(p);
|
| 3813 | }
|
| 3814 |
|
| 3815 | |
| 3816 | * Used to destroy all pidlists lingering waiting for destroy timer. None
|
| 3817 | * should be left afterwards.
|
| 3818 |
|
| 3819 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp)
|
| 3820 | {
|
| 3821 | struct cgroup_pidlist *l, *tmp_l;
|
| 3822 |
|
| 3823 | mutex_lock(&cgrp->pidlist_mutex);
|
| 3824 | list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
|
| 3825 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
|
| 3826 | mutex_unlock(&cgrp->pidlist_mutex);
|
| 3827 |
|
| 3828 | flush_workqueue(cgroup_pidlist_destroy_wq);
|
| 3829 | BUG_ON(!list_empty(&cgrp->pidlists));
|
| 3830 | }
|
| 3831 |
|
| 3832 | static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
|
| 3833 | {
|
| 3834 | struct delayed_work *dwork = to_delayed_work(work);
|
| 3835 | struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
|
| 3836 | destroy_dwork);
|
| 3837 | struct cgroup_pidlist *tofree = NULL;
|
| 3838 |
|
| 3839 | mutex_lock(&l->owner->pidlist_mutex);
|
| 3840 |
|
| 3841 | |
| 3842 | * Destroy iff we didn't get queued again. The state won't change
|
| 3843 | * as destroy_dwork can only be queued while locked.
|
| 3844 |
|
| 3845 | if (!delayed_work_pending(dwork)) {
|
| 3846 | list_del(&l->links);
|
| 3847 | pidlist_free(l->list);
|
| 3848 | put_pid_ns(l->key.ns);
|
| 3849 | tofree = l;
|
| 3850 | }
|
| 3851 |
|
| 3852 | mutex_unlock(&l->owner->pidlist_mutex);
|
| 3853 | kfree(tofree);
|
| 3854 | }
|
| 3855 |
|
| 3856 | |
| 3857 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
|
| 3858 | * Returns the number of unique elements.
|
| 3859 |
|
| 3860 | static int pidlist_uniq(pid_t *list, int length)
|
| 3861 | {
|
| 3862 | int src, dest = 1;
|
| 3863 |
|
| 3864 | |
| 3865 | * we presume the 0th element is unique, so i starts at 1. trivial
|
| 3866 | * edge cases first; no work needs to be done for either
|
| 3867 |
|
| 3868 | if (length == 0 || length == 1)
|
| 3869 | return length;
|
| 3870 |
|
| 3871 | for (src = 1; src < length; src++) {
|
| 3872 |
|
| 3873 | while (list[src] == list[src-1]) {
|
| 3874 | src++;
|
| 3875 | if (src == length)
|
| 3876 | goto after;
|
| 3877 | }
|
| 3878 |
|
| 3879 | list[dest] = list[src];
|
| 3880 | dest++;
|
| 3881 | }
|
| 3882 | after:
|
| 3883 | return dest;
|
| 3884 | }
|
| 3885 |
|
| 3886 | |
| 3887 | * The two pid files - task and cgroup.procs - guaranteed that the result
|
| 3888 | * is sorted, which forced this whole pidlist fiasco. As pid order is
|
| 3889 | * different per namespace, each namespace needs differently sorted list,
|
| 3890 | * making it impossible to use, for example, single rbtree of member tasks
|
| 3891 | * sorted by task pointer. As pidlists can be fairly large, allocating one
|
| 3892 | * per open file is dangerous, so cgroup had to implement shared pool of
|
| 3893 | * pidlists keyed by cgroup and namespace.
|
| 3894 | *
|
| 3895 | * All this extra complexity was caused by the original implementation
|
| 3896 | * committing to an entirely unnecessary property. In the long term, we
|
| 3897 | * want to do away with it. Explicitly scramble sort order if on the
|
| 3898 | * default hierarchy so that no such expectation exists in the new
|
| 3899 | * interface.
|
| 3900 | *
|
| 3901 | * Scrambling is done by swapping every two consecutive bits, which is
|
| 3902 | * non-identity one-to-one mapping which disturbs sort order sufficiently.
|
| 3903 |
|
| 3904 | static pid_t pid_fry(pid_t pid)
|
| 3905 | {
|
| 3906 | unsigned a = pid & 0x55555555;
|
| 3907 | unsigned b = pid & 0xAAAAAAAA;
|
| 3908 |
|
| 3909 | return (a << 1) | (b >> 1);
|
| 3910 | }
|
| 3911 |
|
| 3912 | static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid)
|
| 3913 | {
|
| 3914 | if (cgroup_on_dfl(cgrp))
|
| 3915 | return pid_fry(pid);
|
| 3916 | else
|
| 3917 | return pid;
|
| 3918 | }
|
| 3919 |
|
| 3920 | static int cmppid(const void *a, const void *b)
|
| 3921 | {
|
| 3922 | return *(pid_t *)a - *(pid_t *)b;
|
| 3923 | }
|
| 3924 |
|
| 3925 | static int fried_cmppid(const void *a, const void *b)
|
| 3926 | {
|
| 3927 | return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b);
|
| 3928 | }
|
| 3929 |
|
| 3930 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
|
| 3931 | enum cgroup_filetype type)
|
| 3932 | {
|
| 3933 | struct cgroup_pidlist *l;
|
| 3934 |
|
| 3935 | struct pid_namespace *ns = task_active_pid_ns(current);
|
| 3936 |
|
| 3937 | lockdep_assert_held(&cgrp->pidlist_mutex);
|
| 3938 |
|
| 3939 | list_for_each_entry(l, &cgrp->pidlists, links)
|
| 3940 | if (l->key.type == type && l->key.ns == ns)
|
| 3941 | return l;
|
| 3942 | return NULL;
|
| 3943 | }
|
| 3944 |
|
| 3945 | |
| 3946 | * find the appropriate pidlist for our purpose (given procs vs tasks)
|
| 3947 | * returns with the lock on that pidlist already held, and takes care
|
| 3948 | * of the use count, or returns NULL with no locks held if we're out of
|
| 3949 | * memory.
|
| 3950 |
|
| 3951 | static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
|
| 3952 | enum cgroup_filetype type)
|
| 3953 | {
|
| 3954 | struct cgroup_pidlist *l;
|
| 3955 |
|
| 3956 | lockdep_assert_held(&cgrp->pidlist_mutex);
|
| 3957 |
|
| 3958 | l = cgroup_pidlist_find(cgrp, type);
|
| 3959 | if (l)
|
| 3960 | return l;
|
| 3961 |
|
| 3962 |
|
| 3963 | l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
|
| 3964 | if (!l)
|
| 3965 | return l;
|
| 3966 |
|
| 3967 | INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
|
| 3968 | l->key.type = type;
|
| 3969 |
|
| 3970 | l->key.ns = get_pid_ns(task_active_pid_ns(current));
|
| 3971 | l->owner = cgrp;
|
| 3972 | list_add(&l->links, &cgrp->pidlists);
|
| 3973 | return l;
|
| 3974 | }
|
| 3975 |
|
| 3976 | |
| 3977 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids
|
| 3978 |
|
| 3979 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
|
| 3980 | struct cgroup_pidlist **lp)
|
| 3981 | {
|
| 3982 | pid_t *array;
|
| 3983 | int length;
|
| 3984 | int pid, n = 0;
|
| 3985 | struct css_task_iter it;
|
| 3986 | struct task_struct *tsk;
|
| 3987 | struct cgroup_pidlist *l;
|
| 3988 |
|
| 3989 | lockdep_assert_held(&cgrp->pidlist_mutex);
|
| 3990 |
|
| 3991 | |
| 3992 | * If cgroup gets more users after we read count, we won't have
|
| 3993 | * enough space - tough. This race is indistinguishable to the
|
| 3994 | * caller from the case that the additional cgroup users didn't
|
| 3995 | * show up until sometime later on.
|
| 3996 |
|
| 3997 | length = cgroup_task_count(cgrp);
|
| 3998 | array = pidlist_allocate(length);
|
| 3999 | if (!array)
|
| 4000 | return -ENOMEM;
|
| 4001 |
|
| 4002 | css_task_iter_start(&cgrp->self, &it);
|
| 4003 | while ((tsk = css_task_iter_next(&it))) {
|
| 4004 | if (unlikely(n == length))
|
| 4005 | break;
|
| 4006 |
|
| 4007 | if (type == CGROUP_FILE_PROCS)
|
| 4008 | pid = task_tgid_vnr(tsk);
|
| 4009 | else
|
| 4010 | pid = task_pid_vnr(tsk);
|
| 4011 | if (pid > 0)
|
| 4012 | array[n++] = pid;
|
| 4013 | }
|
| 4014 | css_task_iter_end(&it);
|
| 4015 | length = n;
|
| 4016 |
|
| 4017 | if (cgroup_on_dfl(cgrp))
|
| 4018 | sort(array, length, sizeof(pid_t), fried_cmppid, NULL);
|
| 4019 | else
|
| 4020 | sort(array, length, sizeof(pid_t), cmppid, NULL);
|
| 4021 | if (type == CGROUP_FILE_PROCS)
|
| 4022 | length = pidlist_uniq(array, length);
|
| 4023 |
|
| 4024 | l = cgroup_pidlist_find_create(cgrp, type);
|
| 4025 | if (!l) {
|
| 4026 | pidlist_free(array);
|
| 4027 | return -ENOMEM;
|
| 4028 | }
|
| 4029 |
|
| 4030 |
|
| 4031 | pidlist_free(l->list);
|
| 4032 | l->list = array;
|
| 4033 | l->length = length;
|
| 4034 | *lp = l;
|
| 4035 | return 0;
|
| 4036 | }
|
| 4037 |
|
| 4038 | |
| 4039 | * cgroupstats_build - build and fill cgroupstats
|
| 4040 | * @stats: cgroupstats to fill information into
|
| 4041 | * @dentry: A dentry entry belonging to the cgroup for which stats have
|
| 4042 | * been requested.
