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Date:   Wed, 16 Sep 2020 17:31:38 +0200
From:   Daniel Vetter <daniel@ffwll.ch>
To:     Christian =?iso-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>
Cc:     Alex Deucher <alexdeucher@gmail.com>,
        Ville =?iso-8859-1?Q?Syrj=E4l=E4?= 
        <ville.syrjala@linux.intel.com>, yi.zhang@huawei.com,
        Dave Airlie <airlied@linux.ie>,
        LKML <linux-kernel@vger.kernel.org>,
        amd-gfx list <amd-gfx@lists.freedesktop.org>,
        Zheng Bin <zhengbin13@huawei.com>,
        Maling list - DRI developers 
        <dri-devel@lists.freedesktop.org>,
        "Deucher, Alexander" <alexander.deucher@amd.com>
Subject: Re: [PATCH -next 0/8] drm/amd/amdgpu: fix comparison pointer to bool
 warning
Message-ID: <20200916153138.GR438822@phenom.ffwll.local>
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        Zheng Bin <zhengbin13@huawei.com>,
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On Wed, Sep 16, 2020 at 04:02:18PM +0200, Christian K?nig wrote:
> Am 16.09.20 um 15:36 schrieb Alex Deucher:
> > On Wed, Sep 16, 2020 at 3:51 AM Daniel Vetter <daniel@ffwll.ch> wrote:
> > > On Wed, Sep 16, 2020 at 09:38:34AM +0200, Christian K?nig wrote:
> > > > Am 15.09.20 um 21:35 schrieb Ville Syrj?l?:
> > > > > On Tue, Sep 15, 2020 at 03:16:32PM -0400, Alex Deucher wrote:
> > > > > > I question the value of these warnings.  Why even have a boolean type
> > > > > > if you are going to get warnings when you use them...
> > > > > > That said, applied to avoid getting these patches again and again
> > > > > > every time someone sees this.
> > > > > if (this_is_sparta)
> > > > > if (this_is_sparta == true)
> > > > > if (this_is_sparta != false)
> > > > > 
> > > > > I think the first one reads the best, and avoids having to
> > > > > decide between truth and falsehood :)
> > > > +1
> > > +1, especially because we also have the inversion when using negative
> > > errno codes for failures and 0 as success, which results in
> > > 
> > >          if (errno == 0) /* success case */
> > > 
> > > but
> > >          if (bool == 0) /* failure case */
> > > 
> > > now creative people do sometimes
> > > 
> > >          if (!errno) /* success case */
> > > 
> > > which I think is horribly confusing. So imo for more easier telling apart
> > > of these too I think consistently using the short form for booleans, and
> > > consistently using the more explicit long form for errno checks is a Very
> > > Good Pattern :-)
> > I don't disagree with your logic, but we regularly get patches to
> > convert errno checks to drop the direct comparison because that is the
> > "preferred kernel style".  Arguably, we should be explicit in all
> > cases as that avoids all confusion.  With that in mind, my original
> > point stands.  Why have a type when comparisons against valid settings
> > for that type produce errors?

Oh, I didn't know that this happens for errno too.

I withdraw my +1 and concur this is a bikeshed. I guess still applying to
shut up the patch stream is the most reasonable thing :-/
-Daniel

> Well it isn't an error, but raising a nice warning is most likely a good
> idea.

> 
> Christian.
> 
> > 
> > Alex
> > 
> > > Cheers, Daniel
> > > 
> > > > Christian.
> > > > 
> > > > > > Alex
> > > > > > 
> > > > > > On Wed, Sep 9, 2020 at 9:21 AM Christian K?nig <christian.koenig@amd.com> wrote:
> > > > > > > Acked-by: Christian K?nig <christian.koenig@amd.com> for the series.
> > > > > > > 
> > > > > > > Am 09.09.20 um 15:07 schrieb Zheng Bin:
> > > > > > > > Zheng Bin (8):
> > > > > > > >      drm/amd/amdgpu: fix comparison pointer to bool warning in gfx_v9_0.c
> > > > > > > >      drm/amd/amdgpu: fix comparison pointer to bool warning in gfx_v10_0.c
> > > > > > > >      drm/amd/amdgpu: fix comparison pointer to bool warning in sdma_v5_0.c
> > > > > > > >      drm/amd/amdgpu: fix comparison pointer to bool warning in sdma_v5_2.c
> > > > > > > >      drm/amd/amdgpu: fix comparison pointer to bool warning in si.c
> > > > > > > >      drm/amd/amdgpu: fix comparison pointer to bool warning in uvd_v6_0.c
> > > > > > > >      drm/amd/amdgpu: fix comparison pointer to bool warning in
> > > > > > > >        amdgpu_atpx_handler.c
> > > > > > > >      drm/amd/amdgpu: fix comparison pointer to bool warning in sdma_v4_0.c
> > > > > > > > 
> > > > > > > >     drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c | 4 ++--
> > > > > > > >     drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c           | 2 +-
> > > > > > > >     drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c            | 2 +-
> > > > > > > >     drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c           | 4 ++--
> > > > > > > >     drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c           | 2 +-
> > > > > > > >     drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c           | 2 +-
> > > > > > > >     drivers/gpu/drm/amd/amdgpu/si.c                  | 2 +-
> > > > > > > >     drivers/gpu/drm/amd/amdgpu/uvd_v6_0.c            | 4 ++--
> > > > > > > >     8 files changed, 11 insertions(+), 11 deletions(-)
> > > > > > > > 
> > > > > > > > --
> > > > > > > > 2.26.0.106.g9fadedd
> > > > > > > > 
> > > > > > > _______________________________________________
> > > > > > > amd-gfx mailing list
> > > > > > > amd-gfx@lists.freedesktop.org
> > > > > > > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.freedesktop.org%2Fmailman%2Flistinfo%2Famd-gfx&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7Cdc7a8d7517d341e3a80c08d85a458ba8%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637358602051676053&amp;sdata=MS0vcBcU7unXjEFlbd8kLbJkJ4sKcvIdLjc8yhX4UUI%3D&amp;reserved=0
> > > > > > _______________________________________________
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> > > > > > dri-devel@lists.freedesktop.org
> > > > > > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.freedesktop.org%2Fmailman%2Flistinfo%2Fdri-devel&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7Cdc7a8d7517d341e3a80c08d85a458ba8%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637358602051686051&amp;sdata=MgfR%2BwCVY9gWfhQ9i5kWcKiiYkV1C8O2dEKlZYSqscE%3D&amp;reserved=0
> > > > _______________________________________________
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> > > > dri-devel@lists.freedesktop.org
> > > > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.freedesktop.org%2Fmailman%2Flistinfo%2Fdri-devel&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7Cdc7a8d7517d341e3a80c08d85a458ba8%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637358602051686051&amp;sdata=MgfR%2BwCVY9gWfhQ9i5kWcKiiYkV1C8O2dEKlZYSqscE%3D&amp;reserved=0
> > > --
> > > Daniel Vetter
> > > Software Engineer, Intel Corporation
> > > https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fblog.ffwll.ch%2F&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7Cdc7a8d7517d341e3a80c08d85a458ba8%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637358602051686051&amp;sdata=GvLs5OXw2Ny%2BieJxm8hjawNb0rGA966539iAwlWwPMY%3D&amp;reserved=0
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch