From 6e03f31982991599e168253d3fe8629786803398 Mon Sep 17 00:00:00 2001
From: Bryan Venteicher <bryanv@FreeBSD.org>
Date: Tue, 3 Sep 2013 02:28:31 +0000
Subject: [PATCH] Complete any pending Tx frames before attempting the next
 transmit

Also complete pending frames in the watchdog function when the
EVENT_IDX feature was negotiated just in case the completion
interrupt was postponed.
---
 sys/dev/virtio/network/if_vtnet.c    | 9 +++++++++
 sys/dev/virtio/network/if_vtnetvar.h | 1 +
 2 files changed, 10 insertions(+)

diff --git a/sys/dev/virtio/network/if_vtnet.c b/sys/dev/virtio/network/if_vtnet.c
index 5ab4b970bc72..93c60075ebce 100644
--- a/sys/dev/virtio/network/if_vtnet.c
+++ b/sys/dev/virtio/network/if_vtnet.c
@@ -592,6 +592,9 @@ vtnet_setup_features(struct vtnet_softc *sc)
 
 	vtnet_negotiate_features(sc);
 
+	if (virtio_with_feature(dev, VIRTIO_RING_F_EVENT_IDX))
+		sc->vtnet_flags |= VTNET_FLAG_EVENT_IDX;
+
 	if (virtio_with_feature(dev, VIRTIO_NET_F_MAC)) {
 		/* This feature should always be negotiated. */
 		sc->vtnet_flags |= VTNET_FLAG_MAC;
@@ -2155,6 +2158,8 @@ vtnet_start_locked(struct vtnet_txq *txq, struct ifnet *ifp)
 	    sc->vtnet_link_active == 0)
 		return;
 
+	vtnet_txq_eof(txq);
+
 	while (!IFQ_DRV_IS_EMPTY(&ifp->if_snd)) {
 		if (virtqueue_full(vq))
 			break;
@@ -2226,6 +2231,8 @@ vtnet_txq_mq_start_locked(struct vtnet_txq *txq, struct mbuf *m)
 			return (error);
 	}
 
+	vtnet_txq_eof(txq);
+
 	while ((m = drbr_peek(ifp, br)) != NULL) {
 		error = vtnet_txq_encap(txq, &m);
 		if (error) {
@@ -2471,6 +2478,8 @@ vtnet_watchdog(struct vtnet_txq *txq)
 	sc = txq->vtntx_sc;
 
 	VTNET_TXQ_LOCK(txq);
+	if (sc->vtnet_flags & VTNET_FLAG_EVENT_IDX)
+		vtnet_txq_eof(txq);
 	if (txq->vtntx_watchdog == 0 || --txq->vtntx_watchdog) {
 		VTNET_TXQ_UNLOCK(txq);
 		return (0);
diff --git a/sys/dev/virtio/network/if_vtnetvar.h b/sys/dev/virtio/network/if_vtnetvar.h
index 592110308f5a..7f04a93fa122 100644
--- a/sys/dev/virtio/network/if_vtnetvar.h
+++ b/sys/dev/virtio/network/if_vtnetvar.h
@@ -138,6 +138,7 @@ struct vtnet_softc {
 #define VTNET_FLAG_MRG_RXBUFS	 0x0080
 #define VTNET_FLAG_LRO_NOMRG	 0x0100
 #define VTNET_FLAG_MULTIQ	 0x0200
+#define VTNET_FLAG_EVENT_IDX	 0x0400
 
 	int			 vtnet_link_active;
 	int			 vtnet_hdr_size;