|
| 4043 | *
|
| 4044 | * Build and fill cgroupstats so that taskstats can export it to user
|
| 4045 | * space.
|
| 4046 |
|
| 4047 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
|
| 4048 | {
|
| 4049 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
|
| 4050 | struct cgroup *cgrp;
|
| 4051 | struct css_task_iter it;
|
| 4052 | struct task_struct *tsk;
|
| 4053 |
|
| 4054 |
|
| 4055 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
|
| 4056 | kernfs_type(kn) != KERNFS_DIR)
|
| 4057 | return -EINVAL;
|
| 4058 |
|
| 4059 | mutex_lock(&cgroup_mutex);
|
| 4060 |
|
| 4061 | |
| 4062 | * We aren't being called from kernfs and there's no guarantee on
|
| 4063 | * @kn->priv's validity. For this and css_tryget_online_from_dir(),
|
| 4064 | * @kn->priv is RCU safe. Let's do the RCU dancing.
|
| 4065 |
|
| 4066 | rcu_read_lock();
|
| 4067 | cgrp = rcu_dereference(kn->priv);
|
| 4068 | if (!cgrp || cgroup_is_dead(cgrp)) {
|
| 4069 | rcu_read_unlock();
|
| 4070 | mutex_unlock(&cgroup_mutex);
|
| 4071 | return -ENOENT;
|
| 4072 | }
|
| 4073 | rcu_read_unlock();
|
| 4074 |
|
| 4075 | css_task_iter_start(&cgrp->self, &it);
|
| 4076 | while ((tsk = css_task_iter_next(&it))) {
|
| 4077 | switch (tsk->state) {
|
| 4078 | case TASK_RUNNING:
|
| 4079 | stats->nr_running++;
|
| 4080 | break;
|
| 4081 | case TASK_INTERRUPTIBLE:
|
| 4082 | stats->nr_sleeping++;
|
| 4083 | break;
|
| 4084 | case TASK_UNINTERRUPTIBLE:
|
| 4085 | stats->nr_uninterruptible++;
|
| 4086 | break;
|
| 4087 | case TASK_STOPPED:
|
| 4088 | stats->nr_stopped++;
|
| 4089 | break;
|
| 4090 | default:
|
| 4091 | if (delayacct_is_task_waiting_on_io(tsk))
|
| 4092 | stats->nr_io_wait++;
|
| 4093 | break;
|
| 4094 | }
|
| 4095 | }
|
| 4096 | css_task_iter_end(&it);
|
| 4097 |
|
| 4098 | mutex_unlock(&cgroup_mutex);
|
| 4099 | return 0;
|
| 4100 | }
|
| 4101 |
|
| 4102 |
|
| 4103 | |
| 4104 | * seq_file methods for the tasks/procs files. The seq_file position is the
|
| 4105 | * next pid to display; the seq_file iterator is a pointer to the pid
|
| 4106 | * in the cgroup->l->list array.
|
| 4107 |
|
| 4108 |
|
| 4109 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
|
| 4110 | {
|
| 4111 | |
| 4112 | * Initially we receive a position value that corresponds to
|
| 4113 | * one more than the last pid shown (or 0 on the first call or
|
| 4114 | * after a seek to the start). Use a binary-search to find the
|
| 4115 | * next pid to display, if any
|
| 4116 |
|
| 4117 | struct kernfs_open_file *of = s->private;
|
| 4118 | struct cgroup *cgrp = seq_css(s)->cgroup;
|
| 4119 | struct cgroup_pidlist *l;
|
| 4120 | enum cgroup_filetype type = seq_cft(s)->private;
|
| 4121 | int index = 0, pid = *pos;
|
| 4122 | int *iter, ret;
|
| 4123 |
|
| 4124 | mutex_lock(&cgrp->pidlist_mutex);
|
| 4125 |
|
| 4126 | |
| 4127 | * !NULL @of->priv indicates that this isn't the first start()
|
| 4128 | * after open. If the matching pidlist is around, we can use that.
|
| 4129 | * Look for it. Note that @of->priv can't be used directly. It
|
| 4130 | * could already have been destroyed.
|
| 4131 |
|
| 4132 | if (of->priv)
|
| 4133 | of->priv = cgroup_pidlist_find(cgrp, type);
|
| 4134 |
|
| 4135 | |
| 4136 | * Either this is the first start() after open or the matching
|
| 4137 | * pidlist has been destroyed inbetween. Create a new one.
|
| 4138 |
|
| 4139 | if (!of->priv) {
|
| 4140 | ret = pidlist_array_load(cgrp, type,
|
| 4141 | (struct cgroup_pidlist **)&of->priv);
|
| 4142 | if (ret)
|
| 4143 | return ERR_PTR(ret);
|
| 4144 | }
|
| 4145 | l = of->priv;
|
| 4146 |
|
| 4147 | if (pid) {
|
| 4148 | int end = l->length;
|
| 4149 |
|
| 4150 | while (index < end) {
|
| 4151 | int mid = (index + end) / 2;
|
| 4152 | if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) {
|
| 4153 | index = mid;
|
| 4154 | break;
|
| 4155 | } else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid)
|
| 4156 | index = mid + 1;
|
| 4157 | else
|
| 4158 | end = mid;
|
| 4159 | }
|
| 4160 | }
|
| 4161 |
|
| 4162 | if (index >= l->length)
|
| 4163 | return NULL;
|
| 4164 |
|
| 4165 | iter = l->list + index;
|
| 4166 | *pos = cgroup_pid_fry(cgrp, *iter);
|
| 4167 | return iter;
|
| 4168 | }
|
| 4169 |
|
| 4170 | static void cgroup_pidlist_stop(struct seq_file *s, void *v)
|
| 4171 | {
|
| 4172 | struct kernfs_open_file *of = s->private;
|
| 4173 | struct cgroup_pidlist *l = of->priv;
|
| 4174 |
|
| 4175 | if (l)
|
| 4176 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
|
| 4177 | CGROUP_PIDLIST_DESTROY_DELAY);
|
| 4178 | mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
|
| 4179 | }
|
| 4180 |
|
| 4181 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
|
| 4182 | {
|
| 4183 | struct kernfs_open_file *of = s->private;
|
| 4184 | struct cgroup_pidlist *l = of->priv;
|
| 4185 | pid_t *p = v;
|
| 4186 | pid_t *end = l->list + l->length;
|
| 4187 | |
| 4188 | * Advance to the next pid in the array. If this goes off the
|
| 4189 | * end, we're done
|
| 4190 |
|
| 4191 | p++;
|
| 4192 | if (p >= end) {
|
| 4193 | return NULL;
|
| 4194 | } else {
|
| 4195 | *pos = cgroup_pid_fry(seq_css(s)->cgroup, *p);
|
| 4196 | return p;
|
| 4197 | }
|
| 4198 | }
|
| 4199 |
|
| 4200 | static int cgroup_pidlist_show(struct seq_file *s, void *v)
|
| 4201 | {
|
| 4202 | return seq_printf(s, "%d\n", *(int *)v);
|
| 4203 | }
|
| 4204 |
|
| 4205 | static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
|
| 4206 | struct cftype *cft)
|
| 4207 | {
|
| 4208 | return notify_on_release(css->cgroup);
|
| 4209 | }
|
| 4210 |
|
| 4211 | static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
|
| 4212 | struct cftype *cft, u64 val)
|
| 4213 | {
|
| 4214 | if (val)
|
| 4215 | set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
|
| 4216 | else
|
| 4217 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
|
| 4218 | return 0;
|
| 4219 | }
|
| 4220 |
|
| 4221 | static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
|
| 4222 | struct cftype *cft)
|
| 4223 | {
|
| 4224 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
| 4225 | }
|
| 4226 |
|
| 4227 | static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
|
| 4228 | struct cftype *cft, u64 val)
|
| 4229 | {
|
| 4230 | if (val)
|
| 4231 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
| 4232 | else
|
| 4233 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
| 4234 | return 0;
|
| 4235 | }
|
| 4236 |
|
| 4237 |
|
| 4238 | static struct cftype cgroup_dfl_base_files[] = {
|
| 4239 | {
|
| 4240 | .name = "cgroup.procs",
|
| 4241 | .seq_start = cgroup_pidlist_start,
|
| 4242 | .seq_next = cgroup_pidlist_next,
|
| 4243 | .seq_stop = cgroup_pidlist_stop,
|
| 4244 | .seq_show = cgroup_pidlist_show,
|
| 4245 | .private = CGROUP_FILE_PROCS,
|
| 4246 | .write = cgroup_procs_write,
|
| 4247 | .mode = S_IRUGO | S_IWUSR,
|
| 4248 | },
|
| 4249 | {
|
| 4250 | .name = "cgroup.controllers",
|
| 4251 | .flags = CFTYPE_ONLY_ON_ROOT,
|
| 4252 | .seq_show = cgroup_root_controllers_show,
|
| 4253 | },
|
| 4254 | {
|
| 4255 | .name = "cgroup.controllers",
|
| 4256 | .flags = CFTYPE_NOT_ON_ROOT,
|
| 4257 | .seq_show = cgroup_controllers_show,
|
| 4258 | },
|
| 4259 | {
|
| 4260 | .name = "cgroup.subtree_control",
|
| 4261 | .seq_show = cgroup_subtree_control_show,
|
| 4262 | .write = cgroup_subtree_control_write,
|
| 4263 | },
|
| 4264 | {
|
| 4265 | .name = "cgroup.populated",
|
| 4266 | .flags = CFTYPE_NOT_ON_ROOT,
|
| 4267 | .seq_show = cgroup_populated_show,
|
| 4268 | },
|
| 4269 | { }
|
| 4270 | };
|
| 4271 |
|
| 4272 |
|
| 4273 | static struct cftype cgroup_legacy_base_files[] = {
|
| 4274 | {
|
| 4275 | .name = "cgroup.procs",
|
| 4276 | .seq_start = cgroup_pidlist_start,
|
| 4277 | .seq_next = cgroup_pidlist_next,
|
| 4278 | .seq_stop = cgroup_pidlist_stop,
|
| 4279 | .seq_show = cgroup_pidlist_show,
|
| 4280 | .private = CGROUP_FILE_PROCS,
|
| 4281 | .write = cgroup_procs_write,
|
| 4282 | .mode = S_IRUGO | S_IWUSR,
|
| 4283 | },
|
| 4284 | {
|
| 4285 | .name = "cgroup.clone_children",
|
| 4286 | .read_u64 = cgroup_clone_children_read,
|
| 4287 | .write_u64 = cgroup_clone_children_write,
|
| 4288 | },
|
| 4289 | {
|
| 4290 | .name = "cgroup.sane_behavior",
|
| 4291 | .flags = CFTYPE_ONLY_ON_ROOT,
|
| 4292 | .seq_show = cgroup_sane_behavior_show,
|
| 4293 | },
|
| 4294 | {
|
| 4295 | .name = "tasks",
|
| 4296 | .seq_start = cgroup_pidlist_start,
|
| 4297 | .seq_next = cgroup_pidlist_next,
|
| 4298 | .seq_stop = cgroup_pidlist_stop,
|
| 4299 | .seq_show = cgroup_pidlist_show,
|
| 4300 | .private = CGROUP_FILE_TASKS,
|
| 4301 | .write = cgroup_tasks_write,
|
| 4302 | .mode = S_IRUGO | S_IWUSR,
|
| 4303 | },
|
| 4304 | {
|
| 4305 | .name = "notify_on_release",
|
| 4306 | .read_u64 = cgroup_read_notify_on_release,
|
| 4307 | .write_u64 = cgroup_write_notify_on_release,
|
| 4308 | },
|
| 4309 | {
|
| 4310 | .name = "release_agent",
|
| 4311 | .flags = CFTYPE_ONLY_ON_ROOT,
|
| 4312 | .seq_show = cgroup_release_agent_show,
|
| 4313 | .write = cgroup_release_agent_write,
|
| 4314 | .max_write_len = PATH_MAX - 1,
|
| 4315 | },
|
| 4316 | { }
|
| 4317 | };
|
| 4318 |
|
| 4319 | |
| 4320 | * cgroup_populate_dir - create subsys files in a cgroup directory
|
| 4321 | * @cgrp: target cgroup
|
| 4322 | * @subsys_mask: mask of the subsystem ids whose files should be added
|
| 4323 | *
|
| 4324 | * On failure, no file is added.
