[Qemu-devel] [PATCHv2 4/6] virtio-net: stop/start bh on vm start/stop

["Michael S. Tsirkin" <mst@redhat.com>]

Avoid sending out packets, and modifying
device state, when VM is stopped.

Add a bunch or assert statements to verify this does not happen.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Jason Wang <jasowang@redhat.com>
---
 hw/virtio-net.c |   36 ++++++++++++++++++++++++++----------
 1 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 43a2b3d..366a801 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -675,11 +675,12 @@ static int32_t virtio_net_flush_tx(VirtIONet *n, VirtQueue *vq)
 {
     VirtQueueElement elem;
     int32_t num_packets = 0;
-
     if (!(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK)) {
         return num_packets;
     }
 
+    assert(n->vm_running);
+
     if (n->async_tx.elem.out_num) {
         virtio_queue_set_notification(n->tx_vq, 0);
         return num_packets;
@@ -737,6 +738,7 @@ static int32_t virtio_net_flush_tx(VirtIONet *n, VirtQueue *vq)
 static void virtio_net_handle_tx_timer(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIONet *n = to_virtio_net(vdev);
+    assert(n->vm_running);
 
     if (n->tx_waiting) {
         virtio_queue_set_notification(vq, 1);
@@ -754,6 +756,7 @@ static void virtio_net_handle_tx_timer(VirtIODevice *vdev, VirtQueue *vq)
 static void virtio_net_handle_tx_bh(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIONet *n = to_virtio_net(vdev);
+    assert(n->vm_running);
 
     if (unlikely(n->tx_waiting)) {
         return;
@@ -766,6 +769,7 @@ static void virtio_net_handle_tx_bh(VirtIODevice *vdev, VirtQueue *vq)
 static void virtio_net_tx_timer(void *opaque)
 {
     VirtIONet *n = opaque;
+    assert(n->vm_running);
 
     n->tx_waiting = 0;
 
@@ -781,6 +785,9 @@ static void virtio_net_tx_bh(void *opaque)
 {
     VirtIONet *n = opaque;
     int32_t ret;
+    if (!n->vm_running) {
+        return;
+    }
 
     n->tx_waiting = 0;
 
@@ -926,15 +933,6 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
         }
     }
     n->mac_table.first_multi = i;
-
-    if (n->tx_waiting) {
-        if (n->tx_timer) {
-            qemu_mod_timer(n->tx_timer,
-                           qemu_get_clock(vm_clock) + n->tx_timeout);
-        } else {
-            qemu_bh_schedule(n->tx_bh);
-        }
-    }
     return 0;
 }
 
@@ -962,6 +960,24 @@ static void virtio_net_vmstate_change(void *opaque, int running, int reason)
      * it will start/stop vhost backend if appropriate
      * e.g. after migration. */
     virtio_net_set_status(&n->vdev, n->vdev.status);
+
+    if (!n->tx_waiting) {
+        return;
+    }
+    if (running) {
+        if (n->tx_timer) {
+            qemu_mod_timer(n->tx_timer,
+                           qemu_get_clock(vm_clock) + n->tx_timeout);
+        } else {
+            qemu_bh_schedule(n->tx_bh);
+        }
+    } else {
+        if (n->tx_timer) {
+            qemu_del_timer(n->tx_timer);
+        } else {
+            qemu_bh_cancel(n->tx_bh);
+        }
+    }
 }
 
 VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf,
-- 
1.7.3.2.91.g446ac