From 7f0ec32526d2446fdd79b0c6c6d08e64ef9fb1f3 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Tue, 5 Sep 2017 14:17:58 +0200
Subject: [PATCH] perf/core: Remove wrong barrier

The barrier and comment make no sense:

 - if what the barrier says is true, it should be wmb() but that
   should then be part of the arch driver, not the generic code.

 - if it is an SMP barrier, there must be a matching barrier, and
   there isn't one.

So kill it.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/events/core.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6322e245176c..205a4321f678 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2097,11 +2097,6 @@ event_sched_in(struct perf_event *event,
 		event->hw.interrupts = 0;
 	}
 
-	/*
-	 * The new state must be visible before we turn it on in the hardware:
-	 */
-	smp_wmb();
-
 	perf_pmu_disable(event->pmu);
 
 	perf_set_shadow_time(event, ctx, tstamp);
-- 
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