2 * drivers/power/process.c - Functions for starting/stopping processes on
5 * Originally from swsusp.
11 #include <linux/interrupt.h>
12 #include <linux/oom.h>
13 #include <linux/suspend.h>
14 #include <linux/module.h>
15 #include <linux/syscalls.h>
16 #include <linux/freezer.h>
17 #include <linux/delay.h>
18 #include <linux/workqueue.h>
21 * Timeout for stopping processes
23 #define TIMEOUT (20 * HZ)
25 static inline int freezable(struct task_struct * p)
28 (p->flags & PF_NOFREEZE) ||
34 static int try_to_freeze_tasks(bool sig_only)
36 struct task_struct *g, *p;
37 unsigned long end_time;
40 struct timeval start, end;
42 unsigned int elapsed_csecs;
45 do_gettimeofday(&start);
47 end_time = jiffies + TIMEOUT;
50 freeze_workqueues_begin();
54 read_lock(&tasklist_lock);
55 do_each_thread(g, p) {
56 if (frozen(p) || !freezable(p))
59 if (!freeze_task(p, sig_only))
63 * Now that we've done set_freeze_flag, don't
64 * perturb a task in TASK_STOPPED or TASK_TRACED.
65 * It is "frozen enough". If the task does wake
66 * up, it will immediately call try_to_freeze.
68 * Because freeze_task() goes through p's
69 * scheduler lock after setting TIF_FREEZE, it's
70 * guaranteed that either we see TASK_RUNNING or
71 * try_to_stop() after schedule() in ptrace/signal
72 * stop sees TIF_FREEZE.
74 if (!task_is_stopped_or_traced(p) &&
75 !freezer_should_skip(p))
77 } while_each_thread(g, p);
78 read_unlock(&tasklist_lock);
81 wq_busy = freeze_workqueues_busy();
85 if (!todo || time_after(jiffies, end_time))
88 if (pm_wakeup_pending()) {
94 * We need to retry, but first give the freezing tasks some
95 * time to enter the regrigerator.
100 do_gettimeofday(&end);
101 elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
102 do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
103 elapsed_csecs = elapsed_csecs64;
106 /* This does not unfreeze processes that are already frozen
107 * (we have slightly ugly calling convention in that respect,
108 * and caller must call thaw_processes() if something fails),
109 * but it cleans up leftover PF_FREEZE requests.
112 printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds "
113 "(%d tasks refusing to freeze, wq_busy=%d):\n",
114 wakeup ? "aborted" : "failed",
115 elapsed_csecs / 100, elapsed_csecs % 100,
116 todo - wq_busy, wq_busy);
120 read_lock(&tasklist_lock);
121 do_each_thread(g, p) {
123 if (!wakeup && freezing(p) && !freezer_should_skip(p))
127 } while_each_thread(g, p);
128 read_unlock(&tasklist_lock);
130 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
131 elapsed_csecs % 100);
134 return todo ? -EBUSY : 0;
138 * freeze_processes - Signal user space processes to enter the refrigerator.
140 int freeze_processes(void)
144 printk("Freezing user space processes ... ");
145 error = try_to_freeze_tasks(true);
148 oom_killer_disable();
157 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
159 int freeze_kernel_threads(void)
163 printk("Freezing remaining freezable tasks ... ");
164 error = try_to_freeze_tasks(false);
174 static void thaw_tasks(bool nosig_only)
176 struct task_struct *g, *p;
178 read_lock(&tasklist_lock);
179 do_each_thread(g, p) {
183 if (nosig_only && should_send_signal(p))
186 if (cgroup_freezing_or_frozen(p))
190 } while_each_thread(g, p);
191 read_unlock(&tasklist_lock);
194 void thaw_processes(void)
198 printk("Restarting tasks ... ");