|
| 4325 |
|
| 4326 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned int subsys_mask)
|
| 4327 | {
|
| 4328 | struct cgroup_subsys *ss;
|
| 4329 | int i, ret = 0;
|
| 4330 |
|
| 4331 |
|
| 4332 | for_each_subsys(ss, i) {
|
| 4333 | struct cftype *cfts;
|
| 4334 |
|
| 4335 | if (!(subsys_mask & (1 << i)))
|
| 4336 | continue;
|
| 4337 |
|
| 4338 | list_for_each_entry(cfts, &ss->cfts, node) {
|
| 4339 | ret = cgroup_addrm_files(cgrp, cfts, true);
|
| 4340 | if (ret < 0)
|
| 4341 | goto err;
|
| 4342 | }
|
| 4343 | }
|
| 4344 | return 0;
|
| 4345 | err:
|
| 4346 | cgroup_clear_dir(cgrp, subsys_mask);
|
| 4347 | return ret;
|
| 4348 | }
|
| 4349 |
|
| 4350 | |
| 4351 | * css destruction is four-stage process.
|
| 4352 | *
|
| 4353 | * 1. Destruction starts. Killing of the percpu_ref is initiated.
|
| 4354 | * Implemented in kill_css().
|
| 4355 | *
|
| 4356 | * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
|
| 4357 | * and thus css_tryget_online() is guaranteed to fail, the css can be
|
| 4358 | * offlined by invoking offline_css(). After offlining, the base ref is
|
| 4359 | * put. Implemented in css_killed_work_fn().
|
| 4360 | *
|
| 4361 | * 3. When the percpu_ref reaches zero, the only possible remaining
|
| 4362 | * accessors are inside RCU read sections. css_release() schedules the
|
| 4363 | * RCU callback.
|
| 4364 | *
|
| 4365 | * 4. After the grace period, the css can be freed. Implemented in
|
| 4366 | * css_free_work_fn().
|
| 4367 | *
|
| 4368 | * It is actually hairier because both step 2 and 4 require process context
|
| 4369 | * and thus involve punting to css->destroy_work adding two additional
|
| 4370 | * steps to the already complex sequence.
|
| 4371 |
|
| 4372 | static void css_free_work_fn(struct work_struct *work)
|
| 4373 | {
|
| 4374 | struct cgroup_subsys_state *css =
|
| 4375 | container_of(work, struct cgroup_subsys_state, destroy_work);
|
| 4376 | struct cgroup_subsys *ss = css->ss;
|
| 4377 | struct cgroup *cgrp = css->cgroup;
|
| 4378 |
|
| 4379 | percpu_ref_exit(&css->refcnt);
|
| 4380 |
|
| 4381 | if (ss) {
|
| 4382 |
|
| 4383 | int id = css->id;
|
| 4384 |
|
| 4385 | if (css->parent)
|
| 4386 | css_put(css->parent);
|
| 4387 |
|
| 4388 | ss->css_free(css);
|
| 4389 | cgroup_idr_remove(&ss->css_idr, id);
|
| 4390 | cgroup_put(cgrp);
|
| 4391 | } else {
|
| 4392 |
|
| 4393 | atomic_dec(&cgrp->root->nr_cgrps);
|
| 4394 | cgroup_pidlist_destroy_all(cgrp);
|
| 4395 | cancel_work_sync(&cgrp->release_agent_work);
|
| 4396 |
|
| 4397 | if (cgroup_parent(cgrp)) {
|
| 4398 | |
| 4399 | * We get a ref to the parent, and put the ref when
|
| 4400 | * this cgroup is being freed, so it's guaranteed
|
| 4401 | * that the parent won't be destroyed before its
|
| 4402 | * children.
|
| 4403 |
|
| 4404 | cgroup_put(cgroup_parent(cgrp));
|
| 4405 | kernfs_put(cgrp->kn);
|
| 4406 | kfree(cgrp);
|
| 4407 | } else {
|
| 4408 | |
| 4409 | * This is root cgroup's refcnt reaching zero,
|
| 4410 | * which indicates that the root should be
|
| 4411 | * released.
|
| 4412 |
|
| 4413 | cgroup_destroy_root(cgrp->root);
|
| 4414 | }
|
| 4415 | }
|
| 4416 | }
|
| 4417 |
|
| 4418 | static void css_free_rcu_fn(struct rcu_head *rcu_head)
|
| 4419 | {
|
| 4420 | struct cgroup_subsys_state *css =
|
| 4421 | container_of(rcu_head, struct cgroup_subsys_state, rcu_head);
|
| 4422 |
|
| 4423 | INIT_WORK(&css->destroy_work, css_free_work_fn);
|
| 4424 | queue_work(cgroup_destroy_wq, &css->destroy_work);
|
| 4425 | }
|
| 4426 |
|
| 4427 | static void css_release_work_fn(struct work_struct *work)
|
| 4428 | {
|
| 4429 | struct cgroup_subsys_state *css =
|
| 4430 | container_of(work, struct cgroup_subsys_state, destroy_work);
|
| 4431 | struct cgroup_subsys *ss = css->ss;
|
| 4432 | struct cgroup *cgrp = css->cgroup;
|
| 4433 |
|
| 4434 | mutex_lock(&cgroup_mutex);
|
| 4435 |
|
| 4436 | css->flags |= CSS_RELEASED;
|
| 4437 | list_del_rcu(&css->sibling);
|
| 4438 |
|
| 4439 | if (ss) {
|
| 4440 |
|
| 4441 | cgroup_idr_replace(&ss->css_idr, NULL, css->id);
|
| 4442 | if (ss->css_released)
|
| 4443 | ss->css_released(css);
|
| 4444 | } else {
|
| 4445 |
|
| 4446 | cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
|
| 4447 | cgrp->id = -1;
|
| 4448 |
|
| 4449 | |
| 4450 | * There are two control paths which try to determine
|
| 4451 | * cgroup from dentry without going through kernfs -
|
| 4452 | * cgroupstats_build() and css_tryget_online_from_dir().
|
| 4453 | * Those are supported by RCU protecting clearing of
|
| 4454 | * cgrp->kn->priv backpointer.
