Re: [PATCH] amdgpu: fix integer overflow on 32-bit architectures

[Nick Desaulniers]

See also https://lore.kernel.org/lkml/CADnq5_NdtZh5_RGDWKJ9c_42XLvrncCs5DDU1YSptfZP94KXkQ@xxxxxxxxxxxxxx/T/#me707e09e92c6e487285e8bb382a607e4e782c249

On Tue, May 5, 2020 at 7:17 AM Christian KÃnig <christian.koenig@xxxxxxx> wrote:
>
> Am 05.05.20 um 16:15 schrieb Arnd Bergmann:
> > Multiplying 1000000000 by four overruns a 'long' variable, as clang
> > points out:
> >
> > drivers/gpu/drm/amd/amdgpu/amdgpu_device.c:4160:53: error: overflow in expression; result is -294967296 with type 'long' [-Werror,-Winteger-overflow]
> >                  expires = ktime_get_mono_fast_ns() + NSEC_PER_SEC * 4L;
> >                                                                    ^
> > Make this a 'long long' constant instead.
> >
> > Fixes: 3f12acc8d6d4 ("drm/amdgpu: put the audio codec into suspend state before gpu reset V3")
> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
>
> Reviewed-by: Christian KÃnig <christian.koenig@xxxxxxx>
>
> > ---
> > I'm not sure the ktime_get_mono_fast_ns() call is necessary here
> > either. Is it intentional because ktime_get_ns() doesn't work
> > during a driver suspend, or just a mistake?
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > index 6f93af972b0a..2e07e3e6b036 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > @@ -4157,7 +4157,7 @@ static int amdgpu_device_suspend_display_audio(struct amdgpu_device *adev)
> >                * the audio controller default autosuspend delay setting.
> >                * 4S used here is guaranteed to cover that.
> >                */
> > -             expires = ktime_get_mono_fast_ns() + NSEC_PER_SEC * 4L;
> > +             expires = ktime_get_mono_fast_ns() + NSEC_PER_SEC * 4LL;
> >
> >       while (!pm_runtime_status_suspended(&(p->dev))) {
> >               if (!pm_runtime_suspend(&(p->dev)))
>
> --
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-- 
Thanks,
~Nick Desaulniers