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1/*
2 * drivers/power/process.c - Functions for starting/stopping processes on
3 * suspend transitions.
4 *
5 * Originally from swsusp.
6 */
7
8
9#undef DEBUG
10
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
22/*
23 * Timeout for stopping processes
24 */
25unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
26
27static int try_to_freeze_tasks(bool user_only)
28{
29 struct task_struct *g, *p;
30 unsigned long end_time;
31 unsigned int todo;
32 bool wq_busy = false;
33 ktime_t start, end, elapsed;
34 unsigned int elapsed_msecs;
35 bool wakeup = false;
36 int sleep_usecs = USEC_PER_MSEC;
37
38 start = ktime_get_boottime();
39
40 end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
41
42 if (!user_only)
43 freeze_workqueues_begin();
44
45 while (true) {
46 todo = 0;
47 read_lock(&tasklist_lock);
48 for_each_process_thread(g, p) {
49 if (p == current || !freeze_task(p))
50 continue;
51
52 if (!freezer_should_skip(p))
53 todo++;
54 }
55 read_unlock(&tasklist_lock);
56
57 if (!user_only) {
58 wq_busy = freeze_workqueues_busy();
59 todo += wq_busy;
60 }
61
62 if (!todo || time_after(jiffies, end_time))
63 break;
64
65 if (pm_wakeup_pending()) {
66 wakeup = true;
67 break;
68 }
69
70 /*
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.
74 */
75 usleep_range(sleep_usecs / 2, sleep_usecs);
76 if (sleep_usecs < 8 * USEC_PER_MSEC)
77 sleep_usecs *= 2;
78 }
79
80 end = ktime_get_boottime();
81 elapsed = ktime_sub(end, start);
82 elapsed_msecs = ktime_to_ms(elapsed);
83
84 if (todo) {
85 pr_cont("\n");
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);
91
92 if (wq_busy)
93 show_workqueue_state();
94
95 if (!wakeup) {
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))
100 sched_show_task(p);
101 }
102 read_unlock(&tasklist_lock);
103 }
104 } else {
105 pr_cont("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
106 elapsed_msecs % 1000);
107 }
108
109 return todo ? -EBUSY : 0;
110}
111
112/**
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.
116 *
117 * On success, returns 0. On failure, -errno and system is fully thawed.
118 */
119int freeze_processes(void)
120{
121 int error;
122
123 error = __usermodehelper_disable(UMH_FREEZING);
124 if (error)
125 return error;
126
127 /* Make sure this task doesn't get frozen */
128 current->flags |= PF_SUSPEND_TASK;
129
130 if (!pm_freezing)
131 atomic_inc(&system_freezing_cnt);
132
133 pm_wakeup_clear();
134 pr_info("Freezing user space processes ... ");
135 pm_freezing = true;
136 error = try_to_freeze_tasks(true);
137 if (!error) {
138 __usermodehelper_set_disable_depth(UMH_DISABLED);
139 pr_cont("done.");
140 }
141 pr_cont("\n");
142 BUG_ON(in_atomic());
143
144 /*
145 * Now that the whole userspace is frozen we need to disbale
146 * the OOM killer to disallow any further interference with
147 * killable tasks. There is no guarantee oom victims will
148 * ever reach a point they go away we have to wait with a timeout.
149 */
150 if (!error && !oom_killer_disable(msecs_to_jiffies(freeze_timeout_msecs)))
151 error = -EBUSY;
152
153 if (error)
154 thaw_processes();
155 return error;
156}
157
158/**
159 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
160 *
161 * On success, returns 0. On failure, -errno and only the kernel threads are
162 * thawed, so as to give a chance to the caller to do additional cleanups
163 * (if any) before thawing the userspace tasks. So, it is the responsibility
164 * of the caller to thaw the userspace tasks, when the time is right.
