| 1 | |
| 2 | * drivers/power/process.c - Functions for starting/stopping processes on
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| 3 | * suspend transitions.
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| 4 | *
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| 5 | * Originally from swsusp.
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| 6 |
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| 7 |
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| 8 |
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| 9 | #undef DEBUG
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| 10 |
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| 11 | #include <linux/interrupt.h>
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| 12 | #include <linux/suspend.h>
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| 13 | #include <linux/module.h>
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| 14 | #include <linux/syscalls.h>
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| 15 | #include <linux/freezer.h>
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| 16 |
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| 17 | |
| 18 | * Timeout for stopping processes
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| 19 |
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| 20 | #define TIMEOUT (20 * HZ)
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| 21 |
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| 22 | static inline int freezeable(struct task_struct * p)
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| 23 | {
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| 24 | if ((p == current) ||
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| 25 | (p->flags & PF_NOFREEZE) ||
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| 26 | (p->exit_state != 0))
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| 27 | return 0;
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| 28 | return 1;
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| 29 | }
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| 30 |
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| 31 | static int try_to_freeze_tasks(bool sig_only)
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| 32 | {
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| 33 | struct task_struct *g, *p;
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| 34 | unsigned long end_time;
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| 35 | unsigned int todo;
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| 36 | struct timeval start, end;
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| 37 | u64 elapsed_csecs64;
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| 38 | unsigned int elapsed_csecs;
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| 39 |
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| 40 | do_gettimeofday(&start);
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| 41 |
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| 42 | end_time = jiffies + TIMEOUT;
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| 43 | do {
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| 44 | todo = 0;
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| 45 | read_lock(&tasklist_lock);
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| 46 | do_each_thread(g, p) {
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| 47 | if (frozen(p) || !freezeable(p))
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| 48 | continue;
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| 49 |
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| 50 | if (!freeze_task(p, sig_only))
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| 51 | continue;
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| 52 |
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| 53 | |
| 54 | * Now that we've done set_freeze_flag, don't
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| 55 | * perturb a task in TASK_STOPPED or TASK_TRACED.
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| 56 | * It is "frozen enough". If the task does wake
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| 57 | * up, it will immediately call try_to_freeze.
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| 58 |
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| 59 | if (!task_is_stopped_or_traced(p) &&
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| 60 | !freezer_should_skip(p))
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| 61 | todo++;
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| 62 | } while_each_thread(g, p);
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| 63 | read_unlock(&tasklist_lock);
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| 64 | yield();
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| 65 | if (time_after(jiffies, end_time))
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| 66 | break;
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| 67 | } while (todo);
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| 68 |
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| 69 | do_gettimeofday(&end);
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| 70 | elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
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| 71 | do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
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| 72 | elapsed_csecs = elapsed_csecs64;
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| 73 |
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| 74 | if (todo) {
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| 75 | |
| 76 | * (we have slightly ugly calling convention in that respect,
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| 77 | * and caller must call thaw_processes() if something fails),
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| 78 | * but it cleans up leftover PF_FREEZE requests.
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| 79 |
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| 80 | printk("\n");
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| 81 | printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
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| 82 | "(%d tasks refusing to freeze):\n",
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| 83 | elapsed_csecs / 100, elapsed_csecs % 100, todo);
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| 84 | show_state();
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| 85 | read_lock(&tasklist_lock);
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| 86 | do_each_thread(g, p) {
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| 87 | task_lock(p);
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| 88 | if (freezing(p) && !freezer_should_skip(p))
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| 89 | printk(KERN_ERR " %s\n", p->comm);
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| 90 | cancel_freezing(p);
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| 91 | task_unlock(p);
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| 92 | } while_each_thread(g, p);
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| 93 | read_unlock(&tasklist_lock);
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| 94 | } else {
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| 95 | printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
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| 96 | elapsed_csecs % 100);
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| 97 | }
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| 98 |
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| 99 | return todo ? -EBUSY : 0;
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| 100 | }
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| 101 |
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| 102 | |
| 103 | * freeze_processes - tell processes to enter the refrigerator
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| 104 |
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| 105 | int freeze_processes(void)
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| 106 | {
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| 107 | int error;
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| 108 |
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| 109 | printk("Freezing user space processes ... ");
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| 110 | error = try_to_freeze_tasks(true);
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| 111 | if (error)
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| 112 | goto Exit;
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| 113 | printk("done.\n");
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| 114 |
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| 115 | printk("Freezing remaining freezable tasks ... ");
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| 116 | error = try_to_freeze_tasks(false);
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| 117 | if (error)
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| 118 | goto Exit;
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| 119 | printk("done.");
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| 120 | Exit:
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| 121 | BUG_ON(in_atomic());
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| 122 | printk("\n");
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| 123 | return error;
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| 124 | }
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| 125 |
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| 126 | static void thaw_tasks(bool nosig_only)
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| 127 | {
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| 128 | struct task_struct *g, *p;
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| 129 |
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| 130 | read_lock(&tasklist_lock);
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| 131 | do_each_thread(g, p) {
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| 132 | if (!freezeable(p))
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| 133 | continue;
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| 134 |
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| 135 | if (nosig_only && should_send_signal(p))
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| 136 | continue;
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| 137 |
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| 138 | if (cgroup_frozen(p))
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| 139 | continue;
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| 140 |
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| 141 | thaw_process(p);
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| 142 | } while_each_thread(g, p);
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| 143 | read_unlock(&tasklist_lock);
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| 144 | }
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| 145 |
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| 146 | void thaw_processes(void)
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| 147 | {
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| 148 | printk("Restarting tasks ... ");
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| 149 | thaw_tasks(true);
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| 150 | thaw_tasks(false);
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| 151 | schedule();
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| 152 | printk("done.\n");
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| 153 | }
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| 154 |
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