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 25static inline int freezeable(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 34static 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 44 do_gettimeofday(&start); 45 46 end_time = jiffies + TIMEOUT; 47 48 if (!sig_only) 49 freeze_workqueues_begin(); 50 51 while (true) { 52 todo = 0; 53 read_lock(&tasklist_lock); 54 do_each_thread(g, p) { 55 if (frozen(p) || !freezeable(p)) 56 continue; 57 58 if (!freeze_task(p, sig_only)) 59 continue; 60 61 /* 62 * Now that we've done set_freeze_flag, don't 63 * perturb a task in TASK_STOPPED or TASK_TRACED. 64 * It is "frozen enough". If the task does wake 65 * up, it will immediately call try_to_freeze. 66 */ 67 if (!task_is_stopped_or_traced(p) && 68 !freezer_should_skip(p)) 69 todo++; 70 } while_each_thread(g, p); 71 read_unlock(&tasklist_lock); 72 73 if (!sig_only) { 74 wq_busy = freeze_workqueues_busy(); 75 todo += wq_busy; 76 } 77 78 if (!todo || time_after(jiffies, end_time)) 79 break; 80 81 /* 82 * We need to retry, but first give the freezing tasks some 83 * time to enter the regrigerator. 84 */ 85 msleep(10); 86 } 87 88 do_gettimeofday(&end); 89 elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start); 90 do_div(elapsed_csecs64, NSEC_PER_SEC / 100); 91 elapsed_csecs = elapsed_csecs64; 92 93 if (todo) { 94 /* This does not unfreeze processes that are already frozen 95 * (we have slightly ugly calling convention in that respect, 96 * and caller must call thaw_processes() if something fails), 97 * but it cleans up leftover PF_FREEZE requests. 98 */ 99 printk("\n"); 100 printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds " 101 "(%d tasks refusing to freeze, wq_busy=%d):\n", 102 elapsed_csecs / 100, elapsed_csecs % 100, 103 todo - wq_busy, wq_busy); 104 105 thaw_workqueues(); 106 107 read_lock(&tasklist_lock); 108 do_each_thread(g, p) { 109 task_lock(p); 110 if (freezing(p) && !freezer_should_skip(p)) 111 sched_show_task(p); 112 cancel_freezing(p); 113 task_unlock(p); 114 } while_each_thread(g, p); 115 read_unlock(&tasklist_lock); 116 } else { 117 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100, 118 elapsed_csecs % 100); 119 } 120 121 return todo ? -EBUSY : 0; 122} 123 124/** 125 * freeze_processes - tell processes to enter the refrigerator 126 */ 127int freeze_processes(void) 128{ 129 int error; 130 131 printk("Freezing user space processes ... "); 132 error = try_to_freeze_tasks(true); 133 if (error) 134 goto Exit; 135 printk("done.\n"); 136 137 printk("Freezing remaining freezable tasks ... "); 138 error = try_to_freeze_tasks(false); 139 if (error) 140 goto Exit; 141 printk("done."); 142 143 oom_killer_disable(); 144 Exit: 145 BUG_ON(in_atomic()); 146 printk("\n"); 147 148 return error; 149} 150 151static void thaw_tasks(bool nosig_only) 152{ 153 struct task_struct *g, *p; 154 155 read_lock(&tasklist_lock); 156 do_each_thread(g, p) { 157 if (!freezeable(p)) 158 continue; 159 160 if (nosig_only && should_send_signal(p)) 161 continue; 162 163 if (cgroup_freezing_or_frozen(p)) 164 continue; 165 166 thaw_process(p); 167 } while_each_thread(g, p); 168 read_unlock(&tasklist_lock); 169} 170 171void thaw_processes(void) 172{ 173 oom_killer_enable(); 174 175 printk("Restarting tasks ... "); 176 thaw_workqueues(); 177 thaw_tasks(true); 178 thaw_tasks(false); 179 schedule(); 180 printk("done.\n"); 181} 182