migration/multifd: Cleanup outgoing_args in state destroy

outgoing_args is a global cache of socket address to be reused in multifd.
Freeing the cache in per-channel destructor is more or less a hack.  Move
it to multifd_send_cleanup_state() so it only get checked once.  Use a
small helper to do so because it's internal of socket.c.

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240222095301.171137-5-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

migration/multifd.c

@@ -689,6 +689,7 @@ static bool multifd_send_cleanup_channel(MultiFDSendParams *p, Error **errp)
 
 static void multifd_send_cleanup_state(void)
 {
+    socket_cleanup_outgoing_migration();
     qemu_sem_destroy(&multifd_send_state->channels_created);
     qemu_sem_destroy(&multifd_send_state->channels_ready);
     g_free(multifd_send_state->params);

migration/socket.c

@@ -64,10 +64,6 @@ int socket_send_channel_destroy(QIOChannel *send)
 {
     /* Remove channel */
     object_unref(OBJECT(send));
-    if (outgoing_args.saddr) {
-        qapi_free_SocketAddress(outgoing_args.saddr);
-        outgoing_args.saddr = NULL;
-    }
     return 0;
 }
 
@@ -137,6 +133,14 @@ void socket_start_outgoing_migration(MigrationState *s,
                                      NULL);
 }
 
+void socket_cleanup_outgoing_migration(void)
+{
+    if (outgoing_args.saddr) {
+        qapi_free_SocketAddress(outgoing_args.saddr);
+        outgoing_args.saddr = NULL;
+    }
+}
+
 static void socket_accept_incoming_migration(QIONetListener *listener,
                                              QIOChannelSocket *cioc,
                                              gpointer opaque)

migration/socket.h

@@ -29,4 +29,6 @@ void socket_start_incoming_migration(SocketAddress *saddr, Error **errp);
 
 void socket_start_outgoing_migration(MigrationState *s,
                                      SocketAddress *saddr, Error **errp);
+void socket_cleanup_outgoing_migration(void);
+
 #endif