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Subject: Re: [PATCH] drm/amdgpu: drop redundant null-pointer checks in
 amdgpu_ttm_tt_populate() and amdgpu_ttm_tt_unpopulate()
To:     Tuo Li <islituo@gmail.com>, alexander.deucher@amd.com,
        Xinhui.Pan@amd.com, airlied@linux.ie, daniel@ffwll.ch,
        sumit.semwal@linaro.org, airlied@redhat.com,
        Felix.Kuehling@amd.com, Oak.Zeng@amd.com, nirmoy.das@amd.com,
        tzimmermann@suse.de, Philip.Yang@amd.com
Cc:     amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
        linaro-mm-sig@lists.linaro.org, baijiaju1990@gmail.com,
        TOTE Robot <oslab@tsinghua.edu.cn>
References: <20210804015132.29617-1-islituo@gmail.com>
From:   =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
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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@tsinghua.edu.cn>
> Signed-off-by: Tuo Li <islituo@gmail.com>

Reviewed-by: Christian König <christian.koenig@amd.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;