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.
Acked-by: Ian Romanick <[email protected]> Signed-off-by: Chia-I Wu <[email protected]> --- 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 } -- 1.6.3.3 ------------------------------------------------------------------------------ Enter the BlackBerry Developer Challenge This is your chance to win up to $100,000 in prizes! For a limited time, vendors submitting new applications to BlackBerry App World(TM) will have the opportunity to enter the BlackBerry Developer Challenge. See full prize details at: http://p.sf.net/sfu/Challenge _______________________________________________ Mesa3d-dev mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
