[Mesa-dev] Early calls to st_validate_state

[Marek Olšák]

I think the best way is not to do anything if one of the shaders is
NULL. Just like my patch that I just sent.

Marek

On Fri, Jun 26, 2015 at 3:04 AM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> Hello,
>
> A user reported a crash in wine in finalize_textures (called via
> st_validate_state). In this particular case it was happening through
> st_BlitFramebuffer (piglit test sent), but there are a number of
> callsites of st_validate_state from st/mesa.
>
> The reason it dies is that the fragment program isn't specified. Of
> course if that assumption were relaxed, it'd just crash later on in
> the process. Even though we specify _MaintainTexEnvProgram, that only
> gets bound somewhere down the line.
>
> One solution, which solved a number of different crashes for this user
> was to call _mesa_update_state(ctx) when making a context current for
> the first time. This normalizes a bunch of state, including setting
> the fragment/vertex programs which avoids the crash. Is this the right
> solution?
>
> Another thought I had was to call _mesa_update_state() from
> st_validate_state directly -- all the various state updates rely on
> mesa state being reasonable, and it seems to make sense to first flush
> those changes (which might e.g. update the currently-bound program, or
> all sorts of other things), and only then process the st's updates.
>
> However I'm unfamiliar with the reasoning behind the current system,
> so perhaps I'm also just missing something. Thoughts welcome.
>
>   -ilia