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>
19 #include <linux/kmod.h>
20 #include <trace/events/power.h>
23 * Timeout for stopping processes
25 unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
27 static int try_to_freeze_tasks(bool user_only)
29 struct task_struct *g, *p;
30 unsigned long end_time;
33 struct timeval start, end;
35 unsigned int elapsed_msecs;
37 int sleep_usecs = USEC_PER_MSEC;
39 do_gettimeofday(&start);
41 end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
44 freeze_workqueues_begin();
48 read_lock(&tasklist_lock);
49 do_each_thread(g, p) {
50 if (p == current || !freeze_task(p))
53 if (!freezer_should_skip(p))
55 } while_each_thread(g, p);
56 read_unlock(&tasklist_lock);
59 wq_busy = freeze_workqueues_busy();
63 if (!todo || time_after(jiffies, end_time))
66 if (pm_wakeup_pending()) {
72 * We need to retry, but first give the freezing tasks some
73 * time to enter the refrigerator. Start with an initial
74 * 1 ms sleep followed by exponential backoff until 8 ms.
76 usleep_range(sleep_usecs / 2, sleep_usecs);
77 if (sleep_usecs < 8 * USEC_PER_MSEC)
81 do_gettimeofday(&end);
82 elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
83 do_div(elapsed_msecs64, NSEC_PER_MSEC);
84 elapsed_msecs = elapsed_msecs64;
88 printk(KERN_ERR "Freezing of tasks %s after %d.%03d seconds "
89 "(%d tasks refusing to freeze, wq_busy=%d):\n",
90 wakeup ? "aborted" : "failed",
91 elapsed_msecs / 1000, elapsed_msecs % 1000,
92 todo - wq_busy, wq_busy);
95 read_lock(&tasklist_lock);
96 do_each_thread(g, p) {
97 if (p != current && !freezer_should_skip(p)
98 && freezing(p) && !frozen(p))
100 } while_each_thread(g, p);
101 read_unlock(&tasklist_lock);
104 printk("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
105 elapsed_msecs % 1000);
108 return todo ? -EBUSY : 0;
112 * freeze_processes - Signal user space processes to enter the refrigerator.
113 * The current thread will not be frozen. The same process that calls
114 * freeze_processes must later call thaw_processes.
116 * On success, returns 0. On failure, -errno and system is fully thawed.
118 int freeze_processes(void)
122 error = __usermodehelper_disable(UMH_FREEZING);
126 /* Make sure this task doesn't get frozen */
127 current->flags |= PF_SUSPEND_TASK;
130 atomic_inc(&system_freezing_cnt);
133 printk("Freezing user space processes ... ");
135 error = try_to_freeze_tasks(true);
138 __usermodehelper_set_disable_depth(UMH_DISABLED);
139 oom_killer_disable();
150 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
152 * On success, returns 0. On failure, -errno and only the kernel threads are
153 * thawed, so as to give a chance to the caller to do additional cleanups
154 * (if any) before thawing the userspace tasks. So, it is the responsibility
155 * of the caller to thaw the userspace tasks, when the time is right.
157 int freeze_kernel_threads(void)
161 printk("Freezing remaining freezable tasks ... ");
162 pm_nosig_freezing = true;
163 error = try_to_freeze_tasks(false);
171 thaw_kernel_threads();
175 void thaw_processes(void)
177 struct task_struct *g, *p;
178 struct task_struct *curr = current;
180 trace_suspend_resume(TPS("thaw_processes"), 0, true);
182 atomic_dec(&system_freezing_cnt);
184 pm_nosig_freezing = false;
188 printk("Restarting tasks ... ");
190 __usermodehelper_set_disable_depth(UMH_FREEZING);
193 read_lock(&tasklist_lock);
194 do_each_thread(g, p) {
195 /* No other threads should have PF_SUSPEND_TASK set */
196 WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
198 } while_each_thread(g, p);
199 read_unlock(&tasklist_lock);
201 WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
202 curr->flags &= ~PF_SUSPEND_TASK;
204 usermodehelper_enable();
208 trace_suspend_resume(TPS("thaw_processes"), 0, false);
211 void thaw_kernel_threads(void)
213 struct task_struct *g, *p;
215 pm_nosig_freezing = false;
216 printk("Restarting kernel threads ... ");
220 read_lock(&tasklist_lock);
221 do_each_thread(g, p) {
222 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
224 } while_each_thread(g, p);
225 read_unlock(&tasklist_lock);