[Mesa-dev] [PATCH 1/3] glsl: on UBO/SSBOs link error, the number of active blocks remains 0

[Andres Gomez]

On Sat, 2017-03-11 at 23:24 +1100, Timothy Arceri wrote:
> 
> On 10/03/17 18:53, Andres Gomez wrote:
> > 
> > According with that text it would be OK to report a different number
> > than 0 when asking for the active UBOs to the failed link program but
> > it still will be not OK that, when trying to use that active UBOs, we
> > would get a SIGSEV.
> 
> That is is because of an application bug (not checking that link was 
> successful) not a Mesa bug.

I disagree, the one crashing is Mesa.

> > > > 
> > In other words, I think this is still a bug. The solution could be
> > different but, with current implementation, the most straight forward
> > is the patch I provided, setting the active UBOs to 0, which is
> > coherent with the rest of the internal state saved for the program.
> 
> IMO you are trying to fix something the spec doesn't say needs fixing. I 
> would be surprised if this was the only value that is reported as non 
> zero on failure. If we really wanted to reset things to zero on a link 
> failure we should have a helper that does it for all values on a link 
> failure, not one off cases like this.
> 
> > 
> > Last, this patch is solving the "regression" that was caused by Commit
> > f1293b2f9bc3.
> 
> This is not a regression, it just happens to now return the value that 
> it would be if the link didn't fail, which as far as I can tell is 
> allowed by the spec.

Again, the regression is the crash, not returning 0 or another value.

There is another possibility of fix which would be to actually set the
proper array of active uniforms so it wouldn't crash when trying to use
them.

As I commented before, setting to 0 is the most straight forward
solution and, as you also say, the spec doesn't take a stand on that.

Therefore, why wouldn't we actually do this change and avoid that
crash?

-- 
Br,

Andres
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