|
| 4455 |
|
| 4456 | RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL);
|
| 4457 | }
|
| 4458 |
|
| 4459 | mutex_unlock(&cgroup_mutex);
|
| 4460 |
|
| 4461 | call_rcu(&css->rcu_head, css_free_rcu_fn);
|
| 4462 | }
|
| 4463 |
|
| 4464 | static void css_release(struct percpu_ref *ref)
|
| 4465 | {
|
| 4466 | struct cgroup_subsys_state *css =
|
| 4467 | container_of(ref, struct cgroup_subsys_state, refcnt);
|
| 4468 |
|
| 4469 | INIT_WORK(&css->destroy_work, css_release_work_fn);
|
| 4470 | queue_work(cgroup_destroy_wq, &css->destroy_work);
|
| 4471 | }
|
| 4472 |
|
| 4473 | static void init_and_link_css(struct cgroup_subsys_state *css,
|
| 4474 | struct cgroup_subsys *ss, struct cgroup *cgrp)
|
| 4475 | {
|
| 4476 | lockdep_assert_held(&cgroup_mutex);
|
| 4477 |
|
| 4478 | cgroup_get(cgrp);
|
| 4479 |
|
| 4480 | memset(css, 0, sizeof(*css));
|
| 4481 | css->cgroup = cgrp;
|
| 4482 | css->ss = ss;
|
| 4483 | INIT_LIST_HEAD(&css->sibling);
|
| 4484 | INIT_LIST_HEAD(&css->children);
|
| 4485 | css->serial_nr = css_serial_nr_next++;
|
| 4486 |
|
| 4487 | if (cgroup_parent(cgrp)) {
|
| 4488 | css->parent = cgroup_css(cgroup_parent(cgrp), ss);
|
| 4489 | css_get(css->parent);
|
| 4490 | }
|
| 4491 |
|
| 4492 | BUG_ON(cgroup_css(cgrp, ss));
|
| 4493 | }
|
| 4494 |
|
| 4495 |
|
| 4496 | static int online_css(struct cgroup_subsys_state *css)
|
| 4497 | {
|
| 4498 | struct cgroup_subsys *ss = css->ss;
|
| 4499 | int ret = 0;
|
| 4500 |
|
| 4501 | lockdep_assert_held(&cgroup_mutex);
|
| 4502 |
|
| 4503 | if (ss->css_online)
|
| 4504 | ret = ss->css_online(css);
|
| 4505 | if (!ret) {
|
| 4506 | css->flags |= CSS_ONLINE;
|
| 4507 | rcu_assign_pointer(css->cgroup->subsys[ss->id], css);
|
| 4508 | }
|
| 4509 | return ret;
|
| 4510 | }
|
| 4511 |
|
| 4512 |
|
| 4513 | static void offline_css(struct cgroup_subsys_state *css)
|
| 4514 | {
|
| 4515 | struct cgroup_subsys *ss = css->ss;
|
| 4516 |
|
| 4517 | lockdep_assert_held(&cgroup_mutex);
|
| 4518 |
|
| 4519 | if (!(css->flags & CSS_ONLINE))
|
| 4520 | return;
|
| 4521 |
|
| 4522 | if (ss->css_offline)
|
| 4523 | ss->css_offline(css);
|
| 4524 |
|
| 4525 | css->flags &= ~CSS_ONLINE;
|
| 4526 | RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL);
|
| 4527 |
|
| 4528 | wake_up_all(&css->cgroup->offline_waitq);
|
| 4529 | }
|
| 4530 |
|
| 4531 | |
| 4532 | * create_css - create a cgroup_subsys_state
|
| 4533 | * @cgrp: the cgroup new css will be associated with
|
| 4534 | * @ss: the subsys of new css
|
| 4535 | * @visible: whether to create control knobs for the new css or not
|
| 4536 | *
|
| 4537 | * Create a new css associated with @cgrp - @ss pair. On success, the new
|
| 4538 | * css is online and installed in @cgrp with all interface files created if
|
| 4539 | * @visible. Returns 0 on success, -errno on failure.
|
| 4540 |
|
| 4541 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
|
| 4542 | bool visible)
|
| 4543 | {
|
| 4544 | struct cgroup *parent = cgroup_parent(cgrp);
|
| 4545 | struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss);
|
| 4546 | struct cgroup_subsys_state *css;
|
| 4547 | int err;
|
| 4548 |
|
| 4549 | lockdep_assert_held(&cgroup_mutex);
|
| 4550 |
|
| 4551 | css = ss->css_alloc(parent_css);
|
| 4552 | if (IS_ERR(css))
|
| 4553 | return PTR_ERR(css);
|
| 4554 |
|
| 4555 | init_and_link_css(css, ss, cgrp);
|
| 4556 |
|
| 4557 | err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL);
|
| 4558 | if (err)
|
| 4559 | goto err_free_css;
|
| 4560 |
|
| 4561 | err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_NOWAIT);
|
| 4562 | if (err < 0)
|
| 4563 | goto err_free_percpu_ref;
|
| 4564 | css->id = err;
|
| 4565 |
|
| 4566 | if (visible) {
|
| 4567 | err = cgroup_populate_dir(cgrp, 1 << ss->id);
|
| 4568 | if (err)
|
| 4569 | goto err_free_id;
|
| 4570 | }
|
| 4571 |
|
| 4572 |
|
| 4573 | list_add_tail_rcu(&css->sibling, &parent_css->children);
|
| 4574 | cgroup_idr_replace(&ss->css_idr, css, css->id);
|
| 4575 |
|
| 4576 | err = online_css(css);
|
| 4577 | if (err)
|
| 4578 | goto err_list_del;
|
| 4579 |
|
| 4580 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
|
| 4581 | cgroup_parent(parent)) {
|
| 4582 | pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
|
| 4583 | current->comm, current->pid, ss->name);
|
| 4584 | if (!strcmp(ss->name, "memory"))
|
| 4585 | pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n");
|
| 4586 | ss->warned_broken_hierarchy = true;
|
| 4587 | }
|
| 4588 |
|
| 4589 | return 0;
|
| 4590 |
|
| 4591 | err_list_del:
|
| 4592 | list_del_rcu(&css->sibling);
|
| 4593 | cgroup_clear_dir(css->cgroup, 1 << css->ss->id);
|
| 4594 | err_free_id:
|
| 4595 | cgroup_idr_remove(&ss->css_idr, css->id);
|
| 4596 | err_free_percpu_ref:
|
| 4597 | percpu_ref_exit(&css->refcnt);
|
| 4598 | err_free_css:
|
| 4599 | call_rcu(&css->rcu_head, css_free_rcu_fn);
|
| 4600 | return err;
|
| 4601 | }
|
| 4602 |
|
| 4603 | static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
|
| 4604 | umode_t mode)
|
| 4605 | {
|
| 4606 | struct cgroup *parent, *cgrp;
|
| 4607 | struct cgroup_root *root;
|
| 4608 | struct cgroup_subsys *ss;
|
| 4609 | struct kernfs_node *kn;
|
| 4610 | struct cftype *base_files;
|
| 4611 | int ssid, ret;
|
| 4612 |
|
| 4613 | |
| 4614 |
|
| 4615 | if (strchr(name, '\n'))
|
| 4616 | return -EINVAL;
|
| 4617 |
|
| 4618 | parent = cgroup_kn_lock_live(parent_kn);
|
| 4619 | if (!parent)
|
| 4620 | return -ENODEV;
|
| 4621 | root = parent->root;
|
| 4622 |
|
| 4623 |
|
| 4624 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
|
| 4625 | if (!cgrp) {
|
| 4626 | ret = -ENOMEM;
|
| 4627 | goto out_unlock;
|
| 4628 | }
|
| 4629 |
|
| 4630 | ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL);
|
| 4631 | if (ret)
|
| 4632 | goto out_free_cgrp;
|
| 4633 |
|
| 4634 | |
| 4635 | * Temporarily set the pointer to NULL, so idr_find() won't return
|
| 4636 | * a half-baked cgroup.
|
| 4637 |
|
| 4638 | cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_NOWAIT);
|
| 4639 | if (cgrp->id < 0) {
|
| 4640 | ret = -ENOMEM;
|
| 4641 | goto out_cancel_ref;
|
| 4642 | }
|
| 4643 |
|
| 4644 | init_cgroup_housekeeping(cgrp);
|
| 4645 |
|
| 4646 | cgrp->self.parent = &parent->self;
|
| 4647 | cgrp->root = root;
|
| 4648 |
|
| 4649 | if (notify_on_release(parent))
|
| 4650 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
|
| 4651 |
|
| 4652 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags))
|
| 4653 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
|
| 4654 |
|
| 4655 |
|
| 4656 | kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
|
| 4657 | if (IS_ERR(kn)) {
|
| 4658 | ret = PTR_ERR(kn);
|
| 4659 | goto out_free_id;
|
| 4660 | }
|
| 4661 | cgrp->kn = kn;
|
| 4662 |
|
| 4663 | |
| 4664 | * This extra ref will be put in cgroup_free_fn() and guarantees
|
| 4665 | * that @cgrp->kn is always accessible.
|
| 4666 |
|
| 4667 | kernfs_get(kn);
|
| 4668 |
|
| 4669 | cgrp->self.serial_nr = css_serial_nr_next++;
|
| 4670 |
|
| 4671 |
|
| 4672 | list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children);
|
| 4673 | atomic_inc(&root->nr_cgrps);
|
| 4674 | cgroup_get(parent);
|
| 4675 |
|
| 4676 | |
| 4677 | * @cgrp is now fully operational. If something fails after this
|
| 4678 | * point, it'll be released via the normal destruction path.
|
| 4679 |
|
| 4680 | cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id);
|
| 4681 |
|
| 4682 | ret = cgroup_kn_set_ugid(kn);
|
| 4683 | if (ret)
|
| 4684 | goto out_destroy;
|
| 4685 |
|
| 4686 | if (cgroup_on_dfl(cgrp))
|
| 4687 | base_files = cgroup_dfl_base_files;
|
| 4688 | else
|
| 4689 | base_files = cgroup_legacy_base_files;
|
| 4690 |
|
| 4691 | ret = cgroup_addrm_files(cgrp, base_files, true);
|
| 4692 | if (ret)
|
| 4693 | goto out_destroy;
|
| 4694 |
|
| 4695 |
|
| 4696 | for_each_subsys(ss, ssid) {
|
| 4697 | if (parent->child_subsys_mask & (1 << ssid)) {
|
| 4698 | ret = create_css(cgrp, ss,
|
| 4699 | parent->subtree_control & (1 << ssid));
|
| 4700 | if (ret)
|
| 4701 | goto out_destroy;
|
| 4702 | }
|
| 4703 | }
|
| 4704 |
|
| 4705 | |
| 4706 | * On the default hierarchy, a child doesn't automatically inherit
|
| 4707 | * subtree_control from the parent. Each is configured manually.
