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 ktime_t start
, end
, elapsed
;
34 unsigned int elapsed_msecs
;
36 int sleep_usecs
= USEC_PER_MSEC
;
38 start
= ktime_get_boottime();
40 end_time
= jiffies
+ msecs_to_jiffies(freeze_timeout_msecs
);
43 freeze_workqueues_begin();
47 read_lock(&tasklist_lock
);
48 for_each_process_thread(g
, p
) {
49 if (p
== current
|| !freeze_task(p
))
52 if (!freezer_should_skip(p
))
55 read_unlock(&tasklist_lock
);
58 wq_busy
= freeze_workqueues_busy();
62 if (!todo
|| time_after(jiffies
, end_time
))
65 if (pm_wakeup_pending()) {
71 * We need to retry, but first give the freezing tasks some
72 * time to enter the refrigerator. Start with an initial
73 * 1 ms sleep followed by exponential backoff until 8 ms.
75 usleep_range(sleep_usecs
/ 2, sleep_usecs
);
76 if (sleep_usecs
< 8 * USEC_PER_MSEC
)
80 end
= ktime_get_boottime();
81 elapsed
= ktime_sub(end
, start
);
82 elapsed_msecs
= ktime_to_ms(elapsed
);
86 pr_err("Freezing of tasks %s after %d.%03d seconds "
87 "(%d tasks refusing to freeze, wq_busy=%d):\n",
88 wakeup
? "aborted" : "failed",
89 elapsed_msecs
/ 1000, elapsed_msecs
% 1000,
90 todo
- wq_busy
, wq_busy
);
93 show_workqueue_state();
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())
153 * There is a hard to fix race between oom_reaper kernel thread
154 * and oom_killer_disable. oom_reaper calls exit_oom_victim
155 * before the victim reaches exit_mm so try to freeze all the tasks
156 * again and catch such a left over task.
159 pr_info("Double checking all user space processes after OOM killer disable... ");
160 error
= try_to_freeze_tasks(true);
170 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
172 * On success, returns 0. On failure, -errno and only the kernel threads are
173 * thawed, so as to give a chance to the caller to do additional cleanups
174 * (if any) before thawing the userspace tasks. So, it is the responsibility
175 * of the caller to thaw the userspace tasks, when the time is right.
177 int freeze_kernel_threads(void)
181 pr_info("Freezing remaining freezable tasks ... ");
183 pm_nosig_freezing
= true;
184 error
= try_to_freeze_tasks(false);
192 thaw_kernel_threads();
196 void thaw_processes(void)
198 struct task_struct
*g
, *p
;
199 struct task_struct
*curr
= current
;
201 trace_suspend_resume(TPS("thaw_processes"), 0, true);
203 atomic_dec(&system_freezing_cnt
);
205 pm_nosig_freezing
= false;
209 pr_info("Restarting tasks ... ");
211 __usermodehelper_set_disable_depth(UMH_FREEZING
);
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
);