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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * drivers/power/process.c - Functions for starting/stopping processes on
4 * suspend transitions.
5 *
6 * Originally from swsusp.
7 */
8
9
10#undef DEBUG
11
12#include <linux/interrupt.h>
13#include <linux/oom.h>
14#include <linux/suspend.h>
15#include <linux/module.h>
16#include <linux/sched/debug.h>
17#include <linux/sched/task.h>
18#include <linux/syscalls.h>
19#include <linux/freezer.h>
20#include <linux/delay.h>
21#include <linux/workqueue.h>
22#include <linux/kmod.h>
23#include <trace/events/power.h>
24#include <linux/cpuset.h>
25
26/*
27 * Timeout for stopping processes
28 */
29unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
30
31static int try_to_freeze_tasks(bool user_only)
32{
33 struct task_struct *g, *p;
34 unsigned long end_time;
35 unsigned int todo;
36 bool wq_busy = false;
37 ktime_t start, end, elapsed;
38 unsigned int elapsed_msecs;
39 bool wakeup = false;
40 int sleep_usecs = USEC_PER_MSEC;
41
42 start = ktime_get_boottime();
43
44 end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
45
46 if (!user_only)
47 freeze_workqueues_begin();
48
49 while (true) {
50 todo = 0;
51 read_lock(&tasklist_lock);
52 for_each_process_thread(g, p) {
53 if (p == current || !freeze_task(p))
54 continue;
55
56 if (!freezer_should_skip(p))
57 todo++;
58 }
59 read_unlock(&tasklist_lock);
60
61 if (!user_only) {
62 wq_busy = freeze_workqueues_busy();
63 todo += wq_busy;
64 }
65
66 if (!todo || time_after(jiffies, end_time))
67 break;
68
69 if (pm_wakeup_pending()) {
70 wakeup = true;
71 break;
72 }
73
74 /*
75 * We need to retry, but first give the freezing tasks some
76 * time to enter the refrigerator. Start with an initial
77 * 1 ms sleep followed by exponential backoff until 8 ms.
78 */
79 usleep_range(sleep_usecs / 2, sleep_usecs);
80 if (sleep_usecs < 8 * USEC_PER_MSEC)
81 sleep_usecs *= 2;
82 }
83
84 end = ktime_get_boottime();
85 elapsed = ktime_sub(end, start);
86 elapsed_msecs = ktime_to_ms(elapsed);
87
88 if (todo) {
89 pr_cont("\n");
90 pr_err("Freezing of tasks %s after %d.%03d seconds "
91 "(%d tasks refusing to freeze, wq_busy=%d):\n",
92 wakeup ? "aborted" : "failed",
93 elapsed_msecs / 1000, elapsed_msecs % 1000,
94 todo - wq_busy, wq_busy);
95
96 if (wq_busy)
97 show_workqueue_state();
98
99 if (!wakeup || pm_debug_messages_on) {
100 read_lock(&tasklist_lock);
101 for_each_process_thread(g, p) {
102 if (p != current && !freezer_should_skip(p)
103 && freezing(p) && !frozen(p))
104 sched_show_task(p);
105 }
106 read_unlock(&tasklist_lock);
107 }
108 } else {
109 pr_cont("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
110 elapsed_msecs % 1000);
111 }
112
113 return todo ? -EBUSY : 0;
114}
115
116/**
117 * freeze_processes - Signal user space processes to enter the refrigerator.
118 * The current thread will not be frozen. The same process that calls
119 * freeze_processes must later call thaw_processes.
120 *
121 * On success, returns 0. On failure, -errno and system is fully thawed.
122 */
123int freeze_processes(void)
124{
125 int error;
126
127 error = __usermodehelper_disable(UMH_FREEZING);
128 if (error)
129 return error;
130
131 /* Make sure this task doesn't get frozen */
132 current->flags |= PF_SUSPEND_TASK;
133
134 if (!pm_freezing)
135 atomic_inc(&system_freezing_cnt);
136
137 pm_wakeup_clear(true);
138 pr_info("Freezing user space processes ... ");
139 pm_freezing = true;
140 error = try_to_freeze_tasks(true);
141 if (!error) {
142 __usermodehelper_set_disable_depth(UMH_DISABLED);
143 pr_cont("done.");
144 }
145 pr_cont("\n");
146 BUG_ON(in_atomic());
147
148 /*
149 * Now that the whole userspace is frozen we need to disbale
150 * the OOM killer to disallow any further interference with
151 * killable tasks. There is no guarantee oom victims will
152 * ever reach a point they go away we have to wait with a timeout.
153 */
154 if (!error && !oom_killer_disable(msecs_to_jiffies(freeze_timeout_msecs)))
155 error = -EBUSY;
156
157 if (error)
158 thaw_processes();
159 return error;
160}
161
162/**
163 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
164 *
165 * On success, returns 0. On failure, -errno and only the kernel threads are
166 * thawed, so as to give a chance to the caller to do additional cleanups
167 * (if any) before thawing the userspace tasks. So, it is the responsibility
168 * of the caller to thaw the userspace tasks, when the time is right.
169 */
170int freeze_kernel_threads(void)
171{
172 int error;
173
174 pr_info("Freezing remaining freezable tasks ... ");
175
176 pm_nosig_freezing = true;
177 error = try_to_freeze_tasks(false);
178 if (!error)
179 pr_cont("done.");
180
181 pr_cont("\n");
182 BUG_ON(in_atomic());
183
184 if (error)
185 thaw_kernel_threads();
186 return error;
187}
188
189void thaw_processes(void)
190{
191 struct task_struct *g, *p;
192 struct task_struct *curr = current;
193
194 trace_suspend_resume(TPS("thaw_processes"), 0, true);
195 if (pm_freezing)
196 atomic_dec(&system_freezing_cnt);
197 pm_freezing = false;
198 pm_nosig_freezing = false;
199
200 oom_killer_enable();
201
202 pr_info("Restarting tasks ... ");
203
204 __usermodehelper_set_disable_depth(UMH_FREEZING);
205 thaw_workqueues();
206
207 cpuset_wait_for_hotplug();
208
209 read_lock(&tasklist_lock);
210 for_each_process_thread(g, p) {
211 /* No other threads should have PF_SUSPEND_TASK set */
212 WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
213 __thaw_task(p);
214 }
215 read_unlock(&tasklist_lock);
216
217 WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
218 curr->flags &= ~PF_SUSPEND_TASK;
219
220 usermodehelper_enable();
221
222 schedule();
223 pr_cont("done.\n");
224 trace_suspend_resume(TPS("thaw_processes"), 0, false);
225}
226
227void thaw_kernel_threads(void)
228{
229 struct task_struct *g, *p;
230
231 pm_nosig_freezing = false;
232 pr_info("Restarting kernel threads ... ");
233
234 thaw_workqueues();
235
236 read_lock(&tasklist_lock);
237 for_each_process_thread(g, p) {
238 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
239 __thaw_task(p);
240 }
241 read_unlock(&tasklist_lock);
242
243 schedule();
244 pr_cont("done.\n");
245}
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}