|
| 4708 |
|
| 4709 | if (!cgroup_on_dfl(cgrp)) {
|
| 4710 | cgrp->subtree_control = parent->subtree_control;
|
| 4711 | cgroup_refresh_child_subsys_mask(cgrp);
|
| 4712 | }
|
| 4713 |
|
| 4714 | kernfs_activate(kn);
|
| 4715 |
|
| 4716 | ret = 0;
|
| 4717 | goto out_unlock;
|
| 4718 |
|
| 4719 | out_free_id:
|
| 4720 | cgroup_idr_remove(&root->cgroup_idr, cgrp->id);
|
| 4721 | out_cancel_ref:
|
| 4722 | percpu_ref_exit(&cgrp->self.refcnt);
|
| 4723 | out_free_cgrp:
|
| 4724 | kfree(cgrp);
|
| 4725 | out_unlock:
|
| 4726 | cgroup_kn_unlock(parent_kn);
|
| 4727 | return ret;
|
| 4728 |
|
| 4729 | out_destroy:
|
| 4730 | cgroup_destroy_locked(cgrp);
|
| 4731 | goto out_unlock;
|
| 4732 | }
|
| 4733 |
|
| 4734 | |
| 4735 | * This is called when the refcnt of a css is confirmed to be killed.
|
| 4736 | * css_tryget_online() is now guaranteed to fail. Tell the subsystem to
|
| 4737 | * initate destruction and put the css ref from kill_css().
|
| 4738 |
|
| 4739 | static void css_killed_work_fn(struct work_struct *work)
|
| 4740 | {
|
| 4741 | struct cgroup_subsys_state *css =
|
| 4742 | container_of(work, struct cgroup_subsys_state, destroy_work);
|
| 4743 |
|
| 4744 | mutex_lock(&cgroup_mutex);
|
| 4745 | offline_css(css);
|
| 4746 | mutex_unlock(&cgroup_mutex);
|
| 4747 |
|
| 4748 | css_put(css);
|
| 4749 | }
|
| 4750 |
|
| 4751 |
|
| 4752 | static void css_killed_ref_fn(struct percpu_ref *ref)
|
| 4753 | {
|
| 4754 | struct cgroup_subsys_state *css =
|
| 4755 | container_of(ref, struct cgroup_subsys_state, refcnt);
|
| 4756 |
|
| 4757 | INIT_WORK(&css->destroy_work, css_killed_work_fn);
|
| 4758 | queue_work(cgroup_destroy_wq, &css->destroy_work);
|
| 4759 | }
|
| 4760 |
|
| 4761 | |
| 4762 | * kill_css - destroy a css
|
| 4763 | * @css: css to destroy
|
| 4764 | *
|
| 4765 | * This function initiates destruction of @css by removing cgroup interface
|
| 4766 | * files and putting its base reference. ->css_offline() will be invoked
|
| 4767 | * asynchronously once css_tryget_online() is guaranteed to fail and when
|
| 4768 | * the reference count reaches zero, @css will be released.
|
| 4769 |
|
| 4770 | static void kill_css(struct cgroup_subsys_state *css)
|
| 4771 | {
|
| 4772 | lockdep_assert_held(&cgroup_mutex);
|
| 4773 |
|
| 4774 | |
| 4775 | * This must happen before css is disassociated with its cgroup.
|
| 4776 | * See seq_css() for details.
|
| 4777 |
|
| 4778 | cgroup_clear_dir(css->cgroup, 1 << css->ss->id);
|
| 4779 |
|
| 4780 | |
| 4781 | * Killing would put the base ref, but we need to keep it alive
|
| 4782 | * until after ->css_offline().
|
| 4783 |
|
| 4784 | css_get(css);
|
| 4785 |
|
| 4786 | |
| 4787 | * cgroup core guarantees that, by the time ->css_offline() is
|
| 4788 | * invoked, no new css reference will be given out via
|
| 4789 | * css_tryget_online(). We can't simply call percpu_ref_kill() and
|
| 4790 | * proceed to offlining css's because percpu_ref_kill() doesn't
|
| 4791 | * guarantee that the ref is seen as killed on all CPUs on return.
|
| 4792 | *
|
| 4793 | * Use percpu_ref_kill_and_confirm() to get notifications as each
|
| 4794 | * css is confirmed to be seen as killed on all CPUs.
|
| 4795 |
|
| 4796 | percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);
|
| 4797 | }
|
| 4798 |
|
| 4799 | |
| 4800 | * cgroup_destroy_locked - the first stage of cgroup destruction
|
| 4801 | * @cgrp: cgroup to be destroyed
|
| 4802 | *
|
| 4803 | * css's make use of percpu refcnts whose killing latency shouldn't be
|
| 4804 | * exposed to userland and are RCU protected. Also, cgroup core needs to
|
| 4805 | * guarantee that css_tryget_online() won't succeed by the time
|
| 4806 | * ->css_offline() is invoked. To satisfy all the requirements,
|
| 4807 | * destruction is implemented in the following two steps.
|
| 4808 | *
|
| 4809 | * s1. Verify @cgrp can be destroyed and mark it dying. Remove all
|
| 4810 | * userland visible parts and start killing the percpu refcnts of
|
| 4811 | * css's. Set up so that the next stage will be kicked off once all
|
| 4812 | * the percpu refcnts are confirmed to be killed.
|
| 4813 | *
|
| 4814 | * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
|
| 4815 | * rest of destruction. Once all cgroup references are gone, the
|
| 4816 | * cgroup is RCU-freed.
|
| 4817 | *
|
| 4818 | * This function implements s1. After this step, @cgrp is gone as far as
|
| 4819 | * the userland is concerned and a new cgroup with the same name may be
|
| 4820 | * created. As cgroup doesn't care about the names internally, this
|
| 4821 | * doesn't cause any problem.
|
| 4822 |
|
| 4823 | static int cgroup_destroy_locked(struct cgroup *cgrp)
|
| 4824 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex)
|
| 4825 | {
|
| 4826 | struct cgroup_subsys_state *css;
|
| 4827 | bool empty;
|
| 4828 | int ssid;
|
| 4829 |
|
| 4830 | lockdep_assert_held(&cgroup_mutex);
|
| 4831 |
|
| 4832 | |
| 4833 | * css_set_rwsem synchronizes access to ->cset_links and prevents
|
| 4834 | * @cgrp from being removed while put_css_set() is in progress.
|
| 4835 |
|
| 4836 | down_read(&css_set_rwsem);
|
| 4837 | empty = list_empty(&cgrp->cset_links);
|
| 4838 | up_read(&css_set_rwsem);
|
| 4839 | if (!empty)
|
| 4840 | return -EBUSY;
|
| 4841 |
|
| 4842 | |
| 4843 | * Make sure there's no live children. We can't test emptiness of
|
| 4844 | * ->self.children as dead children linger on it while being
|
| 4845 | * drained; otherwise, "rmdir parent/child parent" may fail.
|
| 4846 |
|
| 4847 | if (css_has_online_children(&cgrp->self))
|
| 4848 | return -EBUSY;
|
| 4849 |
|
| 4850 | |
| 4851 | * Mark @cgrp dead. This prevents further task migration and child
|
| 4852 | * creation by disabling cgroup_lock_live_group().
|
| 4853 |
|
| 4854 | cgrp->self.flags &= ~CSS_ONLINE;
|
| 4855 |
|
| 4856 |
|
| 4857 | for_each_css(css, ssid, cgrp)
|
| 4858 | kill_css(css);
|
| 4859 |
|
| 4860 | |
| 4861 | * Remove @cgrp directory along with the base files. @cgrp has an
|
| 4862 | * extra ref on its kn.
|
| 4863 |
|
| 4864 | kernfs_remove(cgrp->kn);
|
| 4865 |
|
| 4866 | check_for_release(cgroup_parent(cgrp));
|
| 4867 |
|
| 4868 |
|
| 4869 | percpu_ref_kill(&cgrp->self.refcnt);
|
| 4870 |
|
| 4871 | return 0;
|
| 4872 | };
|
| 4873 |
|
| 4874 | static int cgroup_rmdir(struct kernfs_node *kn)
|
| 4875 | {
|
| 4876 | struct cgroup *cgrp;
|
| 4877 | int ret = 0;
|
| 4878 |
|
| 4879 | cgrp = cgroup_kn_lock_live(kn);
|
| 4880 | if (!cgrp)
|
| 4881 | return 0;
|
| 4882 |
|
| 4883 | ret = cgroup_destroy_locked(cgrp);
|
| 4884 |
|
| 4885 | cgroup_kn_unlock(kn);
|
| 4886 | return ret;
|
| 4887 | }
|
| 4888 |
|
| 4889 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
|
| 4890 | .remount_fs = cgroup_remount,
|
| 4891 | .show_options = cgroup_show_options,
|
| 4892 | .mkdir = cgroup_mkdir,
|
| 4893 | .rmdir = cgroup_rmdir,
|
| 4894 | .rename = cgroup_rename,
|
| 4895 | };
|
| 4896 |
|
| 4897 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)
|
| 4898 | {
|
| 4899 | struct cgroup_subsys_state *css;
|
| 4900 |
|
| 4901 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
|
| 4902 |
|
| 4903 | mutex_lock(&cgroup_mutex);
|
| 4904 |
|
| 4905 | idr_init(&ss->css_idr);
|
| 4906 | INIT_LIST_HEAD(&ss->cfts);
|
| 4907 |
|
| 4908 |
|
| 4909 | ss->root = &cgrp_dfl_root;
|
| 4910 | css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss));
|
| 4911 |
|
| 4912 | BUG_ON(IS_ERR(css));
|
| 4913 | init_and_link_css(css, ss, &cgrp_dfl_root.cgrp);
|
| 4914 |
|
| 4915 | |
| 4916 | * Root csses are never destroyed and we can't initialize
|
| 4917 | * percpu_ref during early init. Disable refcnting.
|
| 4918 |
|
| 4919 | css->flags |= CSS_NO_REF;
|
| 4920 |
|
| 4921 | if (early) {
|
| 4922 |
|
| 4923 | css->id = 1;
|
| 4924 | } else {
|
| 4925 | css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL);
|
| 4926 | BUG_ON(css->id < 0);
|
| 4927 | }
|
| 4928 |
|
| 4929 | |
| 4930 | * pointer to this state - since the subsystem is
|
| 4931 | * newly registered, all tasks and hence the
|
| 4932 | * init_css_set is in the subsystem's root cgroup.
