linux-kernel - [PATCH 6/8] epoll: pull all code between fetch_events and send

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Date:   Fri,  6 Nov 2020 18:16:33 -0500
From:   Soheil Hassas Yeganeh <soheil.kdev@...il.com>
To:     torvalds@...ux-foundation.org, viro@...iv.linux.org.uk,
        linux-fsdevel@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        dave@...olabs.net, edumazet@...gle.com, willemb@...gle.com,
        khazhy@...gle.com, guantaol@...gle.com,
        Soheil Hassas Yeganeh <soheil@...gle.com>
Subject: [PATCH 6/8] epoll: pull all code between fetch_events and send_event into the loop

From: Soheil Hassas Yeganeh <soheil@...gle.com>

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

Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Soheil Hassas Yeganeh <soheil@...gle.com>
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
Reviewed-by: Willem de Bruijn <willemb@...gle.com>
Reviewed-by: Khazhismel Kumykov <khazhy@...gle.com>
---
 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