Guard with a mutex in QOpenGLProgramBinaryCache where needed

While there is likely no example of it in Qt itself, applications can
use QOpenGLShaderProgram instances on different threads. These instances
have nothing to do with each other but they do share a global cache object.
This becomes problematic without proper synchronization.

Change-Id: I80faf73f34af7e67349eee916bb3f216e22c07fd
Fixes: QTBUG-77469
Reviewed-by: Christian Strømme <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/gui/opengl/qopenglprogrambinarycache.cpp b/src/gui/opengl/qopenglprogrambinarycache.cpp
index af48cdacc79..40237b9935e 100644
--- a/src/gui/opengl/qopenglprogrambinarycache.cpp
+++ b/src/gui/opengl/qopenglprogrambinarycache.cpp
@@ -263,6 +263,7 @@ public:
 
 bool QOpenGLProgramBinaryCache::load(const QByteArray &cacheKey, uint programId)
 {
+    QMutexLocker lock(&m_mutex);
     if (m_memCache.contains(cacheKey)) {
         const MemCacheEntry *e = m_memCache[cacheKey];
         return setProgramBinary(programId, e->format, e->blob.constData(), e->blob.size());
@@ -401,6 +402,7 @@ void QOpenGLProgramBinaryCache::save(const QByteArray &cacheKey, uint programId)
     GLint outSize = 0;
 #if defined(QT_OPENGL_ES_2)
     if (context->isOpenGLES() && context->format().majorVersion() < 3) {
+        QMutexLocker lock(&m_mutex);
         initializeProgramBinaryOES(context);
         getProgramBinaryOES(programId, blobSize, &outSize, &blobFormat, p);
     } else