[PATCH 6/8] epoll: pull all code between fetch_events and send_event into the loop

From: Soheil Hassas Yeganeh
Date: Fri Nov 06 2020 - 18:18:12 EST


From: Soheil Hassas Yeganeh <soheil@xxxxxxxxxx>

This is a no-op change which simplifies the follow up patches.

Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Soheil Hassas Yeganeh <soheil@xxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Reviewed-by: Khazhismel Kumykov <khazhy@xxxxxxxxxx>
---
fs/eventpoll.c | 41 +++++++++++++++++++++--------------------
1 file changed, 21 insertions(+), 20 deletions(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 28c1d341d2e6..b29bbebe8ca4 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1861,14 +1861,14 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
}

fetch_events:
- eavail = ep_events_available(ep);
- if (!eavail)
- eavail = ep_busy_loop(ep, timed_out);
+ do {
+ eavail = ep_events_available(ep);
+ if (!eavail)
+ eavail = ep_busy_loop(ep, timed_out);

- if (eavail)
- goto send_events;
+ if (eavail)
+ goto send_events;

- do {
if (signal_pending(current))
return -EINTR;

@@ -1917,21 +1917,22 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
* carefully under lock, below.
*/
eavail = 1;
- } while (0);

- if (!list_empty_careful(&wait.entry)) {
- write_lock_irq(&ep->lock);
- /*
- * If the thread timed out and is not on the wait queue, it
- * means that the thread was woken up after its timeout expired
- * before it could reacquire the lock. Thus, when wait.entry is
- * empty, it needs to harvest events.
- */
- if (timed_out)
- eavail = list_empty(&wait.entry);
- __remove_wait_queue(&ep->wq, &wait);
- write_unlock_irq(&ep->lock);
- }
+ if (!list_empty_careful(&wait.entry)) {
+ write_lock_irq(&ep->lock);
+ /*
+ * If the thread timed out and is not on the wait queue,
+ * it means that the thread was woken up after its
+ * timeout expired before it could reacquire the lock.
+ * Thus, when wait.entry is empty, it needs to harvest
+ * events.
+ */
+ if (timed_out)
+ eavail = list_empty(&wait.entry);
+ __remove_wait_queue(&ep->wq, &wait);
+ write_unlock_irq(&ep->lock);
+ }
+ } while (0);

send_events:
/*
--
2.29.1.341.ge80a0c044ae-goog