Re: [PATCH] Staging:media:davinci_vpfe: used devm_kzalloc in place of kzalloc

From: Julia Lawall
Date: Wed Nov 02 2016 - 02:25:20 EST




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@xxxxxxxxx>
> ---
> 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
>
>