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

From: Stephane Eranian
Date: Thu Nov 12 2015 - 05:00:19 EST

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

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(-)


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