linux-kernel - Re: [PATCH] tvp7002: use devm_kzalloc() instead of kzalloc()

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Date:	Thu, 03 Jan 2013 14:31:20 +0100
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	davinci-linux-open-source@...ux.davincidsp.com
Cc:	"Lad, Prabhakar" <prabhakar.csengg@...il.com>,
	LMML <linux-media@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Hans Verkuil <hans.verkuil@...co.com>,
	Mauro Carvalho Chehab <mchehab@...radead.org>
Subject: Re: [PATCH] tvp7002: use devm_kzalloc() instead of kzalloc()

Hi Prabhakar,

Thanks for the patch.

On Thursday 03 January 2013 18:52:42 Lad, Prabhakar wrote:
> I2C drivers can use devm_kzalloc() too in their .probe() methods. Doing so
> simplifies their clean up paths.
> 
> Signed-off-by: Lad, Prabhakar <prabhakar.lad@...com>
> Signed-off-by: Manjunath Hadli <manjunath.hadli@...com>
> ---
>  drivers/media/i2c/tvp7002.c |   10 ++--------
>  1 files changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/media/i2c/tvp7002.c b/drivers/media/i2c/tvp7002.c
> index fb6a5b5..2d4c86e 100644
> --- a/drivers/media/i2c/tvp7002.c
> +++ b/drivers/media/i2c/tvp7002.c
> @@ -1036,7 +1036,7 @@ static int tvp7002_probe(struct i2c_client *c, const
> struct i2c_device_id *id) return -ENODEV;
>  	}
> 
> -	device = kzalloc(sizeof(struct tvp7002), GFP_KERNEL);
> +	device = devm_kzalloc(&c->dev, sizeof(struct tvp7002), GFP_KERNEL);
> 
>  	if (!device)
>  		return -ENOMEM;
> @@ -1088,17 +1088,12 @@ static int tvp7002_probe(struct i2c_client *c, const
> struct i2c_device_id *id) V4L2_CID_GAIN, 0, 255, 1, 0);
>  	sd->ctrl_handler = &device->hdl;
>  	if (device->hdl.error) {
> -		int err = device->hdl.error;
> -
>  		v4l2_ctrl_handler_free(&device->hdl);
> -		kfree(device);
> -		return err;
> +		return device->hdl.error;

At this point device->hdl as been freed (or rather uninitialized, as the 
structure is not dynamically allocated by the control framework), so device-
>hdl.error is undefined. That's why you need the local err variable.

>  	}
>  	v4l2_ctrl_handler_setup(&device->hdl);
> 
>  found_error:
> -	if (error < 0)
> -		kfree(device);

You can remove the found_error label and return errors directly instead of 
using goto's.

>  	return error;

And this can then be turned into return 0.

>  }
> @@ -1120,7 +1115,6 @@ static int tvp7002_remove(struct i2c_client *c)
> 
>  	v4l2_device_unregister_subdev(sd);
>  	v4l2_ctrl_handler_free(&device->hdl);
> -	kfree(device);
>  	return 0;
>  }
-- 
Regards,

Laurent Pinchart

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