|
| 4933 | init_css_set.subsys[ss->id] = css;
|
| 4934 |
|
| 4935 | need_forkexit_callback |= ss->fork || ss->exit;
|
| 4936 |
|
| 4937 | |
| 4938 | * registered, no tasks have been forked, so we don't
|
| 4939 | * need to invoke fork callbacks here.
|
| 4940 | BUG_ON(!list_empty(&init_task.tasks));
|
| 4941 |
|
| 4942 | BUG_ON(online_css(css));
|
| 4943 |
|
| 4944 | mutex_unlock(&cgroup_mutex);
|
| 4945 | }
|
| 4946 |
|
| 4947 | |
| 4948 | * cgroup_init_early - cgroup initialization at system boot
|
| 4949 | *
|
| 4950 | * Initialize cgroups at system boot, and initialize any
|
| 4951 | * subsystems that request early init.
|
| 4952 |
|
| 4953 | int __init cgroup_init_early(void)
|
| 4954 | {
|
| 4955 | static struct cgroup_sb_opts __initdata opts;
|
| 4956 | struct cgroup_subsys *ss;
|
| 4957 | int i;
|
| 4958 |
|
| 4959 | init_cgroup_root(&cgrp_dfl_root, &opts);
|
| 4960 | cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF;
|
| 4961 |
|
| 4962 | RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
|
| 4963 |
|
| 4964 | for_each_subsys(ss, i) {
|
| 4965 | WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id,
|
| 4966 | "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n",
|
| 4967 | i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free,
|
| 4968 | ss->id, ss->name);
|
| 4969 | WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN,
|
| 4970 | "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]);
|
| 4971 |
|
| 4972 | ss->id = i;
|
| 4973 | ss->name = cgroup_subsys_name[i];
|
| 4974 |
|
| 4975 | if (ss->early_init)
|
| 4976 | cgroup_init_subsys(ss, true);
|
| 4977 | }
|
| 4978 | return 0;
|
| 4979 | }
|
| 4980 |
|
| 4981 | |
| 4982 | * cgroup_init - cgroup initialization
|
| 4983 | *
|
| 4984 | * Register cgroup filesystem and /proc file, and initialize
|
| 4985 | * any subsystems that didn't request early init.
|
| 4986 |
|
| 4987 | int __init cgroup_init(void)
|
| 4988 | {
|
| 4989 | struct cgroup_subsys *ss;
|
| 4990 | unsigned long key;
|
| 4991 | int ssid, err;
|
| 4992 |
|
| 4993 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files));
|
| 4994 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files));
|
| 4995 |
|
| 4996 | mutex_lock(&cgroup_mutex);
|
| 4997 |
|
| 4998 |
|
| 4999 | key = css_set_hash(init_css_set.subsys);
|
| 5000 | hash_add(css_set_table, &init_css_set.hlist, key);
|
| 5001 |
|
| 5002 | BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0));
|
| 5003 |
|
| 5004 | mutex_unlock(&cgroup_mutex);
|
| 5005 |
|
| 5006 | for_each_subsys(ss, ssid) {
|
| 5007 | if (ss->early_init) {
|
| 5008 | struct cgroup_subsys_state *css =
|
| 5009 | init_css_set.subsys[ss->id];
|
| 5010 |
|
| 5011 | css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2,
|
| 5012 | GFP_KERNEL);
|
| 5013 | BUG_ON(css->id < 0);
|
| 5014 | } else {
|
| 5015 | cgroup_init_subsys(ss, false);
|
| 5016 | }
|
| 5017 |
|
| 5018 | list_add_tail(&init_css_set.e_cset_node[ssid],
|
| 5019 | &cgrp_dfl_root.cgrp.e_csets[ssid]);
|
| 5020 |
|
| 5021 | |
| 5022 | * Setting dfl_root subsys_mask needs to consider the
|
| 5023 | * disabled flag and cftype registration needs kmalloc,
|
| 5024 | * both of which aren't available during early_init.
|
| 5025 |
|
| 5026 | if (ss->disabled)
|
| 5027 | continue;
|
| 5028 |
|
| 5029 | cgrp_dfl_root.subsys_mask |= 1 << ss->id;
|
| 5030 |
|
| 5031 | if (cgroup_legacy_files_on_dfl && !ss->dfl_cftypes)
|
| 5032 | ss->dfl_cftypes = ss->legacy_cftypes;
|
| 5033 |
|
| 5034 | if (!ss->dfl_cftypes)
|
| 5035 | cgrp_dfl_root_inhibit_ss_mask |= 1 << ss->id;
|
| 5036 |
|
| 5037 | if (ss->dfl_cftypes == ss->legacy_cftypes) {
|
| 5038 | WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes));
|
| 5039 | } else {
|
| 5040 | WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes));
|
| 5041 | WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes));
|
| 5042 | }
|
| 5043 | }
|
| 5044 |
|
| 5045 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);
|
| 5046 | if (!cgroup_kobj)
|
| 5047 | return -ENOMEM;
|
| 5048 |
|
| 5049 | err = register_filesystem(&cgroup_fs_type);
|
| 5050 | if (err < 0) {
|
| 5051 | kobject_put(cgroup_kobj);
|
| 5052 | return err;
|
| 5053 | }
|
| 5054 |
|
| 5055 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations);
|
| 5056 | return 0;
|
| 5057 | }
|
| 5058 |
|
| 5059 | static int __init cgroup_wq_init(void)
|
| 5060 | {
|
| 5061 | |
| 5062 | * There isn't much point in executing destruction path in
|
| 5063 | * parallel. Good chunk is serialized with cgroup_mutex anyway.
|
| 5064 | * Use 1 for @max_active.
|
| 5065 | *
|
| 5066 | * We would prefer to do this in cgroup_init() above, but that
|
| 5067 | * is called before init_workqueues(): so leave this until after.
|
| 5068 |
|
| 5069 | cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
|
| 5070 | BUG_ON(!cgroup_destroy_wq);
|
| 5071 |
|
| 5072 | |
| 5073 | * Used to destroy pidlists and separate to serve as flush domain.
|
| 5074 | * Cap @max_active to 1 too.
|
| 5075 |
|
| 5076 | cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
|
| 5077 | 0, 1);
|
| 5078 | BUG_ON(!cgroup_pidlist_destroy_wq);
|
| 5079 |
|
| 5080 | return 0;
|
| 5081 | }
|
| 5082 | core_initcall(cgroup_wq_init);
|
| 5083 |
|
| 5084 | |
| 5085 | * proc_cgroup_show()
|
| 5086 | * - Print task's cgroup paths into seq_file, one line for each hierarchy
|
| 5087 | * - Used for /proc/<pid>/cgroup.
|
| 5088 |
|
| 5089 | int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
|
| 5090 | struct pid *pid, struct task_struct *tsk)
|
| 5091 | {
|
| 5092 | char *buf, *path;
|
| 5093 | int retval;
|
| 5094 | struct cgroup_root *root;
|
| 5095 |
|
| 5096 | retval = -ENOMEM;
|
| 5097 | buf = kmalloc(PATH_MAX, GFP_KERNEL);
|
| 5098 | if (!buf)
|
| 5099 | goto out;
|
| 5100 |
|
| 5101 | mutex_lock(&cgroup_mutex);
|
| 5102 | down_read(&css_set_rwsem);
|
| 5103 |
|
| 5104 | for_each_root(root) {
|
| 5105 | struct cgroup_subsys *ss;
|
| 5106 | struct cgroup *cgrp;
|
| 5107 | int ssid, count = 0;
|
| 5108 |
|
| 5109 | if (root == &cgrp_dfl_root && !cgrp_dfl_root_visible)
|
| 5110 | continue;
|
| 5111 |
|
| 5112 | seq_printf(m, "%d:", root->hierarchy_id);
|
| 5113 | for_each_subsys(ss, ssid)
|
| 5114 | if (root->subsys_mask & (1 << ssid))
|
| 5115 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
|
| 5116 | if (strlen(root->name))
|
| 5117 | seq_printf(m, "%sname=%s", count ? "," : "",
|
| 5118 | root->name);
|
| 5119 | seq_putc(m, ':');
|
| 5120 | cgrp = task_cgroup_from_root(tsk, root);
|
| 5121 | path = cgroup_path(cgrp, buf, PATH_MAX);
|
| 5122 | if (!path) {
|
| 5123 | retval = -ENAMETOOLONG;
|
| 5124 | goto out_unlock;
|
| 5125 | }
|
| 5126 | seq_puts(m, path);
|
| 5127 | seq_putc(m, '\n');
|
| 5128 | }
|
| 5129 |
|
| 5130 | retval = 0;
|
| 5131 | out_unlock:
|
| 5132 | up_read(&css_set_rwsem);
|
| 5133 | mutex_unlock(&cgroup_mutex);
|
| 5134 | kfree(buf);
|
| 5135 | out:
|
| 5136 | return retval;
|
| 5137 | }
|
| 5138 |
|
| 5139 |
|
| 5140 | static int proc_cgroupstats_show(struct seq_file *m, void *v)
|
| 5141 | {
|
| 5142 | struct cgroup_subsys *ss;
|
| 5143 | int i;
|
| 5144 |
|
| 5145 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
|
| 5146 | |
| 5147 | * ideally we don't want subsystems moving around while we do this.
|
| 5148 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of
|
| 5149 | * subsys/hierarchy state.
|
| 5150 |
|
| 5151 | mutex_lock(&cgroup_mutex);
|
| 5152 |
|
| 5153 | for_each_subsys(ss, i)
|
| 5154 | seq_printf(m, "%s\t%d\t%d\t%d\n",
|
| 5155 | ss->name, ss->root->hierarchy_id,
|
| 5156 | atomic_read(&ss->root->nr_cgrps), !ss->disabled);
|
| 5157 |
|
| 5158 | mutex_unlock(&cgroup_mutex);
|
| 5159 | return 0;
|
| 5160 | }
|
| 5161 |
|
| 5162 | static int cgroupstats_open(struct inode *inode, struct file *file)
|
| 5163 | {
|
| 5164 | return single_open(file, proc_cgroupstats_show, NULL);
|
| 5165 | }
|
| 5166 |
|
| 5167 | static const struct file_operations proc_cgroupstats_operations = {
|
| 5168 | .open = cgroupstats_open,
|
| 5169 | .read = seq_read,
|
| 5170 | .llseek = seq_lseek,
|
| 5171 | .release = single_release,
|
| 5172 | };
|
| 5173 |
|
| 5174 | |
| 5175 | * cgroup_fork - initialize cgroup related fields during copy_process()
|
| 5176 | * @child: pointer to task_struct of forking parent process.
