Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) // SPDX-License-Identifier: GPL-2.0-only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3)  * Generic waiting primitives.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5)  * (C) 2004 Nadia Yvette Chambers, Oracle
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7) #include "sched.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8) #include <trace/hooks/sched.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10) void __init_waitqueue_head(struct wait_queue_head *wq_head, const char *name, struct lock_class_key *key)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12) 	spin_lock_init(&wq_head->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13) 	lockdep_set_class_and_name(&wq_head->lock, key, name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14) 	INIT_LIST_HEAD(&wq_head->head);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17) EXPORT_SYMBOL(__init_waitqueue_head);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19) void add_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21) 	unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23) 	wq_entry->flags &= ~WQ_FLAG_EXCLUSIVE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24) 	spin_lock_irqsave(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25) 	__add_wait_queue(wq_head, wq_entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26) 	spin_unlock_irqrestore(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28) EXPORT_SYMBOL(add_wait_queue);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30) void add_wait_queue_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32) 	unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) 	wq_entry->flags |= WQ_FLAG_EXCLUSIVE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) 	spin_lock_irqsave(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) 	__add_wait_queue_entry_tail(wq_head, wq_entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) 	spin_unlock_irqrestore(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) EXPORT_SYMBOL(add_wait_queue_exclusive);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) void remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43) 	unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45) 	spin_lock_irqsave(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46) 	__remove_wait_queue(wq_head, wq_entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47) 	spin_unlock_irqrestore(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49) EXPORT_SYMBOL(remove_wait_queue);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52)  * Scan threshold to break wait queue walk.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53)  * This allows a waker to take a break from holding the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54)  * wait queue lock during the wait queue walk.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56) #define WAITQUEUE_WALK_BREAK_CNT 64
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59)  * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60)  * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61)  * number) then we wake all the non-exclusive tasks and one exclusive task.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63)  * There are circumstances in which we can try to wake a task which has already
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64)  * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65)  * zero in this (rare) case, and we handle it by continuing to scan the queue.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) static int __wake_up_common(struct wait_queue_head *wq_head, unsigned int mode,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) 			int nr_exclusive, int wake_flags, void *key,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) 			wait_queue_entry_t *bookmark)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71) 	wait_queue_entry_t *curr, *next;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72) 	int cnt = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74) 	lockdep_assert_held(&wq_head->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76) 	if (bookmark && (bookmark->flags & WQ_FLAG_BOOKMARK)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77) 		curr = list_next_entry(bookmark, entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79) 		list_del(&bookmark->entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80) 		bookmark->flags = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81) 	} else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82) 		curr = list_first_entry(&wq_head->head, wait_queue_entry_t, entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84) 	if (&curr->entry == &wq_head->head)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85) 		return nr_exclusive;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87) 	list_for_each_entry_safe_from(curr, next, &wq_head->head, entry) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88) 		unsigned flags = curr->flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) 		int ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) 		if (flags & WQ_FLAG_BOOKMARK)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) 			continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) 		ret = curr->func(curr, mode, wake_flags, key);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95) 		if (ret < 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96) 			break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97) 		if (ret && (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98) 			break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) 		if (bookmark && (++cnt > WAITQUEUE_WALK_BREAK_CNT) &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) 				(&next->entry != &wq_head->head)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) 			bookmark->flags = WQ_FLAG_BOOKMARK;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) 			list_add_tail(&bookmark->entry, &next->entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) 			break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) 	return nr_exclusive;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) static void __wake_up_common_lock(struct wait_queue_head *wq_head, unsigned int mode,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) 			int nr_exclusive, int wake_flags, void *key)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) 	unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) 	wait_queue_entry_t bookmark;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) 	bookmark.flags = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) 	bookmark.private = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) 	bookmark.func = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) 	INIT_LIST_HEAD(&bookmark.entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) 	do {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) 		spin_lock_irqsave(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) 		nr_exclusive = __wake_up_common(wq_head, mode, nr_exclusive,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) 						wake_flags, key, &bookmark);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) 		spin_unlock_irqrestore(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) 	} while (bookmark.flags & WQ_FLAG_BOOKMARK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131)  * __wake_up - wake up threads blocked on a waitqueue.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132)  * @wq_head: the waitqueue
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133)  * @mode: which threads
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134)  * @nr_exclusive: how many wake-one or wake-many threads to wake up
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135)  * @key: is directly passed to the wakeup function
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137)  * If this function wakes up a task, it executes a full memory barrier before
