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