Re: [PATCH] drm/amdkfd: Remove vla

[Laura Abbott]

On 04/09/2018 11:38 PM, Christian KÃnig wrote:
> Am 09.04.2018 um 23:06 schrieb Laura Abbott:
> > There's an ongoing effort to remove VLAs[1] from the kernel to eventually
> > turn on -Wvla. The single VLA usage in the amdkfd driver is actually
> > constant across all current platforms.
>
> Actually that isn't correct.
>
> Could be that we haven't upstreamed KFD support for them, but Vega10 have a different interrupt ring entry size and so would cause the error message here.
>
> > Switch to a constant size array
> > instead.
>
> I would say to just make make the array bigger.
>
> Regards,
> Christian.

What array size would accommodate future chips?

> > [1] https://lkml.org/lkml/2018/3/7/621
> >
> > Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
> > ---
> > Â drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c | 8 +++++---
> > Â 1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> > index 035c351f47c5..c9863858f343 100644
> > --- a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> > @@ -139,10 +139,12 @@ static void interrupt_wq(struct work_struct *work)
> > Â {
> > ÂÂÂÂÂ struct kfd_dev *dev = container_of(work, struct kfd_dev,
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ interrupt_work);
> > +ÂÂÂ uint32_t ih_ring_entry[4];
> > -ÂÂÂ uint32_t ih_ring_entry[DIV_ROUND_UP(
> > -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ dev->device_info->ih_ring_entry_size,
> > -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ sizeof(uint32_t))];
> > +ÂÂÂ if (dev->device_info->ih_ring_entry_size > (4 * sizeof(uint32_t))) {
> > +ÂÂÂÂÂÂÂ dev_err(kfd_chardev(), "Ring entry too small\n");
> > +ÂÂÂÂÂÂÂ return;
> > +ÂÂÂ }
> > ÂÂÂÂÂ while (dequeue_ih_ring_entry(dev, ih_ring_entry))
> > ÂÂÂÂÂÂÂÂÂ dev->device_info->event_interrupt_class->interrupt_wq(dev,