Multiple threads might call _glapi_check_multithread at roughly the same
time. It is possbile that all of them are wrongly regarded as firstCall
if there is no mutex. This bug causes xeglthreads to crash sometimes.
---
src/mesa/glapi/glapi.c | 29 +++++++++++++++--------------
1 files changed, 15 insertions(+), 14 deletions(-)
diff --git a/src/mesa/glapi/glapi.c b/src/mesa/glapi/glapi.c
index 2b105d0..30aec20 100644
--- a/src/mesa/glapi/glapi.c
+++ b/src/mesa/glapi/glapi.c
@@ -198,6 +198,7 @@ PUBLIC const void *_glapi_Context = NULL;
#if defined(THREADS)
+_glthread_DECLARE_STATIC_MUTEX(ThreadCheckMutex);
static GLboolean ThreadSafe = GL_FALSE; /**< In thread-safe mode? */
_glthread_TSD _gl_DispatchTSD; /**< Per-thread dispatch pointer */
static _glthread_TSD ContextTSD; /**< Per-thread context pointer */
@@ -231,23 +232,23 @@ void
_glapi_check_multithread(void)
{
#if defined(THREADS) && !defined(GLX_USE_TLS)
- if (!ThreadSafe) {
- static unsigned long knownID;
- static GLboolean firstCall = GL_TRUE;
- if (firstCall) {
- knownID = _glthread_GetID();
- firstCall = GL_FALSE;
- }
- else if (knownID != _glthread_GetID()) {
- ThreadSafe = GL_TRUE;
- _glapi_set_dispatch(NULL);
- _glapi_set_context(NULL);
- }
+ static unsigned long knownID;
+ static GLboolean firstCall = GL_TRUE;
+
+ if (ThreadSafe)
+ return;
+
+ _glthread_LOCK_MUTEX(ThreadCheckMutex);
+ if (firstCall) {
+ knownID = _glthread_GetID();
+ firstCall = GL_FALSE;
}
- else if (!_glapi_get_dispatch()) {
- /* make sure that this thread's dispatch pointer isn't null */
+ else if (knownID != _glthread_GetID()) {
+ ThreadSafe = GL_TRUE;
_glapi_set_dispatch(NULL);
+ _glapi_set_context(NULL);
}
+ _glthread_UNLOCK_MUTEX(ThreadCheckMutex);
#endif
}
--
1.6.2.4
------------------------------------------------------------------------------
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