The patch titled
Subject: epoll: replace gotos with a proper loop
has been added to the -mm tree. Its filename is
epoll-replace-gotos-with-a-proper-loop.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/epoll-replace-gotos-with-a-proper-loop.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/epoll-replace-gotos-with-a-proper-loop.patch
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------------------------------------------------------
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
@@ -1830,7 +1830,7 @@ 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;
@@ -1856,18 +1856,30 @@ 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;
@@ -1932,19 +1944,7 @@ 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;
+ }
}
/**
_
Patches currently in -mm which might be from soheil@xxxxxxxxxx are
epoll-check-for-events-when-removing-a-timed-out-thread-from-the-wait-queue.patch
epoll-simplify-signal-handling.patch
epoll-pull-fatal-signal-checks-into-ep_send_events.patch
epoll-move-eavail-next-to-the-list_empty_careful-check.patch
epoll-simplify-and-optimize-busy-loop-logic.patch
epoll-pull-all-code-between-fetch_events-and-send_event-into-the-loop.patch
epoll-replace-gotos-with-a-proper-loop.patch
epoll-eliminate-unnecessary-lock-for-zero-timeout.patch
