[PATCH v3 0/2] perf/core: rcu fixes

[Stephane Eranian <eranian@google.com>]

This short patch series fixes some issues with RCU locking in the generic
perf layer.

Patch 1 fixes cgroup switching rcu issues related to the fact that
perf_cgroup_sched_out() and perf_cgroup_sched_in() were missing some
rcu read lock to protect the reference to the cgroup. Consequently,
we moved the rcu readlock out of perf_cgroup_switch() to avoid double
calls.

Patch 2 reinforces the testing for the rcu locking in perf cgorup code.
Either we have to hold the rcu read lock or we must have the ctx->lock
which guarantees the task cannot leave the cgroup.

Thanks to Peter and Eric from their suggestions on how to fix this correctly.

Stephane Eranian (2):
  perf/core: fix RCU problem with cgroup context switching code
  perf/core: robustify perf_cgroup_from_task rcu checks

 arch/x86/kernel/cpu/perf_event_intel_cqm.c |  2 +-
 include/linux/perf_event.h                 |  6 ++++--
 kernel/events/core.c                       | 31 ++++++++++++++++++++----------
 3 files changed, 26 insertions(+), 13 deletions(-)

-- 
2.5.0