From: Soheil Hassas Yeganeh <soheil@xxxxxxxxxx> Subject: 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@xxxxxxxxx Signed-off-by: Soheil Hassas Yeganeh <soheil@xxxxxxxxxx> Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx> Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx> Reviewed-by: Khazhismel Kumykov <khazhy@xxxxxxxxxx> Cc: Guantao Liu <guantaol@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/eventpoll.c | 42 +++++++++++++++++++++--------------------- 1 file changed, 21 insertions(+), 21 deletions(-) --- a/fs/eventpoll.c~epoll-replace-gotos-with-a-proper-loop +++ a/fs/eventpoll.c @@ -1743,7 +1743,7 @@ static inline struct timespec64 ep_set_m 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, write_lock_irq(&ep->lock); eavail = ep_events_available(ep); write_unlock_irq(&ep->lock); - - goto send_events; } -fetch_events: - do { + 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) - 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; + } } /** _
