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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
20/*
21 * Timeout for stopping processes
22 */
23#define TIMEOUT (20 * HZ)
24
25static inline int freezable(struct task_struct * p)
26{
27 if ((p == current) ||
28 (p->flags & PF_NOFREEZE) ||
29 (p->exit_state != 0))
30 return 0;
31 return 1;
32}
33
34static int try_to_freeze_tasks(bool sig_only)
35{
36 struct task_struct *g, *p;
37 unsigned long end_time;
38 unsigned int todo;
39 bool wq_busy = false;
40 struct timeval start, end;
41 u64 elapsed_csecs64;
42 unsigned int elapsed_csecs;
43 bool wakeup = false;
44
45 do_gettimeofday(&start);
46
47 end_time = jiffies + TIMEOUT;
48
49 if (!sig_only)
50 freeze_workqueues_begin();
51
52 while (true) {
53 todo = 0;
54 read_lock(&tasklist_lock);
55 do_each_thread(g, p) {
56 if (frozen(p) || !freezable(p))
57 continue;
58
59 if (!freeze_task(p, sig_only))
60 continue;
61
62 /*
63 * Now that we've done set_freeze_flag, don't
64 * perturb a task in TASK_STOPPED or TASK_TRACED.
65 * It is "frozen enough". If the task does wake
66 * up, it will immediately call try_to_freeze.
67 *
68 * Because freeze_task() goes through p's
69 * scheduler lock after setting TIF_FREEZE, it's
70 * guaranteed that either we see TASK_RUNNING or
71 * try_to_stop() after schedule() in ptrace/signal
72 * stop sees TIF_FREEZE.
73 */
74 if (!task_is_stopped_or_traced(p) &&
75 !freezer_should_skip(p))
76 todo++;
77 } while_each_thread(g, p);
78 read_unlock(&tasklist_lock);
79
80 if (!sig_only) {
81 wq_busy = freeze_workqueues_busy();
82 todo += wq_busy;
83 }
84
85 if (!todo || time_after(jiffies, end_time))
86 break;
87
88 if (pm_wakeup_pending()) {
89 wakeup = true;
90 break;
91 }
92
93 /*
94 * We need to retry, but first give the freezing tasks some
95 * time to enter the regrigerator.
96 */
97 msleep(10);
98 }
99
100 do_gettimeofday(&end);
101 elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
102 do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
103 elapsed_csecs = elapsed_csecs64;
104
105 if (todo) {
106 /* This does not unfreeze processes that are already frozen
107 * (we have slightly ugly calling convention in that respect,
108 * and caller must call thaw_processes() if something fails),
109 * but it cleans up leftover PF_FREEZE requests.
110 */
111 printk("\n");
112 printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds "
113 "(%d tasks refusing to freeze, wq_busy=%d):\n",
114 wakeup ? "aborted" : "failed",
115 elapsed_csecs / 100, elapsed_csecs % 100,
116 todo - wq_busy, wq_busy);
117
118 thaw_workqueues();
119
120 read_lock(&tasklist_lock);
121 do_each_thread(g, p) {
122 task_lock(p);
123 if (!wakeup && freezing(p) && !freezer_should_skip(p))
124 sched_show_task(p);
125 cancel_freezing(p);
126 task_unlock(p);
127 } while_each_thread(g, p);
128 read_unlock(&tasklist_lock);
129 } else {
130 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
131 elapsed_csecs % 100);
132 }
133
134 return todo ? -EBUSY : 0;
135}
136
137/**
138 * freeze_processes - tell processes to enter the refrigerator
139 */
140int freeze_processes(void)
141{
142 int error;
143
144 printk("Freezing user space processes ... ");
145 error = try_to_freeze_tasks(true);
146 if (error)
147 goto Exit;
148 printk("done.\n");
149
150 printk("Freezing remaining freezable tasks ... ");
151 error = try_to_freeze_tasks(false);
152 if (error)
153 goto Exit;
154 printk("done.");
155
156 oom_killer_disable();
157 Exit:
158 BUG_ON(in_atomic());
159 printk("\n");
160
161 return error;
162}
163
164static void thaw_tasks(bool nosig_only)
165{
166 struct task_struct *g, *p;
167
168 read_lock(&tasklist_lock);
169 do_each_thread(g, p) {
170 if (!freezable(p))
171 continue;
172
173 if (nosig_only && should_send_signal(p))
174 continue;
175
176 if (cgroup_freezing_or_frozen(p))
177 continue;
178
179 thaw_process(p);
180 } while_each_thread(g, p);
181 read_unlock(&tasklist_lock);
182}
183
184void thaw_processes(void)
185{
186 oom_killer_enable();
187
188 printk("Restarting tasks ... ");
189 thaw_workqueues();
190 thaw_tasks(true);
191 thaw_tasks(false);
192 schedule();
193 printk("done.\n");
194}
195
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) {
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}