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 #include <trace/events/power.h>
21 #include <linux/wakeup_reason.h>
22 #include <linux/cpuset.h>
23
24 /*
25 * Timeout for stopping processes
26 */
27 unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
28
try_to_freeze_tasks(bool user_only)29 static int try_to_freeze_tasks(bool user_only)
30 {
31 struct task_struct *g, *p;
32 unsigned long end_time;
33 unsigned int todo;
34 bool wq_busy = false;
35 struct timeval start, end;
36 u64 elapsed_msecs64;
37 unsigned int elapsed_msecs;
38 bool wakeup = false;
39 int sleep_usecs = USEC_PER_MSEC;
40 #ifdef CONFIG_PM_SLEEP
41 char suspend_abort[MAX_SUSPEND_ABORT_LEN];
42 #endif
43
44 do_gettimeofday(&start);
45
46 end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
47
48 if (!user_only)
49 freeze_workqueues_begin();
50
51 while (true) {
52 todo = 0;
53 read_lock(&tasklist_lock);
54 for_each_process_thread(g, p) {
55 if (p == current || !freeze_task(p))
56 continue;
57
58 if (!freezer_should_skip(p))
59 todo++;
60 }
61 read_unlock(&tasklist_lock);
62
63 if (!user_only) {
64 wq_busy = freeze_workqueues_busy();
65 todo += wq_busy;
66 }
67
68 if (!todo || time_after(jiffies, end_time))
69 break;
70
71 if (pm_wakeup_pending()) {
72 #ifdef CONFIG_PM_SLEEP
73 pm_get_active_wakeup_sources(suspend_abort,
74 MAX_SUSPEND_ABORT_LEN);
75 log_suspend_abort_reason(suspend_abort);
76 #endif
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 refrigerator. Start with an initial
84 * 1 ms sleep followed by exponential backoff until 8 ms.
85 */
86 usleep_range(sleep_usecs / 2, sleep_usecs);
87 if (sleep_usecs < 8 * USEC_PER_MSEC)
88 sleep_usecs *= 2;
89 }
90
91 do_gettimeofday(&end);
92 elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
93 do_div(elapsed_msecs64, NSEC_PER_MSEC);
94 elapsed_msecs = elapsed_msecs64;
95
96 if (wakeup) {
97 pr_cont("\n");
98 pr_err("Freezing of tasks aborted after %d.%03d seconds",
99 elapsed_msecs / 1000, elapsed_msecs % 1000);
100 } else if (todo) {
101 pr_cont("\n");
102 pr_err("Freezing of tasks failed after %d.%03d seconds"
103 " (%d tasks refusing to freeze, wq_busy=%d):\n",
104 elapsed_msecs / 1000, elapsed_msecs % 1000,
105 todo - wq_busy, wq_busy);
106
107 read_lock(&tasklist_lock);
108 for_each_process_thread(g, p) {
109 if (p != current && !freezer_should_skip(p)
110 && freezing(p) && !frozen(p))
111 sched_show_task(p);
112 }
113 read_unlock(&tasklist_lock);
114 } else {
115 pr_cont("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
116 elapsed_msecs % 1000);
117 }
118
119 return todo ? -EBUSY : 0;
120 }
121
122 /**
123 * freeze_processes - Signal user space processes to enter the refrigerator.
124 * The current thread will not be frozen. The same process that calls
125 * freeze_processes must later call thaw_processes.
126 *
127 * On success, returns 0. On failure, -errno and system is fully thawed.
128 */
freeze_processes(void)129 int freeze_processes(void)
130 {
131 int error;
132
133 error = __usermodehelper_disable(UMH_FREEZING);
134 if (error)
135 return error;
136
137 /* Make sure this task doesn't get frozen */
138 current->flags |= PF_SUSPEND_TASK;
139
140 if (!pm_freezing)
141 atomic_inc(&system_freezing_cnt);
142
143 pm_wakeup_clear();
144 pr_info("Freezing user space processes ... ");
145 pm_freezing = true;
146 error = try_to_freeze_tasks(true);
147 if (!error) {
148 __usermodehelper_set_disable_depth(UMH_DISABLED);
149 pr_cont("done.");
150 }
151 pr_cont("\n");
152 BUG_ON(in_atomic());
153
154 /*
155 * Now that the whole userspace is frozen we need to disbale
156 * the OOM killer to disallow any further interference with
157 * killable tasks.
158 */
159 if (!error && !oom_killer_disable())
160 error = -EBUSY;
161
162 if (error)
163 thaw_processes();
164 return error;
165 }
166
167 /**
168 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
169 *
170 * On success, returns 0. On failure, -errno and only the kernel threads are
171 * thawed, so as to give a chance to the caller to do additional cleanups
172 * (if any) before thawing the userspace tasks. So, it is the responsibility
173 * of the caller to thaw the userspace tasks, when the time is right.
174 */
freeze_kernel_threads(void)175 int freeze_kernel_threads(void)
176 {
177 int error;
178
179 pr_info("Freezing remaining freezable tasks ... ");
180
181 pm_nosig_freezing = true;
182 error = try_to_freeze_tasks(false);
183 if (!error)
184 pr_cont("done.");
185
186 pr_cont("\n");
187 BUG_ON(in_atomic());
188
189 if (error)
190 thaw_kernel_threads();
191 return error;
192 }
193
thaw_processes(void)194 void thaw_processes(void)
195 {
196 struct task_struct *g, *p;
197 struct task_struct *curr = current;
198
199 trace_suspend_resume(TPS("thaw_processes"), 0, true);
200 if (pm_freezing)
201 atomic_dec(&system_freezing_cnt);
202 pm_freezing = false;
203 pm_nosig_freezing = false;
204
205 oom_killer_enable();
206
207 pr_info("Restarting tasks ... ");
208
209 __usermodehelper_set_disable_depth(UMH_FREEZING);
210 thaw_workqueues();
211
212 cpuset_wait_for_hotplug();
213
214 read_lock(&tasklist_lock);
215 for_each_process_thread(g, p) {
216 /* No other threads should have PF_SUSPEND_TASK set */
217 WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
218 __thaw_task(p);
219 }
220 read_unlock(&tasklist_lock);
221
222 WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
223 curr->flags &= ~PF_SUSPEND_TASK;
224
225 usermodehelper_enable();
226
227 schedule();
228 pr_cont("done.\n");
229 trace_suspend_resume(TPS("thaw_processes"), 0, false);
230 }
231
thaw_kernel_threads(void)232 void thaw_kernel_threads(void)
233 {
234 struct task_struct *g, *p;
235
236 pm_nosig_freezing = false;
237 pr_info("Restarting kernel threads ... ");
238
239 thaw_workqueues();
240
241 read_lock(&tasklist_lock);
242 for_each_process_thread(g, p) {
243 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
244 __thaw_task(p);
245 }
246 read_unlock(&tasklist_lock);
247
248 schedule();
249 pr_cont("done.\n");
250 }
251