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

[Chad Versace]

Patch is pushed. It sat on the list for 24 hours, and
without it all the glesconform suites segfault.

On 04/23/2013 09:47 AM, Chad Versace wrote:
> 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;
>