linux-kernel - Re: [PATCH] drm/amdgpu: drop redundant null-pointer checks in amdgpu_ttm_tt_populate() and amdgpu_ttm_tt

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Message-ID: <f515880f-17f8-66b3-20d9-c1a46a252463@amd.com>
Date:   Wed, 4 Aug 2021 08:49:12 +0200
From:   Christian König <christian.koenig@....com>
To:     Tuo Li <islituo@...il.com>, alexander.deucher@....com,
        Xinhui.Pan@....com, airlied@...ux.ie, daniel@...ll.ch,
        sumit.semwal@...aro.org, airlied@...hat.com,
        Felix.Kuehling@....com, Oak.Zeng@....com, nirmoy.das@....com,
        tzimmermann@...e.de, Philip.Yang@....com
Cc:     amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linaro-mm-sig@...ts.linaro.org, baijiaju1990@...il.com,
        TOTE Robot <oslab@...nghua.edu.cn>
Subject: Re: [PATCH] drm/amdgpu: drop redundant null-pointer checks in
 amdgpu_ttm_tt_populate() and amdgpu_ttm_tt_unpopulate()

Am 04.08.21 um 03:51 schrieb Tuo Li:
> The varialbe gtt in the function amdgpu_ttm_tt_populate() and
> amdgpu_ttm_tt_unpopulate() is guaranteed to be not NULL in the context.
> Thus the null-pointer checks are redundant and can be dropped.
>
> Reported-by: TOTE Robot <oslab@...nghua.edu.cn>
> Signed-off-by: Tuo Li <islituo@...il.com>

Reviewed-by: Christian König <christian.koenig@....com>

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 3a55f08e00e1..719539bd6c44 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1121,7 +1121,7 @@ static int amdgpu_ttm_tt_populate(struct ttm_device *bdev,
>   	struct amdgpu_ttm_tt *gtt = (void *)ttm;
>   
>   	/* user pages are bound by amdgpu_ttm_tt_pin_userptr() */
> -	if (gtt && gtt->userptr) {
> +	if (gtt->userptr) {
>   		ttm->sg = kzalloc(sizeof(struct sg_table), GFP_KERNEL);
>   		if (!ttm->sg)
>   			return -ENOMEM;
> @@ -1146,7 +1146,7 @@ static void amdgpu_ttm_tt_unpopulate(struct ttm_device *bdev,
>   	struct amdgpu_ttm_tt *gtt = (void *)ttm;
>   	struct amdgpu_device *adev;
>   
> -	if (gtt && gtt->userptr) {
> +	if (gtt->userptr) {
>   		amdgpu_ttm_tt_set_user_pages(ttm, NULL);
>   		kfree(ttm->sg);
>   		ttm->sg = NULL;