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Subject[PATCH 4.18 01/44] perf/core: Add sanity check to deal with pinned event failure
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Reinette Chatre <reinette.chatre@intel.com>

commit befb1b3c2703897c5b8ffb0044dc5d0e5f27c5d7 upstream.

It is possible that a failure can occur during the scheduling of a
pinned event. The initial portion of perf_event_read_local() contains
the various error checks an event should pass before it can be
considered valid. Ensure that the potential scheduling failure
of a pinned event is checked for and have a credible error.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: fenghua.yu@intel.com
Cc: tony.luck@intel.com
Cc: acme@kernel.org
Cc: gavin.hindman@intel.com
Cc: jithu.joseph@intel.com
Cc: dave.hansen@intel.com
Cc: hpa@zytor.com
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/6486385d1f30336e9973b24c8c65f5079543d3d3.1537377064.git.reinette.chatre@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3940,6 +3940,12 @@ int perf_event_read_local(struct perf_ev
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

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