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Commit d02d2700 authored by Gerd Hoffmann's avatar Gerd Hoffmann Committed by Sean Paul
Browse files

drm/virtio: fix vq wait_event condition 



Wait until we have enough space in the virt queue to actually queue up
our request.  Avoids the guest spinning in case we have a non-zero
amount of free entries but not enough for the request.

Cc: stable@vger.kernel.org
Reported-by: default avatarAlain Magloire <amagloire@blackberry.com>
Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
Reviewed-by: default avatarDave Airlie <airlied@redhat.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20180403095904.11152-1-kraxel@redhat.com


Signed-off-by: default avatarSean Paul <seanpaul@chromium.org>
parent 7a31805b

drivers/gpu/drm/virtio/virtgpu_vq.c

+2 −2
Original line number Diff line number Diff line
@@ -293,7 +293,7 @@ static int virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, 
	ret = virtqueue_add_sgs(vq, sgs, outcnt, incnt, vbuf, GFP_ATOMIC);

	if (ret == -ENOSPC) {

		spin_unlock(&vgdev->ctrlq.qlock);

		wait_event(vgdev->ctrlq.ack_queue, vq->num_free);

		wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= outcnt + incnt);

		spin_lock(&vgdev->ctrlq.qlock);

		goto retry;

	} else {
@@ -368,7 +368,7 @@ static int virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev, 
	ret = virtqueue_add_sgs(vq, sgs, outcnt, 0, vbuf, GFP_ATOMIC);

	if (ret == -ENOSPC) {

		spin_unlock(&vgdev->cursorq.qlock);

		wait_event(vgdev->cursorq.ack_queue, vq->num_free);

		wait_event(vgdev->cursorq.ack_queue, vq->num_free >= outcnt);

		spin_lock(&vgdev->cursorq.qlock);

		goto retry;

	} else {