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Commit a93d2f17 authored by Changli Gao's avatar Changli Gao Committed by Ingo Molnar
Browse files

sched, wait: Use wrapper functions 



epoll should not touch flags in wait_queue_t. This patch introduces a new
function __add_wait_queue_exclusive(), for the users, who use wait queue as a
LIFO queue.

__add_wait_queue_tail_exclusive() is introduced too instead of
add_wait_queue_exclusive_locked(). remove_wait_queue_locked() is removed, as
it is a duplicate of __remove_wait_queue(), disliked by users, and with less
users.

Signed-off-by: default avatarChangli Gao <xiaosuo@gmail.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: <containers@lists.linux-foundation.org>
LKML-Reference: <1273214006-2979-1-git-send-email-xiaosuo@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent af507ae8

fs/eventpoll.c

+1 −2
Original line number Diff line number Diff line
@@ -1140,8 +1140,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, 
		 * ep_poll_callback() when events will become available.

		 */

		init_waitqueue_entry(&wait, current);

		wait.flags |= WQ_FLAG_EXCLUSIVE;

		__add_wait_queue(&ep->wq, &wait);

		__add_wait_queue_exclusive(&ep->wq, &wait);



		for (;;) {

			/*

include/linux/wait.h

+15 −20
Original line number Diff line number Diff line
@@ -127,12 +127,26 @@ static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new) 
/*

 * Used for wake-one threads:

 */

static inline void __add_wait_queue_exclusive(wait_queue_head_t *q,

					      wait_queue_t *wait)

{

	wait->flags |= WQ_FLAG_EXCLUSIVE;

	__add_wait_queue(q, wait);

}



static inline void __add_wait_queue_tail(wait_queue_head_t *head,

					 wait_queue_t *new)

{

	list_add_tail(&new->task_list, &head->task_list);

}



static inline void __add_wait_queue_tail_exclusive(wait_queue_head_t *q,

					      wait_queue_t *wait)

{

	wait->flags |= WQ_FLAG_EXCLUSIVE;

	__add_wait_queue_tail(q, wait);

}



static inline void __remove_wait_queue(wait_queue_head_t *head,

							wait_queue_t *old)

{
@@ -403,25 +417,6 @@ do { \ 
	__ret;								\

})



/*

 * Must be called with the spinlock in the wait_queue_head_t held.

 */

static inline void add_wait_queue_exclusive_locked(wait_queue_head_t *q,

						   wait_queue_t * wait)

{

	wait->flags |= WQ_FLAG_EXCLUSIVE;

	__add_wait_queue_tail(q,  wait);

}



/*

 * Must be called with the spinlock in the wait_queue_head_t held.

 */

static inline void remove_wait_queue_locked(wait_queue_head_t *q,

					    wait_queue_t * wait)

{

	__remove_wait_queue(q,  wait);

}



/*

 * These are the old interfaces to sleep waiting for an event.

 * They are racy.  DO NOT use them, use the wait_event* interfaces above.

kernel/cgroup.c

+1 −1
Original line number Diff line number Diff line
@@ -3010,7 +3010,7 @@ static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, 
	unsigned long flags = (unsigned long)key;



	if (flags & POLLHUP) {

		remove_wait_queue_locked(event->wqh, &event->wait);

		__remove_wait_queue(event->wqh, &event->wait);

		spin_lock(&cgrp->event_list_lock);

		list_del(&event->list);

		spin_unlock(&cgrp->event_list_lock);

kernel/sched.c

+1 −2
Original line number Diff line number Diff line
@@ -3983,8 +3983,7 @@ do_wait_for_common(struct completion *x, long timeout, int state) 
	if (!x->done) {

		DECLARE_WAITQUEUE(wait, current);



		wait.flags |= WQ_FLAG_EXCLUSIVE;

		__add_wait_queue_tail(&x->wait, &wait);

		__add_wait_queue_tail_exclusive(&x->wait, &wait);

		do {

			if (signal_pending_state(state, current)) {

				timeout = -ERESTARTSYS;