linux-kernel - Re: [PATCH 1/1] VIDEO: ivtvfb, remove unneeded NULL test

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Date:	Mon, 19 Jul 2010 17:39:00 -0400
From:	Andy Walls <awalls@...metrocast.net>
To:	Jiri Slaby <jslaby@...e.cz>
Cc:	mchehab@...radead.org, jirislaby@...il.com,
	linux-kernel@...r.kernel.org, Tejun Heo <tj@...nel.org>,
	Ian Armstrong <ian@...mst.demon.co.uk>,
	ivtv-devel@...vdriver.org, linux-media@...r.kernel.org
Subject: Re: [PATCH 1/1] VIDEO: ivtvfb, remove unneeded NULL test

On Mon, 2010-07-19 at 19:39 +0200, Jiri Slaby wrote:
> Stanse found that in ivtvfb_callback_cleanup and ivtvfb_callback_init
> there are unneeded tests for itv being NULL. But itv is initialized
> as container_of with non-zero offset in those functions, so it is
> never NULL (even if v4l2_dev is). This was found because itv is
> dereferenced earlier than the test.
> 
> Signed-off-by: Jiri Slaby <jslaby@...e.cz>
> Cc: Andy Walls <awalls@...metrocast.net>

Looks fine to me.

Reviewed-by: Andy Walls <awalls@...metrocast.net>

Regards,
Andy

> Cc: Mauro Carvalho Chehab <mchehab@...radead.org>
> Cc: Tejun Heo <tj@...nel.org>
> Cc: Ian Armstrong <ian@...mst.demon.co.uk>
> Cc: ivtv-devel@...vdriver.org
> Cc: linux-media@...r.kernel.org
> ---
>  drivers/media/video/ivtv/ivtvfb.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/video/ivtv/ivtvfb.c b/drivers/media/video/ivtv/ivtvfb.c
> index 9ff3425..9c77bfa 100644
> --- a/drivers/media/video/ivtv/ivtvfb.c
> +++ b/drivers/media/video/ivtv/ivtvfb.c
> @@ -1203,7 +1203,7 @@ static int __init ivtvfb_callback_init(struct device *dev, void *p)
>  	struct v4l2_device *v4l2_dev = dev_get_drvdata(dev);
>  	struct ivtv *itv = container_of(v4l2_dev, struct ivtv, v4l2_dev);
>  
> -	if (itv && (itv->v4l2_cap & V4L2_CAP_VIDEO_OUTPUT)) {
> +	if (itv->v4l2_cap & V4L2_CAP_VIDEO_OUTPUT) {
>  		if (ivtvfb_init_card(itv) == 0) {
>  			IVTVFB_INFO("Framebuffer registered on %s\n",
>  					itv->v4l2_dev.name);
> @@ -1219,7 +1219,7 @@ static int ivtvfb_callback_cleanup(struct device *dev, void *p)
>  	struct ivtv *itv = container_of(v4l2_dev, struct ivtv, v4l2_dev);
>  	struct osd_info *oi = itv->osd_info;
>  
> -	if (itv && (itv->v4l2_cap & V4L2_CAP_VIDEO_OUTPUT)) {
> +	if (itv->v4l2_cap & V4L2_CAP_VIDEO_OUTPUT) {
>  		if (unregister_framebuffer(&itv->osd_info->ivtvfb_info)) {
>  			IVTVFB_WARN("Framebuffer %d is in use, cannot unload\n",
>  				       itv->instance);


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