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138)  * accessing the task state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) void __wake_up(struct wait_queue_head *wq_head, unsigned int mode,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) 			int nr_exclusive, void *key)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) 	__wake_up_common_lock(wq_head, mode, nr_exclusive, 0, key);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) EXPORT_SYMBOL(__wake_up);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148)  * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) void __wake_up_locked(struct wait_queue_head *wq_head, unsigned int mode, int nr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) 	__wake_up_common(wq_head, mode, nr, 0, NULL, NULL);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) EXPORT_SYMBOL_GPL(__wake_up_locked);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) void __wake_up_locked_key(struct wait_queue_head *wq_head, unsigned int mode, void *key)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) 	__wake_up_common(wq_head, mode, 1, 0, key, NULL);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) EXPORT_SYMBOL_GPL(__wake_up_locked_key);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) void __wake_up_locked_key_bookmark(struct wait_queue_head *wq_head,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) 		unsigned int mode, void *key, wait_queue_entry_t *bookmark)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) 	__wake_up_common(wq_head, mode, 1, 0, key, bookmark);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) EXPORT_SYMBOL_GPL(__wake_up_locked_key_bookmark);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170)  * __wake_up_sync_key - wake up threads blocked on a waitqueue.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171)  * @wq_head: the waitqueue
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172)  * @mode: which threads
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173)  * @key: opaque value to be passed to wakeup targets
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175)  * The sync wakeup differs that the waker knows that it will schedule
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176)  * away soon, so while the target thread will be woken up, it will not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177)  * be migrated to another CPU - ie. the two threads are 'synchronized'
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178)  * with each other. This can prevent needless bouncing between CPUs.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180)  * On UP it can prevent extra preemption.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182)  * If this function wakes up a task, it executes a full memory barrier before
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183)  * accessing the task state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) void __wake_up_sync_key(struct wait_queue_head *wq_head, unsigned int mode,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) 			void *key)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) 	int wake_flags = WF_SYNC;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) 	if (unlikely(!wq_head))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) 	trace_android_vh_set_wake_flags(&wake_flags, &mode);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) 	__wake_up_common_lock(wq_head, mode, 1, wake_flags, key);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) EXPORT_SYMBOL_GPL(__wake_up_sync_key);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199)  * __wake_up_locked_sync_key - wake up a thread blocked on a locked waitqueue.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200)  * @wq_head: the waitqueue
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201)  * @mode: which threads
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202)  * @key: opaque value to be passed to wakeup targets
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204)  * The sync wakeup differs in that the waker knows that it will schedule
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205)  * away soon, so while the target thread will be woken up, it will not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206)  * be migrated to another CPU - ie. the two threads are 'synchronized'
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207)  * with each other. This can prevent needless bouncing between CPUs.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209)  * On UP it can prevent extra preemption.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211)  * If this function wakes up a task, it executes a full memory barrier before
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212)  * accessing the task state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) void __wake_up_locked_sync_key(struct wait_queue_head *wq_head,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) 			       unsigned int mode, void *key)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217)         __wake_up_common(wq_head, mode, 1, WF_SYNC, key, NULL);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) EXPORT_SYMBOL_GPL(__wake_up_locked_sync_key);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222)  * __wake_up_sync - see __wake_up_sync_key()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) void __wake_up_sync(struct wait_queue_head *wq_head, unsigned int mode)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) 	__wake_up_sync_key(wq_head, mode, NULL);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) EXPORT_SYMBOL_GPL(__wake_up_sync);	/* For internal use only */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) void __wake_up_pollfree(struct wait_queue_head *wq_head)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) 	__wake_up(wq_head, TASK_NORMAL, 0, poll_to_key(EPOLLHUP | POLLFREE));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) 	/* POLLFREE must have cleared the queue. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) 	WARN_ON_ONCE(waitqueue_active(wq_head));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238)  * Note: we use "set_current_state()" _after_ the wait-queue add,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239)  * because we need a memory barrier there on SMP, so that any
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240)  * wake-function that tests for the wait-queue being active
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241)  * will be guaranteed to see waitqueue addition _or_ subsequent
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242)  * tests in this thread will see the wakeup having taken place.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244)  * The spin_unlock() itself is semi-permeable and only protects
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245)  * one way (it only protects stuff inside the critical region and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246)  * stops them from bleeding out - it would still allow subsequent
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247)  * loads to move into the critical region).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) void
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) prepare_to_wait(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry, int state)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252) 	unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254) 	wq_entry->flags &= ~WQ_FLAG_EXCLUSIVE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255) 	spin_lock_irqsave(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) 	if (list_empty(&wq_entry->entry))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) 		__add_wait_queue(wq_head, wq_entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258) 	set_current_state(state);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) 	spin_unlock_irqrestore(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261) EXPORT_SYMBOL(prepare_to_wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) /* Returns true if we are the first waiter in the queue, false otherwise. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264) bool
