projects/linux·blob v3.5 · refs

220 lines · 4.7 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 /*
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}