From b0d1506b7205ebf29fa8348379f7fa85def49595 Mon Sep 17 00:00:00 2001
From: Alessandro Pasotti <elpaso@itopen.it>
Date: Wed, 12 Dec 2018 18:45:22 +0100
Subject: [PATCH] Fix QgsReadWriteLocker changeMode

since mMode was never updated, the lock
was never toggled from read to write or
vice-versa.

This was leading to crashes because the
paths that were meant to be serialized
and thread safe were not.

Fixes #20789 and probably many more
random crashes where QgsFeaturePool
was used.
---
 src/core/qgsreadwritelocker.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/core/qgsreadwritelocker.cpp b/src/core/qgsreadwritelocker.cpp
index c0c711cabdc..b71b050649d 100644
--- a/src/core/qgsreadwritelocker.cpp
+++ b/src/core/qgsreadwritelocker.cpp
@@ -34,6 +34,8 @@ void QgsReadWriteLocker::changeMode( QgsReadWriteLocker::Mode mode )
 
   unlock();
 
+  mMode = mode;
+
   if ( mMode == Read )
     mLock.lockForRead();
   else if ( mMode == Write )