[Qemu-devel] [PATCH 2/3] net: complete all queued packets on VM stop

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

This completes all packets, ensuring that callbacks
will not run when VM is stopped.

Cc: qemu-stable@nongnu.org
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 net/net.c | 33 ++++++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/net/net.c b/net/net.c
index 6d930ea..25fdb07 100644
--- a/net/net.c
+++ b/net/net.c
@@ -47,6 +47,7 @@
 # define CONFIG_NET_BRIDGE
 #endif
 
+static VMChangeStateEntry *net_change_state_entry;
 static QTAILQ_HEAD(, NetClientState) net_clients;
 
 const char *host_net_devices[] = {
@@ -504,7 +505,8 @@ void qemu_purge_queued_packets(NetClientState *nc)
     qemu_net_queue_purge(nc->peer->incoming_queue, nc);
 }
 
-void qemu_flush_queued_packets(NetClientState *nc)
+static
+void qemu_flush_or_purge_queued_packets(NetClientState *nc, bool purge)
 {
     nc->receive_disabled = 0;
 
@@ -518,9 +520,17 @@ void qemu_flush_queued_packets(NetClientState *nc)
          * the file descriptor (for tap, for example).
          */
         qemu_notify_event();
+    } else if (purge) {
+        /* Unable to empty the queue, purge remaining packets */
+        qemu_net_queue_purge(nc->incoming_queue, nc);
     }
 }
 
+void qemu_flush_queued_packets(NetClientState *nc)
+{
+    qemu_flush_or_purge_queued_packets(nc, false);
+}
+
 static ssize_t qemu_send_packet_async_with_flags(NetClientState *sender,
                                                  unsigned flags,
                                                  const uint8_t *buf, int size,
@@ -1168,6 +1178,22 @@ void qmp_set_link(const char *name, bool up, Error **errp)
     }
 }
 
+static void net_vm_change_state_handler(void *opaque, int running,
+                                        RunState state)
+{
+    /* Complete all queued packets, to guarantee we don't modify
+     * state later when VM is not running.
+     */
+    if (!running) {
+        NetClientState *nc;
+        NetClientState *tmp;
+
+        QTAILQ_FOREACH_SAFE(nc, &net_clients, next, tmp) {
+            qemu_flush_or_purge_queued_packets(nc, true);
+        }
+    }
+}
+
 void net_cleanup(void)
 {
     NetClientState *nc;
@@ -1183,6 +1209,8 @@ void net_cleanup(void)
             qemu_del_net_client(nc);
         }
     }
+
+    qemu_del_vm_change_state_handler(net_change_state_entry);
 }
 
 void net_check_clients(void)
@@ -1268,6 +1296,9 @@ int net_init_clients(void)
 #endif
     }
 
+    net_change_state_entry =
+        qemu_add_vm_change_state_handler(net_vm_change_state_handler, NULL);
+
     QTAILQ_INIT(&net_clients);
 
     if (qemu_opts_foreach(qemu_find_opts("netdev"), net_init_netdev, NULL, 1) == -1)
-- 
MST