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From 59bdfd752c491ce0e7253d78e379b0bd8c5cd00e Mon Sep 17 00:00:00 2001
From: "Daniel P. Berrange" <berrange@redhat.com>
Date: Thu, 8 Feb 2018 17:50:18 +0100
Subject: [PATCH 04/27] vnc: return directly if no vnc client connected

RH-Author: Daniel P. Berrange <berrange@redhat.com>
Message-id: <20180208175041.5634-5-berrange@redhat.com>
Patchwork-id: 78950
O-Subject: [RHEL-7.5 qemu-kvm PATCH v1 04/27] vnc: return directly if no vnc client connected
Bugzilla: 1527405
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

From: ChenLiang <chenliang88@huawei.com>

graphic_hw_update and vnc_refresh_server_surface aren't
need to do when no vnc client connected. It can reduce
lock contention, because vnc_refresh will hold global big
lock two millisecond every three seconds.

Signed-off-by: ChenLiang <chenliang88@huawei.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit 9d6b20704734fe1ab789400806ebd54f579d50a2)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 ui/vnc.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/ui/vnc.c b/ui/vnc.c
index 42070b4..9047862 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -2677,6 +2677,11 @@ static void vnc_refresh(DisplayChangeListener *dcl)
     VncState *vs, *vn;
     int has_dirty, rects = 0;
 
+    if (QTAILQ_EMPTY(&vd->clients)) {
+        update_displaychangelistener(&vd->dcl, VNC_REFRESH_INTERVAL_MAX);
+        return;
+    }
+
     graphic_hw_update(NULL);
 
     if (vnc_trylock_display(vd)) {
@@ -2692,11 +2697,6 @@ static void vnc_refresh(DisplayChangeListener *dcl)
         /* vs might be free()ed here */
     }
 
-    if (QTAILQ_EMPTY(&vd->clients)) {
-        update_displaychangelistener(&vd->dcl, VNC_REFRESH_INTERVAL_MAX);
-        return;
-    }
-
     if (has_dirty && rects) {
         vd->dcl.update_interval /= 2;
         if (vd->dcl.update_interval < VNC_REFRESH_INTERVAL_BASE) {
-- 
1.8.3.1