linux-kernel - [tip:perf/urgent] perf, nmi: Fix unknown NMI warning

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Date:	Fri, 21 Feb 2014 13:14:08 -0800
From:	tip-bot for Markus Metzger <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	peterz@...radead.org, ak@...ux.intel.com,
	markus.t.metzger@...el.com, tglx@...utronix.de
Subject: [tip:perf/urgent] perf, nmi: Fix unknown NMI warning

Commit-ID:  a3ef2229c94ff70998724cb64b9cb4c77db9e950
Gitweb:     http://git.kernel.org/tip/a3ef2229c94ff70998724cb64b9cb4c77db9e950
Author:     Markus Metzger <markus.t.metzger@...el.com>
AuthorDate: Fri, 14 Feb 2014 16:44:08 -0800
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Fri, 21 Feb 2014 22:09:01 +0100

perf, nmi: Fix unknown NMI warning

When using BTS on Core i7-4*, I get the below kernel warning.

$ perf record -c 1 -e branches:u ls
Message from syslogd@...pc1501 at Nov 11 15:49:25 ...
 kernel:[  438.317893] Uhhuh. NMI received for unknown reason 31 on CPU 2.

Message from syslogd@...pc1501 at Nov 11 15:49:25 ...
 kernel:[  438.317920] Do you have a strange power saving mode enabled?

Message from syslogd@...pc1501 at Nov 11 15:49:25 ...
 kernel:[  438.317945] Dazed and confused, but trying to continue

Make intel_pmu_handle_irq() take the full exit path when returning early.

Cc: eranian@...gle.com
Cc: peterz@...radead.org
Cc: mingo@...nel.org
Signed-off-by: Markus Metzger <markus.t.metzger@...el.com>
Signed-off-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/r/1392425048-5309-1-git-send-email-andi@firstfloor.org
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/kernel/cpu/perf_event_intel.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 0fa4f24..698ae77 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -1361,10 +1361,8 @@ static int intel_pmu_handle_irq(struct pt_regs *regs)
 	intel_pmu_disable_all();
 	handled = intel_pmu_drain_bts_buffer();
 	status = intel_pmu_get_status();
-	if (!status) {
-		intel_pmu_enable_all(0);
-		return handled;
-	}
+	if (!status)
+		goto done;
 
 	loops = 0;
 again:
--
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