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 22 /* 23 * Timeout for stopping processes 24 */ 25 unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC; 26 27 static int try_to_freeze_tasks(bool user_only) 28 { 29 struct task_struct *g, *p; 30 unsigned long end_time; 31 unsigned int todo; 32 bool wq_busy = false; 33 struct timeval start, end; 34 u64 elapsed_msecs64; 35 unsigned int elapsed_msecs; 36 bool wakeup = false; 37 int sleep_usecs = USEC_PER_MSEC; 38 39 do_gettimeofday(&start); 40 41 end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs); 42 43 if (!user_only) 44 freeze_workqueues_begin(); 45 46 while (true) { 47 todo = 0; 48 read_lock(&tasklist_lock); 49 for_each_process_thread(g, p) { 50 if (p == current || !freeze_task(p)) 51 continue; 52 53 if (!freezer_should_skip(p)) 54 todo++; 55 } 56 read_unlock(&tasklist_lock); 57 58 if (!user_only) { 59 wq_busy = freeze_workqueues_busy(); 60 todo += wq_busy; 61 } 62 63 if (!todo || time_after(jiffies, end_time)) 64 break; 65 66 if (pm_wakeup_pending()) { 67 wakeup = true; 68 break; 69 } 70 71 /* 72 * We need to retry, but first give the freezing tasks some 73 * time to enter the refrigerator. Start with an initial 74 * 1 ms sleep followed by exponential backoff until 8 ms. 75 */ 76 usleep_range(sleep_usecs / 2, sleep_usecs); 77 if (sleep_usecs < 8 * USEC_PER_MSEC) 78 sleep_usecs *= 2; 79 } 80 81 do_gettimeofday(&end); 82 elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start); 83 do_div(elapsed_msecs64, NSEC_PER_MSEC); 84 elapsed_msecs = elapsed_msecs64; 85 86 if (todo) { 87 pr_cont("\n"); 88 pr_err("Freezing of tasks %s after %d.%03d seconds " 89 "(%d tasks refusing to freeze, wq_busy=%d):\n", 90 wakeup ? "aborted" : "failed", 91 elapsed_msecs / 1000, elapsed_msecs % 1000, 92 todo - wq_busy, wq_busy); 93 94 if (!wakeup) { 95 read_lock(&tasklist_lock); 96 for_each_process_thread(g, p) { 97 if (p != current && !freezer_should_skip(p) 98 && freezing(p) && !frozen(p)) 99 sched_show_task(p); 100 } 101 read_unlock(&tasklist_lock); 102 } 103 } else { 104 pr_cont("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000, 105 elapsed_msecs % 1000); 106 } 107 108 return todo ? -EBUSY : 0; 109 } 110 111 /** 112 * freeze_processes - Signal user space processes to enter the refrigerator. 113 * The current thread will not be frozen. The same process that calls 114 * freeze_processes must later call thaw_processes. 115 * 116 * On success, returns 0. On failure, -errno and system is fully thawed. 117 */ 118 int freeze_processes(void) 119 { 120 int error; 121 122 error = __usermodehelper_disable(UMH_FREEZING); 123 if (error) 124 return error; 125 126 /* Make sure this task doesn't get frozen */ 127 current->flags |= PF_SUSPEND_TASK; 128 129 if (!pm_freezing) 130 atomic_inc(&system_freezing_cnt); 131 132 pm_wakeup_clear(); 133 pr_info("Freezing user space processes ... "); 134 pm_freezing = true; 135 error = try_to_freeze_tasks(true); 136 if (!error) { 137 __usermodehelper_set_disable_depth(UMH_DISABLED); 138 pr_cont("done."); 139 } 140 pr_cont("\n"); 141 BUG_ON(in_atomic()); 142 143 /* 144 * Now that the whole userspace is frozen we need to disbale 145 * the OOM killer to disallow any further interference with 146 * killable tasks. 147 */ 148 if (!error && !oom_killer_disable()) 149 error = -EBUSY; 150 151 if (error) 152 thaw_processes(); 153 return error; 154 } 155 156 /** 157 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator. 158 * 159 * On success, returns 0. On failure, -errno and only the kernel threads are 160 * thawed, so as to give a chance to the caller to do additional cleanups 161 * (if any) before thawing the userspace tasks. So, it is the responsibility 162 * of the caller to thaw the userspace tasks, when the time is right. 163 */ 164 int freeze_kernel_threads(void) 165 { 166 int error; 167 168 pr_info("Freezing remaining freezable tasks ... "); 169 170 pm_nosig_freezing = true; 171 error = try_to_freeze_tasks(false); 172 if (!error) 173 pr_cont("done."); 174 175 pr_cont("\n"); 176 BUG_ON(in_atomic()); 177 178 if (error) 179 thaw_kernel_threads(); 180 return error; 181 } 182 183 void thaw_processes(void) 184 { 185 struct task_struct *g, *p; 186 struct task_struct *curr = current; 187 188 trace_suspend_resume(TPS("thaw_processes"), 0, true); 189 if (pm_freezing) 190 atomic_dec(&system_freezing_cnt); 191 pm_freezing = false; 192 pm_nosig_freezing = false; 193 194 oom_killer_enable(); 195 196 pr_info("Restarting tasks ... "); 197 198 __usermodehelper_set_disable_depth(UMH_FREEZING); 199 thaw_workqueues(); 200 201 read_lock(&tasklist_lock); 202 for_each_process_thread(g, p) { 203 /* No other threads should have PF_SUSPEND_TASK set */ 204 WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK)); 205 __thaw_task(p); 206 } 207 read_unlock(&tasklist_lock); 208 209 WARN_ON(!(curr->flags & PF_SUSPEND_TASK)); 210 curr->flags &= ~PF_SUSPEND_TASK; 211 212 usermodehelper_enable(); 213 214 schedule(); 215 pr_cont("done.\n"); 216 trace_suspend_resume(TPS("thaw_processes"), 0, false); 217 } 218 219 void thaw_kernel_threads(void) 220 { 221 struct task_struct *g, *p; 222 223 pm_nosig_freezing = false; 224 pr_info("Restarting kernel threads ... "); 225 226 thaw_workqueues(); 227 228 read_lock(&tasklist_lock); 229 for_each_process_thread(g, p) { 230 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER)) 231 __thaw_task(p); 232 } 233 read_unlock(&tasklist_lock); 234 235 schedule(); 236 pr_cont("done.\n"); 237 } 238