linux-kernel - Re: [Patch v3 1/1] media: am437x-vpfe: Fix a race condition during release

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Date:	Tue, 7 Jul 2015 12:12:18 +0100
From:	"Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:	Benoit Parrot <bparrot@...com>
Cc:	Hans Verkuil <hverkuil@...all.nl>,
	linux-media <linux-media@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>, stable@...r.kernel.org
Subject: Re: [Patch v3 1/1] media: am437x-vpfe: Fix a race condition during release

On Mon, Jun 29, 2015 at 10:18 PM, Benoit Parrot <bparrot@...com> 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.
>
> Fixes: 417d2e507edc ("[media] media: platform: add VPFE capture driver support for AM437X")
> Cc: <stable@...r.kernel.org> # v4.0+
> Signed-off-by: Benoit Parrot <bparrot@...com>

Acked-by: Lad, Prabhakar <prabhakar.csengg@...il.com>

Cheers,
--Prabhakar Lad

> ---
> Changes since v2:
> - fix the stable commit reference syntax
>
>  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 a30cc2f7e4f1..eb25c43da126 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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