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
);
132 printk("Freezing user space processes ... ");
134 error
= try_to_freeze_tasks(true);
137 __usermodehelper_set_disable_depth(UMH_DISABLED
);
138 oom_killer_disable();
149 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
151 * On success, returns 0. On failure, -errno and only the kernel threads are
152 * thawed, so as to give a chance to the caller to do additional cleanups
153 * (if any) before thawing the userspace tasks. So, it is the responsibility
154 * of the caller to thaw the userspace tasks, when the time is right.
156 int freeze_kernel_threads(void)
160 printk("Freezing remaining freezable tasks ... ");
161 pm_nosig_freezing
= true;
162 error
= try_to_freeze_tasks(false);
170 thaw_kernel_threads();
174 void thaw_processes(void)
176 struct task_struct
*g
, *p
;
177 struct task_struct
*curr
= current
;
179 trace_suspend_resume(TPS("thaw_processes"), 0, true);
181 atomic_dec(&system_freezing_cnt
);
183 pm_nosig_freezing
= false;
187 printk("Restarting tasks ... ");
189 __usermodehelper_set_disable_depth(UMH_FREEZING
);
192 read_lock(&tasklist_lock
);
193 do_each_thread(g
, p
) {
194 /* No other threads should have PF_SUSPEND_TASK set */
195 WARN_ON((p
!= curr
) && (p
->flags
& PF_SUSPEND_TASK
));
197 } while_each_thread(g
, p
);
198 read_unlock(&tasklist_lock
);
200 WARN_ON(!(curr
->flags
& PF_SUSPEND_TASK
));
201 curr
->flags
&= ~PF_SUSPEND_TASK
;
203 usermodehelper_enable();
207 trace_suspend_resume(TPS("thaw_processes"), 0, false);
210 void thaw_kernel_threads(void)
212 struct task_struct
*g
, *p
;
214 pm_nosig_freezing
= false;
215 printk("Restarting kernel threads ... ");
219 read_lock(&tasklist_lock
);
220 do_each_thread(g
, p
) {
221 if (p
->flags
& (PF_KTHREAD
| PF_WQ_WORKER
))
223 } while_each_thread(g
, p
);
224 read_unlock(&tasklist_lock
);