Re: [PATCH -next 0/8] drm/amd/amdgpu: fix comparison pointer to bool warning

From: "Christian König" <christian.koenig@amd.com>
To: "Alex Deucher" <alexdeucher@gmail.com>,
	"Ville Syrjälä" <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
Date: Wed, 16 Sep 2020 16:02:18 +0200	[thread overview]
Message-ID: <372d7001-22cc-79b6-83b8-2fd75a1804d5@amd.com> (raw)
In-Reply-To: <CADnq5_OS814FxmadZ9yBkrY6ije8h7FxswWstsxNr3rw=Bum=Q@mail.gmail.com>

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 König wrote:
>>> Am 15.09.20 um 21:35 schrieb Ville Syrjälä:
>>>> 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?

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 König <christian.koenig@amd.com> wrote:
>>>>>> Acked-by: Christian König <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
>>>>>>>
>>>>>> _______________________________________________
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>> --
>> 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