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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: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Soheil Hassas Yeganeh 2020-12-18 14:02:03 -08:00 committed by Linus Torvalds
parent e8c85328b1
commit 00b27634bc
1 changed files with 22 additions and 22 deletions
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44
fs/eventpoll.c
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@ -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;
}
fetch_events:
do {
eavail = ep_events_available(ep);
if (!eavail)
eavail = ep_busy_loop(ep, timed_out);
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;
}
if (timed_out)
return 0;
eavail = ep_events_available(ep);
if (eavail)
goto send_events;
continue;
eavail = ep_busy_loop(ep, timed_out);
if (eavail)
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;
}
}
/**