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>
21 #include <linux/cpuset.h>
24 * Timeout for stopping processes
26 unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
28 static int try_to_freeze_tasks(bool user_only)
30 struct task_struct *g, *p;
31 unsigned long end_time;
34 struct timeval start, end;
36 unsigned int elapsed_msecs;
38 int sleep_usecs = USEC_PER_MSEC;
40 do_gettimeofday(&start);
42 end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
45 freeze_workqueues_begin();
49 read_lock(&tasklist_lock);
50 for_each_process_thread(g, p) {
51 if (p == current || !freeze_task(p))
54 if (!freezer_should_skip(p))
57 read_unlock(&tasklist_lock);
60 wq_busy = freeze_workqueues_busy();
64 if (!todo || time_after(jiffies, end_time))
67 if (pm_wakeup_pending()) {
73 * We need to retry, but first give the freezing tasks some
74 * time to enter the refrigerator. Start with an initial
75 * 1 ms sleep followed by exponential backoff until 8 ms.
77 usleep_range(sleep_usecs / 2, sleep_usecs);
78 if (sleep_usecs < 8 * USEC_PER_MSEC)
82 do_gettimeofday(&end);
83 elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
84 do_div(elapsed_msecs64, NSEC_PER_MSEC);
85 elapsed_msecs = elapsed_msecs64;
89 pr_err("Freezing of tasks %s after %d.%03d seconds "
90 "(%d tasks refusing to freeze, wq_busy=%d):\n",
91 wakeup ? "aborted" : "failed",
92 elapsed_msecs / 1000, elapsed_msecs % 1000,
93 todo - wq_busy, wq_busy);
96 read_lock(&tasklist_lock);
97 for_each_process_thread(g, p) {
98 if (p != current && !freezer_should_skip(p)
99 && freezing(p) && !frozen(p))
102 read_unlock(&tasklist_lock);
105 pr_cont("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
106 elapsed_msecs % 1000);
109 return todo ? -EBUSY : 0;
113 * freeze_processes - Signal user space processes to enter the refrigerator.
114 * The current thread will not be frozen. The same process that calls
115 * freeze_processes must later call thaw_processes.
117 * On success, returns 0. On failure, -errno and system is fully thawed.
119 int freeze_processes(void)
123 error = __usermodehelper_disable(UMH_FREEZING);
127 /* Make sure this task doesn't get frozen */
128 current->flags |= PF_SUSPEND_TASK;
131 atomic_inc(&system_freezing_cnt);
134 pr_info("Freezing user space processes ... ");
136 error = try_to_freeze_tasks(true);
138 __usermodehelper_set_disable_depth(UMH_DISABLED);
145 * Now that the whole userspace is frozen we need to disbale
146 * the OOM killer to disallow any further interference with
149 if (!error && !oom_killer_disable())
158 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
160 * On success, returns 0. On failure, -errno and only the kernel threads are
161 * thawed, so as to give a chance to the caller to do additional cleanups
162 * (if any) before thawing the userspace tasks. So, it is the responsibility
163 * of the caller to thaw the userspace tasks, when the time is right.
165 int freeze_kernel_threads(void)
169 pr_info("Freezing remaining freezable tasks ... ");
171 pm_nosig_freezing = true;
172 error = try_to_freeze_tasks(false);
180 thaw_kernel_threads();
184 void thaw_processes(void)
186 struct task_struct *g, *p;
187 struct task_struct *curr = current;
189 trace_suspend_resume(TPS("thaw_processes"), 0, true);
191 atomic_dec(&system_freezing_cnt);
193 pm_nosig_freezing = false;
197 pr_info("Restarting tasks ... ");
199 __usermodehelper_set_disable_depth(UMH_FREEZING);
202 cpuset_wait_for_hotplug();
204 read_lock(&tasklist_lock);
205 for_each_process_thread(g, p) {
206 /* No other threads should have PF_SUSPEND_TASK set */
207 WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
210 read_unlock(&tasklist_lock);
212 WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
213 curr->flags &= ~PF_SUSPEND_TASK;
215 usermodehelper_enable();
219 trace_suspend_resume(TPS("thaw_processes"), 0, false);
222 void thaw_kernel_threads(void)
224 struct task_struct *g, *p;
226 pm_nosig_freezing = false;
227 pr_info("Restarting kernel threads ... ");
231 read_lock(&tasklist_lock);
232 for_each_process_thread(g, p) {
233 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
236 read_unlock(&tasklist_lock);