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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
21/*
22 * Timeout for stopping processes
23 */
24#define TIMEOUT (20 * HZ)
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_csecs64;
34 unsigned int elapsed_csecs;
35 bool wakeup = false;
36
37 do_gettimeofday(&start);
38
39 end_time = jiffies + TIMEOUT;
40
41 if (!user_only)
42 freeze_workqueues_begin();
43
44 while (true) {
45 todo = 0;
46 read_lock(&tasklist_lock);
47 do_each_thread(g, p) {
48 if (p == current || !freeze_task(p))
49 continue;
50
51 /*
52 * Now that we've done set_freeze_flag, don't
53 * perturb a task in TASK_STOPPED or TASK_TRACED.
54 * It is "frozen enough". If the task does wake
55 * up, it will immediately call try_to_freeze.
56 *
57 * Because freeze_task() goes through p's scheduler lock, it's
58 * guaranteed that TASK_STOPPED/TRACED -> TASK_RUNNING
59 * transition can't race with task state testing here.
60 */
61 if (!task_is_stopped_or_traced(p) &&
62 !freezer_should_skip(p))
63 todo++;
64 } while_each_thread(g, p);
65 read_unlock(&tasklist_lock);
66
67 if (!user_only) {
68 wq_busy = freeze_workqueues_busy();
69 todo += wq_busy;
70 }
71
72 if (!todo || time_after(jiffies, end_time))
73 break;
74
75 if (pm_wakeup_pending()) {
76 wakeup = true;
77 break;
78 }
79
80 /*
81 * We need to retry, but first give the freezing tasks some
82 * time to enter the regrigerator.
83 */
84 msleep(10);
85 }
86
87 do_gettimeofday(&end);
88 elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
89 do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
90 elapsed_csecs = elapsed_csecs64;
91
92 if (todo) {
93 printk("\n");
94 printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds "
95 "(%d tasks refusing to freeze, wq_busy=%d):\n",
96 wakeup ? "aborted" : "failed",
97 elapsed_csecs / 100, elapsed_csecs % 100,
98 todo - wq_busy, wq_busy);
99
100 if (!wakeup) {
101 read_lock(&tasklist_lock);
102 do_each_thread(g, p) {
103 if (p != current && !freezer_should_skip(p)
104 && freezing(p) && !frozen(p))
105 sched_show_task(p);
106 } while_each_thread(g, p);
107 read_unlock(&tasklist_lock);
108 }
109 } else {
110 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
111 elapsed_csecs % 100);
112 }
113
114 return todo ? -EBUSY : 0;
115}
116
117/**
118 * freeze_processes - Signal user space processes to enter the refrigerator.
119 *
120 * On success, returns 0. On failure, -errno and system is fully thawed.
121 */
122int freeze_processes(void)
123{
124 int error;
125
126 error = __usermodehelper_disable(UMH_FREEZING);
127 if (error)
128 return error;
129
130 if (!pm_freezing)
131 atomic_inc(&system_freezing_cnt);
132
133 printk("Freezing user space processes ... ");
134 pm_freezing = true;
135 error = try_to_freeze_tasks(true);
136 if (!error) {
137 printk("done.");
138 __usermodehelper_set_disable_depth(UMH_DISABLED);
139 oom_killer_disable();
140 }
141 printk("\n");
142 BUG_ON(in_atomic());
143
144 if (error)
145 thaw_processes();
146 return error;
147}
148
149/**
150 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
151 *
152 * On success, returns 0. On failure, -errno and only the kernel threads are
153 * thawed, so as to give a chance to the caller to do additional cleanups
154 * (if any) before thawing the userspace tasks. So, it is the responsibility
155 * of the caller to thaw the userspace tasks, when the time is right.
156 */
157int freeze_kernel_threads(void)
158{
159 int error;
160
161 printk("Freezing remaining freezable tasks ... ");
162 pm_nosig_freezing = true;
163 error = try_to_freeze_tasks(false);
164 if (!error)
165 printk("done.");
166
167 printk("\n");
168 BUG_ON(in_atomic());
169
170 if (error)
171 thaw_kernel_threads();
172 return error;
173}
174
175void thaw_processes(void)
176{
177 struct task_struct *g, *p;
178
179 if (pm_freezing)
180 atomic_dec(&system_freezing_cnt);
181 pm_freezing = false;
182 pm_nosig_freezing = false;
183
184 oom_killer_enable();
185
186 printk("Restarting tasks ... ");
187
188 thaw_workqueues();
189
190 read_lock(&tasklist_lock);
191 do_each_thread(g, p) {
192 __thaw_task(p);
193 } while_each_thread(g, p);
194 read_unlock(&tasklist_lock);
195
196 usermodehelper_enable();
197
198 schedule();
199 printk("done.\n");
200}
201
202void thaw_kernel_threads(void)
203{
204 struct task_struct *g, *p;
205
206 pm_nosig_freezing = false;
207 printk("Restarting kernel threads ... ");
208
209 thaw_workqueues();
210
211 read_lock(&tasklist_lock);
212 do_each_thread(g, p) {
213 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
214 __thaw_task(p);
215 } while_each_thread(g, p);
216 read_unlock(&tasklist_lock);
217
218 schedule();
219 printk("done.\n");
220}