[Intel-gfx] [PATCH 2/5] drm/i915: Expose list of clients in sysfs

[Chris Wilson]

Quoting Tvrtko Ursulin (2019-12-16 12:07:01)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> Expose a list of clients with open file handles in sysfs.
> 
> This will be a basis for a top-like utility showing per-client and per-
> engine GPU load.
> 
> Currently we only expose each client's pid and name under opaque numbered
> directories in /sys/class/drm/card0/clients/.
> 
> For instance:
> 
> /sys/class/drm/card0/clients/3/name: Xorg
> /sys/class/drm/card0/clients/3/pid: 5664
> 
> v2:
>  Chris Wilson:
>  * Enclose new members into dedicated structs.
>  * Protect against failed sysfs registration.
> 
> v3:
>  * sysfs_attr_init.
> 
> v4:
>  * Fix for internal clients.
> 
> v5:
>  * Use cyclic ida for client id. (Chris)

I think we are now in the age of xa_alloc_cyclic(). At least the
immediate benefit is that we don't have to worry about the ida locking.
-Chris