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

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Date:   Tue, 10 Jan 2023 10:54:58 -0500
From:   Rodrigo Siqueira Jordao <Rodrigo.Siqueira@....com>
To:     Deepak R Varma <drv@...lo.com>,
        Harry Wentland <harry.wentland@....com>,
        Leo Li <sunpeng.li@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     Saurabh Singh Sengar <ssengar@...rosoft.com>,
        Praveen Kumar <kumarpraveen@...ux.microsoft.com>
Subject: Re: [PATCH] drm/amd/display: No need for Null pointer check before
 kfree



On 12/27/22 13:39, Deepak R Varma wrote:
> kfree() & vfree() internally performs 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/amd/display/dc/clk_mgr/dcn30/dcn30_clk_mgr.c | 3 +--
>   drivers/gpu/drm/amd/display/dc/clk_mgr/dcn32/dcn32_clk_mgr.c | 3 +--
>   2 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn30/dcn30_clk_mgr.c b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn30/dcn30_clk_mgr.c
> index 3ce0ee0d012f..694a9d3d92ae 100644
> --- a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn30/dcn30_clk_mgr.c
> +++ b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn30/dcn30_clk_mgr.c
> @@ -577,8 +577,7 @@ void dcn3_clk_mgr_construct(
> 
>   void dcn3_clk_mgr_destroy(struct clk_mgr_internal *clk_mgr)
>   {
> -	if (clk_mgr->base.bw_params)
> -		kfree(clk_mgr->base.bw_params);
> +	kfree(clk_mgr->base.bw_params);
> 
>   	if (clk_mgr->wm_range_table)
>   		dm_helpers_free_gpu_mem(clk_mgr->base.ctx, DC_MEM_ALLOC_TYPE_GART,
> diff --git a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn32/dcn32_clk_mgr.c b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn32/dcn32_clk_mgr.c
> index 200fcec19186..ba9814f88f48 100644
> --- a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn32/dcn32_clk_mgr.c
> +++ b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn32/dcn32_clk_mgr.c
> @@ -783,8 +783,7 @@ void dcn32_clk_mgr_construct(
> 
>   void dcn32_clk_mgr_destroy(struct clk_mgr_internal *clk_mgr)
>   {
> -	if (clk_mgr->base.bw_params)
> -		kfree(clk_mgr->base.bw_params);
> +	kfree(clk_mgr->base.bw_params);
> 
>   	if (clk_mgr->wm_range_table)
>   		dm_helpers_free_gpu_mem(clk_mgr->base.ctx, DC_MEM_ALLOC_TYPE_GART,
> --
> 2.34.1
> 
> 
> 

Hi,

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@....com>

And applied to amd-staging-drm-next.

Thanks
Siqueira