Commit 38705bb5 authored Jul 15, 2015 by Fam Zheng Committed by Michael S. Tsirkin Jul 20, 2015

virtio-net: Flush incoming queues when DRIVER_OK is being set



This patch fixes network hang after "stop" then "cont", while network
packets keep arriving.

Tested both manually (tap, host pinging guest) and with Jason's qtest
series (plus his "[PATCH 2.4] socket: pass correct size in
net_socket_send()" fix).

As virtio_net_set_status is called when guest driver is setting status
byte and when vm state is changing, it is a good opportunity to flush
queued packets.

This is necessary because during vm stop the backend (e.g. tap) would
stop rx processing after .can_receive returns false, until the queue is
explicitly flushed or purged.

The other interesting condition in .can_receive, virtio_queue_ready(),
is handled by virtio_net_handle_rx() when guest kicks; the 3rd condition
is invalid queue index which doesn't need flushing.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

parent 9a2a6623

hw/net/virtio-net.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -162,6 +162,8 @@ static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status)
		virtio_net_vhost_status(n, status);

		for (i = 0; i < n->max_queues; i++) {
		NetClientState *ncs = qemu_get_subqueue(n->nic, i);
		bool queue_started;
		q = &n->vqs[i];

		if ((!n->multiqueue && i != 0) \|\| i >= n->curr_queues) {
		@@ -169,12 +171,18 @@ static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status)
		} else {
		queue_status = status;
		}
		queue_started =
		virtio_net_started(n, queue_status) && !n->vhost_started;

		if (queue_started) {
		qemu_flush_queued_packets(ncs);
		}

		if (!q->tx_waiting) {
		continue;
		}

		if (virtio_net_started(n, queue_status) && !n->vhost_started) {
		if (queue_started) {
		if (q->tx_timer) {
		timer_mod(q->tx_timer,
		qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + n->tx_timeout);