linux-kernel - Re: [PATCH] media: v4l2-async: Put fwnode after last access

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Date:   Mon, 28 Dec 2020 15:16:58 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Ezequiel Garcia <ezequiel@...labora.com>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel@...labora.com, Hans Verkuil <hverkuil@...all.nl>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
Subject: Re: [PATCH] media: v4l2-async: Put fwnode after last access

Hi Ezequiel,

Thank you for the patch.

On Mon, Dec 28, 2020 at 09:17:25AM -0300, Ezequiel Garcia wrote:
> fwnode_handle_put() should be called after the fwnode
> is last accessed. Fix it.
> 
> Fixes: b98158d837ef ("media: v4l2-async: Accept endpoints and devices for fwnode matching")
> Signed-off-by: Ezequiel Garcia <ezequiel@...labora.com>
> ---
>  drivers/media/v4l2-core/v4l2-async.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> index e3ab003a6c85..1303c9b83138 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -78,6 +78,7 @@ static bool match_fwnode(struct v4l2_async_notifier *notifier,
>  	bool asd_fwnode_is_ep;
>  	bool sd_fwnode_is_ep;
>  	struct device *dev;
> +	bool match;
>  
>  	/*
>  	 * Both the subdev and the async subdev can provide either an endpoint
> @@ -113,9 +114,10 @@ static bool match_fwnode(struct v4l2_async_notifier *notifier,
>  		other_fwnode = sd->fwnode;
>  	}
>  
> -	fwnode_handle_put(dev_fwnode);
> +	match = (dev_fwnode == other_fwnode);
>  
> -	if (dev_fwnode != other_fwnode)

This only performs a pointer comparison, it doesn't access dev_fwnode. I
don't think the change is necessary.

> +	fwnode_handle_put(dev_fwnode);
> +	if (!match)
>  		return false;
>  
>  	/*

-- 
Regards,

Laurent Pinchart