projects/linux·blob v2.6.33 · refs

166 lines · 3.5 KiB

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
19/*
20 * Timeout for stopping processes
21 */
22#define TIMEOUT (20 * HZ)
23
24static inline int freezeable(struct task_struct * p)
25{
26 if ((p == current) ||
27 (p->flags & PF_NOFREEZE) ||
28 (p->exit_state != 0))
29 return 0;
30 return 1;
31}
32
33static int try_to_freeze_tasks(bool sig_only)
34{
35 struct task_struct *g, *p;
36 unsigned long end_time;
37 unsigned int todo;
38 struct timeval start, end;
39 u64 elapsed_csecs64;
40 unsigned int elapsed_csecs;
41
42 do_gettimeofday(&start);
43
44 end_time = jiffies + TIMEOUT;
45 while (true) {
46 todo = 0;
47 read_lock(&tasklist_lock);
48 do_each_thread(g, p) {
49 if (frozen(p) || !freezeable(p))
50 continue;
51
52 if (!freeze_task(p, sig_only))
53 continue;
54
55 /*
56 * Now that we've done set_freeze_flag, don't
57 * perturb a task in TASK_STOPPED or TASK_TRACED.
58 * It is "frozen enough". If the task does wake
59 * up, it will immediately call try_to_freeze.
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 if (!todo || time_after(jiffies, end_time))
67 break;
68
69 /*
70 * We need to retry, but first give the freezing tasks some
71 * time to enter the regrigerator.
72 */
73 msleep(10);
74 }
75
76 do_gettimeofday(&end);
77 elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
78 do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
79 elapsed_csecs = elapsed_csecs64;
80
81 if (todo) {
82 /* This does not unfreeze processes that are already frozen
83 * (we have slightly ugly calling convention in that respect,
84 * and caller must call thaw_processes() if something fails),
85 * but it cleans up leftover PF_FREEZE requests.
86 */
87 printk("\n");
88 printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
89 "(%d tasks refusing to freeze):\n",
90 elapsed_csecs / 100, elapsed_csecs % 100, todo);
91 show_state();
92 read_lock(&tasklist_lock);
93 do_each_thread(g, p) {
94 task_lock(p);
95 if (freezing(p) && !freezer_should_skip(p))
96 printk(KERN_ERR " %s\n", p->comm);
97 cancel_freezing(p);
98 task_unlock(p);
99 } while_each_thread(g, p);
100 read_unlock(&tasklist_lock);
101 } else {
102 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
103 elapsed_csecs % 100);
104 }
105
106 return todo ? -EBUSY : 0;
107}
108
109/**
110 * freeze_processes - tell processes to enter the refrigerator
111 */
112int freeze_processes(void)
113{
114 int error;
115
116 printk("Freezing user space processes ... ");
117 error = try_to_freeze_tasks(true);
118 if (error)
119 goto Exit;
120 printk("done.\n");
121
122 printk("Freezing remaining freezable tasks ... ");
123 error = try_to_freeze_tasks(false);
124 if (error)
125 goto Exit;
126 printk("done.");
127
128 oom_killer_disable();
129 Exit:
130 BUG_ON(in_atomic());
131 printk("\n");
132
133 return error;
134}
135
136static void thaw_tasks(bool nosig_only)
137{
138 struct task_struct *g, *p;
139
140 read_lock(&tasklist_lock);
141 do_each_thread(g, p) {
142 if (!freezeable(p))
143 continue;
144
145 if (nosig_only && should_send_signal(p))
146 continue;
147
148 if (cgroup_frozen(p))
149 continue;
150
151 thaw_process(p);
152 } while_each_thread(g, p);
153 read_unlock(&tasklist_lock);
154}
155
156void thaw_processes(void)
157{
158 oom_killer_enable();
159
160 printk("Restarting tasks ... ");
161 thaw_tasks(true);
162 thaw_tasks(false);
163 schedule();
164 printk("done.\n");
165}
166