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 21 /* 22 * Timeout for stopping processes 23 */ 24 unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC; 25 26 static 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_msecs64; 34 unsigned int elapsed_msecs; 35 bool wakeup = false; 36 int sleep_usecs = USEC_PER_MSEC; 37 38 do_gettimeofday(&start); 39 40 end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs); 41 42 if (!user_only) 43 freeze_workqueues_begin(); 44 45 while (true) { 46 todo = 0; 47 read_lock(&tasklist_lock); 48 do_each_thread(g, p) { 49 if (p == current || !freeze_task(p)) 50 continue; 51 52 if (!freezer_should_skip(p)) 53 todo++; 54 } while_each_thread(g, p); 55 read_unlock(&tasklist_lock); 56 57 if (!user_only) { 58 wq_busy = freeze_workqueues_busy(); 59 todo += wq_busy; 60 } 61 62 if (!todo || time_after(jiffies, end_time)) 63 break; 64 65 if (pm_wakeup_pending()) { 66 wakeup = true; 67 break; 68 } 69 70 /* 71 * We need to retry, but first give the freezing tasks some 72 * time to enter the refrigerator. Start with an initial 73 * 1 ms sleep followed by exponential backoff until 8 ms. 74 */ 75 usleep_range(sleep_usecs / 2, sleep_usecs); 76 if (sleep_usecs < 8 * USEC_PER_MSEC) 77 sleep_usecs *= 2; 78 } 79 80 do_gettimeofday(&end); 81 elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start); 82 do_div(elapsed_msecs64, NSEC_PER_MSEC); 83 elapsed_msecs = elapsed_msecs64; 84 85 if (todo) { 86 printk("\n"); 87 printk(KERN_ERR "Freezing of tasks %s after %d.%03d seconds " 88 "(%d tasks refusing to freeze, wq_busy=%d):\n", 89 wakeup ? "aborted" : "failed", 90 elapsed_msecs / 1000, elapsed_msecs % 1000, 91 todo - wq_busy, wq_busy); 92 93 if (!wakeup) { 94 read_lock(&tasklist_lock); 95 do_each_thread(g, p) { 96 if (p != current && !freezer_should_skip(p) 97 && freezing(p) && !frozen(p)) 98 sched_show_task(p); 99 } while_each_thread(g, p); 100 read_unlock(&tasklist_lock); 101 } 102 } else { 103 printk("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000, 104 elapsed_msecs % 1000); 105 } 106 107 return todo ? -EBUSY : 0; 108 } 109 110 /** 111 * freeze_processes - Signal user space processes to enter the refrigerator. 112 * 113 * On success, returns 0. On failure, -errno and system is fully thawed. 114 */ 115 int freeze_processes(void) 116 { 117 int error; 118 119 error = __usermodehelper_disable(UMH_FREEZING); 120 if (error) 121 return error; 122 123 if (!pm_freezing) 124 atomic_inc(&system_freezing_cnt); 125 126 printk("Freezing user space processes ... "); 127 pm_freezing = true; 128 error = try_to_freeze_tasks(true); 129 if (!error) { 130 printk("done."); 131 __usermodehelper_set_disable_depth(UMH_DISABLED); 132 oom_killer_disable(); 133 } 134 printk("\n"); 135 BUG_ON(in_atomic()); 136 137 if (error) 138 thaw_processes(); 139 return error; 140 } 141 142 /** 143 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator. 144 * 145 * On success, returns 0. On failure, -errno and only the kernel threads are 146 * thawed, so as to give a chance to the caller to do additional cleanups 147 * (if any) before thawing the userspace tasks. So, it is the responsibility 148 * of the caller to thaw the userspace tasks, when the time is right. 149 */ 150 int freeze_kernel_threads(void) 151 { 152 int error; 153 154 printk("Freezing remaining freezable tasks ... "); 155 pm_nosig_freezing = true; 156 error = try_to_freeze_tasks(false); 157 if (!error) 158 printk("done."); 159 160 printk("\n"); 161 BUG_ON(in_atomic()); 162 163 if (error) 164 thaw_kernel_threads(); 165 return error; 166 } 167 168 void thaw_processes(void) 169 { 170 struct task_struct *g, *p; 171 172 if (pm_freezing) 173 atomic_dec(&system_freezing_cnt); 174 pm_freezing = false; 175 pm_nosig_freezing = false; 176 177 oom_killer_enable(); 178 179 printk("Restarting tasks ... "); 180 181 thaw_workqueues(); 182 183 read_lock(&tasklist_lock); 184 do_each_thread(g, p) { 185 __thaw_task(p); 186 } while_each_thread(g, p); 187 read_unlock(&tasklist_lock); 188 189 usermodehelper_enable(); 190 191 schedule(); 192 printk("done.\n"); 193 } 194 195 void thaw_kernel_threads(void) 196 { 197 struct task_struct *g, *p; 198 199 pm_nosig_freezing = false; 200 printk("Restarting kernel threads ... "); 201 202 thaw_workqueues(); 203 204 read_lock(&tasklist_lock); 205 do_each_thread(g, p) { 206 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER)) 207 __thaw_task(p); 208 } while_each_thread(g, p); 209 read_unlock(&tasklist_lock); 210 211 schedule(); 212 printk("done.\n"); 213 } 214