projects/linux·blob v3.3 · refs

212 lines · 4.5 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#include <linux/workqueue.h>
19
20/*
21 * Timeout for stopping processes
22 */
23#define TIMEOUT (20 * HZ)
24
25static int try_to_freeze_tasks(bool user_only)
26{
27 struct task_struct *g, *p;
28 unsigned long end_time;
29 unsigned int todo;
30 bool wq_busy = false;
31 struct timeval start, end;
32 u64 elapsed_csecs64;
33 unsigned int elapsed_csecs;
34 bool wakeup = false;
35
36 do_gettimeofday(&start);
37
38 end_time = jiffies + TIMEOUT;
39
40 if (!user_only)
41 freeze_workqueues_begin();
42
43 while (true) {
44 todo = 0;
45 read_lock(&tasklist_lock);
46 do_each_thread(g, p) {
47 if (p == current || !freeze_task(p))
48 continue;
49
50 /*
51 * Now that we've done set_freeze_flag, don't
52 * perturb a task in TASK_STOPPED or TASK_TRACED.
53 * It is "frozen enough". If the task does wake
54 * up, it will immediately call try_to_freeze.
55 *
56 * Because freeze_task() goes through p's
57 * scheduler lock after setting TIF_FREEZE, it's
58 * guaranteed that either we see TASK_RUNNING or
59 * try_to_stop() after schedule() in ptrace/signal
60 * stop sees TIF_FREEZE.
61 */
62 if (!task_is_stopped_or_traced(p) &&
63 !freezer_should_skip(p))
64 todo++;
65 } while_each_thread(g, p);
66 read_unlock(&tasklist_lock);
67
68 if (!user_only) {
69 wq_busy = freeze_workqueues_busy();
70 todo += wq_busy;
71 }
72
73 if (!todo || time_after(jiffies, end_time))
74 break;
75
76 if (pm_wakeup_pending()) {
77 wakeup = true;
78 break;
79 }
80
81 /*
82 * We need to retry, but first give the freezing tasks some
83 * time to enter the regrigerator.
84 */
85 msleep(10);
86 }
87
88 do_gettimeofday(&end);
89 elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
90 do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
91 elapsed_csecs = elapsed_csecs64;
92
93 if (todo) {
94 printk("\n");
95 printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds "
96 "(%d tasks refusing to freeze, wq_busy=%d):\n",
97 wakeup ? "aborted" : "failed",
98 elapsed_csecs / 100, elapsed_csecs % 100,
99 todo - wq_busy, wq_busy);
100
101 read_lock(&tasklist_lock);
102 do_each_thread(g, p) {
103 if (!wakeup && !freezer_should_skip(p) &&
104 p != current && freezing(p) && !frozen(p))
105 sched_show_task(p);
106 } while_each_thread(g, p);
107 read_unlock(&tasklist_lock);
108 } else {
109 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
110 elapsed_csecs % 100);
111 }
112
113 return todo ? -EBUSY : 0;
114}
115
116/**
117 * freeze_processes - Signal user space processes to enter the refrigerator.
118 *
119 * On success, returns 0. On failure, -errno and system is fully thawed.
120 */
121int freeze_processes(void)
122{
123 int error;
124
125 if (!pm_freezing)
126 atomic_inc(&system_freezing_cnt);
127
128 printk("Freezing user space processes ... ");
129 pm_freezing = true;
130 error = try_to_freeze_tasks(true);
131 if (!error) {
132 printk("done.");
133 oom_killer_disable();
134 }
135 printk("\n");
136 BUG_ON(in_atomic());
137
138 if (error)
139 thaw_processes();
140 return error;
141}
142
143/**
144 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
145 *
146 * On success, returns 0. On failure, -errno and only the kernel threads are
147 * thawed, so as to give a chance to the caller to do additional cleanups
148 * (if any) before thawing the userspace tasks. So, it is the responsibility
149 * of the caller to thaw the userspace tasks, when the time is right.
150 */
151int freeze_kernel_threads(void)
152{
153 int error;
154
155 printk("Freezing remaining freezable tasks ... ");
156 pm_nosig_freezing = true;
157 error = try_to_freeze_tasks(false);
158 if (!error)
159 printk("done.");
160
161 printk("\n");
162 BUG_ON(in_atomic());
163
164 if (error)
165 thaw_kernel_threads();
166 return error;
167}
168
169void thaw_processes(void)
170{
171 struct task_struct *g, *p;
172
173 if (pm_freezing)
174 atomic_dec(&system_freezing_cnt);
175 pm_freezing = false;
176 pm_nosig_freezing = false;
177
178 oom_killer_enable();
179
180 printk("Restarting tasks ... ");
181
182 thaw_workqueues();
183
184 read_lock(&tasklist_lock);
185 do_each_thread(g, p) {
186 __thaw_task(p);
187 } while_each_thread(g, p);
188 read_unlock(&tasklist_lock);
189
190 schedule();
191 printk("done.\n");
192}
193
194void thaw_kernel_threads(void)
195{
196 struct task_struct *g, *p;
197
198 pm_nosig_freezing = false;
199 printk("Restarting kernel threads ... ");
200
201 thaw_workqueues();
202
203 read_lock(&tasklist_lock);
204 do_each_thread(g, p) {
205 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
206 __thaw_task(p);
207 } while_each_thread(g, p);
208 read_unlock(&tasklist_lock);
209
210 schedule();
211 printk("done.\n");
212}