[Intel-gfx] [PATCH] drm/i915/pmu: Return -EINVAL when selecting the inactive CPU

[Chris Wilson]

Quoting Tvrtko Ursulin (2017-11-28 10:55:15)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> In commit 0426c0465461 ("drm/i915/pmu: Only allow running on a single
> CPU") I attempted to clarify the CPU hotplug logic in our PMU
> implementation, but missed that a more logical error to return, when
> attempting to initialize an event on a currently inactive CPU, is -EINVAL
> rather than -ENODEV.
> 
> This is because i915 PMU explicitly disallows running counters on more
> than one CPU at a time, and is not reporting that the requested CPU does
> not exist, or is off-line.

I would have mentioned that perf core also reports EINVAL for running on
an absent processor. (Or whatever exactly the reason that UP returned a
different error code).
 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Reported-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris