linux-kernel - Re: [PATCH v2] media: i2c: imx214: Exit early on control init errors

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Message-ID: <aPZ_YRwpDNPFjePX@valkosipuli.retiisi.eu>
Date: Mon, 20 Oct 2025 21:28:49 +0300
From: Sakari Ailus <sakari.ailus@....fi>
To: Ricardo Ribalda <ribalda@...omium.org>
Cc: Ricardo Ribalda <ribalda@...nel.org>,
	Hans Verkuil <hverkuil+cisco@...nel.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] media: i2c: imx214: Exit early on control init errors

Hi Ricardo,

On Tue, Oct 14, 2025 at 11:00:17AM +0000, Ricardo Ribalda wrote:
> Now we try to initialize all the controls and at the very end check
> ctrl_hdlr->error to check if one of them has failed.
> 
> This confuses smatch, who do not know how to track the state of
> imx214->link_freq.
> 
> drivers/media/i2c/imx214.c:1109 imx214_ctrls_init() error: we previously assumed 'imx214->link_freq' could be null (see line 1017)
> 
> Fix this by exiting early on control initialization errors.
> 
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> ---
> Right now we are handling this with a quirk in media-ci, if Dan cannot
> fix smatch in a kernel cycle we should merge this patch.
> ---
> Changes in v2:
> - Fix typo in commit message commit
> - Move error tag where it belongs (Thanks Hans!)
> - Link to v1: https://lore.kernel.org/r/20250829-imx214-smatch-v1-1-f3d1653b48e4@chromium.org
> ---
>  drivers/media/i2c/imx214.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/i2c/imx214.c b/drivers/media/i2c/imx214.c
> index 94ebe625c9e6ee0fb67fe1d89b48b2f1bf58ffc6..c66f0e18726c3fc15df91c37888a797bcea82134 100644
> --- a/drivers/media/i2c/imx214.c
> +++ b/drivers/media/i2c/imx214.c
> @@ -1014,8 +1014,10 @@ static int imx214_ctrls_init(struct imx214 *imx214)
>  						   V4L2_CID_LINK_FREQ,
>  						   imx214->bus_cfg.nr_of_link_frequencies - 1,
>  						   0, imx214->bus_cfg.link_frequencies);
> -	if (imx214->link_freq)
> -		imx214->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> +	if (!imx214->link_freq)
> +		goto err_init_ctrl;
> +
> +	imx214->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;

You could do this cleaner by simply moving the assignment after the handler
error check. Some drivers do that already.

I wonder why this seems to be a problem for smatch in the imx214 driver as
the pattern is widely used across the sensor drivers.

>  
>  	/*
>  	 * WARNING!
> @@ -1099,6 +1101,7 @@ static int imx214_ctrls_init(struct imx214 *imx214)
>  
>  	v4l2_ctrl_new_fwnode_properties(ctrl_hdlr, &imx214_ctrl_ops, &props);
>  
> +err_init_ctrl:
>  	ret = ctrl_hdlr->error;
>  	if (ret) {
>  		v4l2_ctrl_handler_free(ctrl_hdlr);
> 

-- 
Kind regards,

Sakari Ailus