165 */
166int freeze_kernel_threads(void)
167{
168 int error;
169
170 pr_info("Freezing remaining freezable tasks ... ");
171
172 pm_nosig_freezing = true;
173 error = try_to_freeze_tasks(false);
174 if (!error)
175 pr_cont("done.");
176
177 pr_cont("\n");
178 BUG_ON(in_atomic());
179
180 if (error)
181 thaw_kernel_threads();
182 return error;
183}
184
185void thaw_processes(void)
186{
187 struct task_struct *g, *p;
188 struct task_struct *curr = current;
189
190 trace_suspend_resume(TPS("thaw_processes"), 0, true);
191 if (pm_freezing)
192 atomic_dec(&system_freezing_cnt);
193 pm_freezing = false;
194 pm_nosig_freezing = false;
195
196 oom_killer_enable();
197
198 pr_info("Restarting tasks ... ");
199
200 __usermodehelper_set_disable_depth(UMH_FREEZING);
201 thaw_workqueues();
202
203 read_lock(&tasklist_lock);
204 for_each_process_thread(g, p) {
205 /* No other threads should have PF_SUSPEND_TASK set */
206 WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
207 __thaw_task(p);
208 }
209 read_unlock(&tasklist_lock);
210
211 WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
212 curr->flags &= ~PF_SUSPEND_TASK;
213
214 usermodehelper_enable();
215
216 schedule();
217 pr_cont("done.\n");
218 trace_suspend_resume(TPS("thaw_processes"), 0, false);
219}
220
221void thaw_kernel_threads(void)
222{
223 struct task_struct *g, *p;
224
225 pm_nosig_freezing = false;
226 pr_info("Restarting kernel threads ... ");
227
228 thaw_workqueues();
229
230 read_lock(&tasklist_lock);
231 for_each_process_thread(g, p) {
232 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
233 __thaw_task(p);
234 }
235 read_unlock(&tasklist_lock);
236
237 schedule();
238 pr_cont("done.\n");
239}
1/*
2 * drivers/power/process.c - Functions for starting/stopping processes on
3 * suspend transitions.
4 *
5 * Originally from swsusp.
6 */
7
8
9#undef DEBUG
10
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
22/*
23 * Timeout for stopping processes
24 */
25unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
26
27static int try_to_freeze_tasks(bool user_only)
28{
29 struct task_struct *g, *p;
30 unsigned long end_time;
31 unsigned int todo;
32 bool wq_busy = false;
33 ktime_t start, end, elapsed;
34 unsigned int elapsed_msecs;
35 bool wakeup = false;
36 int sleep_usecs = USEC_PER_MSEC;
37
38 start = ktime_get_boottime();
39
40 end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
41
42 if (!user_only)
43 freeze_workqueues_begin();
44
45 while (true) {
46 todo = 0;
47 read_lock(&tasklist_lock);
48 for_each_process_thread(g, p) {
49 if (p == current || !freeze_task(p))
50 continue;
51
52 if (!freezer_should_skip(p))
53 todo++;
54 }
55 read_unlock(&tasklist_lock);
56
57 if (!user_only) {
58 wq_busy = freeze_workqueues_busy();
59 todo += wq_busy;
60 }
61
62 if (!todo || time_after(jiffies, end_time))
63 break;
64
65 if (pm_wakeup_pending()) {
66 wakeup = true;
67 break;
68 }
69
70 /*
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.
74 */
75 usleep_range(sleep_usecs / 2, sleep_usecs);
76 if (sleep_usecs < 8 * USEC_PER_MSEC)
77 sleep_usecs *= 2;
78 }
79
80 end = ktime_get_boottime();
81 elapsed = ktime_sub(end, start);
82 elapsed_msecs = ktime_to_ms(elapsed);
83
84 if (todo) {
85 pr_cont("\n");
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);
91
92 if (!wakeup) {
93 read_lock(&tasklist_lock);
94 for_each_process_thread(g, p) {
95 if (p != current && !freezer_should_skip(p)
96 && freezing(p) && !frozen(p))
97 sched_show_task(p);
98 }
99 read_unlock(&tasklist_lock);
100 }
101 } else {
102 pr_cont("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
103 elapsed_msecs % 1000);
104 }
105
106 return todo ? -EBUSY : 0;
107}
108
109/**
110 * freeze_processes - Signal user space processes to enter the refrigerator.
