From 60113056bc4c328f62808d1c0fa2a1abec481f78 Mon Sep 17 00:00:00 2001
From: Artem Dyomin <artem.dyomin@qt.io>
Date: Tue, 12 Sep 2023 14:46:30 +0200
Subject: [PATCH] Optimize cond var notification

Notification of a conditional variable shouldn't be under the locked
mutex, as it may affect extra mutex contentions.

Pick-to: 6.5 6.6
Change-Id: Ie8429eca3f36e9a6e8e5ad2e0337bbf508f5b326
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/thread/qsemaphore.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/corelib/thread/qsemaphore.cpp b/src/corelib/thread/qsemaphore.cpp
index c472e62698c..2437c96595b 100644
--- a/src/corelib/thread/qsemaphore.cpp
+++ b/src/corelib/thread/qsemaphore.cpp
@@ -400,8 +400,10 @@ void QSemaphore::release(int n)
         return;
     }
 
-    const auto locker = qt_scoped_lock(d->mutex);
-    d->avail += n;
+    {
+        const auto locker = qt_scoped_lock(d->mutex);
+        d->avail += n;
+    }
     d->cond.notify_all();
 }