[PATCH 00/19] perf: Make perf_pmu_unregister() usable

[Peter Zijlstra]

Hi,

Lucas convinced me that perf_pmu_unregister() is a trainwreck; after
considering a few options I was like, how hard could it be..

So find here a few patches that clean things up in preparation and then a final
patch that makes unregistering a PMU work by introducing a new event state
(REVOKED) and ensuring that any event in such a state will never get to using
it's PMU methods ever again.