linux-kernel - Re: [PATCH -v4 02/10] futex: Add missing error handling to FUTEX_REQUEUE

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Date:   Fri, 16 Dec 2016 16:06:39 -0800
From:   Darren Hart <dvhart@...radead.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     tglx@...utronix.de, mingo@...nel.org, juri.lelli@....com,
        rostedt@...dmis.org, xlpang@...hat.com, bigeasy@...utronix.de,
        linux-kernel@...r.kernel.org, mathieu.desnoyers@...icios.com,
        jdesfossez@...icios.com, bristot@...hat.com
Subject: Re: [PATCH -v4 02/10] futex: Add missing error handling to
 FUTEX_REQUEUE_PI

On Tue, Dec 13, 2016 at 09:36:40AM +0100, Peter Zijlstra wrote:
> Thomas spotted that fixup_pi_state_owner() can return errors and we
> fail to unlock the rt_mutex in that case.
> 

We handled this explicitly before Patch 1/10, so can this be rolled into 1/10
(er 9) as a single commit?

> Reported-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
>  kernel/futex.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> --- a/kernel/futex.c
> +++ b/kernel/futex.c
> @@ -2896,6 +2896,8 @@ static int futex_wait_requeue_pi(u32 __u
>  		if (q.pi_state && (q.pi_state->owner != current)) {
>  			spin_lock(q.lock_ptr);
>  			ret = fixup_pi_state_owner(uaddr2, &q, current);
> +			if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current)
> +				rt_mutex_unlock(&q.pi_state->pi_mutex);
>  			/*
>  			 * Drop the reference to the pi state which
>  			 * the requeue_pi() code acquired for us.
> 
> 
> 

-- 
Darren Hart
Intel Open Source Technology Center