linux-kernel - Re: [PATCH 1/4] Remove redundant return value check

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Message-ID: <b2aa6ccb-0a9a-449f-1341-fd71d5c545fd@redhat.com>
Date:   Thu, 2 Nov 2023 15:21:04 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Alexandra Diupina <adiupina@...ralinux.ru>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Shevchenko <andy@...nel.org>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        linux-media@...r.kernel.org, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org, lvc-project@...uxtesting.org
Subject: Re: [PATCH 1/4] Remove redundant return value check

Hi Alexandra,

On 11/2/23 15:11, Alexandra Diupina wrote:
> media_entity_pads_init() will not return 0 only if the
> 2nd parameter >= MEDIA_ENTITY_MAX_PADS (512), but 1 is
> passed, so checking the return value is redundant

Generally speaking functions which can fail should always be
error-checked even if their invocation today happen to be
such that they will not fail.

Either the invocation or the function itself my change
causing it to fail in the future. Which is why we want
to keep the error checks.

But maybe media_entity_pads_init() is special and
does not need to be error checked.

Sakari, Laurent do you have any opinion on this ?

> Found by Linux Verification Center (linuxtesting.org) with SVACE.

This feels like a false positive of the tool to me,
but lets wait and see what Sakari or Laurent have
to say.

Regards,

Hans



> 
> Fixes: ad85094b293e ("Revert "media: staging: atomisp: Remove driver"")
> Signed-off-by: Alexandra Diupina <adiupina@...ralinux.ru>
> ---
>  drivers/staging/media/atomisp/i2c/atomisp-gc2235.c        | 4 +---
>  drivers/staging/media/atomisp/i2c/atomisp-mt9m114.c       | 6 +-----
>  drivers/staging/media/atomisp/i2c/atomisp-ov2722.c        | 2 --
>  drivers/staging/media/atomisp/i2c/ov5693/atomisp-ov5693.c | 2 --
>  4 files changed, 2 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/staging/media/atomisp/i2c/atomisp-gc2235.c b/drivers/staging/media/atomisp/i2c/atomisp-gc2235.c
> index 9fa390fbc5f3..f10931a03285 100644
> --- a/drivers/staging/media/atomisp/i2c/atomisp-gc2235.c
> +++ b/drivers/staging/media/atomisp/i2c/atomisp-gc2235.c
> @@ -840,9 +840,7 @@ static int gc2235_probe(struct i2c_client *client)
>  	dev->ctrl_handler.lock = &dev->input_lock;
>  	dev->sd.ctrl_handler = &dev->ctrl_handler;
>  
> -	ret = media_entity_pads_init(&dev->sd.entity, 1, &dev->pad);
> -	if (ret)
> -		gc2235_remove(client);
> +	media_entity_pads_init(&dev->sd.entity, 1, &dev->pad);
>  
>  	return atomisp_register_i2c_module(&dev->sd, gcpdev, RAW_CAMERA);
>  
> diff --git a/drivers/staging/media/atomisp/i2c/atomisp-mt9m114.c b/drivers/staging/media/atomisp/i2c/atomisp-mt9m114.c
> index 1c6643c442ef..b7a940fdbd0a 100644
> --- a/drivers/staging/media/atomisp/i2c/atomisp-mt9m114.c
> +++ b/drivers/staging/media/atomisp/i2c/atomisp-mt9m114.c
> @@ -1581,11 +1581,7 @@ static int mt9m114_probe(struct i2c_client *client)
>  
>  	/* REVISIT: Do we need media controller? */
>  	ret = media_entity_pads_init(&dev->sd.entity, 1, &dev->pad);
> -	if (ret) {
> -		mt9m114_remove(client);
> -		return ret;
> -	}
> -	return 0;
> +	return ret;
>  }
>  
>  static const struct acpi_device_id mt9m114_acpi_match[] = {
> diff --git a/drivers/staging/media/atomisp/i2c/atomisp-ov2722.c b/drivers/staging/media/atomisp/i2c/atomisp-ov2722.c
> index 6a72691ed5b7..922774293bf4 100644
> --- a/drivers/staging/media/atomisp/i2c/atomisp-ov2722.c
> +++ b/drivers/staging/media/atomisp/i2c/atomisp-ov2722.c
> @@ -993,8 +993,6 @@ static int ov2722_probe(struct i2c_client *client)
>  	dev->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
>  
>  	ret = media_entity_pads_init(&dev->sd.entity, 1, &dev->pad);
> -	if (ret)
> -		ov2722_remove(client);
>  
>  	return atomisp_register_i2c_module(&dev->sd, ovpdev, RAW_CAMERA);
>  
> diff --git a/drivers/staging/media/atomisp/i2c/ov5693/atomisp-ov5693.c b/drivers/staging/media/atomisp/i2c/ov5693/atomisp-ov5693.c
> index 460a4e34c55b..8d5b74fb5d9c 100644
> --- a/drivers/staging/media/atomisp/i2c/ov5693/atomisp-ov5693.c
> +++ b/drivers/staging/media/atomisp/i2c/ov5693/atomisp-ov5693.c
> @@ -1733,8 +1733,6 @@ static int ov5693_probe(struct i2c_client *client)
>  	dev->sd.ctrl_handler = &dev->ctrl_handler;
>  
>  	ret = media_entity_pads_init(&dev->sd.entity, 1, &dev->pad);
> -	if (ret)
> -		ov5693_remove(client);
>  
>  	return ret;
>  out_free: