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>
20 * Timeout for stopping processes
22 #define TIMEOUT (20 * HZ)
24 static inline int freezeable(struct task_struct * p)
27 (p->flags & PF_NOFREEZE) ||
33 static int try_to_freeze_tasks(bool sig_only)
35 struct task_struct *g, *p;
36 unsigned long end_time;
38 struct timeval start, end;
40 unsigned int elapsed_csecs;
42 do_gettimeofday(&start);
44 end_time = jiffies + TIMEOUT;
47 read_lock(&tasklist_lock);
48 do_each_thread(g, p) {
49 if (frozen(p) || !freezeable(p))
52 if (!freeze_task(p, sig_only))
56 * Now that we've done set_freeze_flag, don't
57 * perturb a task in TASK_STOPPED or TASK_TRACED.
58 * It is "frozen enough". If the task does wake
59 * up, it will immediately call try_to_freeze.
61 if (!task_is_stopped_or_traced(p) &&
62 !freezer_should_skip(p))
64 } while_each_thread(g, p);
65 read_unlock(&tasklist_lock);
66 if (!todo || time_after(jiffies, end_time))
70 * We need to retry, but first give the freezing tasks some
71 * time to enter the regrigerator.
76 do_gettimeofday(&end);
77 elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
78 do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
79 elapsed_csecs = elapsed_csecs64;
82 /* This does not unfreeze processes that are already frozen
83 * (we have slightly ugly calling convention in that respect,
84 * and caller must call thaw_processes() if something fails),
85 * but it cleans up leftover PF_FREEZE requests.
88 printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
89 "(%d tasks refusing to freeze):\n",
90 elapsed_csecs / 100, elapsed_csecs % 100, todo);
92 read_lock(&tasklist_lock);
93 do_each_thread(g, p) {
95 if (freezing(p) && !freezer_should_skip(p))
96 printk(KERN_ERR " %s\n", p->comm);
99 } while_each_thread(g, p);
100 read_unlock(&tasklist_lock);
102 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
103 elapsed_csecs % 100);
106 return todo ? -EBUSY : 0;
110 * freeze_processes - tell processes to enter the refrigerator
112 int freeze_processes(void)
116 printk("Freezing user space processes ... ");
117 error = try_to_freeze_tasks(true);
122 printk("Freezing remaining freezable tasks ... ");
123 error = try_to_freeze_tasks(false);
128 oom_killer_disable();
136 static void thaw_tasks(bool nosig_only)
138 struct task_struct *g, *p;
140 read_lock(&tasklist_lock);
141 do_each_thread(g, p) {
145 if (nosig_only && should_send_signal(p))
148 if (cgroup_frozen(p))
152 } while_each_thread(g, p);
153 read_unlock(&tasklist_lock);
156 void thaw_processes(void)
160 printk("Restarting tasks ... ");