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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/*
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