[PATCH] allow DRM_MASTER to change client's priorities

[Andres Rodriguez]

Hey Everyone,

This series is the first spin-off from my RFC "Exclusive gpu access for SteamVR
usecases". It also includes an updated version of my priority patchset.

Some notable changes to the old priority patches:
  * Patch 1: DRM_MASTER is now allowed to allocate high priority contexts
  * Patch 1: Split HIGH into HIGH_SW and HIGH_HW, same for LOW_*
  * Patch 2: raise ring priority when a job is submitted, instead of job_run

I've also fixed the problem pointed out in the RFC thread. When all requests to
change a process's priority end, that process's contexts will return to the
priority specified at allocation time.

Changes to raise the minimum required priority for the scheduler to schedule a
job will follow in a separate series.

Series available in the wip-process-priorities-v1 branch of:
git://people.freedesktop.org/~lostgoat/linux