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From:   Alex Deucher <alexdeucher@gmail.com>
Date:   Thu, 5 Aug 2021 00:32:47 -0400
Message-ID: <CADnq5_MSp=PAqbaTrS771ssKJzVpT2LyDTjZCSx2hh-DFo3MXg@mail.gmail.com>
Subject: Re: [PATCH] drm/amdgpu: drop redundant null-pointer checks in
 amdgpu_ttm_tt_populate() and amdgpu_ttm_tt_unpopulate()
To:     =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>
Cc:     Tuo Li <islituo@gmail.com>,
        "Deucher, Alexander" <alexander.deucher@amd.com>,
        xinhui pan <Xinhui.Pan@amd.com>,
        Dave Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        Dave Airlie <airlied@redhat.com>,
        "Kuehling, Felix" <Felix.Kuehling@amd.com>,
        Oak Zeng <Oak.Zeng@amd.com>, Nirmoy Das <nirmoy.das@amd.com>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        "Yang, Philip" <Philip.Yang@amd.com>,
        amd-gfx list <amd-gfx@lists.freedesktop.org>,
        Maling list - DRI developers 
        <dri-devel@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-media <linux-media@vger.kernel.org>,
        "moderated list:DMA BUFFER SHARING FRAMEWORK" 
        <linaro-mm-sig@lists.linaro.org>,
        Jia-Ju Bai <baijiaju1990@gmail.com>,
        TOTE Robot <oslab@tsinghua.edu.cn>
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Applied.  Thanks!

Alex

On Wed, Aug 4, 2021 at 2:49 AM Christian K=C3=B6nig <christian.koenig@amd.c=
om> wrote:
>
> 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 K=C3=B6nig <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_devi=
ce *bdev,
> >       struct amdgpu_ttm_tt *gtt =3D (void *)ttm;
> >
> >       /* user pages are bound by amdgpu_ttm_tt_pin_userptr() */
> > -     if (gtt && gtt->userptr) {
> > +     if (gtt->userptr) {
> >               ttm->sg =3D kzalloc(sizeof(struct sg_table), GFP_KERNEL);
> >               if (!ttm->sg)
> >                       return -ENOMEM;
> > @@ -1146,7 +1146,7 @@ static void amdgpu_ttm_tt_unpopulate(struct ttm_d=
evice *bdev,
> >       struct amdgpu_ttm_tt *gtt =3D (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 =3D NULL;
>