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* [PATCH] drm/virtio: fix vq wait_event condition
@ 2018-04-03  9:59 Gerd Hoffmann
  2018-04-20  7:22 ` Gerd Hoffmann
  0 siblings, 1 reply; 3+ messages in thread
From: Gerd Hoffmann @ 2018-04-03  9:59 UTC (permalink / raw)
  To: dri-devel
  Cc: amagloire, Gerd Hoffmann, stable, David Airlie,
	open list:VIRTIO GPU DRIVER, open list

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: Alain Magloire <amagloire@blackberry.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 drivers/gpu/drm/virtio/virtgpu_vq.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 48e4f1df6e..020070d483 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -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 {
-- 
2.9.3

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2018-04-23  1:24 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2018-04-03  9:59 [PATCH] drm/virtio: fix vq wait_event condition Gerd Hoffmann
2018-04-20  7:22 ` Gerd Hoffmann
2018-04-23  1:24   ` Dave Airlie

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