[PATCH v3] drm/virtio: conditionally allocate virtio_gpu_fence

[Dmitry Osipenko]

On 7/7/23 18:43, Gurchetan Singh wrote:
> @@ -161,21 +157,27 @@ static int virtio_gpu_init_submit(struct virtio_gpu_submit *submit,
>  				  struct drm_file *file,
>  				  u64 fence_ctx, u32 ring_idx)
>  {
> +	int err;
> +	struct virtio_gpu_fence *out_fence;
>  	struct virtio_gpu_fpriv *vfpriv = file->driver_priv;
>  	struct virtio_gpu_device *vgdev = dev->dev_private;
> -	struct virtio_gpu_fence *out_fence;
> -	int err;
> +	bool drm_fence_event = (exbuf->flags & VIRTGPU_EXECBUF_RING_IDX) &&
> +			       (vfpriv->ring_idx_mask & BIT_ULL(ring_idx));

Previously, when VIRTGPU_EXECBUF_RING_IDX flag wasn't specified, the
fence event was created for a default ring_idx=0. Now you changed this
behaviour and event will never be created without
VIRTGPU_EXECBUF_RING_IDX flag being set.

Could you please point me at the corresponding userspace code that polls
DRM FD fence event?

It's unclear whether there is a possible userspace regression here or
not. If there is no regression, then in general such behavioural changes
should be done in a separate commit having detailed description
explaining why behaviour changes.

-- 
Best regards,
Dmitry