Commit dc151282 authored by Tonghao Zhang's avatar Tonghao Zhang Committed by David S. Miller
Browse files

net: vhost: factor out busy polling logic to vhost_net_busy_poll() 



Factor out generic busy polling logic and will be
used for in tx path in the next patch. And with the patch,
qemu can set differently the busyloop_timeout for rx queue.

To avoid duplicate codes, introduce the helper functions:
* sock_has_rx_data(changed from sk_has_rx_data)
* vhost_net_busy_poll_try_queue

Signed-off-by: default avatarTonghao Zhang <xiangxia.m.yue@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a6a67a2f

drivers/vhost/net.c

+70 −40
Original line number Diff line number Diff line
@@ -480,6 +480,74 @@ signal_used: 
	nvq->batched_xdp = 0;

}



static int sock_has_rx_data(struct socket *sock)

{

	if (unlikely(!sock))

		return 0;



	if (sock->ops->peek_len)

		return sock->ops->peek_len(sock);



	return skb_queue_empty(&sock->sk->sk_receive_queue);

}



static void vhost_net_busy_poll_try_queue(struct vhost_net *net,

					  struct vhost_virtqueue *vq)

{

	if (!vhost_vq_avail_empty(&net->dev, vq)) {

		vhost_poll_queue(&vq->poll);

	} else if (unlikely(vhost_enable_notify(&net->dev, vq))) {

		vhost_disable_notify(&net->dev, vq);

		vhost_poll_queue(&vq->poll);

	}

}



static void vhost_net_busy_poll(struct vhost_net *net,

				struct vhost_virtqueue *rvq,

				struct vhost_virtqueue *tvq,

				bool *busyloop_intr,

				bool poll_rx)

{

	unsigned long busyloop_timeout;

	unsigned long endtime;

	struct socket *sock;

	struct vhost_virtqueue *vq = poll_rx ? tvq : rvq;



	mutex_lock_nested(&vq->mutex, poll_rx ? VHOST_NET_VQ_TX: VHOST_NET_VQ_RX);

	vhost_disable_notify(&net->dev, vq);

	sock = rvq->private_data;



	busyloop_timeout = poll_rx ? rvq->busyloop_timeout:

				     tvq->busyloop_timeout;



	preempt_disable();

	endtime = busy_clock() + busyloop_timeout;



	while (vhost_can_busy_poll(endtime)) {

		if (vhost_has_work(&net->dev)) {

			*busyloop_intr = true;

			break;

		}



		if ((sock_has_rx_data(sock) &&

		     !vhost_vq_avail_empty(&net->dev, rvq)) ||

		    !vhost_vq_avail_empty(&net->dev, tvq))

			break;



		cpu_relax();

	}



	preempt_enable();



	if (poll_rx || sock_has_rx_data(sock))

		vhost_net_busy_poll_try_queue(net, vq);

	else if (!poll_rx) /* On tx here, sock has no rx data. */

		vhost_enable_notify(&net->dev, rvq);



	mutex_unlock(&vq->mutex);

}





static int vhost_net_tx_get_vq_desc(struct vhost_net *net,

				    struct vhost_net_virtqueue *nvq,

				    unsigned int *out_num, unsigned int *in_num,
@@ -897,16 +965,6 @@ static int peek_head_len(struct vhost_net_virtqueue *rvq, struct sock *sk) 
	return len;

}



static int sk_has_rx_data(struct sock *sk)

{

	struct socket *sock = sk->sk_socket;



	if (sock->ops->peek_len)

		return sock->ops->peek_len(sock);



	return skb_queue_empty(&sk->sk_receive_queue);

}



static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk,

				      bool *busyloop_intr)

{
@@ -914,41 +972,13 @@ static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk, 
	struct vhost_net_virtqueue *tnvq = &net->vqs[VHOST_NET_VQ_TX];

	struct vhost_virtqueue *rvq = &rnvq->vq;

	struct vhost_virtqueue *tvq = &tnvq->vq;

	unsigned long uninitialized_var(endtime);

	int len = peek_head_len(rnvq, sk);



	if (!len && tvq->busyloop_timeout) {

	if (!len && rvq->busyloop_timeout) {

		/* Flush batched heads first */

		vhost_net_signal_used(rnvq);

		/* Both tx vq and rx socket were polled here */

		mutex_lock_nested(&tvq->mutex, VHOST_NET_VQ_TX);

		vhost_disable_notify(&net->dev, tvq);



		preempt_disable();

		endtime = busy_clock() + tvq->busyloop_timeout;



		while (vhost_can_busy_poll(endtime)) {

			if (vhost_has_work(&net->dev)) {

				*busyloop_intr = true;

				break;

			}

			if ((sk_has_rx_data(sk) &&

			     !vhost_vq_avail_empty(&net->dev, rvq)) ||

			    !vhost_vq_avail_empty(&net->dev, tvq))

				break;

			cpu_relax();

		}



		preempt_enable();



		if (!vhost_vq_avail_empty(&net->dev, tvq)) {

			vhost_poll_queue(&tvq->poll);

		} else if (unlikely(vhost_enable_notify(&net->dev, tvq))) {

			vhost_disable_notify(&net->dev, tvq);

			vhost_poll_queue(&tvq->poll);

		}



		mutex_unlock(&tvq->mutex);

		vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, true);



		len = peek_head_len(rnvq, sk);

	}

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