linux-kernel - Re: [PATCH] drm/tegra: submit: No need for Null pointer check before kfree

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Message-ID: <864f2fdd-4289-a178-bbf1-c2a6a579c58c@kapsi.fi>
Date:   Wed, 28 Dec 2022 14:28:54 +0200
From:   Mikko Perttunen <cyndis@...si.fi>
To:     Deepak R Varma <drv@...lo.com>,
        Thierry Reding <thierry.reding@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Jonathan Hunter <jonathanh@...dia.com>,
        dri-devel@...ts.freedesktop.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Saurabh Singh Sengar <ssengar@...rosoft.com>,
        Praveen Kumar <kumarpraveen@...ux.microsoft.com>
Subject: Re: [PATCH] drm/tegra: submit: No need for Null pointer check before
 kfree

On 12/27/22 19:14, Deepak R Varma wrote:
> kfree() & vfree() internally perform NULL check on the pointer handed
> to it and take no action if it indeed is NULL. Hence there is no need
> for a pre-check of the memory pointer before handing it to
> kfree()/vfree().
> 
> Issue reported by ifnullfree.cocci Coccinelle semantic patch script.
> 
> Signed-off-by: Deepak R Varma <drv@...lo.com>
> ---
>   drivers/gpu/drm/tegra/submit.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/tegra/submit.c b/drivers/gpu/drm/tegra/submit.c
> index 066f88564169..06f836db99d0 100644
> --- a/drivers/gpu/drm/tegra/submit.c
> +++ b/drivers/gpu/drm/tegra/submit.c
> @@ -680,8 +680,8 @@ int tegra_drm_ioctl_channel_submit(struct drm_device *drm, void *data,
>   		kfree(job_data->used_mappings);
>   	}
> 
> -	if (job_data)
> -		kfree(job_data);
> +	kfree(job_data);
> +
>   put_bo:
>   	gather_bo_put(&bo->base);
>   unlock:
> --
> 2.34.1
> 
> 
> 

It continues to be the case that I think this transform is bad. Same 
applies to the host1x patch.

Mikko