Re: [PATCH v2 8/8] drm/xe/gt_throttle: Avoid TOCTOU when monitoring reasons

[Raag Jadav <raag.jadav@intel.com>]

On Sun, Oct 26, 2025 at 10:57:20PM -0700, Lucas De Marchi wrote:
> It's currently not possible to safely monitor if there's throttling
> happening and what are the reasons. The approach of reading the status
> and then reading the reasons is not reliable as by the time sysadmin
> reads the reason, the throttling could not be happening anymore.
> 
> Previous tentative to fix that[1] was breaking the ABI and potentially
> sysadmin's scripts. This takes a different approach of adding and
> documenting the additional attribute. It's still valuable, though
> redundant, to provide the simpler 0/1 interface.
> 
> In order to avoid userspace knowledge on the bitmask meaning and to be
> able to maintain the kernel side in sync with possible changes in
> future, just walk the attribute group and check what are the masks that
> match the value read.
> 
> [1] https://lore.kernel.org/intel-xe/20241025092238.167042-1-raag.jadav@intel.com/

Thanks for looking into this, but following the recent developments on [2]
I'm beginning to have my doubts about this.

I don't have any strong opinions but we can probably hold on to this one
until we reach some conclusion on the matter.

[2] https://lore.kernel.org/intel-xe/20251014053257.3417575-2-riana.tauro@intel.com/

Raag