linux-kernel - Re: [PATCH] Staging:media:davinci_vpfe: used devm

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Message-ID: <alpine.DEB.2.20.1611020720250.2081@hadrien>
Date:   Wed, 2 Nov 2016 07:24:29 +0100 (CET)
From:   Julia Lawall <julia.lawall@...6.fr>
To:     Nadim Almas <nadim.902@...il.com>
cc:     mchehab@...nel.org, gregkh@...uxfoundation.org,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Staging:media:davinci_vpfe: used devm_kzalloc in place
 of kzalloc



On Wed, 2 Nov 2016, Nadim Almas wrote:

> Switch to resource-managed function devm_kzalloc instead
> of kzolloc and remove unneeded kzfree
>
> Also, remove kzfree in probe function and  remove
> function,vpfe_remove as it is now has nothing to do.
> The Coccinelle semantic patch used to make this change is as follows:
> /<smpl>
> @platform@
> identifier p, probefn, removefn;
> @@
> struct platform_driver p = {
> .probe = probefn,
> .remove = removefn,
> };
>
> @prb@
> identifier platform.probefn, pdev;
> expression e, e1, e2;
> @@
> probefn(struct platform_device *pdev, ...) {
> <+...
> - e = kzalloc(e1, e2)
> + e = devm_kzalloc(&pdev->dev, e1, e2)
> ...
> ?-kzfree(e);
> ...+>
> }
> @rem depends on prb@
> identifier platform.removefn;
> expression prb.e;
> @@
> removefn(...) {
> <...
> - kzfree(e);
> ...>
> }
> //</smpl>
>
> Signed-off-by: Nadim Almas <nadim.902@...il.com>
> ---
>  drivers/staging/media/davinci_vpfe/vpfe_mc_capture.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/staging/media/davinci_vpfe/vpfe_mc_capture.c b/drivers/staging/media/davinci_vpfe/vpfe_mc_capture.c
> index bf077f8..cd44f0f 100644
> --- a/drivers/staging/media/davinci_vpfe/vpfe_mc_capture.c
> +++ b/drivers/staging/media/davinci_vpfe/vpfe_mc_capture.c
> @@ -579,7 +579,7 @@ static int vpfe_probe(struct platform_device *pdev)
>  	struct resource *res1;
>  	int ret = -ENOMEM;
>
> -	vpfe_dev = kzalloc(sizeof(*vpfe_dev), GFP_KERNEL);
> +	vpfe_dev = devm_kzalloc(&pdev->dev, sizeof(*vpfe_dev), GFP_KERNEL);
>  	if (!vpfe_dev)
>  		return ret;
>
> @@ -681,7 +681,6 @@ static int vpfe_probe(struct platform_device *pdev)
>  probe_disable_clock:
>  	vpfe_disable_clock(vpfe_dev);
>  probe_free_dev_mem:
> -	kzfree(vpfe_dev);

Kzfree zeroes the data before freeing it.  Devm_kzalloc only causes a
kfree to happen, not a kzfree.  If the kzfree is needed, then a memset 0
would need to replace the calls to kzfree.

There are some other minor issues with the patch.  In the subject line,
there is normally a space after each :.  There is a spelling mistake in
the commit message.  In the commit message there should be one space
betwee words within a sentence, and there should be a space after a comma,
or other puctuation.

julia

>
>  	return ret;
>  }
> @@ -702,7 +701,6 @@ static int vpfe_remove(struct platform_device *pdev)
>  	v4l2_device_unregister(&vpfe_dev->v4l2_dev);
>  	media_device_unregister(&vpfe_dev->media_dev);
>  	vpfe_disable_clock(vpfe_dev);
> -	kzfree(vpfe_dev);
>
>  	return 0;
>  }
> --
> 2.7.4
>
>