chardev: tcp: postpone async connection setup

This patch allows the socket chardev async connection be setup with
non-default gcontext.  We do it by postponing the setup to machine done,
since until then we can know which context we should run the async
operation on.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180306053320.15401-8-peterx@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

chardev/char-socket.c

@@ -1005,9 +1005,8 @@ static void qmp_chardev_open_socket(Chardev *chr,
         s->reconnect_time = reconnect;
     }
 
-    if (s->reconnect_time) {
-        tcp_chr_connect_async(chr);
-    } else {
+    /* If reconnect_time is set, will do that in chr_machine_done. */
+    if (!s->reconnect_time) {
         if (s->is_listen) {
             char *name;
             s->listener = qio_net_listener_new();
@@ -1139,6 +1138,17 @@ char_socket_get_connected(Object *obj, Error **errp)
     return s->connected;
 }
 
+static int tcp_chr_machine_done_hook(Chardev *chr)
+{
+    SocketChardev *s = SOCKET_CHARDEV(chr);
+
+    if (s->reconnect_time) {
+        tcp_chr_connect_async(chr);
+    }
+
+    return 0;
+}
+
 static void char_socket_class_init(ObjectClass *oc, void *data)
 {
     ChardevClass *cc = CHARDEV_CLASS(oc);
@@ -1154,6 +1164,7 @@ static void char_socket_class_init(ObjectClass *oc, void *data)
     cc->chr_add_client = tcp_chr_add_client;
     cc->chr_add_watch = tcp_chr_add_watch;
     cc->chr_update_read_handler = tcp_chr_update_read_handler;
+    cc->chr_machine_done = tcp_chr_machine_done_hook;
 
     object_class_property_add(oc, "addr", "SocketAddress",
                               char_socket_get_addr, NULL,