No reason to setup notifier on each queue of multique tap,
when we actually want to run downscript only once.
As well, let's not setup notifier, when downscript is
not enabled (downsciprt="no").

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Maksim Davydov <davydov-max@yandex-team.ru>
---
 net/tap.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/net/tap.c b/net/tap.c
index 994e885c5f..17ad561f9c 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -326,11 +326,9 @@ static void tap_exit_notify(Notifier *notifier, void *data)
     TAPState *s = container_of(notifier, TAPState, exit);
     Error *err = NULL;
 
-    if (s->down_script[0]) {
-        launch_script(s->down_script, s->down_script_arg, s->fd, &err);
-        if (err) {
-            error_report_err(err);
-        }
+    launch_script(s->down_script, s->down_script_arg, s->fd, &err);
+    if (err) {
+        error_report_err(err);
     }
 }
 
@@ -346,8 +344,11 @@ static void tap_cleanup(NetClientState *nc)
 
     qemu_purge_queued_packets(nc);
 
-    tap_exit_notify(&s->exit, NULL);
-    qemu_remove_exit_notifier(&s->exit);
+    if (s->exit.notify) {
+        tap_exit_notify(&s->exit, NULL);
+        qemu_remove_exit_notifier(&s->exit);
+        s->exit.notify = NULL;
+    }
 
     tap_read_poll(s, false);
     tap_write_poll(s, false);
@@ -443,9 +444,6 @@ static TAPState *net_tap_fd_init(NetClientState *peer,
     tap_read_poll(s, true);
     s->vhost_net = NULL;
 
-    s->exit.notify = tap_exit_notify;
-    qemu_add_exit_notifier(&s->exit);
-
     return s;
 }
 
@@ -725,6 +723,8 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
             snprintf(s->down_script, sizeof(s->down_script), "%s", downscript);
             snprintf(s->down_script_arg, sizeof(s->down_script_arg),
                      "%s", ifname);
+            s->exit.notify = tap_exit_notify;
+            qemu_add_exit_notifier(&s->exit);
         }
     }
 
-- 
2.48.1