linux-kernel - Re: [PATCH] drm/amdgpu: Add braces to initialize task_info subojects

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Message-ID: <CADnq5_MHoZXf+16ZqoA-h974-=2Ewk1TwbdiuAs71X6WiuL4GQ@mail.gmail.com>
Date:   Wed, 12 Sep 2018 14:44:34 -0400
From:   Alex Deucher <alexdeucher@...il.com>
To:     natechancellor@...il.com
Cc:     ndesaulniers@...gle.com, Chunming Zhou <David1.Zhou@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>, richardsmith@...gle.com,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        "Deucher, Alexander" <alexander.deucher@....com>,
        Christian Koenig <christian.koenig@....com>
Subject: Re: [PATCH] drm/amdgpu: Add braces to initialize task_info subojects

On Wed, Sep 12, 2018 at 2:40 PM Nathan Chancellor
<natechancellor@...il.com> wrote:
>
> On Wed, Sep 12, 2018 at 10:38:30AM -0700, Nick Desaulniers wrote:
> > On Tue, Sep 11, 2018 at 5:26 PM Nathan Chancellor
> > <natechancellor@...il.com> wrote:
> > >
> > > Clang warns if there are missing braces around a subobject
> > > initializer.
> > >
> > > drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c:1447:41: warning: suggest braces
> > > around initialization of subobject [-Wmissing-braces]
> > >                 struct amdgpu_task_info task_info = { 0 };
> > >                                                       ^
> > >                                                       {}
> > > 1 warning generated.
> > >
> > > drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c:262:41: warning: suggest braces
> > > around initialization of subobject [-Wmissing-braces]
> > >                 struct amdgpu_task_info task_info = { 0 };
> > >                                                       ^
> > >                                                       {}
> > > 1 warning generated.
> > >
> > > Reported-by: Nick Desaulniers <ndesaulniers@...gle.com>
> > > Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> > > ---
> > >  drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c | 2 +-
> > >  drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 2 +-
> > >  2 files changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
> > > index 9333109b210d..968cc1b8cdff 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
> > > +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
> > > @@ -1444,7 +1444,7 @@ static int gmc_v8_0_process_interrupt(struct amdgpu_device *adev,
> > >                 gmc_v8_0_set_fault_enable_default(adev, false);
> > >
> > >         if (printk_ratelimit()) {
> > > -               struct amdgpu_task_info task_info = { 0 };
> > > +               struct amdgpu_task_info task_info = { { 0 } };
> >
> > Hi Nathan,
> > Thanks for this patch.  I discussed this syntax with our language
> > lawyers.  Turns out, this is not quite correct, as you're now saying
> > "initialize the first subobject to zero, but not the rest of the
> > object."  -Wmissing-field-initializers would highlight this, but it's
> > not part of -Wall.  It would be more correct to zero initialize the
> > full struct, including all of its subobjects with `= {};`.
> >
>
> Good point, I was debating on which one was correct. There are several
> places in this driver that use the multiple brace + 0 idiom, which is
> why I used this form. I will spin up a v2 with your suggestion, thank
> you for the review!

Feel free to fix up the others as well. The others were only changed
due to the same warning you sent the patch for.

Alex

>
> Nathan
>
> > >
> > >                 amdgpu_vm_get_task_info(adev, entry->pasid, &task_info);
> > >
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> > > index 72f8018fa2a8..a781a5027212 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> > > +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> > > @@ -259,7 +259,7 @@ static int gmc_v9_0_process_interrupt(struct amdgpu_device *adev,
> > >         }
> > >
> > >         if (printk_ratelimit()) {
> > > -               struct amdgpu_task_info task_info = { 0 };
> > > +               struct amdgpu_task_info task_info = { { 0 } };
> > >
> > >                 amdgpu_vm_get_task_info(adev, entry->pasid, &task_info);
> > >
> > > --
> > > 2.18.0
> > >
> >
> >
> > --
> > Thanks,
> > ~Nick Desaulniers
> _______________________________________________
> amd-gfx mailing list
> amd-gfx@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx

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