projects/linux·blob v3.8 · refs

209 lines · 4.3 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#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 if (!freezer_should_skip(p))
52 todo++;
53 } while_each_thread(g, p);
54 read_unlock(&tasklist_lock);
55
56 if (!user_only) {
57 wq_busy = freeze_workqueues_busy();
58 todo += wq_busy;
59 }
60
61 if (!todo || time_after(jiffies, end_time))
62 break;
63
64 if (pm_wakeup_pending()) {
65 wakeup = true;
66 break;
67 }
68
69 /*
70 * We need to retry, but first give the freezing tasks some
71 * time to enter the refrigerator.
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 printk("\n");
83 printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds "
84 "(%d tasks refusing to freeze, wq_busy=%d):\n",
85 wakeup ? "aborted" : "failed",
86 elapsed_csecs / 100, elapsed_csecs % 100,
87 todo - wq_busy, wq_busy);
88
89 if (!wakeup) {
90 read_lock(&tasklist_lock);
91 do_each_thread(g, p) {
92 if (p != current && !freezer_should_skip(p)
93 && freezing(p) && !frozen(p))
94 sched_show_task(p);
95 } while_each_thread(g, p);
96 read_unlock(&tasklist_lock);
97 }
98 } else {
99 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
100 elapsed_csecs % 100);
101 }
102
103 return todo ? -EBUSY : 0;
104}
105
106/**
107 * freeze_processes - Signal user space processes to enter the refrigerator.
108 *
109 * On success, returns 0. On failure, -errno and system is fully thawed.
110 */
111int freeze_processes(void)
112{
113 int error;
114
115 error = __usermodehelper_disable(UMH_FREEZING);
116 if (error)
117 return error;
118
119 if (!pm_freezing)
120 atomic_inc(&system_freezing_cnt);
121
122 printk("Freezing user space processes ... ");
123 pm_freezing = true;
124 error = try_to_freeze_tasks(true);
125 if (!error) {
126 printk("done.");
127 __usermodehelper_set_disable_depth(UMH_DISABLED);
128 oom_killer_disable();
129 }
130 printk("\n");
131 BUG_ON(in_atomic());
132
133 if (error)
134 thaw_processes();
135 return error;
136}
137
138/**
139 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
140 *
141 * On success, returns 0. On failure, -errno and only the kernel threads are
142 * thawed, so as to give a chance to the caller to do additional cleanups
143 * (if any) before thawing the userspace tasks. So, it is the responsibility
144 * of the caller to thaw the userspace tasks, when the time is right.
145 */
146int freeze_kernel_threads(void)
147{
148 int error;
149
150 printk("Freezing remaining freezable tasks ... ");
151 pm_nosig_freezing = true;
152 error = try_to_freeze_tasks(false);
153 if (!error)
154 printk("done.");
155
156 printk("\n");
157 BUG_ON(in_atomic());
158
159 if (error)
160 thaw_kernel_threads();
161 return error;
162}
163
164void thaw_processes(void)
165{
166 struct task_struct *g, *p;
167
168 if (pm_freezing)
169 atomic_dec(&system_freezing_cnt);
170 pm_freezing = false;
171 pm_nosig_freezing = false;
172
173 oom_killer_enable();
174
175 printk("Restarting tasks ... ");
176
177 thaw_workqueues();
178
179 read_lock(&tasklist_lock);
180 do_each_thread(g, p) {
181 __thaw_task(p);
182 } while_each_thread(g, p);
183 read_unlock(&tasklist_lock);
184
185 usermodehelper_enable();
186
187 schedule();
188 printk("done.\n");
189}
190
191void thaw_kernel_threads(void)
192{
193 struct task_struct *g, *p;
194
195 pm_nosig_freezing = false;
196 printk("Restarting kernel threads ... ");
197
198 thaw_workqueues();
199
200 read_lock(&tasklist_lock);
201 do_each_thread(g, p) {
202 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
203 __thaw_task(p);
204 } while_each_thread(g, p);
205 read_unlock(&tasklist_lock);
206
207 schedule();
208 printk("done.\n");
209}