diff options
Diffstat (limited to 'drivers/virtio/virtio_ring.c')
| -rw-r--r-- | drivers/virtio/virtio_ring.c | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index a5fadc40c448..68b9136847af 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -376,6 +376,33 @@ bool virtqueue_enable_cb(struct virtqueue *_vq) } EXPORT_SYMBOL_GPL(virtqueue_enable_cb); +bool virtqueue_enable_cb_delayed(struct virtqueue *_vq) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + u16 bufs; + + START_USE(vq); + + /* We optimistically turn back on interrupts, then check if there was + * more to do. */ + /* Depending on the VIRTIO_RING_F_USED_EVENT_IDX feature, we need to + * either clear the flags bit or point the event index at the next + * entry. Always do both to keep code simple. */ + vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; + /* TODO: tune this threshold */ + bufs = (u16)(vq->vring.avail->idx - vq->last_used_idx) * 3 / 4; + vring_used_event(&vq->vring) = vq->last_used_idx + bufs; + virtio_mb(); + if (unlikely((u16)(vq->vring.used->idx - vq->last_used_idx) > bufs)) { + END_USE(vq); + return false; + } + + END_USE(vq); + return true; +} +EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed); + void *virtqueue_detach_unused_buf(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); |