Commit 80285b75 authored by Al Viro's avatar Al Viro
Browse files

epoll: switch epitem->pwqlist to single-linked list 



We only traverse it once to destroy all associated eppoll_entry at
epitem destruction time.  The order of traversal is irrelevant there.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3650b228

fs/eventpoll.c

+25 −26
Original line number Diff line number Diff line
@@ -128,6 +128,24 @@ struct nested_calls { 
	spinlock_t lock;

};



/* Wait structure used by the poll hooks */

struct eppoll_entry {

	/* List header used to link this structure to the "struct epitem" */

	struct eppoll_entry *next;



	/* The "base" pointer is set to the container "struct epitem" */

	struct epitem *base;



	/*

	 * Wait queue item that will be linked to the target file wait

	 * queue head.

	 */

	wait_queue_entry_t wait;



	/* The wait queue head that linked the "wait" wait queue item */

	wait_queue_head_t *whead;

};



/*

 * Each file descriptor added to the eventpoll interface will

 * have an entry of this type linked to the "rbr" RB tree.
@@ -158,7 +176,7 @@ struct epitem { 
	int nwait;



	/* List containing poll wait queues */

	struct list_head pwqlist;

	struct eppoll_entry *pwqlist;



	/* The "container" of this item */

	struct eventpoll *ep;
@@ -231,24 +249,6 @@ struct eventpoll { 
#endif

};



/* Wait structure used by the poll hooks */

struct eppoll_entry {

	/* List header used to link this structure to the "struct epitem" */

	struct list_head llink;



	/* The "base" pointer is set to the container "struct epitem" */

	struct epitem *base;



	/*

	 * Wait queue item that will be linked to the target file wait

	 * queue head.

	 */

	wait_queue_entry_t wait;



	/* The wait queue head that linked the "wait" wait queue item */

	wait_queue_head_t *whead;

};



/* Wrapper struct used by poll queueing */

struct ep_pqueue {

	poll_table pt;
@@ -617,13 +617,11 @@ static void ep_remove_wait_queue(struct eppoll_entry *pwq) 
 */

static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi)

{

	struct list_head *lsthead = &epi->pwqlist;

	struct eppoll_entry **p = &epi->pwqlist;

	struct eppoll_entry *pwq;



	while (!list_empty(lsthead)) {

		pwq = list_first_entry(lsthead, struct eppoll_entry, llink);



		list_del(&pwq->llink);

	while ((pwq = *p) != NULL) {

		*p = pwq->next;

		ep_remove_wait_queue(pwq);

		kmem_cache_free(pwq_cache, pwq);

	}
@@ -1320,7 +1318,8 @@ static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, 
			add_wait_queue_exclusive(whead, &pwq->wait);

		else

			add_wait_queue(whead, &pwq->wait);

		list_add_tail(&pwq->llink, &epi->pwqlist);

		pwq->next = epi->pwqlist;

		epi->pwqlist = pwq;

		epi->nwait++;

	} else {

		/* We have to signal that an error occurred */
@@ -1507,7 +1506,7 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, 
	/* Item initialization follow here ... */

	INIT_LIST_HEAD(&epi->rdllink);

	INIT_LIST_HEAD(&epi->fllink);

	INIT_LIST_HEAD(&epi->pwqlist);

	epi->pwqlist = NULL;

	epi->ep = ep;

	ep_set_ffd(&epi->ffd, tfile, fd);

	epi->event = *event;