linux-kernel - Re: [PATCH RFC 24/33] drm: zynqmp_dp: Fix a deadlock in zynqmp_dp_ignore_hpd

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Message-ID: <25e047ee-cc48-42a0-9ee2-88753114f4a4@linux.dev>
Date: Thu, 6 Feb 2025 14:22:56 -0500
From: Sean Anderson <sean.anderson@...ux.dev>
To: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
 Bart Van Assche <bvanassche@....org>
Cc: Will Deacon <will@...nel.org>, Christoph Hellwig <hch@....de>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Marco Elver <elver@...gle.com>, Nick Desaulniers <ndesaulniers@...gle.com>,
 Nathan Chancellor <nathan@...nel.org>, Kees Cook <kees@...nel.org>,
 Jann Horn <jannh@...gle.com>, linux-kernel@...r.kernel.org,
 Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH RFC 24/33] drm: zynqmp_dp: Fix a deadlock in
 zynqmp_dp_ignore_hpd_set()

On 2/6/25 12:51, Bart Van Assche wrote:
> Instead of attempting the same mutex twice, lock and unlock it.
> 
> This bug has been detected by the Clang thread-safety analyzer.
> 
> Cc: Sean Anderson <sean.anderson@...ux.dev>
> Cc: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
> Fixes: 28edaacb821c ("drm: zynqmp_dp: Add debugfs interface for compliance testing")
> Signed-off-by: Bart Van Assche <bvanassche@....org>
> ---
>  drivers/gpu/drm/xlnx/zynqmp_dp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
> index 979f6d3239ba..189a08cdc73c 100644
> --- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
> +++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
> @@ -2295,7 +2295,7 @@ static int zynqmp_dp_ignore_hpd_set(void *data, u64 val)
>  
>  	mutex_lock(&dp->lock);
>  	dp->ignore_hpd = val;
> -	mutex_lock(&dp->lock);
> +	mutex_unlock(&dp->lock);
>  	return 0;
>  }
>  

Reviewed-by: Sean Anderson <sean.anderson@...o.com>

Since this patch is marked RFC will it be applied soon? I am about to
send a patch which conflicts with this one. I would like to just add
this patch to my series.

--Sean