[Mesa-dev] [PATCH] egl/dri2: Fix min/max swap interval of configs

[Chad Versace]

The commit below exposed a bug in dri2_add_config.

    commit 3998f8c6b5da1a223926249755e54d8f701f81ab
    Author: Ralf Jung <post at ralfj.de>
    Date:   Tue Apr 9 14:09:50 2013 +0200

	egl/x11: Fix initialisation of swap_interval

This little code snippet near the bottom of dri2_add_config,

    if (double_buffer) {
       ...
       conf->base.MinSwapInterval = dri2_dpy->min_swap_interval;
       conf->base.MaxSwapInterval = dri2_dpy->max_swap_interval;
    }

it never did what it claimed to do. The assignment never changed the value
of conf->base.MaxSwapInterval, because dri2_dpy->max_swap_interval was,
until the above exposing commit, unitialized here. That is,
conf->base.MaxSwapInterval was 0 before and after assignment. Ditto for
the min swap interval.

Above the troublesome code snippet, the call to _eglFilterArray rejects
the config as unmatching if its swap interval bounds differ from the base
config's.  Before the exposing commit, at the call to _eglFilterArray, the
swap interval bounds were always [0,0], and hence no config was rejected
due to swap interval.

After the exposing commit, _eglFilterArray incorrectly rejected some
configs, which prevented dri2_egl_config::dri_double_config from getting
set for the rejected config, which resulted in a NULL pointer getting
passed into dri2CreateNewDrawable, and then segfault.

The solution: set the swap interval bounds before _eglFilterArray.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=63447
Tested-by: Lu Hua <huax.lu at intel.com>
Signed-off-by: Chad Versace <chad.versace at linux.intel.com>
---
 src/egl/drivers/dri2/egl_dri2.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/egl/drivers/dri2/egl_dri2.c b/src/egl/drivers/dri2/egl_dri2.c
index 06a21d7..1011f27 100644
--- a/src/egl/drivers/dri2/egl_dri2.c
+++ b/src/egl/drivers/dri2/egl_dri2.c
@@ -221,6 +221,9 @@ dri2_add_config(_EGLDisplay *disp, const __DRIconfig *dri_config, int id,
    base.RenderableType = disp->ClientAPIs;
    base.Conformant = disp->ClientAPIs;
 
+   base.MinSwapInterval = dri2_dpy->min_swap_interval;
+   base.MaxSwapInterval = dri2_dpy->max_swap_interval;
+
    if (!_eglValidateConfig(&base, EGL_FALSE)) {
       _eglLog(_EGL_DEBUG, "DRI2: failed to validate config %d", id);
       return NULL;
@@ -268,9 +271,6 @@ dri2_add_config(_EGLDisplay *disp, const __DRIconfig *dri_config, int id,
 
    if (double_buffer) {
       surface_type &= ~EGL_PIXMAP_BIT;
-
-      conf->base.MinSwapInterval = dri2_dpy->min_swap_interval;
-      conf->base.MaxSwapInterval = dri2_dpy->max_swap_interval;
    }
 
    conf->base.SurfaceType |= surface_type;
-- 
1.8.1.4