kernel/sched/swait.c

   1 #include <linux/sched.h>
   2 #include <linux/swait.h>
   3 #include <linux/suspend.h>
   4
   5 void __init_swait_queue_head(struct swait_queue_head *q, const char *name,
   6                              struct lock_class_key *key)
   7 {
   8         raw_spin_lock_init(&q->lock);
   9         lockdep_set_class_and_name(&q->lock, key, name);
  10         INIT_LIST_HEAD(&q->task_list);
  11 }
  12 EXPORT_SYMBOL(__init_swait_queue_head);
  13
  14 /*
  15  * The thing about the wake_up_state() return value; I think we can ignore it.
  16  *
  17  * If for some reason it would return 0, that means the previously waiting
  18  * task is already running, so it will observe condition true (or has already).
  19  */
  20 void swake_up_locked(struct swait_queue_head *q)
  21 {
  22         struct swait_queue *curr;
  23
  24         if (list_empty(&q->task_list))
  25                 return;
  26
  27         curr = list_first_entry(&q->task_list, typeof(*curr), task_list);
  28         wake_up_process(curr->task);
  29         list_del_init(&curr->task_list);
  30 }
  31 EXPORT_SYMBOL(swake_up_locked);
  32
  33 void swake_up_all_locked(struct swait_queue_head *q)
  34 {
  35         struct swait_queue *curr;
  36         int wakes = 0;
  37
  38         while (!list_empty(&q->task_list)) {
  39
  40                 curr = list_first_entry(&q->task_list, typeof(*curr),
  41                                         task_list);
  42                 wake_up_process(curr->task);
  43                 list_del_init(&curr->task_list);
  44                 wakes++;
  45         }
  46         if (pm_in_action)
  47                 return;
  48         WARN(wakes > 2, "complete_all() with %d waiters\n", wakes);
  49 }
  50 EXPORT_SYMBOL(swake_up_all_locked);
  51
  52 void swake_up(struct swait_queue_head *q)
  53 {
  54         unsigned long flags;
  55
  56         if (!swait_active(q))
  57                 return;
  58
  59         raw_spin_lock_irqsave(&q->lock, flags);
  60         swake_up_locked(q);
  61         raw_spin_unlock_irqrestore(&q->lock, flags);
  62 }
  63 EXPORT_SYMBOL(swake_up);
  64
  65 /*
  66  * Does not allow usage from IRQ disabled, since we must be able to
  67  * release IRQs to guarantee bounded hold time.
  68  */
  69 void swake_up_all(struct swait_queue_head *q)
  70 {
  71         struct swait_queue *curr;
  72         LIST_HEAD(tmp);
  73
  74         if (!swait_active(q))
  75                 return;
  76
  77         WARN_ON(irqs_disabled());
  78         raw_spin_lock_irq(&q->lock);
  79         list_splice_init(&q->task_list, &tmp);
  80         while (!list_empty(&tmp)) {
  81                 curr = list_first_entry(&tmp, typeof(*curr), task_list);
  82
  83                 wake_up_state(curr->task, TASK_NORMAL);
  84                 list_del_init(&curr->task_list);
  85
  86                 if (list_empty(&tmp))
  87                         break;
  88
  89                 raw_spin_unlock_irq(&q->lock);
  90                 raw_spin_lock_irq(&q->lock);
  91         }
  92         raw_spin_unlock_irq(&q->lock);
  93 }
  94 EXPORT_SYMBOL(swake_up_all);
  95
  96 void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait)
  97 {
  98         wait->task = current;
  99         if (list_empty(&wait->task_list))
 100                 list_add(&wait->task_list, &q->task_list);
 101 }
 102
 103 void prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait, int state)
 104 {
 105         unsigned long flags;
 106
 107         raw_spin_lock_irqsave(&q->lock, flags);
 108         __prepare_to_swait(q, wait);
 109         set_current_state(state);
 110         raw_spin_unlock_irqrestore(&q->lock, flags);
 111 }
 112 EXPORT_SYMBOL(prepare_to_swait);
 113
 114 long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state)
 115 {
 116         if (signal_pending_state(state, current))
 117                 return -ERESTARTSYS;
 118
 119         prepare_to_swait(q, wait, state);
 120
 121         return 0;
 122 }
 123 EXPORT_SYMBOL(prepare_to_swait_event);
 124
 125 void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait)
 126 {
 127         __set_current_state(TASK_RUNNING);
 128         if (!list_empty(&wait->task_list))
 129                 list_del_init(&wait->task_list);
 130 }
 131
 132 void finish_swait(struct swait_queue_head *q, struct swait_queue *wait)
 133 {
 134         unsigned long flags;
 135
 136         __set_current_state(TASK_RUNNING);
 137
 138         if (!list_empty_careful(&wait->task_list)) {
 139                 raw_spin_lock_irqsave(&q->lock, flags);
 140                 list_del_init(&wait->task_list);
 141                 raw_spin_unlock_irqrestore(&q->lock, flags);
 142         }
 143 }
 144 EXPORT_SYMBOL(finish_swait);