linux-kernel - Re: [Patch 1/1] media: am437x-vpfe: Fix a race condition during release

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Message-ID: <20150629194537.GF1019@saruman.tx.rr.com>
Date:	Mon, 29 Jun 2015 14:45:37 -0500
From:	Felipe Balbi <balbi@...com>
To:	Benoit Parrot <bparrot@...com>
CC:	Hans Verkuil <hverkuil@...all.nl>,
	Prabhakar Lad <prabhakar.csengg@...il.com>,
	<linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [Patch 1/1] media: am437x-vpfe: Fix a race condition during
 release

On Mon, Jun 29, 2015 at 02:41:53PM -0500, Benoit Parrot wrote:
> There was a race condition where during cleanup/release operation
> on-going streaming would cause a kernel panic because the hardware
> module was disabled prematurely with IRQ still pending.
> 
> Signed-off-by: Benoit Parrot <bparrot@...com>

should this go to stable too ?

> ---
>  drivers/media/platform/am437x/am437x-vpfe.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/am437x/am437x-vpfe.c b/drivers/media/platform/am437x/am437x-vpfe.c
> index a30cc2f..eb25c43 100644
> --- a/drivers/media/platform/am437x/am437x-vpfe.c
> +++ b/drivers/media/platform/am437x/am437x-vpfe.c
> @@ -1185,14 +1185,21 @@ static int vpfe_initialize_device(struct vpfe_device *vpfe)
>  static int vpfe_release(struct file *file)
>  {
>  	struct vpfe_device *vpfe = video_drvdata(file);
> +	bool fh_singular = v4l2_fh_is_singular_file(file);
>  	int ret;
>  
>  	mutex_lock(&vpfe->lock);
>  
> -	if (v4l2_fh_is_singular_file(file))
> -		vpfe_ccdc_close(&vpfe->ccdc, vpfe->pdev);
> +	/* the release helper will cleanup any on-going streaming */
>  	ret = _vb2_fop_release(file, NULL);
>  
> +	/*
> +	 * If this was the last open file.
> +	 * Then de-initialize hw module.
> +	 */
> +	if (fh_singular)
> +		vpfe_ccdc_close(&vpfe->ccdc, vpfe->pdev);
> +
>  	mutex_unlock(&vpfe->lock);
>  
>  	return ret;
> -- 
> 1.8.5.1
> 
> --
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-- 
balbi

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