Re: [PATCH][next] futex: fix assigned ret variable that is never read

From: Davidlohr Bueso <dave@stgolabs.net>
To: Colin King <colin.king@canonical.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Darren Hart <dvhart@infradead.org>,
	kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH][next] futex: fix assigned ret variable that is never read
Date: Wed, 1 Sep 2021 13:24:25 -0700	[thread overview]
Message-ID: <20210901202425.v5sym64dqjzakimb@offworld> (raw)
In-Reply-To: <20210818131840.34262-1-colin.king@canonical.com>

On Wed, 18 Aug 2021, Colin King wrote:

>From: Colin Ian King <colin.king@canonical.com>
>
>Currently the check on the rt_waiter and top_waiter->pi_state is
>assigning an error return code to ret but this later gets re-assigned,
>hence the check is currently ineffective. I believe the original
>intent was to return -EINVAL rather than assign it to ret. Fix this.

LGTM.

Acked-by: Davidlohr Bueso <dbueso@suse.de>

>
>Addresses-Coverity: ("Unused value")
>Fixes: dc7109aaa233 ("futex: Validate waiter correctly in futex_proxy_trylock_atomic()")
>Signed-off-by: Colin Ian King <colin.king@canonical.com>
>---
> kernel/futex.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/kernel/futex.c b/kernel/futex.c
>index e7b4c6121da4..30e7daebaec8 100644
>--- a/kernel/futex.c
>+++ b/kernel/futex.c
>@@ -2025,7 +2025,7 @@ futex_proxy_trylock_atomic(u32 __user *pifutex, struct futex_hash_bucket *hb1,
>	 * and waiting on the 'waitqueue' futex which is always !PI.
>	 */
>	if (!top_waiter->rt_waiter || top_waiter->pi_state)
>-		ret = -EINVAL;
>+		return -EINVAL;
>
>	/* Ensure we requeue to the expected futex. */
>	if (!match_futex(top_waiter->requeue_pi_key, key2))
>--
>2.32.0
>