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265) prepare_to_wait_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry, int state)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267) 	unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268) 	bool was_empty = false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270) 	wq_entry->flags |= WQ_FLAG_EXCLUSIVE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271) 	spin_lock_irqsave(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272) 	if (list_empty(&wq_entry->entry)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273) 		was_empty = list_empty(&wq_head->head);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) 		__add_wait_queue_entry_tail(wq_head, wq_entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) 	set_current_state(state);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277) 	spin_unlock_irqrestore(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278) 	return was_empty;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) EXPORT_SYMBOL(prepare_to_wait_exclusive);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282) void init_wait_entry(struct wait_queue_entry *wq_entry, int flags)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284) 	wq_entry->flags = flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285) 	wq_entry->private = current;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286) 	wq_entry->func = autoremove_wake_function;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287) 	INIT_LIST_HEAD(&wq_entry->entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) EXPORT_SYMBOL(init_wait_entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291) long prepare_to_wait_event(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry, int state)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293) 	unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294) 	long ret = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) 	spin_lock_irqsave(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297) 	if (signal_pending_state(state, current)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) 		/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) 		 * Exclusive waiter must not fail if it was selected by wakeup,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300) 		 * it should "consume" the condition we were waiting for.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) 		 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 302) 		 * The caller will recheck the condition and return success if
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 303) 		 * we were already woken up, we can not miss the event because
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 304) 		 * wakeup locks/unlocks the same wq_head->lock.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 305) 		 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 306) 		 * But we need to ensure that set-condition + wakeup after that
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 307) 		 * can't see us, it should wake up another exclusive waiter if
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 308) 		 * we fail.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 309) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 310) 		list_del_init(&wq_entry->entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 311) 		ret = -ERESTARTSYS;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 312) 	} else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 313) 		if (list_empty(&wq_entry->entry)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 314) 			if (wq_entry->flags & WQ_FLAG_EXCLUSIVE)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 315) 				__add_wait_queue_entry_tail(wq_head, wq_entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 316) 			else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 317) 				__add_wait_queue(wq_head, wq_entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 318) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 319) 		set_current_state(state);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 320) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 321) 	spin_unlock_irqrestore(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 322) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 323) 	return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 324) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 325) EXPORT_SYMBOL(prepare_to_wait_event);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 326) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 327) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 328)  * Note! These two wait functions are entered with the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 329)  * wait-queue lock held (and interrupts off in the _irq
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 330)  * case), so there is no race with testing the wakeup
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 331)  * condition in the caller before they add the wait
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 332)  * entry to the wake queue.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 333)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 334) int do_wait_intr(wait_queue_head_t *wq, wait_queue_entry_t *wait)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 335) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 336) 	if (likely(list_empty(&wait->entry)))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 337) 		__add_wait_queue_entry_tail(wq, wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 338) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 339) 	set_current_state(TASK_INTERRUPTIBLE);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 340) 	if (signal_pending(current))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 341) 		return -ERESTARTSYS;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 342) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 343) 	spin_unlock(&wq->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 344) 	schedule();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 345) 	spin_lock(&wq->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 346) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 347) 	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 348) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 349) EXPORT_SYMBOL(do_wait_intr);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 350) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 351) int do_wait_intr_irq(wait_queue_head_t *wq, wait_queue_entry_t *wait)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 352) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 353) 	if (likely(list_empty(&wait->entry)))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 354) 		__add_wait_queue_entry_tail(wq, wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 355) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 356) 	set_current_state(TASK_INTERRUPTIBLE);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 357) 	if (signal_pending(current))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 358) 		return -ERESTARTSYS;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 359) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 360) 	spin_unlock_irq(&wq->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 361) 	schedule();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 362) 	spin_lock_irq(&wq->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 363) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 364) 	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 365) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 366) EXPORT_SYMBOL(do_wait_intr_irq);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 367) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 368) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 369)  * finish_wait - clean up after waiting in a queue
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 370)  * @wq_head: waitqueue waited on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 371)  * @wq_entry: wait descriptor
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 372)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 373)  * Sets current thread back to running state and removes
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 374)  * the wait descriptor from the given waitqueue if still
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 375)  * queued.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 376)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 377) void finish_wait(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 378) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 379) 	unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 380) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 381) 	__set_current_state(TASK_RUNNING);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 382) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 383) 	 * We can check for list emptiness outside the lock
