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/wakeup_reason.h>
22 #include <linux/cpuset.h>
25 * Timeout for stopping processes
27 unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
29 static int try_to_freeze_tasks(bool user_only)
31 struct task_struct *g, *p;
32 unsigned long end_time;
35 struct timeval start, end;
37 unsigned int elapsed_msecs;
39 int sleep_usecs = USEC_PER_MSEC;
40 #ifdef CONFIG_PM_SLEEP
41 char suspend_abort[MAX_SUSPEND_ABORT_LEN];
44 do_gettimeofday(&start);
46 end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
49 freeze_workqueues_begin();
53 read_lock(&tasklist_lock);
54 for_each_process_thread(g, p) {
55 if (p == current || !freeze_task(p))
58 if (!freezer_should_skip(p))
61 read_unlock(&tasklist_lock);
64 wq_busy = freeze_workqueues_busy();
68 if (!todo || time_after(jiffies, end_time))
71 if (pm_wakeup_pending()) {
72 #ifdef CONFIG_PM_SLEEP
73 pm_get_active_wakeup_sources(suspend_abort,
74 MAX_SUSPEND_ABORT_LEN);
75 log_suspend_abort_reason(suspend_abort);
82 * We need to retry, but first give the freezing tasks some
83 * time to enter the refrigerator. Start with an initial
84 * 1 ms sleep followed by exponential backoff until 8 ms.
86 usleep_range(sleep_usecs / 2, sleep_usecs);
87 if (sleep_usecs < 8 * USEC_PER_MSEC)
91 do_gettimeofday(&end);
92 elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
93 do_div(elapsed_msecs64, NSEC_PER_MSEC);
94 elapsed_msecs = elapsed_msecs64;
98 pr_err("Freezing of tasks aborted after %d.%03d seconds",
99 elapsed_msecs / 1000, elapsed_msecs % 1000);
102 pr_err("Freezing of tasks failed after %d.%03d seconds"
103 " (%d tasks refusing to freeze, wq_busy=%d):\n",
104 elapsed_msecs / 1000, elapsed_msecs % 1000,
105 todo - wq_busy, wq_busy);
107 read_lock(&tasklist_lock);
108 for_each_process_thread(g, p) {
109 if (p != current && !freezer_should_skip(p)
110 && freezing(p) && !frozen(p))
113 read_unlock(&tasklist_lock);
115 pr_cont("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
116 elapsed_msecs % 1000);
119 return todo ? -EBUSY : 0;
123 * freeze_processes - Signal user space processes to enter the refrigerator.
124 * The current thread will not be frozen. The same process that calls
125 * freeze_processes must later call thaw_processes.
127 * On success, returns 0. On failure, -errno and system is fully thawed.
129 int freeze_processes(void)
133 error = __usermodehelper_disable(UMH_FREEZING);
137 /* Make sure this task doesn't get frozen */
138 current->flags |= PF_SUSPEND_TASK;
141 atomic_inc(&system_freezing_cnt);
144 pr_info("Freezing user space processes ... ");
146 error = try_to_freeze_tasks(true);
148 __usermodehelper_set_disable_depth(UMH_DISABLED);
155 * Now that the whole userspace is frozen we need to disbale
156 * the OOM killer to disallow any further interference with
159 if (!error && !oom_killer_disable())
168 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
170 * On success, returns 0. On failure, -errno and only the kernel threads are
171 * thawed, so as to give a chance to the caller to do additional cleanups
172 * (if any) before thawing the userspace tasks. So, it is the responsibility
173 * of the caller to thaw the userspace tasks, when the time is right.
175 int freeze_kernel_threads(void)
179 pr_info("Freezing remaining freezable tasks ... ");
181 pm_nosig_freezing = true;
182 error = try_to_freeze_tasks(false);
190 thaw_kernel_threads();
194 void thaw_processes(void)
196 struct task_struct *g, *p;
197 struct task_struct *curr = current;
199 trace_suspend_resume(TPS("thaw_processes"), 0, true);
201 atomic_dec(&system_freezing_cnt);
203 pm_nosig_freezing = false;
207 pr_info("Restarting tasks ... ");
209 __usermodehelper_set_disable_depth(UMH_FREEZING);
212 cpuset_wait_for_hotplug();
214 read_lock(&tasklist_lock);
215 for_each_process_thread(g, p) {
216 /* No other threads should have PF_SUSPEND_TASK set */
217 WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
220 read_unlock(&tasklist_lock);
222 WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
223 curr->flags &= ~PF_SUSPEND_TASK;
225 usermodehelper_enable();
229 trace_suspend_resume(TPS("thaw_processes"), 0, false);
232 void thaw_kernel_threads(void)
234 struct task_struct *g, *p;
236 pm_nosig_freezing = false;
237 pr_info("Restarting kernel threads ... ");
241 read_lock(&tasklist_lock);
242 for_each_process_thread(g, p) {
243 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
246 read_unlock(&tasklist_lock);