remote_daemon_stream: Fix @client locking in daemonStreamFilter()

When dispatching a message read from client it is first passed
through registered filters. If one of the filters consumes the
message no further processing of the message is done. However,
the filter callbacks are called with the client object locked.
This breaks lock ordering in case of virStream filter, we always
acquire stream private data lock without the client object
locked. In other words, the daemonStreamFilter() does not follow
the lock ordering.
Signed-off-by: NLanceLiu <liu.lance.89@gmail.com>
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>

src/remote/remote_daemon_stream.c

@@ -286,14 +286,16 @@ daemonStreamEvent(virStreamPtr st, int events, void *opaque)
  * -1 on fatal client error
  */
 static int
-daemonStreamFilter(virNetServerClientPtr client G_GNUC_UNUSED,
+daemonStreamFilter(virNetServerClientPtr client,
                    virNetMessagePtr msg,
                    void *opaque)
 {
     daemonClientStream *stream = opaque;
     int ret = 0;
 
+    virObjectUnlock(client);
     virMutexLock(&stream->priv->lock);
+    virObjectLock(client);
 
     if (msg->header.type != VIR_NET_STREAM &&
         msg->header.type != VIR_NET_STREAM_HOLE)

src/rpc/virnetserverclient.h

@@ -40,6 +40,9 @@ typedef void (*virNetServerClientDispatchFunc)(virNetServerClientPtr client,
                                                virNetMessagePtr msg,
                                                void *opaque);
 
+/*
+ * @client is locked when this callback is called
+ */
 typedef int (*virNetServerClientFilterFunc)(virNetServerClientPtr client,
                                             virNetMessagePtr msg,
                                             void *opaque);