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 20 /* 21 * Timeout for stopping processes 22 */ 23 #define TIMEOUT (20 * HZ) 24 25 static inline int freezable(struct task_struct * p) 26 { 27 if ((p == current) || 28 (p->flags & PF_NOFREEZE) || 29 (p->exit_state != 0)) 30 return 0; 31 return 1; 32 } 33 34 static int try_to_freeze_tasks(bool sig_only) 35 { 36 struct task_struct *g, *p; 37 unsigned long end_time; 38 unsigned int todo; 39 bool wq_busy = false; 40 struct timeval start, end; 41 u64 elapsed_csecs64; 42 unsigned int elapsed_csecs; 43 bool wakeup = false; 44 45 do_gettimeofday(&start); 46 47 end_time = jiffies + TIMEOUT; 48 49 if (!sig_only) 50 freeze_workqueues_begin(); 51 52 while (true) { 53 todo = 0; 54 read_lock(&tasklist_lock); 55 do_each_thread(g, p) { 56 if (frozen(p) || !freezable(p)) 57 continue; 58 59 if (!freeze_task(p, sig_only)) 60 continue; 61 62 /* 63 * Now that we've done set_freeze_flag, don't 64 * perturb a task in TASK_STOPPED or TASK_TRACED. 65 * It is "frozen enough". If the task does wake 66 * up, it will immediately call try_to_freeze. 67 * 68 * Because freeze_task() goes through p's 69 * scheduler lock after setting TIF_FREEZE, it's 70 * guaranteed that either we see TASK_RUNNING or 71 * try_to_stop() after schedule() in ptrace/signal 72 * stop sees TIF_FREEZE. 73 */ 74 if (!task_is_stopped_or_traced(p) && 75 !freezer_should_skip(p)) 76 todo++; 77 } while_each_thread(g, p); 78 read_unlock(&tasklist_lock); 79 80 if (!sig_only) { 81 wq_busy = freeze_workqueues_busy(); 82 todo += wq_busy; 83 } 84 85 if (!todo || time_after(jiffies, end_time)) 86 break; 87 88 if (pm_wakeup_pending()) { 89 wakeup = true; 90 break; 91 } 92 93 /* 94 * We need to retry, but first give the freezing tasks some 95 * time to enter the regrigerator. 96 */ 97 msleep(10); 98 } 99 100 do_gettimeofday(&end); 101 elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start); 102 do_div(elapsed_csecs64, NSEC_PER_SEC / 100); 103 elapsed_csecs = elapsed_csecs64; 104 105 if (todo) { 106 /* This does not unfreeze processes that are already frozen 107 * (we have slightly ugly calling convention in that respect, 108 * and caller must call thaw_processes() if something fails), 109 * but it cleans up leftover PF_FREEZE requests. 110 */ 111 printk("\n"); 112 printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds " 113 "(%d tasks refusing to freeze, wq_busy=%d):\n", 114 wakeup ? "aborted" : "failed", 115 elapsed_csecs / 100, elapsed_csecs % 100, 116 todo - wq_busy, wq_busy); 117 118 thaw_workqueues(); 119 120 read_lock(&tasklist_lock); 121 do_each_thread(g, p) { 122 task_lock(p); 123 if (!wakeup && freezing(p) && !freezer_should_skip(p)) 124 sched_show_task(p); 125 cancel_freezing(p); 126 task_unlock(p); 127 } while_each_thread(g, p); 128 read_unlock(&tasklist_lock); 129 } else { 130 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100, 131 elapsed_csecs % 100); 132 } 133 134 return todo ? -EBUSY : 0; 135 } 136 137 /** 138 * freeze_processes - Signal user space processes to enter the refrigerator. 139 */ 140 int freeze_processes(void) 141 { 142 int error; 143 144 printk("Freezing user space processes ... "); 145 error = try_to_freeze_tasks(true); 146 if (!error) { 147 printk("done."); 148 oom_killer_disable(); 149 } 150 printk("\n"); 151 BUG_ON(in_atomic()); 152 153 return error; 154 } 155 156 /** 157 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator. 158 */ 159 int freeze_kernel_threads(void) 160 { 161 int error; 162 163 printk("Freezing remaining freezable tasks ... "); 164 error = try_to_freeze_tasks(false); 165 if (!error) 166 printk("done."); 167 168 printk("\n"); 169 BUG_ON(in_atomic()); 170 171 return error; 172 } 173 174 static void thaw_tasks(bool nosig_only) 175 { 176 struct task_struct *g, *p; 177 178 read_lock(&tasklist_lock); 179 do_each_thread(g, p) { 180 if (!freezable(p)) 181 continue; 182 183 if (nosig_only && should_send_signal(p)) 184 continue; 185 186 if (cgroup_freezing_or_frozen(p)) 187 continue; 188 189 thaw_process(p); 190 } while_each_thread(g, p); 191 read_unlock(&tasklist_lock); 192 } 193 194 void thaw_processes(void) 195 { 196 oom_killer_enable(); 197 198 printk("Restarting tasks ... "); 199 thaw_workqueues(); 200 thaw_tasks(true); 201 thaw_tasks(false); 202 schedule(); 203 printk("done.\n"); 204 } 205 206