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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
21/*
22 * Timeout for stopping processes
23 */
24unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
25
26static int try_to_freeze_tasks(bool user_only)
27{
28 struct task_struct *g, *p;
29 unsigned long end_time;
30 unsigned int todo;
31 bool wq_busy = false;
32 struct timeval start, end;
33 u64 elapsed_msecs64;
34 unsigned int elapsed_msecs;
35 bool wakeup = false;
36 int sleep_usecs = USEC_PER_MSEC;
37
38 do_gettimeofday(&start);
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 do_each_thread(g, p) {
49 if (p == current || !freeze_task(p))
50 continue;
51
52 if (!freezer_should_skip(p))
53 todo++;
54 } while_each_thread(g, p);
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 do_gettimeofday(&end);
81 elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
82 do_div(elapsed_msecs64, NSEC_PER_MSEC);
83 elapsed_msecs = elapsed_msecs64;
84
85 if (todo) {
86 printk("\n");
87 printk(KERN_ERR "Freezing of tasks %s after %d.%03d seconds "
88 "(%d tasks refusing to freeze, wq_busy=%d):\n",
89 wakeup ? "aborted" : "failed",
90 elapsed_msecs / 1000, elapsed_msecs % 1000,
91 todo - wq_busy, wq_busy);
92
93 if (!wakeup) {
94 read_lock(&tasklist_lock);
95 do_each_thread(g, p) {
96 if (p != current && !freezer_should_skip(p)
97 && freezing(p) && !frozen(p))
98 sched_show_task(p);
99 } while_each_thread(g, p);
100 read_unlock(&tasklist_lock);
101 }
102 } else {
103 printk("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
104 elapsed_msecs % 1000);
105 }
106
107 return todo ? -EBUSY : 0;
108}
109
110/**
111 * freeze_processes - Signal user space processes to enter the refrigerator.
112 * The current thread will not be frozen. The same process that calls
113 * freeze_processes must later call thaw_processes.
114 *
115 * On success, returns 0. On failure, -errno and system is fully thawed.
116 */
117int freeze_processes(void)
118{
119 int error;
120
121 error = __usermodehelper_disable(UMH_FREEZING);
122 if (error)
123 return error;
124
125 /* Make sure this task doesn't get frozen */
126 current->flags |= PF_SUSPEND_TASK;
127
128 if (!pm_freezing)
129 atomic_inc(&system_freezing_cnt);
130
131 printk("Freezing user space processes ... ");
132 pm_freezing = true;
133 error = try_to_freeze_tasks(true);
134 if (!error) {
135 printk("done.");
136 __usermodehelper_set_disable_depth(UMH_DISABLED);
137 oom_killer_disable();
138 }
139 printk("\n");
140 BUG_ON(in_atomic());
141
142 if (error)
143 thaw_processes();
144 return error;
145}
146
147/**
148 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
149 *
150 * On success, returns 0. On failure, -errno and only the kernel threads are
151 * thawed, so as to give a chance to the caller to do additional cleanups
152 * (if any) before thawing the userspace tasks. So, it is the responsibility
153 * of the caller to thaw the userspace tasks, when the time is right.
154 */
155int freeze_kernel_threads(void)
156{
157 int error;
158
159 printk("Freezing remaining freezable tasks ... ");
160 pm_nosig_freezing = true;
161 error = try_to_freeze_tasks(false);
162 if (!error)
163 printk("done.");
164
165 printk("\n");
166 BUG_ON(in_atomic());
167
168 if (error)
169 thaw_kernel_threads();
170 return error;
171}
172
173void thaw_processes(void)
174{
175 struct task_struct *g, *p;
176 struct task_struct *curr = current;
177
178 if (pm_freezing)
179 atomic_dec(&system_freezing_cnt);
180 pm_freezing = false;
181 pm_nosig_freezing = false;
182
183 oom_killer_enable();
184
185 printk("Restarting tasks ... ");
186
187 thaw_workqueues();
188
189 read_lock(&tasklist_lock);
190 do_each_thread(g, p) {
191 /* No other threads should have PF_SUSPEND_TASK set */
192 WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
193 __thaw_task(p);
194 } while_each_thread(g, p);
195 read_unlock(&tasklist_lock);
196
197 WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
198 curr->flags &= ~PF_SUSPEND_TASK;
199
200 usermodehelper_enable();
201
202 schedule();
203 printk("done.\n");
204}
205
206void thaw_kernel_threads(void)
207{
208 struct task_struct *g, *p;
209
210 pm_nosig_freezing = false;
211 printk("Restarting kernel threads ... ");
212
213 thaw_workqueues();
214
215 read_lock(&tasklist_lock);
216 do_each_thread(g, p) {
217 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
218 __thaw_task(p);
219 } while_each_thread(g, p);
220 read_unlock(&tasklist_lock);
221
222 schedule();
223 printk("done.\n");
224}
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_freezable_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}