From 6369fec5be0aad4965bb13cc8f26a621ff39cc65 Mon Sep 17 00:00:00 2001 From: Toshiaki Makita Date: Tue, 3 Jul 2018 16:31:34 +0900 Subject: [PATCH] vhost_net: Avoid rx vring kicks during busyloop We may run out of avail rx ring descriptor under heavy load but busypoll did not detect it so busypoll may have exited prematurely. Avoid this by checking rx ring full during busypoll. Signed-off-by: Toshiaki Makita Acked-by: Jason Wang Signed-off-by: David S. Miller --- drivers/vhost/net.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 791bc8b22aac..b2240361f1a1 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -658,6 +658,7 @@ static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk, { struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX]; 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); @@ -677,7 +678,8 @@ static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk, *busyloop_intr = true; break; } - if (sk_has_rx_data(sk) || + if ((sk_has_rx_data(sk) && + !vhost_vq_avail_empty(&net->dev, rvq)) || !vhost_vq_avail_empty(&net->dev, tvq)) break; cpu_relax(); @@ -827,7 +829,6 @@ static void handle_rx(struct vhost_net *net) while ((sock_len = vhost_net_rx_peek_head_len(net, sock->sk, &busyloop_intr))) { - busyloop_intr = false; sock_len += sock_hlen; vhost_len = sock_len + vhost_hlen; headcount = get_rx_bufs(vq, vq->heads + nvq->done_idx, @@ -838,7 +839,9 @@ static void handle_rx(struct vhost_net *net) goto out; /* OK, now we need to know about added descriptors. */ if (!headcount) { - if (unlikely(vhost_enable_notify(&net->dev, vq))) { + if (unlikely(busyloop_intr)) { + vhost_poll_queue(&vq->poll); + } else if (unlikely(vhost_enable_notify(&net->dev, vq))) { /* They have slipped one in as we were * doing that: check again. */ vhost_disable_notify(&net->dev, vq); @@ -848,6 +851,7 @@ static void handle_rx(struct vhost_net *net) * they refilled. */ goto out; } + busyloop_intr = false; if (nvq->rx_ring) msg.msg_control = vhost_net_buf_consume(&nvq->rxq); /* On overrun, truncate and discard */ -- 2.45.2