|
| 5177 | *
|
| 5178 | * A task is associated with the init_css_set until cgroup_post_fork()
|
| 5179 | * attaches it to the parent's css_set. Empty cg_list indicates that
|
| 5180 | * @child isn't holding reference to its css_set.
|
| 5181 |
|
| 5182 | void cgroup_fork(struct task_struct *child)
|
| 5183 | {
|
| 5184 | RCU_INIT_POINTER(child->cgroups, &init_css_set);
|
| 5185 | INIT_LIST_HEAD(&child->cg_list);
|
| 5186 | }
|
| 5187 |
|
| 5188 | |
| 5189 | * cgroup_post_fork - called on a new task after adding it to the task list
|
| 5190 | * @child: the task in question
|
| 5191 | *
|
| 5192 | * Adds the task to the list running through its css_set if necessary and
|
| 5193 | * call the subsystem fork() callbacks. Has to be after the task is
|
| 5194 | * visible on the task list in case we race with the first call to
|
| 5195 | * cgroup_task_iter_start() - to guarantee that the new task ends up on its
|
| 5196 | * list.
|
| 5197 |
|
| 5198 | void cgroup_post_fork(struct task_struct *child)
|
| 5199 | {
|
| 5200 | struct cgroup_subsys *ss;
|
| 5201 | int i;
|
| 5202 |
|
| 5203 | |
| 5204 | * This may race against cgroup_enable_task_cg_lists(). As that
|
| 5205 | * function sets use_task_css_set_links before grabbing
|
| 5206 | * tasklist_lock and we just went through tasklist_lock to add
|
| 5207 | * @child, it's guaranteed that either we see the set
|
| 5208 | * use_task_css_set_links or cgroup_enable_task_cg_lists() sees
|
| 5209 | * @child during its iteration.
|
| 5210 | *
|
| 5211 | * If we won the race, @child is associated with %current's
|
| 5212 | * css_set. Grabbing css_set_rwsem guarantees both that the
|
| 5213 | * association is stable, and, on completion of the parent's
|
| 5214 | * migration, @child is visible in the source of migration or
|
| 5215 | * already in the destination cgroup. This guarantee is necessary
|
| 5216 | * when implementing operations which need to migrate all tasks of
|
| 5217 | * a cgroup to another.
|
| 5218 | *
|
| 5219 | * Note that if we lose to cgroup_enable_task_cg_lists(), @child
|
| 5220 | * will remain in init_css_set. This is safe because all tasks are
|
| 5221 | * in the init_css_set before cg_links is enabled and there's no
|
| 5222 | * operation which transfers all tasks out of init_css_set.
|
| 5223 |
|
| 5224 | if (use_task_css_set_links) {
|
| 5225 | struct css_set *cset;
|
| 5226 |
|
| 5227 | down_write(&css_set_rwsem);
|
| 5228 | cset = task_css_set(current);
|
| 5229 | if (list_empty(&child->cg_list)) {
|
| 5230 | rcu_assign_pointer(child->cgroups, cset);
|
| 5231 | list_add(&child->cg_list, &cset->tasks);
|
| 5232 | get_css_set(cset);
|
| 5233 | }
|
| 5234 | up_write(&css_set_rwsem);
|
| 5235 | }
|
| 5236 |
|
| 5237 | |
| 5238 | * Call ss->fork(). This must happen after @child is linked on
|
| 5239 | * css_set; otherwise, @child might change state between ->fork()
|
| 5240 | * and addition to css_set.
|
| 5241 |
|
| 5242 | if (need_forkexit_callback) {
|
| 5243 | for_each_subsys(ss, i)
|
| 5244 | if (ss->fork)
|
| 5245 | ss->fork(child);
|
| 5246 | }
|
| 5247 | }
|
| 5248 |
|
| 5249 | |
| 5250 | * cgroup_exit - detach cgroup from exiting task
|
| 5251 | * @tsk: pointer to task_struct of exiting process
|
| 5252 | *
|
| 5253 | * Description: Detach cgroup from @tsk and release it.
|
| 5254 | *
|
| 5255 | * Note that cgroups marked notify_on_release force every task in
|
| 5256 | * them to take the global cgroup_mutex mutex when exiting.
|
| 5257 | * This could impact scaling on very large systems. Be reluctant to
|
| 5258 | * use notify_on_release cgroups where very high task exit scaling
|
| 5259 | * is required on large systems.
|
| 5260 | *
|
| 5261 | * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We
|
| 5262 | * call cgroup_exit() while the task is still competent to handle
|
| 5263 | * notify_on_release(), then leave the task attached to the root cgroup in
|
| 5264 | * each hierarchy for the remainder of its exit. No need to bother with
|
| 5265 | * init_css_set refcnting. init_css_set never goes away and we can't race
|
| 5266 | * with migration path - PF_EXITING is visible to migration path.
|
| 5267 |
|
| 5268 | void cgroup_exit(struct task_struct *tsk)
|
| 5269 | {
|
| 5270 | struct cgroup_subsys *ss;
|
| 5271 | struct css_set *cset;
|
| 5272 | bool put_cset = false;
|
| 5273 | int i;
|
| 5274 |
|
| 5275 | |
| 5276 | * Unlink from @tsk from its css_set. As migration path can't race
|
| 5277 | * with us, we can check cg_list without grabbing css_set_rwsem.
|
| 5278 |
|
| 5279 | if (!list_empty(&tsk->cg_list)) {
|
| 5280 | down_write(&css_set_rwsem);
|
| 5281 | list_del_init(&tsk->cg_list);
|
| 5282 | up_write(&css_set_rwsem);
|
| 5283 | put_cset = true;
|
| 5284 | }
|
| 5285 |
|
| 5286 |
|
| 5287 | cset = task_css_set(tsk);
|
| 5288 | RCU_INIT_POINTER(tsk->cgroups, &init_css_set);
|
| 5289 |
|
| 5290 | if (need_forkexit_callback) {
|
| 5291 |
|
| 5292 | for_each_subsys(ss, i) {
|
| 5293 | if (ss->exit) {
|
| 5294 | struct cgroup_subsys_state *old_css = cset->subsys[i];
|
| 5295 | struct cgroup_subsys_state *css = task_css(tsk, i);
|
| 5296 |
|
| 5297 | ss->exit(css, old_css, tsk);
|
| 5298 | }
|
| 5299 | }
|
| 5300 | }
|
| 5301 |
|
| 5302 | if (put_cset)
|
| 5303 | put_css_set(cset);
|
| 5304 | }
|
| 5305 |
|
| 5306 | static void check_for_release(struct cgroup *cgrp)
|
| 5307 | {
|
| 5308 | if (notify_on_release(cgrp) && !cgroup_has_tasks(cgrp) &&
|
| 5309 | !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
|
| 5310 | schedule_work(&cgrp->release_agent_work);
|
| 5311 | }
|
| 5312 |
|
| 5313 | |
| 5314 | * Notify userspace when a cgroup is released, by running the
|
| 5315 | * configured release agent with the name of the cgroup (path
|
| 5316 | * relative to the root of cgroup file system) as the argument.
|
| 5317 | *
|
| 5318 | * Most likely, this user command will try to rmdir this cgroup.
|
| 5319 | *
|
| 5320 | * This races with the possibility that some other task will be
|
| 5321 | * attached to this cgroup before it is removed, or that some other
|
| 5322 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
|
| 5323 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer
|
| 5324 | * unused, and this cgroup will be reprieved from its death sentence,
|
| 5325 | * to continue to serve a useful existence. Next time it's released,
|
| 5326 | * we will get notified again, if it still has 'notify_on_release' set.
|
| 5327 | *
|
| 5328 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
|
| 5329 | * means only wait until the task is successfully execve()'d. The
|
| 5330 | * separate release agent task is forked by call_usermodehelper(),
|
| 5331 | * then control in this thread returns here, without waiting for the
|
| 5332 | * release agent task. We don't bother to wait because the caller of
|
| 5333 | * this routine has no use for the exit status of the release agent
|
| 5334 | * task, so no sense holding our caller up for that.
