[GIT pull] perf fix for 4.19

From: Thomas Gleixner
Date: Sat Sep 29 2018 - 14:25:51 EST


Greg,

please pull the latest perf-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-for-linus

A single fix for a missing sanity check when a pinned event is tried to be
read on the wrong CPU due to a legit event scheduling failure.

Thanks,

tglx

------------------>
Reinette Chatre (1):
perf/core: Add sanity check to deal with pinned event failure


kernel/events/core.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index c80549bf82c6..dcb093e7b377 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3935,6 +3935,12 @@ int perf_event_read_local(struct perf_event *event, u64 *value,
goto out;
}

+ /* If this is a pinned event it must be running on this CPU */
+ if (event->attr.pinned && event->oncpu != smp_processor_id()) {
+ ret = -EBUSY;
+ goto out;
+ }
+
/*
* If the event is currently on this CPU, its either a per-task event,
* or local to this CPU. Furthermore it means its ACTIVE (otherwise