blob: 286ff570f3b762a30d95ca14d806889f4dcbf1e5 [file] [log] [blame]
lh9ed821d2023-04-07 01:36:19 -07001/*
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 * Returns true if all freezable tasks (except for current) are frozen already
119 */
120static bool check_frozen_processes(void)
121{
122 struct task_struct *g, *p;
123 bool ret = true;
124
125 read_lock(&tasklist_lock);
126 for_each_process_thread(g, p) {
127 if (p != current && !freezer_should_skip(p) &&
128 !frozen(p)) {
129 ret = false;
130 goto done;
131 }
132 }
133done:
134 read_unlock(&tasklist_lock);
135
136 return ret;
137}
138
139/**
140 * freeze_processes - Signal user space processes to enter the refrigerator.
141 *
142 * On success, returns 0. On failure, -errno and system is fully thawed.
143 */
144int freeze_processes(void)
145{
146 int error;
147 int oom_kills_saved;
148
149 error = __usermodehelper_disable(UMH_FREEZING);
150 if (error)
151 return error;
152
153 if (!pm_freezing)
154 atomic_inc(&system_freezing_cnt);
155
156 printk("Freezing user space processes ... ");
157 pm_freezing = true;
158 oom_kills_saved = oom_kills_count();
159 error = try_to_freeze_tasks(true);
160 if (!error) {
161 __usermodehelper_set_disable_depth(UMH_DISABLED);
162 oom_killer_disable();
163
164 /*
165 * There might have been an OOM kill while we were
166 * freezing tasks and the killed task might be still
167 * on the way out so we have to double check for race.
168 */
169 if (oom_kills_count() != oom_kills_saved &&
170 !check_frozen_processes()) {
171 __usermodehelper_set_disable_depth(UMH_ENABLED);
172 printk("OOM in progress.");
173 error = -EBUSY;
174 goto done;
175 }
176 printk("done.");
177 }
178done:
179 printk("\n");
180 BUG_ON(in_atomic());
181
182 if (error)
183 thaw_processes();
184 return error;
185}
186
187/**
188 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
189 *
190 * On success, returns 0. On failure, -errno and only the kernel threads are
191 * thawed, so as to give a chance to the caller to do additional cleanups
192 * (if any) before thawing the userspace tasks. So, it is the responsibility
193 * of the caller to thaw the userspace tasks, when the time is right.
194 */
195int freeze_kernel_threads(void)
196{
197 int error;
198
199 printk("Freezing remaining freezable tasks ... ");
200 pm_nosig_freezing = true;
201 error = try_to_freeze_tasks(false);
202 if (!error)
203 printk("done.");
204
205 printk("\n");
206 BUG_ON(in_atomic());
207
208 if (error)
209 thaw_kernel_threads();
210 return error;
211}
212
213void thaw_processes(void)
214{
215 struct task_struct *g, *p;
216
217 if (pm_freezing)
218 atomic_dec(&system_freezing_cnt);
219 pm_freezing = false;
220 pm_nosig_freezing = false;
221
222 oom_killer_enable();
223
224 printk("Restarting tasks ... ");
225
226 __usermodehelper_set_disable_depth(UMH_FREEZING);
227 thaw_workqueues();
228
229 read_lock(&tasklist_lock);
230 do_each_thread(g, p) {
231 __thaw_task(p);
232 } while_each_thread(g, p);
233 read_unlock(&tasklist_lock);
234
235 usermodehelper_enable();
236
237 schedule();
238 printk("done.\n");
239}
240
241void thaw_kernel_threads(void)
242{
243 struct task_struct *g, *p;
244
245 pm_nosig_freezing = false;
246 printk("Restarting kernel threads ... ");
247
248 thaw_workqueues();
249
250 read_lock(&tasklist_lock);
251 do_each_thread(g, p) {
252 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
253 __thaw_task(p);
254 } while_each_thread(g, p);
255 read_unlock(&tasklist_lock);
256
257 schedule();
258 printk("done.\n");
259}