[Intel-gfx] [PATCH 1/2] tests/gem_eio: New ABI - no EIO even from wait_ioctl

[Chris Wilson]

On Thu, Nov 26, 2015 at 12:34:34PM +0100, Daniel Vetter wrote:
> So there's 3 competing proposals for what wait_ioctl should do wrt
> -EIO:
> 
> - return -EIO when the gpu is wedged. Not terribly useful for
>   userspace since it might race with a hang and then there's no
>   guarantee that a subsequent execbuf won't end up in an -EIO.
>   Terminally wedge really can only be reliably signalled at execbuf
>   time, and userspace needs to cope with that (or decide not to
>   bother).
> 
> - EIO for any obj that suffered from a reset. This means big internal
>   reorginazation in the kernel since currently we track reset stats
>   per-ctx and not on the obj. That's also what arb robustness wants.
>   We could do this, but this feels like new ABI territory with the
>   usual userspace requirements and high hurdles.
> 
> - No -EIO at all. Consistent with set_domain_ioctl and simplest to
>   implement. Which is what this patch does.

Since no one else is weighing into the ABI discussion, I'm happy with
losing EIO here. I thought it could be useful, but as no one is using or
seems likely to start using it, begone.

> We can always opt to change this later on if there's a real need.
> 
> To make the test really exercise this do a full wedged gpu hang, to
> make sure -EIO doesn't leak out at all.
> 
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
>  tests/gem_eio.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/gem_eio.c b/tests/gem_eio.c
> index a24c8f1c53b5..8345d1a7a429 100644
> --- a/tests/gem_eio.c
> +++ b/tests/gem_eio.c
> @@ -161,10 +161,14 @@ static void test_wait(int fd)
>  {
>  	igt_hang_ring_t hang;
>  
> +	igt_require(i915_reset_control(false));

However, this is not required to test the ABI change above as the wait
itself will still hang, whether or not it wedges the GPU.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre