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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
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}