|
| 5335 |
|
| 5336 | static void cgroup_release_agent(struct work_struct *work)
|
| 5337 | {
|
| 5338 | struct cgroup *cgrp =
|
| 5339 | container_of(work, struct cgroup, release_agent_work);
|
| 5340 | char *pathbuf = NULL, *agentbuf = NULL, *path;
|
| 5341 | char *argv[3], *envp[3];
|
| 5342 |
|
| 5343 | mutex_lock(&cgroup_mutex);
|
| 5344 |
|
| 5345 | pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
|
| 5346 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
|
| 5347 | if (!pathbuf || !agentbuf)
|
| 5348 | goto out;
|
| 5349 |
|
| 5350 | path = cgroup_path(cgrp, pathbuf, PATH_MAX);
|
| 5351 | if (!path)
|
| 5352 | goto out;
|
| 5353 |
|
| 5354 | argv[0] = agentbuf;
|
| 5355 | argv[1] = path;
|
| 5356 | argv[2] = NULL;
|
| 5357 |
|
| 5358 |
|
| 5359 | envp[0] = "HOME=/";
|
| 5360 | envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
|
| 5361 | envp[2] = NULL;
|
| 5362 |
|
| 5363 | mutex_unlock(&cgroup_mutex);
|
| 5364 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
|
| 5365 | goto out_free;
|
| 5366 | out:
|
| 5367 | mutex_unlock(&cgroup_mutex);
|
| 5368 | out_free:
|
| 5369 | kfree(agentbuf);
|
| 5370 | kfree(pathbuf);
|
| 5371 | }
|
| 5372 |
|
| 5373 | static int __init cgroup_disable(char *str)
|
| 5374 | {
|
| 5375 | struct cgroup_subsys *ss;
|
| 5376 | char *token;
|
| 5377 | int i;
|
| 5378 |
|
| 5379 | while ((token = strsep(&str, ",")) != NULL) {
|
| 5380 | if (!*token)
|
| 5381 | continue;
|
| 5382 |
|
| 5383 | for_each_subsys(ss, i) {
|
| 5384 | if (!strcmp(token, ss->name)) {
|
| 5385 | ss->disabled = 1;
|
| 5386 | printk(KERN_INFO "Disabling %s control group"
|
| 5387 | " subsystem\n", ss->name);
|
| 5388 | break;
|
| 5389 | }
|
| 5390 | }
|
| 5391 | }
|
| 5392 | return 1;
|
| 5393 | }
|
| 5394 | __setup("cgroup_disable=", cgroup_disable);
|
| 5395 |
|
| 5396 | static int __init cgroup_set_legacy_files_on_dfl(char *str)
|
| 5397 | {
|
| 5398 | printk("cgroup: using legacy files on the default hierarchy\n");
|
| 5399 | cgroup_legacy_files_on_dfl = true;
|
| 5400 | return 0;
|
| 5401 | }
|
| 5402 | __setup("cgroup__DEVEL__legacy_files_on_dfl", cgroup_set_legacy_files_on_dfl);
|
| 5403 |
|
| 5404 | |
| 5405 | * css_tryget_online_from_dir - get corresponding css from a cgroup dentry
|
| 5406 | * @dentry: directory dentry of interest
|
| 5407 | * @ss: subsystem of interest
|
| 5408 | *
|
| 5409 | * If @dentry is a directory for a cgroup which has @ss enabled on it, try
|
| 5410 | * to get the corresponding css and return it. If such css doesn't exist
|
| 5411 | * or can't be pinned, an ERR_PTR value is returned.
|
| 5412 |
|
| 5413 | struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
|
| 5414 | struct cgroup_subsys *ss)
|
| 5415 | {
|
| 5416 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
|
| 5417 | struct cgroup_subsys_state *css = NULL;
|
| 5418 | struct cgroup *cgrp;
|
| 5419 |
|
| 5420 |
|
| 5421 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
|
| 5422 | kernfs_type(kn) != KERNFS_DIR)
|
| 5423 | return ERR_PTR(-EBADF);
|
| 5424 |
|
| 5425 | rcu_read_lock();
|
| 5426 |
|
| 5427 | |
| 5428 | * This path doesn't originate from kernfs and @kn could already
|
| 5429 | * have been or be removed at any point. @kn->priv is RCU
|
| 5430 | * protected for this access. See css_release_work_fn() for details.
|
| 5431 |
|
| 5432 | cgrp = rcu_dereference(kn->priv);
|
| 5433 | if (cgrp)
|
| 5434 | css = cgroup_css(cgrp, ss);
|
| 5435 |
|
| 5436 | if (!css || !css_tryget_online(css))
|
| 5437 | css = ERR_PTR(-ENOENT);
|
| 5438 |
|
| 5439 | rcu_read_unlock();
|
| 5440 | return css;
|
| 5441 | }
|
| 5442 |
|
| 5443 | |
| 5444 | * css_from_id - lookup css by id
|
| 5445 | * @id: the cgroup id
|
| 5446 | * @ss: cgroup subsys to be looked into
|
| 5447 | *
|
| 5448 | * Returns the css if there's valid one with @id, otherwise returns NULL.
|
| 5449 | * Should be called under rcu_read_lock().
|
| 5450 |
|
| 5451 | struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
|
| 5452 | {
|
| 5453 | WARN_ON_ONCE(!rcu_read_lock_held());
|
| 5454 | return idr_find(&ss->css_idr, id);
|
| 5455 | }
|
| 5456 |
|
| 5457 | #ifdef CONFIG_CGROUP_DEBUG
|
| 5458 | static struct cgroup_subsys_state *
|
| 5459 | debug_css_alloc(struct cgroup_subsys_state *parent_css)
|
| 5460 | {
|
| 5461 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
|
| 5462 |
|
| 5463 | if (!css)
|
| 5464 | return ERR_PTR(-ENOMEM);
|
| 5465 |
|
| 5466 | return css;
|
| 5467 | }
|
| 5468 |
|
| 5469 | static void debug_css_free(struct cgroup_subsys_state *css)
|
| 5470 | {
|
| 5471 | kfree(css);
|
| 5472 | }
|
| 5473 |
|
| 5474 | static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
|
| 5475 | struct cftype *cft)
|
| 5476 | {
|
| 5477 | return cgroup_task_count(css->cgroup);
|
| 5478 | }
|
| 5479 |
|
| 5480 | static u64 current_css_set_read(struct cgroup_subsys_state *css,
|
| 5481 | struct cftype *cft)
|
| 5482 | {
|
| 5483 | return (u64)(unsigned long)current->cgroups;
|
| 5484 | }
|
| 5485 |
|
| 5486 | static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
|
| 5487 | struct cftype *cft)
|
| 5488 | {
|
| 5489 | u64 count;
|
| 5490 |
|
| 5491 | rcu_read_lock();
|
| 5492 | count = atomic_read(&task_css_set(current)->refcount);
|
| 5493 | rcu_read_unlock();
|
| 5494 | return count;
|
| 5495 | }
|
| 5496 |
|
| 5497 | static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
|
| 5498 | {
|
| 5499 | struct cgrp_cset_link *link;
|
| 5500 | struct css_set *cset;
|
| 5501 | char *name_buf;
|
| 5502 |
|
| 5503 | name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
|
| 5504 | if (!name_buf)
|
| 5505 | return -ENOMEM;
|
| 5506 |
|
| 5507 | down_read(&css_set_rwsem);
|
| 5508 | rcu_read_lock();
|
| 5509 | cset = rcu_dereference(current->cgroups);
|
| 5510 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
|
| 5511 | struct cgroup *c = link->cgrp;
|
| 5512 |
|
| 5513 | cgroup_name(c, name_buf, NAME_MAX + 1);
|
| 5514 | seq_printf(seq, "Root %d group %s\n",
|
| 5515 | c->root->hierarchy_id, name_buf);
|
| 5516 | }
|
| 5517 | rcu_read_unlock();
|
| 5518 | up_read(&css_set_rwsem);
|
| 5519 | kfree(name_buf);
|
| 5520 | return 0;
|
| 5521 | }
|
| 5522 |
|
| 5523 | #define MAX_TASKS_SHOWN_PER_CSS 25
|
| 5524 | static int cgroup_css_links_read(struct seq_file *seq, void *v)
|
| 5525 | {
|
| 5526 | struct cgroup_subsys_state *css = seq_css(seq);
|
| 5527 | struct cgrp_cset_link *link;
|
| 5528 |
|
| 5529 | down_read(&css_set_rwsem);
|
| 5530 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
|
| 5531 | struct css_set *cset = link->cset;
|
| 5532 | struct task_struct *task;
|
| 5533 | int count = 0;
|
| 5534 |
|
| 5535 | seq_printf(seq, "css_set %p\n", cset);
|
| 5536 |
|
| 5537 | list_for_each_entry(task, &cset->tasks, cg_list) {
|
| 5538 | if (count++ > MAX_TASKS_SHOWN_PER_CSS)
|
| 5539 | goto overflow;
|
| 5540 | seq_printf(seq, " task %d\n", task_pid_vnr(task));
|
| 5541 | }
|
| 5542 |
|
| 5543 | list_for_each_entry(task, &cset->mg_tasks, cg_list) {
|
| 5544 | if (count++ > MAX_TASKS_SHOWN_PER_CSS)
|
| 5545 | goto overflow;
|
| 5546 | seq_printf(seq, " task %d\n", task_pid_vnr(task));
|
| 5547 | }
|
| 5548 | continue;
|
| 5549 | overflow:
|
| 5550 | seq_puts(seq, " ...\n");
|
| 5551 | }
|
| 5552 | up_read(&css_set_rwsem);
|
| 5553 | return 0;
|
| 5554 | }
|
| 5555 |
|
| 5556 | static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
|
| 5557 | {
|
| 5558 | return (!cgroup_has_tasks(css->cgroup) &&
|
| 5559 | !css_has_online_children(&css->cgroup->self));
|
| 5560 | }
|
| 5561 |
|
| 5562 | static struct cftype debug_files[] = {
|
| 5563 | {
|
| 5564 | .name = "taskcount",
|
| 5565 | .read_u64 = debug_taskcount_read,
|
| 5566 | },
|
| 5567 |
|
| 5568 | {
|
| 5569 | .name = "current_css_set",
|
| 5570 | .read_u64 = current_css_set_read,
|
| 5571 | },
|
| 5572 |
|
| 5573 | {
|
| 5574 | .name = "current_css_set_refcount",
|
| 5575 | .read_u64 = current_css_set_refcount_read,
|
| 5576 | },
|
| 5577 |
|
| 5578 | {
|
| 5579 | .name = "current_css_set_cg_links",
|
| 5580 | .seq_show = current_css_set_cg_links_read,
|
| 5581 | },
|
| 5582 |
|
| 5583 | {
|
| 5584 | .name = "cgroup_css_links",
|
| 5585 | .seq_show = cgroup_css_links_read,
|
| 5586 | },
|
| 5587 |
|
| 5588 | {
|
| 5589 | .name = "releasable",
|
| 5590 | .read_u64 = releasable_read,
|
| 5591 | },
|
| 5592 |
|
| 5593 | { }
|
| 5594 | };
|
| 5595 |
|
| 5596 | struct cgroup_subsys debug_cgrp_subsys = {
|
| 5597 | .css_alloc = debug_css_alloc,
|
| 5598 | .css_free = debug_css_free,
|
| 5599 | .legacy_cftypes = debug_files,
|
| 5600 | };
|
| 5601 | #endif
|