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/smp_lock.h> 12 #include <linux/interrupt.h> 13 #include <linux/suspend.h> 14 #include <linux/module.h> 15 16 /* 17 * Timeout for stopping processes 18 */ 19 #define TIMEOUT (6 * HZ) 20 21 22 static inline int freezeable(struct task_struct * p) 23 { 24 if ((p == current) || 25 (p->flags & PF_NOFREEZE) || 26 (p->exit_state == EXIT_ZOMBIE) || 27 (p->exit_state == EXIT_DEAD) || 28 (p->state == TASK_STOPPED) || 29 (p->state == TASK_TRACED)) 30 return 0; 31 return 1; 32 } 33 34 /* Refrigerator is place where frozen processes are stored :-). */ 35 void refrigerator(unsigned long flag) 36 { 37 /* Hmm, should we be allowed to suspend when there are realtime 38 processes around? */ 39 long save; 40 save = current->state; 41 current->state = TASK_UNINTERRUPTIBLE; 42 pr_debug("%s entered refrigerator\n", current->comm); 43 printk("="); 44 current->flags &= ~PF_FREEZE; 45 46 spin_lock_irq(¤t->sighand->siglock); 47 recalc_sigpending(); /* We sent fake signal, clean it up */ 48 spin_unlock_irq(¤t->sighand->siglock); 49 50 current->flags |= PF_FROZEN; 51 while (current->flags & PF_FROZEN) 52 schedule(); 53 pr_debug("%s left refrigerator\n", current->comm); 54 current->state = save; 55 } 56 57 /* 0 = success, else # of processes that we failed to stop */ 58 int freeze_processes(void) 59 { 60 int todo; 61 unsigned long start_time; 62 struct task_struct *g, *p; 63 64 printk( "Stopping tasks: " ); 65 start_time = jiffies; 66 do { 67 todo = 0; 68 read_lock(&tasklist_lock); 69 do_each_thread(g, p) { 70 unsigned long flags; 71 if (!freezeable(p)) 72 continue; 73 if ((p->flags & PF_FROZEN) || 74 (p->state == TASK_TRACED) || 75 (p->state == TASK_STOPPED)) 76 continue; 77 78 /* FIXME: smp problem here: we may not access other process' flags 79 without locking */ 80 p->flags |= PF_FREEZE; 81 spin_lock_irqsave(&p->sighand->siglock, flags); 82 signal_wake_up(p, 0); 83 spin_unlock_irqrestore(&p->sighand->siglock, flags); 84 todo++; 85 } while_each_thread(g, p); 86 read_unlock(&tasklist_lock); 87 yield(); /* Yield is okay here */ 88 if (time_after(jiffies, start_time + TIMEOUT)) { 89 printk( "\n" ); 90 printk(KERN_ERR " stopping tasks failed (%d tasks remaining)\n", todo ); 91 return todo; 92 } 93 } while(todo); 94 95 printk( "|\n" ); 96 BUG_ON(in_atomic()); 97 return 0; 98 } 99 100 void thaw_processes(void) 101 { 102 struct task_struct *g, *p; 103 104 printk( "Restarting tasks..." ); 105 read_lock(&tasklist_lock); 106 do_each_thread(g, p) { 107 if (!freezeable(p)) 108 continue; 109 if (p->flags & PF_FROZEN) { 110 p->flags &= ~PF_FROZEN; 111 wake_up_process(p); 112 } else 113 printk(KERN_INFO " Strange, %s not stopped\n", p->comm ); 114 } while_each_thread(g, p); 115 116 read_unlock(&tasklist_lock); 117 schedule(); 118 printk( " done\n" ); 119 } 120 121 EXPORT_SYMBOL(refrigerator); 122