Commit 00b27634 authored by Soheil Hassas Yeganeh's avatar Soheil Hassas Yeganeh Committed by Linus Torvalds
Browse files

epoll: replace gotos with a proper loop 

The existing loop is pointless, and the labels make it really hard to
follow the structure.

Replace that control structure with a simple loop that returns when there
are new events, there is a signal, or the thread has timed out.

Link: https://lkml.kernel.org/r/20201106231635.3528496-8-soheil.kdev@gmail.com


Signed-off-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Reviewed-by: default avatarKhazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e8c85328

fs/eventpoll.c

+21 −21
Original line number Diff line number Diff line
@@ -1743,7 +1743,7 @@ static inline struct timespec64 ep_set_mstimeout(long ms) 
static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,

		   int maxevents, long timeout)

{

	int res, eavail, timed_out = 0;

	int res, eavail = 0, timed_out = 0;

	u64 slack = 0;

	wait_queue_entry_t wait;

	ktime_t expires, *to = NULL;
@@ -1769,18 +1769,30 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, 
		write_lock_irq(&ep->lock);

		eavail = ep_events_available(ep);

		write_unlock_irq(&ep->lock);

	}



		goto send_events;

	while (1) {

		if (eavail) {

			/*

			 * Try to transfer events to user space. In case we get

			 * 0 events and there's still timeout left over, we go

			 * trying again in search of more luck.

			 */

			res = ep_send_events(ep, events, maxevents);

			if (res)

				return res;

		}



fetch_events:

	do {

		if (timed_out)

			return 0;



		eavail = ep_events_available(ep);

		if (!eavail)

			eavail = ep_busy_loop(ep, timed_out);

		if (eavail)

			continue;



		eavail = ep_busy_loop(ep, timed_out);

		if (eavail)

			goto send_events;

			continue;



		if (signal_pending(current))

			return -EINTR;
@@ -1845,19 +1857,7 @@ fetch_events: 
			__remove_wait_queue(&ep->wq, &wait);

			write_unlock_irq(&ep->lock);

		}

	} while (0);



send_events:

	/*

	 * Try to transfer events to user space. In case we get 0 events and

	 * there's still timeout left over, we go trying again in search of

	 * more luck.

	 */

	if (eavail &&

	    !(res = ep_send_events(ep, events, maxevents)) && !timed_out)

		goto fetch_events;



	return res;

	}

}



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