| Message ID | 20200206111416.31269-1-kraxel@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/virtio: fix ring free check | expand |
On Thu, Feb 6, 2020 at 3:14 AM Gerd Hoffmann <kraxel@redhat.com> wrote: > > If the virtio device supports indirect ring descriptors we need only one > ring entry for the whole command. Take that into account when checking > whenever the virtqueue has enough free entries for our command. > > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> > --- > drivers/gpu/drm/virtio/virtgpu_vq.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c > index 41e475fbd67b..a2ec09dba530 100644 > --- a/drivers/gpu/drm/virtio/virtgpu_vq.c > +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c > @@ -328,7 +328,8 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev, > { > struct virtqueue *vq = vgdev->ctrlq.vq; > bool notify = false; > - int ret; > + bool indirect; > + int vqcnt, ret; > > again: > spin_lock(&vgdev->ctrlq.qlock); > @@ -341,9 +342,11 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev, > return; > } > > - if (vq->num_free < elemcnt) { > + indirect = virtio_has_feature(vgdev->vdev, VIRTIO_RING_F_INDIRECT_DESC); > + vqcnt = indirect ? 1 : elemcnt; Is the feature dynamic and require the lock held? If not, the result can be cached and the fixup can happen before grabbing the lock if (vgdev->has_indirect_desc) elemcnt = 1; Either way, patch is Reviewed-by: Chia-I Wu <olvaffe@gmail.com> > + if (vq->num_free < vqcnt) { > spin_unlock(&vgdev->ctrlq.qlock); > - wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= elemcnt); > + wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= vqcnt); > goto again; > } > > -- > 2.18.1 >
Hi, > > + indirect = virtio_has_feature(vgdev->vdev, VIRTIO_RING_F_INDIRECT_DESC); > > + vqcnt = indirect ? 1 : elemcnt; > Is the feature dynamic and require the lock held? If not, the result > can be cached and the fixup can happen before grabbing the lock Not dynamic, so yes, caching makes sense. cheers, Gerd
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c index 41e475fbd67b..a2ec09dba530 100644 --- a/drivers/gpu/drm/virtio/virtgpu_vq.c +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c @@ -328,7 +328,8 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev, { struct virtqueue *vq = vgdev->ctrlq.vq; bool notify = false; - int ret; + bool indirect; + int vqcnt, ret; again: spin_lock(&vgdev->ctrlq.qlock); @@ -341,9 +342,11 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev, return; } - if (vq->num_free < elemcnt) { + indirect = virtio_has_feature(vgdev->vdev, VIRTIO_RING_F_INDIRECT_DESC); + vqcnt = indirect ? 1 : elemcnt; + if (vq->num_free < vqcnt) { spin_unlock(&vgdev->ctrlq.qlock); - wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= elemcnt); + wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= vqcnt); goto again; }
If the virtio device supports indirect ring descriptors we need only one ring entry for the whole command. Take that into account when checking whenever the virtqueue has enough free entries for our command. Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> --- drivers/gpu/drm/virtio/virtgpu_vq.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)