From f047b66cb86f27fc7b6b26a8efcacda7feefbc4f Mon Sep 17 00:00:00 2001
From: Jon Evans <jon@craftyjon.com>
Date: Sat, 8 Feb 2025 20:27:26 -0500
Subject: [PATCH] Guard against multi-threaded access to connectivity rebuild

Fixes https://gitlab.com/kicad/code/kicad/-/issues/19884
---
 pcbnew/connectivity/connectivity_algo.cpp | 1 +
 pcbnew/connectivity/connectivity_algo.h   | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/pcbnew/connectivity/connectivity_algo.cpp b/pcbnew/connectivity/connectivity_algo.cpp
index f5dae8b5d5..a96e9ff5e5 100644
--- a/pcbnew/connectivity/connectivity_algo.cpp
+++ b/pcbnew/connectivity/connectivity_algo.cpp
@@ -228,6 +228,7 @@ void CN_CONNECTIVITY_ALGO::RemoveInvalidRefs()
 
 void CN_CONNECTIVITY_ALGO::searchConnections()
 {
+    std::lock_guard lock( m_mutex );
 #ifdef PROFILE
     PROF_TIMER garbage_collection( "garbage-collection" );
 #endif
diff --git a/pcbnew/connectivity/connectivity_algo.h b/pcbnew/connectivity/connectivity_algo.h
index 641273edde..9954f715d7 100644
--- a/pcbnew/connectivity/connectivity_algo.h
+++ b/pcbnew/connectivity/connectivity_algo.h
@@ -298,6 +298,8 @@ private:
     bool                                                  m_isLocal;
     std::shared_ptr<CONNECTIVITY_DATA>                    m_globalConnectivityData;
 
+    std::mutex m_mutex;
+
     PROGRESS_REPORTER* m_progressReporter = nullptr;
 };