1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/sched/signal.h> 3 #include <linux/swait.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(struct swait_queue_head *q) 34 { 35 unsigned long flags; 36 37 raw_spin_lock_irqsave(&q->lock, flags); 38 swake_up_locked(q); 39 raw_spin_unlock_irqrestore(&q->lock, flags); 40 } 41 EXPORT_SYMBOL(swake_up); 42 43 /* 44 * Does not allow usage from IRQ disabled, since we must be able to 45 * release IRQs to guarantee bounded hold time. 46 */ 47 void swake_up_all(struct swait_queue_head *q) 48 { 49 struct swait_queue *curr; 50 LIST_HEAD(tmp); 51 52 raw_spin_lock_irq(&q->lock); 53 list_splice_init(&q->task_list, &tmp); 54 while (!list_empty(&tmp)) { 55 curr = list_first_entry(&tmp, typeof(*curr), task_list); 56 57 wake_up_state(curr->task, TASK_NORMAL); 58 list_del_init(&curr->task_list); 59 60 if (list_empty(&tmp)) 61 break; 62 63 raw_spin_unlock_irq(&q->lock); 64 raw_spin_lock_irq(&q->lock); 65 } 66 raw_spin_unlock_irq(&q->lock); 67 } 68 EXPORT_SYMBOL(swake_up_all); 69 70 void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait) 71 { 72 wait->task = current; 73 if (list_empty(&wait->task_list)) 74 list_add(&wait->task_list, &q->task_list); 75 } 76 77 void prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait, int state) 78 { 79 unsigned long flags; 80 81 raw_spin_lock_irqsave(&q->lock, flags); 82 __prepare_to_swait(q, wait); 83 set_current_state(state); 84 raw_spin_unlock_irqrestore(&q->lock, flags); 85 } 86 EXPORT_SYMBOL(prepare_to_swait); 87 88 long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state) 89 { 90 if (signal_pending_state(state, current)) 91 return -ERESTARTSYS; 92 93 prepare_to_swait(q, wait, state); 94 95 return 0; 96 } 97 EXPORT_SYMBOL(prepare_to_swait_event); 98 99 void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait) 100 { 101 __set_current_state(TASK_RUNNING); 102 if (!list_empty(&wait->task_list)) 103 list_del_init(&wait->task_list); 104 } 105 106 void finish_swait(struct swait_queue_head *q, struct swait_queue *wait) 107 { 108 unsigned long flags; 109 110 __set_current_state(TASK_RUNNING); 111 112 if (!list_empty_careful(&wait->task_list)) { 113 raw_spin_lock_irqsave(&q->lock, flags); 114 list_del_init(&wait->task_list); 115 raw_spin_unlock_irqrestore(&q->lock, flags); 116 } 117 } 118 EXPORT_SYMBOL(finish_swait); 119