From: Davide Libenzi <davidel@xmailserver.org>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
shawn.bohrer@gmail.com, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org, mm-commits@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [patch] epoll-fix-compiler-warning-and-optimize-the-non-blocking-path-fix
Date: Wed, 26 Jan 2011 07:05:07 -0800 (PST) [thread overview]
Message-ID: <alpine.DEB.2.00.1101260704050.1889@localhost6.localdomain6> (raw)
In-Reply-To: <20110126102020.GA2244@cmpxchg.org>
On Wed, 26 Jan 2011, Johannes Weiner wrote:
> 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@cmpxchg.org>
> Cc: Shawn Bohrer <shawn.bohrer@gmail.com>
> Cc: Davide Libenzi <davidel@xmailserver.org>
Thank you for posting it. Obvious ACK.
> ---
> 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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prev parent reply other threads:[~2011-01-26 15:06 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-25 23:48 mmotm 2011-01-25-15-47 uploaded akpm
2011-01-26 8:45 ` CAI Qian
2011-01-26 13:52 ` Andrea Arcangeli
2011-01-28 6:44 ` CAI Qian
2011-01-28 16:50 ` pgd_lock must be taken with irqs enabled Andrea Arcangeli
2011-01-26 10:20 ` [patch] epoll-fix-compiler-warning-and-optimize-the-non-blocking-path-fix Johannes Weiner
2011-01-26 15:05 ` Davide Libenzi [this message]
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