Commit f8d4f44d authored by Al Viro's avatar Al Viro
Browse files

epoll: do not insert into poll queues until all sanity checks are done 



Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 77f4689d

fs/eventpoll.c

+18 −19
Original line number Diff line number Diff line
@@ -1522,6 +1522,22 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, 
		RCU_INIT_POINTER(epi->ws, NULL);

	}



	/* Add the current item to the list of active epoll hook for this file */

	spin_lock(&tfile->f_lock);

	list_add_tail_rcu(&epi->fllink, &tfile->f_ep_links);

	spin_unlock(&tfile->f_lock);



	/*

	 * Add the current item to the RB tree. All RB tree operations are

	 * protected by "mtx", and ep_insert() is called with "mtx" held.

	 */

	ep_rbtree_insert(ep, epi);



	/* now check if we've created too many backpaths */

	error = -EINVAL;

	if (full_check && reverse_path_check())

		goto error_remove_epi;



	/* Initialize the poll table using the queue callback */

	epq.epi = epi;

	init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
@@ -1544,22 +1560,6 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, 
	if (epi->nwait < 0)

		goto error_unregister;



	/* Add the current item to the list of active epoll hook for this file */

	spin_lock(&tfile->f_lock);

	list_add_tail_rcu(&epi->fllink, &tfile->f_ep_links);

	spin_unlock(&tfile->f_lock);



	/*

	 * Add the current item to the RB tree. All RB tree operations are

	 * protected by "mtx", and ep_insert() is called with "mtx" held.

	 */

	ep_rbtree_insert(ep, epi);



	/* now check if we've created too many backpaths */

	error = -EINVAL;

	if (full_check && reverse_path_check())

		goto error_remove_epi;



	/* We have to drop the new item inside our item list to keep track of it */

	write_lock_irq(&ep->lock);
@@ -1588,6 +1588,8 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, 


	return 0;



error_unregister:

	ep_unregister_pollwait(ep, epi);

error_remove_epi:

	spin_lock(&tfile->f_lock);

	list_del_rcu(&epi->fllink);
@@ -1595,9 +1597,6 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, 


	rb_erase_cached(&epi->rbn, &ep->rbr);



error_unregister:

	ep_unregister_pollwait(ep, epi);



	/*

	 * We need to do this because an event could have been arrived on some

	 * allocated wait queue. Note that we don't care about the ep->ovflist