kernel/power/process.c

   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(void)
  36 {
  37         /* Hmm, should we be allowed to suspend when there are realtime
  38            processes around? */
  39         long save;
  40         save = current->state;
  41         pr_debug("%s entered refrigerator\n", current->comm);
  42         printk("=");
  43
  44         frozen_process(current);
  45         spin_lock_irq(&current->sighand->siglock);
  46         recalc_sigpending(); /* We sent fake signal, clean it up */
  47         spin_unlock_irq(&current->sighand->siglock);
  48
  49         while (frozen(current)) {
  50                 current->state = TASK_UNINTERRUPTIBLE;
  51                 schedule();
  52         }
  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         unsigned long flags;
  64
  65         printk( "Stopping tasks: " );
  66         start_time = jiffies;
  67         do {
  68                 todo = 0;
  69                 read_lock(&tasklist_lock);
  70                 do_each_thread(g, p) {
  71                         if (!freezeable(p))
  72                                 continue;
  73                         if (frozen(p))
  74                                 continue;
  75
  76                         freeze(p);
  77                         spin_lock_irqsave(&p->sighand->siglock, flags);
  78                         signal_wake_up(p, 0);
  79                         spin_unlock_irqrestore(&p->sighand->siglock, flags);
  80                         todo++;
  81                 } while_each_thread(g, p);
  82                 read_unlock(&tasklist_lock);
  83                 yield();                        /* Yield is okay here */
  84                 if (todo && time_after(jiffies, start_time + TIMEOUT)) {
  85                         printk( "\n" );
  86                         printk(KERN_ERR " stopping tasks failed (%d tasks remaining)\n", todo );
  87                         break;
  88                 }
  89         } while(todo);
  90
  91         /* This does not unfreeze processes that are already frozen
  92          * (we have slightly ugly calling convention in that respect,
  93          * and caller must call thaw_processes() if something fails),
  94          * but it cleans up leftover PF_FREEZE requests.
  95          */
  96         if (todo) {
  97                 read_lock(&tasklist_lock);
  98                 do_each_thread(g, p)
  99                         if (freezing(p)) {
 100                                 pr_debug("  clean up: %s\n", p->comm);
 101                                 p->flags &= ~PF_FREEZE;
 102                                 spin_lock_irqsave(&p->sighand->siglock, flags);
 103                                 recalc_sigpending_tsk(p);
 104                                 spin_unlock_irqrestore(&p->sighand->siglock, flags);
 105                         }
 106                 while_each_thread(g, p);
 107                 read_unlock(&tasklist_lock);
 108                 return todo;
 109         }
 110
 111         printk( "|\n" );
 112         BUG_ON(in_atomic());
 113         return 0;
 114 }
 115
 116 void thaw_processes(void)
 117 {
 118         struct task_struct *g, *p;
 119
 120         printk( "Restarting tasks..." );
 121         read_lock(&tasklist_lock);
 122         do_each_thread(g, p) {
 123                 if (!freezeable(p))
 124                         continue;
 125                 if (!thaw_process(p))
 126                         printk(KERN_INFO " Strange, %s not stopped\n", p->comm );
 127         } while_each_thread(g, p);
 128
 129         read_unlock(&tasklist_lock);
 130         schedule();
 131         printk( " done\n" );
 132 }
 133
 134 EXPORT_SYMBOL(refrigerator);