Re: [PATCH 4/5] media: rcar-csi2: Allocate v4l2_async_subdev dynamically

From: "Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>
To: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Cc: linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
	Jacopo Mondi <jacopo+renesas@jmondi.org>,
	Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
	Ramesh Shanmugasundaram <rashanmu@gmail.com>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Steve Longerbeam <slongerbeam@gmail.com>
Subject: Re: [PATCH 4/5] media: rcar-csi2: Allocate v4l2_async_subdev dynamically
Date: Tue, 11 Aug 2020 23:43:24 +0200	[thread overview]
Message-ID: <20200811214324.GB1061689@oden.dyn.berto.se> (raw)
In-Reply-To: <20200811205939.19550-5-laurent.pinchart+renesas@ideasonboard.com>

Hi Laurent,

Thanks for your work.

On 2020-08-11 23:59:38 +0300, Laurent Pinchart wrote:
> v4l2_async_notifier_add_subdev() requires the asd to be allocated
> dynamically, but the rcar-csi2 driver embeds it in the rcar_csi2
> structure. This causes memory corruption when the notifier is destroyed
> at remove time with v4l2_async_notifier_cleanup().
> 
> Fix this issue by registering the asd with
> v4l2_async_notifier_add_fwnode_subdev(), which allocates it dynamically
> internally.

This patch conflicts with [1] which I think is a nicer solution to the 
problem, provided 1/2 of that series is palatable for everyone :-)

1. [PATCH 2/2] rcar-csi2: Use V4L2 async helpers to create the notifier

> 
> Fixes: 769afd212b16 ("media: rcar-csi2: add Renesas R-Car MIPI CSI-2 receiver driver")
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> ---
>  drivers/media/platform/rcar-vin/rcar-csi2.c | 24 +++++++++------------
>  1 file changed, 10 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
> index c6cc4f473a07..a16c492b3143 100644
> --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
> +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
> @@ -362,7 +362,6 @@ struct rcar_csi2 {
>  	struct media_pad pads[NR_OF_RCAR_CSI2_PAD];
>  
>  	struct v4l2_async_notifier notifier;
> -	struct v4l2_async_subdev asd;
>  	struct v4l2_subdev *remote;
>  
>  	struct v4l2_mbus_framefmt mf;
> @@ -811,6 +810,8 @@ static int rcsi2_parse_v4l2(struct rcar_csi2 *priv,
>  
>  static int rcsi2_parse_dt(struct rcar_csi2 *priv)
>  {
> +	struct v4l2_async_subdev *asd;
> +	struct fwnode_handle *fwnode;
>  	struct device_node *ep;
>  	struct v4l2_fwnode_endpoint v4l2_ep = { .bus_type = 0 };
>  	int ret;
> @@ -834,24 +835,19 @@ static int rcsi2_parse_dt(struct rcar_csi2 *priv)
>  		return ret;
>  	}
>  
> -	priv->asd.match.fwnode =
> -		fwnode_graph_get_remote_endpoint(of_fwnode_handle(ep));
> -	priv->asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
> -
> +	fwnode = fwnode_graph_get_remote_endpoint(of_fwnode_handle(ep));
>  	of_node_put(ep);
>  
> +	dev_dbg(priv->dev, "Found '%pOF'\n", to_of_node(fwnode));
> +
>  	v4l2_async_notifier_init(&priv->notifier);
> -
> -	ret = v4l2_async_notifier_add_subdev(&priv->notifier, &priv->asd);
> -	if (ret) {
> -		fwnode_handle_put(priv->asd.match.fwnode);
> -		return ret;
> -	}
> -
>  	priv->notifier.ops = &rcar_csi2_notify_ops;
>  
> -	dev_dbg(priv->dev, "Found '%pOF'\n",
> -		to_of_node(priv->asd.match.fwnode));
> +	asd = v4l2_async_notifier_add_fwnode_subdev(&priv->notifier, fwnode,
> +						    sizeof(*asd));
> +	fwnode_handle_put(fwnode);
> +	if (IS_ERR(asd))
> +		return PTR_ERR(asd);
>  
>  	ret = v4l2_async_subdev_notifier_register(&priv->subdev,
>  						  &priv->notifier);
> -- 
> Regards,
> 
> Laurent Pinchart
> 

-- 
Regards,
Niklas Söderlund