Re: [PATCH v3] virtio-net: Fix VLAN filter table reset timing

[Michael Tokarev]

On 27.07.2025 09:22, Akihiko Odaki wrote:
...

@@ -3942,6 +3943,7 @@ static void virtio_net_device_realize(DeviceState *dev, 
Error **errp)
      n->mac_table.macs = g_malloc0(MAC_TABLE_ENTRIES * ETH_ALEN);

n->vlans = g_malloc0(MAX_VLAN >> 3);

+    memset(n->vlans, 0xff, MAX_VLAN >> 3);

A nitpick: we don't need to init this memory with 0 before
initing it with 0xff.

But looking at this, why can't we embed n->vlans directly into
this structure, something like the attached patch?

This, and maybe a few other fields like it?

Thanks,

/mjt
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 6b5b5dace3..1a79b06cff 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -931,7 +931,7 @@ static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features)
 
     if (virtio_has_feature(vdev->guest_features ^ features, VIRTIO_NET_F_CTRL_VLAN)) {
         bool vlan = virtio_has_feature(features, VIRTIO_NET_F_CTRL_VLAN);
-        memset(n->vlans, vlan ? 0 : 0xff, MAX_VLAN >> 3);
+        memset(n->vlans, vlan ? 0 : 0xff, sizeof(n->vlans));
     }
 
     if (virtio_has_feature(features, VIRTIO_NET_F_STANDBY)) {
@@ -3942,8 +3942,7 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
 
     n->mac_table.macs = g_malloc0(MAC_TABLE_ENTRIES * ETH_ALEN);
 
-    n->vlans = g_malloc0(MAX_VLAN >> 3);
-    memset(n->vlans, 0xff, MAX_VLAN >> 3);
+    memset(n->vlans, 0xff, sizeof(n->vlans));
 
     nc = qemu_get_queue(n->nic);
     nc->rxfilter_notify_enabled = 1;
@@ -3992,7 +3991,6 @@ static void virtio_net_device_unrealize(DeviceState *dev)
     n->netclient_type = NULL;
 
     g_free(n->mac_table.macs);
-    g_free(n->vlans);
 
     if (n->failover) {
         qobject_unref(n->primary_opts);
diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index 73fdefc0dc..4a0cc34ae6 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -202,7 +202,7 @@ struct VirtIONet {
         uint8_t uni_overflow;
         uint8_t *macs;
     } mac_table;
-    uint32_t *vlans;
+    uint32_t vlans[MAX_VLAN];
     virtio_net_conf net_conf;
     NICConf nic_conf;
     DeviceState *qdev;