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/suspend.h> 13 #include <linux/module.h> 14 #include <linux/syscalls.h> 15 #include <linux/freezer.h> 16 17 /* 18 * Timeout for stopping processes 19 */ 20 #define TIMEOUT (20 * HZ) 21 22 static inline int freezeable(struct task_struct * p) 23 { 24 if ((p == current) || 25 (p->flags & PF_NOFREEZE) || 26 (p->exit_state != 0)) 27 return 0; 28 return 1; 29 } 30 31 static int try_to_freeze_tasks(bool sig_only) 32 { 33 struct task_struct *g, *p; 34 unsigned long end_time; 35 unsigned int todo; 36 struct timeval start, end; 37 u64 elapsed_csecs64; 38 unsigned int elapsed_csecs; 39 40 do_gettimeofday(&start); 41 42 end_time = jiffies + TIMEOUT; 43 do { 44 todo = 0; 45 read_lock(&tasklist_lock); 46 do_each_thread(g, p) { 47 if (frozen(p) || !freezeable(p)) 48 continue; 49 50 if (!freeze_task(p, sig_only)) 51 continue; 52 53 /* 54 * Now that we've done set_freeze_flag, don't 55 * perturb a task in TASK_STOPPED or TASK_TRACED. 56 * It is "frozen enough". If the task does wake 57 * up, it will immediately call try_to_freeze. 58 */ 59 if (!task_is_stopped_or_traced(p) && 60 !freezer_should_skip(p)) 61 todo++; 62 } while_each_thread(g, p); 63 read_unlock(&tasklist_lock); 64 yield(); /* Yield is okay here */ 65 if (time_after(jiffies, end_time)) 66 break; 67 } while (todo); 68 69 do_gettimeofday(&end); 70 elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start); 71 do_div(elapsed_csecs64, NSEC_PER_SEC / 100); 72 elapsed_csecs = elapsed_csecs64; 73 74 if (todo) { 75 /* This does not unfreeze processes that are already frozen 76 * (we have slightly ugly calling convention in that respect, 77 * and caller must call thaw_processes() if something fails), 78 * but it cleans up leftover PF_FREEZE requests. 79 */ 80 printk("\n"); 81 printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds " 82 "(%d tasks refusing to freeze):\n", 83 elapsed_csecs / 100, elapsed_csecs % 100, todo); 84 show_state(); 85 read_lock(&tasklist_lock); 86 do_each_thread(g, p) { 87 task_lock(p); 88 if (freezing(p) && !freezer_should_skip(p)) 89 printk(KERN_ERR " %s\n", p->comm); 90 cancel_freezing(p); 91 task_unlock(p); 92 } while_each_thread(g, p); 93 read_unlock(&tasklist_lock); 94 } else { 95 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100, 96 elapsed_csecs % 100); 97 } 98 99 return todo ? -EBUSY : 0; 100 } 101 102 /** 103 * freeze_processes - tell processes to enter the refrigerator 104 */ 105 int freeze_processes(void) 106 { 107 int error; 108 109 printk("Freezing user space processes ... "); 110 error = try_to_freeze_tasks(true); 111 if (error) 112 goto Exit; 113 printk("done.\n"); 114 115 printk("Freezing remaining freezable tasks ... "); 116 error = try_to_freeze_tasks(false); 117 if (error) 118 goto Exit; 119 printk("done."); 120 121 oom_killer_disable(); 122 Exit: 123 BUG_ON(in_atomic()); 124 printk("\n"); 125 126 return error; 127 } 128 129 static void thaw_tasks(bool nosig_only) 130 { 131 struct task_struct *g, *p; 132 133 read_lock(&tasklist_lock); 134 do_each_thread(g, p) { 135 if (!freezeable(p)) 136 continue; 137 138 if (nosig_only && should_send_signal(p)) 139 continue; 140 141 if (cgroup_frozen(p)) 142 continue; 143 144 thaw_process(p); 145 } while_each_thread(g, p); 146 read_unlock(&tasklist_lock); 147 } 148 149 void thaw_processes(void) 150 { 151 oom_killer_enable(); 152 153 printk("Restarting tasks ... "); 154 thaw_tasks(true); 155 thaw_tasks(false); 156 schedule(); 157 printk("done.\n"); 158 } 159 160