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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#include <linux/interrupt.h>
10#include <linux/oom.h>
11#include <linux/suspend.h>
12#include <linux/module.h>
13#include <linux/sched/debug.h>
14#include <linux/sched/task.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/cpuset.h>
22
23/*
24 * Timeout for stopping processes
25 */
26unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
27
28static int try_to_freeze_tasks(bool user_only)
29{
30 const char *what = user_only ? "user space processes" :
31 "remaining freezable tasks";
32 struct task_struct *g, *p;
33 unsigned long end_time;
34 unsigned int todo;
35 bool wq_busy = false;
36 ktime_t start, end, elapsed;
37 unsigned int elapsed_msecs;
38 bool wakeup = false;
39 int sleep_usecs = USEC_PER_MSEC;
40
41 pr_info("Freezing %s\n", what);
42
43 start = ktime_get_boottime();
44
45 end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
46
47 if (!user_only)
48 freeze_workqueues_begin();
49
50 while (true) {
51 todo = 0;
52 read_lock(&tasklist_lock);
53 for_each_process_thread(g, p) {
54 if (p == current || !freeze_task(p))
55 continue;
56
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_err("Freezing %s %s after %d.%03d seconds "
90 "(%d tasks refusing to freeze, wq_busy=%d):\n", what,
91 wakeup ? "aborted" : "failed",
92 elapsed_msecs / 1000, elapsed_msecs % 1000,
93 todo - wq_busy, wq_busy);
94
95 if (wq_busy)
96 show_all_workqueues();
97
98 if (!wakeup || pm_debug_messages_on) {
99 read_lock(&tasklist_lock);
100 for_each_process_thread(g, p) {
101 if (p != current && freezing(p) && !frozen(p))
102 sched_show_task(p);
103 }
104 read_unlock(&tasklist_lock);
105 }
106 } else {
107 pr_info("Freezing %s completed (elapsed %d.%03d seconds)\n",
108 what, elapsed_msecs / 1000, elapsed_msecs % 1000);
109 }
110
111 return todo ? -EBUSY : 0;
112}
113
114/**
115 * freeze_processes - Signal user space processes to enter the refrigerator.
116 * The current thread will not be frozen. The same process that calls
117 * freeze_processes must later call thaw_processes.
118 *
119 * On success, returns 0. On failure, -errno and system is fully thawed.
120 */
121int freeze_processes(void)
122{
123 int error;
124
125 error = __usermodehelper_disable(UMH_FREEZING);
126 if (error)
127 return error;
128
129 /* Make sure this task doesn't get frozen */
130 current->flags |= PF_SUSPEND_TASK;
131
132 if (!pm_freezing)
133 static_branch_inc(&freezer_active);
134
135 pm_wakeup_clear(0);
136 pm_freezing = true;
137 error = try_to_freeze_tasks(true);
138 if (!error)
139 __usermodehelper_set_disable_depth(UMH_DISABLED);
140
141 BUG_ON(in_atomic());
142
143 /*
144 * Now that the whole userspace is frozen we need to disable
145 * the OOM killer to disallow any further interference with
146 * killable tasks. There is no guarantee oom victims will
147 * ever reach a point they go away we have to wait with a timeout.
148 */
149 if (!error && !oom_killer_disable(msecs_to_jiffies(freeze_timeout_msecs)))
150 error = -EBUSY;
151
152 if (error)
153 thaw_processes();
154 return error;
155}
156
157/**
158 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
159 *
160 * On success, returns 0. On failure, -errno and only the kernel threads are
161 * thawed, so as to give a chance to the caller to do additional cleanups
162 * (if any) before thawing the userspace tasks. So, it is the responsibility
163 * of the caller to thaw the userspace tasks, when the time is right.
164 */
165int freeze_kernel_threads(void)
166{
167 int error;
168
169 pm_nosig_freezing = true;
170 error = try_to_freeze_tasks(false);
171
172 BUG_ON(in_atomic());
173
174 if (error)
175 thaw_kernel_threads();
176 return error;
177}
178
179void thaw_processes(void)
180{
181 struct task_struct *g, *p;
182 struct task_struct *curr = current;
183
184 trace_suspend_resume(TPS("thaw_processes"), 0, true);
185 if (pm_freezing)
186 static_branch_dec(&freezer_active);
187 pm_freezing = false;
188 pm_nosig_freezing = false;
189
190 oom_killer_enable();
191
192 pr_info("Restarting tasks ... ");
193
194 __usermodehelper_set_disable_depth(UMH_FREEZING);
195 thaw_workqueues();
196
197 cpuset_wait_for_hotplug();
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)
229 __thaw_task(p);
230 }
231 read_unlock(&tasklist_lock);
232
233 schedule();
234 pr_cont("done.\n");
235}
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}