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/suspend.h>
13 #include <linux/module.h>
14 #include <linux/syscalls.h>
15 #include <linux/freezer.h>
16 #include <linux/wakelock.h>
17
18 /*
19 * Timeout for stopping processes
20 */
21 #define TIMEOUT (20 * HZ)
22
freezeable(struct task_struct * p)23 static inline int freezeable(struct task_struct * p)
24 {
25 if ((p == current) ||
26 (p->flags & PF_NOFREEZE) ||
27 (p->exit_state != 0))
28 return 0;
29 return 1;
30 }
31
try_to_freeze_tasks(bool sig_only)32 static int try_to_freeze_tasks(bool sig_only)
33 {
34 struct task_struct *g, *p;
35 unsigned long end_time;
36 unsigned int todo;
37 struct timeval start, end;
38 u64 elapsed_csecs64;
39 unsigned int elapsed_csecs;
40 unsigned int wakeup = 0;
41
42 do_gettimeofday(&start);
43
44 end_time = jiffies + TIMEOUT;
45 do {
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 yield(); /* Yield is okay here */
67 if (todo && has_wake_lock(WAKE_LOCK_SUSPEND)) {
68 wakeup = 1;
69 break;
70 }
71 if (time_after(jiffies, end_time))
72 break;
73 } while (todo);
74
75 do_gettimeofday(&end);
76 elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
77 do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
78 elapsed_csecs = elapsed_csecs64;
79
80 if (todo) {
81 /* This does not unfreeze processes that are already frozen
82 * (we have slightly ugly calling convention in that respect,
83 * and caller must call thaw_processes() if something fails),
84 * but it cleans up leftover PF_FREEZE requests.
85 */
86 if(wakeup) {
87 printk("\n");
88 printk(KERN_ERR "Freezing of %s aborted\n",
89 sig_only ? "user space " : "tasks ");
90 }
91 else {
92 printk("\n");
93 printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
94 "(%d tasks refusing to freeze):\n",
95 elapsed_csecs / 100, elapsed_csecs % 100, todo);
96 show_state();
97 }
98 read_lock(&tasklist_lock);
99 do_each_thread(g, p) {
100 task_lock(p);
101 if (freezing(p) && !freezer_should_skip(p))
102 printk(KERN_ERR " %s\n", p->comm);
103 cancel_freezing(p);
104 task_unlock(p);
105 } while_each_thread(g, p);
106 read_unlock(&tasklist_lock);
107 } else {
108 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
109 elapsed_csecs % 100);
110 }
111
112 return todo ? -EBUSY : 0;
113 }
114
115 /**
116 * freeze_processes - tell processes to enter the refrigerator
117 */
freeze_processes(void)118 int freeze_processes(void)
119 {
120 int error;
121
122 printk("Freezing user space processes ... ");
123 error = try_to_freeze_tasks(true);
124 if (error)
125 goto Exit;
126 printk("done.\n");
127
128 printk("Freezing remaining freezable tasks ... ");
129 error = try_to_freeze_tasks(false);
130 if (error)
131 goto Exit;
132 printk("done.");
133 Exit:
134 BUG_ON(in_atomic());
135 printk("\n");
136 return error;
137 }
138
thaw_tasks(bool nosig_only)139 static void thaw_tasks(bool nosig_only)
140 {
141 struct task_struct *g, *p;
142
143 read_lock(&tasklist_lock);
144 do_each_thread(g, p) {
145 if (!freezeable(p))
146 continue;
147
148 if (nosig_only && should_send_signal(p))
149 continue;
150
151 if (cgroup_frozen(p))
152 continue;
153
154 thaw_process(p);
155 } while_each_thread(g, p);
156 read_unlock(&tasklist_lock);
157 }
158
thaw_processes(void)159 void thaw_processes(void)
160 {
161 printk("Restarting tasks ... ");
162 thaw_tasks(true);
163 thaw_tasks(false);
164 schedule();
165 printk("done.\n");
166 }
167
168