linux-kernel - [patch] epoll-fix-compiler-warning-and-optimize-the-non-blocking-path-fix

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Message-ID: <20110126102020.GA2244@cmpxchg.org>
Date:	Wed, 26 Jan 2011 11:20:20 +0100
From:	Johannes Weiner <hannes@...xchg.org>
To:	akpm@...ux-foundation.org
Cc:	shawn.bohrer@...il.com, davidel@...ilserver.org,
	linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
	mm-commits@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [patch]
 epoll-fix-compiler-warning-and-optimize-the-non-blocking-path-fix

The non-blocking ep_poll path optimization introduced skipping over
the return value setup.

Initialize it properly, my userspace gets upset by epoll_wait()
returning random things.

In addition, remove the reinitialization at the fetch_events label,
the return value is garuanteed to be zero when execution reaches
there.

Signed-off-by: Johannes Weiner <hannes@...xchg.org>
Cc: Shawn Bohrer <shawn.bohrer@...il.com>
Cc: Davide Libenzi <davidel@...ilserver.org>
---
 fs/eventpoll.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index f7cb6cb..afe4238 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1147,7 +1147,7 @@ static int ep_send_events(struct eventpoll *ep,
 static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
 		   int maxevents, long timeout)
 {
-	int res, eavail, timed_out = 0;
+	int res = 0, eavail, timed_out = 0;
 	unsigned long flags;
 	long slack = 0;
 	wait_queue_t wait;
@@ -1173,7 +1173,6 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
 fetch_events:
 	spin_lock_irqsave(&ep->lock, flags);
 
-	res = 0;
 	if (!ep_events_available(ep)) {
 		/*
 		 * We don't have any available event to return to the caller.
-- 
1.7.3.5
--
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