[GIT pull] perf fix for 4.19

[Thomas Gleixner]

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