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 384) 	 * IFF:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 385) 	 *  - we use the "careful" check that verifies both
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 386) 	 *    the next and prev pointers, so that there cannot
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 387) 	 *    be any half-pending updates in progress on other
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 388) 	 *    CPU's that we haven't seen yet (and that might
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 389) 	 *    still change the stack area.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 390) 	 * and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 391) 	 *  - all other users take the lock (ie we can only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 392) 	 *    have _one_ other CPU that looks at or modifies
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 393) 	 *    the list).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 394) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 395) 	if (!list_empty_careful(&wq_entry->entry)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 396) 		spin_lock_irqsave(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 397) 		list_del_init(&wq_entry->entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 398) 		spin_unlock_irqrestore(&wq_head->lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 399) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 400) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 401) EXPORT_SYMBOL(finish_wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 402) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 403) __sched int autoremove_wake_function(struct wait_queue_entry *wq_entry, unsigned int mode,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 404) 				     int sync, void *key)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 405) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 406) 	int ret = default_wake_function(wq_entry, mode, sync, key);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 407) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 408) 	if (ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 409) 		list_del_init_careful(&wq_entry->entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 410) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 411) 	return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 412) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 413) EXPORT_SYMBOL(autoremove_wake_function);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 414) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 415) static inline bool is_kthread_should_stop(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 416) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 417) 	return (current->flags & PF_KTHREAD) && kthread_should_stop();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 418) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 419) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 420) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 421)  * DEFINE_WAIT_FUNC(wait, woken_wake_func);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 422)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 423)  * add_wait_queue(&wq_head, &wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 424)  * for (;;) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 425)  *     if (condition)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 426)  *         break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 427)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 428)  *     // in wait_woken()			// in woken_wake_function()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 429)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 430)  *     p->state = mode;				wq_entry->flags |= WQ_FLAG_WOKEN;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 431)  *     smp_mb(); // A				try_to_wake_up():
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 432)  *     if (!(wq_entry->flags & WQ_FLAG_WOKEN))	   <full barrier>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 433)  *         schedule()				   if (p->state & mode)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 434)  *     p->state = TASK_RUNNING;			      p->state = TASK_RUNNING;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 435)  *     wq_entry->flags &= ~WQ_FLAG_WOKEN;	~~~~~~~~~~~~~~~~~~
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 436)  *     smp_mb(); // B				condition = true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 437)  * }						smp_mb(); // C
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 438)  * remove_wait_queue(&wq_head, &wait);		wq_entry->flags |= WQ_FLAG_WOKEN;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 439)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 440) __sched long wait_woken(struct wait_queue_entry *wq_entry, unsigned int mode, long timeout)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 441) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 442) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 443) 	 * The below executes an smp_mb(), which matches with the full barrier
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 444) 	 * executed by the try_to_wake_up() in woken_wake_function() such that
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 445) 	 * either we see the store to wq_entry->flags in woken_wake_function()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 446) 	 * or woken_wake_function() sees our store to current->state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 447) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 448) 	set_current_state(mode); /* A */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 449) 	if (!(wq_entry->flags & WQ_FLAG_WOKEN) && !is_kthread_should_stop())
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 450) 		timeout = schedule_timeout(timeout);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 451) 	__set_current_state(TASK_RUNNING);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 452) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 453) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 454) 	 * The below executes an smp_mb(), which matches with the smp_mb() (C)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 455) 	 * in woken_wake_function() such that either we see the wait condition
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 456) 	 * being true or the store to wq_entry->flags in woken_wake_function()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 457) 	 * follows ours in the coherence order.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 458) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 459) 	smp_store_mb(wq_entry->flags, wq_entry->flags & ~WQ_FLAG_WOKEN); /* B */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 460) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 461) 	return timeout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 462) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 463) EXPORT_SYMBOL(wait_woken);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 464) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 465) __sched int woken_wake_function(struct wait_queue_entry *wq_entry, unsigned int mode,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 466) 				int sync, void *key)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 467) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 468) 	/* Pairs with the smp_store_mb() in wait_woken(). */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 469) 	smp_mb(); /* C */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 470) 	wq_entry->flags |= WQ_FLAG_WOKEN;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 471) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 472) 	return default_wake_function(wq_entry, mode, sync, key);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 473) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 474) EXPORT_SYMBOL(woken_wake_function);