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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/*
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}