linux-kernel - [PATCH] perf, nmi: fix unknown NMI warning

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Date:	Tue, 11 Feb 2014 15:51:33 -0800
From:	Andi Kleen <andi@...stfloor.org>
To:	peterz@...radead.org
Cc:	linux-kernel@...r.kernel.org,
	Markus Metzger <markus.t.metzger@...el.com>,
	Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH] perf, nmi: fix unknown NMI warning

From: Markus Metzger <markus.t.metzger@...el.com>

[From Markus, just sending for him because he had problems with his mail]

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.

Signed-off-by: Markus Metzger <markus.t.metzger@...el.com>
Signed-off-by: Andi Kleen <ak@...ux.intel.com>
---
 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:
-- 
1.8.5.3

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