111 * The current thread will not be frozen. The same process that calls
112 * freeze_processes must later call thaw_processes.
113 *
114 * On success, returns 0. On failure, -errno and system is fully thawed.
115 */
116int freeze_processes(void)
117{
118 int error;
119
120 error = __usermodehelper_disable(UMH_FREEZING);
121 if (error)
122 return error;
123
124 /* Make sure this task doesn't get frozen */
125 current->flags |= PF_SUSPEND_TASK;
126
127 if (!pm_freezing)
128 atomic_inc(&system_freezing_cnt);
129
130 pm_wakeup_clear();
131 pr_info("Freezing user space processes ... ");
132 pm_freezing = true;
133 error = try_to_freeze_tasks(true);
134 if (!error) {
135 __usermodehelper_set_disable_depth(UMH_DISABLED);
136 pr_cont("done.");
137 }
138 pr_cont("\n");
139 BUG_ON(in_atomic());
140
141 /*
142 * Now that the whole userspace is frozen we need to disbale
143 * the OOM killer to disallow any further interference with
144 * killable tasks.
145 */
146 if (!error && !oom_killer_disable())
147 error = -EBUSY;
148
149 if (error)
150 thaw_processes();
151 return error;
152}
153
154/**
155 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
156 *
157 * On success, returns 0. On failure, -errno and only the kernel threads are
158 * thawed, so as to give a chance to the caller to do additional cleanups
159 * (if any) before thawing the userspace tasks. So, it is the responsibility
160 * of the caller to thaw the userspace tasks, when the time is right.
161 */
162int freeze_kernel_threads(void)
163{
164 int error;
165
166 pr_info("Freezing remaining freezable tasks ... ");
167
168 pm_nosig_freezing = true;
169 error = try_to_freeze_tasks(false);
170 if (!error)
171 pr_cont("done.");
172
173 pr_cont("\n");
174 BUG_ON(in_atomic());
175
176 if (error)
177 thaw_kernel_threads();
178 return error;
179}
180
181void thaw_processes(void)
182{
183 struct task_struct *g, *p;
184 struct task_struct *curr = current;
185
186 trace_suspend_resume(TPS("thaw_processes"), 0, true);
187 if (pm_freezing)
188 atomic_dec(&system_freezing_cnt);
189 pm_freezing = false;
190 pm_nosig_freezing = false;
191
192 oom_killer_enable();
193
194 pr_info("Restarting tasks ... ");
195
196 __usermodehelper_set_disable_depth(UMH_FREEZING);
197 thaw_workqueues();
198
199 read_lock(&tasklist_lock);
200 for_each_process_thread(g, p) {
201 /* No other threads should have PF_SUSPEND_TASK set */
202 WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
203 __thaw_task(p);
204 }
205 read_unlock(&tasklist_lock);
206
207 WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
208 curr->flags &= ~PF_SUSPEND_TASK;
209
210 usermodehelper_enable();
211
212 schedule();
213 pr_cont("done.\n");
214 trace_suspend_resume(TPS("thaw_processes"), 0, false);
215}
216
217void thaw_kernel_threads(void)
218{
219 struct task_struct *g, *p;
220
221 pm_nosig_freezing = false;
222 pr_info("Restarting kernel threads ... ");
223
224 thaw_workqueues();
225
226 read_lock(&tasklist_lock);
227 for_each_process_thread(g, p) {
228 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
229 __thaw_task(p);
230 }
231 read_unlock(&tasklist_lock);
232
233 schedule();
234 pr_cont("done.\n");
235}