linux-kernel - Re: [PATCH 2/2] media: stm32-dcmi: add mandatory of_node

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Date:   Mon, 18 Jun 2018 09:49:44 +0000
From:   Hugues FRUCHET <hugues.fruchet@...com>
To:     Nicholas Mc Guire <hofrat@...dl.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
CC:     Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre TORGUE <alexandre.torgue@...com>,
        Hans Verkuil <hans.verkuil@...co.com>,
        "Philipp Zabel" <p.zabel@...gutronix.de>,
        Niklas Soderlund <niklas.soderlund+renesas@...natech.se>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        "Gustavo A. R. Silva" <garsilva@...eddedor.com>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] media: stm32-dcmi: add mandatory of_node_put() in
 success path

Hi Nicholas,
Thanks for patch.
BR,
Hugues.

On 06/12/2018 07:22 PM, Nicholas Mc Guire wrote:
> The endpoint allocated by of_graph_get_next_endpoint() needs an of_node_put()
> in both error and success path. As  ep  is not used the refcount decrement
> can be right after the last use of  ep.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
Acked-by: Hugues Fruchet <hugues.fruchet@...com>

> Fixes: commit 37404f91ef8b ("[media] stm32-dcmi: STM32 DCMI camera interface driver")
> ---
> 
> Problem located with an experimental coccinelle script
> 
> Patch was compile tested with: x86_64_defconfig, MEDIA_SUPPORT=y
> MEDIA_CAMERA_SUPPORT=y, V4L_PLATFORM_DRIVERS=y, OF=y, COMPILE_TEST=y
> CONFIG_VIDEO_STM32_DCMI=y
> (There are a number of sparse warnings - not related to the changes though)
> 
> Patch is on top of "[PATCH 1/2] media: stm32-dcmi: drop unneceeary while(1)
> loop" against 4.17.0 (localversion-next is next-20180608)
> 
>   drivers/media/platform/stm32/stm32-dcmi.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
> index 70b81d2..542d148 100644
> --- a/drivers/media/platform/stm32/stm32-dcmi.c
> +++ b/drivers/media/platform/stm32/stm32-dcmi.c
> @@ -1610,10 +1610,9 @@ static int dcmi_graph_parse(struct stm32_dcmi *dcmi, struct device_node *node)
>   		return -EINVAL;
>   
>   	remote = of_graph_get_remote_port_parent(ep);
> -	if (!remote) {
> -		of_node_put(ep);
> +	of_node_put(ep);
> +	if (!remote)
>   		return -EINVAL;
> -	}
>   
>   	/* Remote node to connect */
>   	dcmi->entity.node = remote;
>