[Mesa-dev] [PATCH 1/2] intel: make intel_flush_front safe to call during initial MakeCurrent

Paul Berry stereotype441 at gmail.com
Thu May 30 07:44:09 PDT 2013

The patch that follows will fix a bug that prevents
intel_flush_front() from being called often enough.  In doing so, it
will create a situation where intel_flush_front() during the initial
call to glXMakeCurrent().  In this circumstance, ctx->DrawBuffer
hasn't been initialized yet and is NULL.  Fortunately,
intel->front_buffer_dirty is false, so intel_flush_front() doesn't
actually need to do anything.  To avoid a segfault, swap the order of
terms in intel_flush_front()'s if statement.
 src/mesa/drivers/dri/intel/intel_context.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mesa/drivers/dri/intel/intel_context.c b/src/mesa/drivers/dri/intel/intel_context.c
index 88cc247..495cc73 100644
--- a/src/mesa/drivers/dri/intel/intel_context.c
+++ b/src/mesa/drivers/dri/intel/intel_context.c
@@ -286,7 +286,7 @@ intel_flush_front(struct gl_context *ctx)
     __DRIdrawable *driDrawable = driContext->driDrawablePriv;
     __DRIscreen *const screen = intel->intelScreen->driScrnPriv;
-    if (_mesa_is_winsys_fbo(ctx->DrawBuffer) && intel->front_buffer_dirty) {
+    if (intel->front_buffer_dirty && _mesa_is_winsys_fbo(ctx->DrawBuffer)) {
       if (screen->dri2.loader->flushFrontBuffer != NULL &&
           driDrawable &&
           driDrawable->loaderPrivate) {

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