diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index c9e00387d9996e3c5b0660a57bf296e4ff15f3d5..42d670a468f89462a4e31ebde531c6a0e9c3b644 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -602,7 +602,7 @@ static int virtnet_poll(struct napi_struct *napi, int budget) container_of(napi, struct receive_queue, napi); struct virtnet_info *vi = rq->vq->vdev->priv; void *buf; - unsigned int len, received = 0; + unsigned int r, len, received = 0; again: while (received < budget && @@ -619,8 +619,9 @@ static int virtnet_poll(struct napi_struct *napi, int budget) /* Out of packets? */ if (received < budget) { + r = virtqueue_enable_cb_prepare(rq->vq); napi_complete(napi); - if (unlikely(!virtqueue_enable_cb(rq->vq)) && + if (unlikely(virtqueue_poll(rq->vq, r)) && napi_schedule_prep(napi)) { virtqueue_disable_cb(rq->vq); __napi_schedule(napi); diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 5217baf5528c0ef85dca9c4282cfb081f158a30c..37d58f84dc50accce2581a9f7b7bf1485d2df7d0 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -607,19 +607,21 @@ void virtqueue_disable_cb(struct virtqueue *_vq) EXPORT_SYMBOL_GPL(virtqueue_disable_cb); /** - * virtqueue_enable_cb - restart callbacks after disable_cb. + * virtqueue_enable_cb_prepare - restart callbacks after disable_cb * @vq: the struct virtqueue we're talking about. * - * This re-enables callbacks; it returns "false" if there are pending - * buffers in the queue, to detect a possible race between the driver - * checking for more work, and enabling callbacks. + * This re-enables callbacks; it returns current queue state + * in an opaque unsigned value. This value should be later tested by + * virtqueue_poll, to detect a possible race between the driver checking for + * more work, and enabling callbacks. * * Caller must ensure we don't call this with other virtqueue * operations at the same time (except where noted). */ -bool virtqueue_enable_cb(struct virtqueue *_vq) +unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); + u16 last_used_idx; START_USE(vq); @@ -629,15 +631,45 @@ bool virtqueue_enable_cb(struct virtqueue *_vq) * 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; - vring_used_event(&vq->vring) = vq->last_used_idx; + vring_used_event(&vq->vring) = last_used_idx = vq->last_used_idx; + END_USE(vq); + return last_used_idx; +} +EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare); + +/** + * virtqueue_poll - query pending used buffers + * @vq: the struct virtqueue we're talking about. + * @last_used_idx: virtqueue state (from call to virtqueue_enable_cb_prepare). + * + * Returns "true" if there are pending used buffers in the queue. + * + * This does not need to be serialized. + */ +bool virtqueue_poll(struct virtqueue *_vq, unsigned last_used_idx) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + virtio_mb(vq->weak_barriers); - if (unlikely(more_used(vq))) { - END_USE(vq); - return false; - } + return (u16)last_used_idx != vq->vring.used->idx; +} +EXPORT_SYMBOL_GPL(virtqueue_poll); - END_USE(vq); - return true; +/** + * virtqueue_enable_cb - restart callbacks after disable_cb. + * @vq: the struct virtqueue we're talking about. + * + * This re-enables callbacks; it returns "false" if there are pending + * buffers in the queue, to detect a possible race between the driver + * checking for more work, and enabling callbacks. + * + * Caller must ensure we don't call this with other virtqueue + * operations at the same time (except where noted). + */ +bool virtqueue_enable_cb(struct virtqueue *_vq) +{ + unsigned last_used_idx = virtqueue_enable_cb_prepare(_vq); + return !virtqueue_poll(_vq, last_used_idx); } EXPORT_SYMBOL_GPL(virtqueue_enable_cb); diff --git a/include/linux/virtio.h b/include/linux/virtio.h index 9ff8645b7e0be05cee6dbbcf7498690425a1f3f4..72398eea6e86e6a1b736b05fc310f021d204bdb6 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -70,6 +70,10 @@ void virtqueue_disable_cb(struct virtqueue *vq); bool virtqueue_enable_cb(struct virtqueue *vq); +unsigned virtqueue_enable_cb_prepare(struct virtqueue *vq); + +bool virtqueue_poll(struct virtqueue *vq, unsigned); + bool virtqueue_enable_cb_delayed(struct virtqueue *vq); void *virtqueue_detach_unused_buf(struct virtqueue *vq);