[Intel-gfx] [PATCH i-g-t v2] lib/igt_sysfs: Let igt_sysfs_read|write return -errno

[Chris Wilson]

Quoting Michal Wajdeczko (2017-12-07 16:52:46)
> In some cases debugfs or sysfs may return errors that we
> want to check. Return -errno from helper functions to make
> asserts easier.
> 
> v2: don't forget about EOF ret=0 (Chris)
>     small re-write (Michal)
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

Just tests/drv_hangman.c needs to fixed to use
igt_require(sysfs >= 0);
-Chris