From ecff80fcd1607ea1b84bd15cfcd1c33c0c5f1a87 Mon Sep 17 00:00:00 2001
From: Hans Petter Selasky <hps@selasky.org>
Date: Tue, 18 Aug 2020 20:51:08 +0200
Subject: [PATCH] Fix for crash when using the JACK backend and quickly
 reconfiguring.

Need to ensure that JACK callbacks see the running flag as false after
being stopped. Use a QMutex for this.

Signed-off-by: Hans Petter Selasky <hps@selasky.org>
---
 linux/sound.cpp   |  3 +++
 src/soundbase.cpp | 10 +++++-----
 src/soundbase.h   |  2 ++
 3 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/linux/sound.cpp b/linux/sound.cpp
index 3db291f7a9..7ea475a91a 100755
--- a/linux/sound.cpp
+++ b/linux/sound.cpp
@@ -240,6 +240,9 @@ int CSound::process ( jack_nframes_t nframes, void* arg )
     CSound* pSound = static_cast<CSound*> ( arg );
     int     i;
 
+    // make sure we are locked during execution
+    QMutexLocker locker(&pSound->MutexAudioProcessCb);
+
     if ( pSound->IsRunning() && ( nframes == static_cast<jack_nframes_t> ( pSound->iJACKBufferSizeMono ) ) )
     {
         // get input data pointer
diff --git a/src/soundbase.cpp b/src/soundbase.cpp
index 5807479c37..18b2870f5d 100755
--- a/src/soundbase.cpp
+++ b/src/soundbase.cpp
@@ -75,15 +75,15 @@ void CSoundBase::Stop()
     // set flag so that thread can leave the main loop
     bRun = false;
 
-    // give thread some time to terminate
-    if ( !bIsCallbackAudioInterface )
-    {
-        wait ( 5000 );
-    }
+    // drain the audio process callback
+    QMutexLocker locker(&MutexAudioProcessCb);
 }
 
 void CSoundBase::run()
 {
+    // make sure we are locked during execution
+    QMutexLocker locker(&MutexAudioProcessCb);
+
     // main loop of working thread
     while ( bRun )
     {
diff --git a/src/soundbase.h b/src/soundbase.h
index ab588a4678..562482a238 100755
--- a/src/soundbase.h
+++ b/src/soundbase.h
@@ -26,6 +26,7 @@
 
 #include <QThread>
 #include <QString>
+#include <QMutex>
 #ifndef HEADLESS
 # include <QMessageBox>
 #endif
@@ -137,6 +138,7 @@ class CSoundBase : public QThread
 
     void run();
     bool bRun;
+    QMutex MutexAudioProcessCb;
 
     void             ParseMIDIMessage ( const CVector<uint8_t>& vMIDIPaketBytes );