From cada1d8d5107b95ef6be094bd663490652adfd4e Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Thu, 14 May 2009 14:52:17 +0200
Subject: [PATCH] --- yaml --- r: 147455 b: refs/heads/master c:
 a4016a79fcbd139e7378944c0d86a39fdbc70ecc h: refs/heads/master i:   147453:
 13407e6686b245a63aff59c4e461e380b5fc0e26   147451:
 dd80159656fc98216dd5c57b8e0c3f89db14096e   147447:
 df72c8ee150f7f789b502b1c38e61f8aa923a44a   147439:
 335f59e2e19af0552c04ee067bef32af2f3f9716   147423:
 26ac0b54945c79b8edb01abaeb776747dffa0a0d   147391:
 63ffa2e237dc9f3a7b61642a2340ca8aa9bc2696   147327:
 db523527f7e036f89a5601f3e4a27cc09aa13886   147199:
 dd9b4770d2d761042403aa92d79655517c7be861   146943:
 5d9e81e75e4d303065e6ebc3d299eb1b13be5a55   146431:
 943ba7b8f6994e5aaef3e14ea8e01655525fc647   145407:
 166de486808a60d90701b0818a1c9c31faaad02b   143359:
 808b3c9e30989b03e7757567bebd8f8dadb0602a   139263:
 78d0ae86fae40371c332f42aaab3a939df3e8856   131071:
 5e1d55329a1e76f29215b146a22e31dd45999a04 v: v3

---
 [refs]                                   |  2 +-
 trunk/arch/x86/kernel/cpu/perf_counter.c | 16 +++++++++++++---
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/[refs] b/[refs]
index 2350a88e96db..250cf050efb7 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 9e35ad388bea89f7d6f375af4c0ae98803688666
+refs/heads/master: a4016a79fcbd139e7378944c0d86a39fdbc70ecc
diff --git a/trunk/arch/x86/kernel/cpu/perf_counter.c b/trunk/arch/x86/kernel/cpu/perf_counter.c
index 313638cecbb5..1dcf67057f16 100644
--- a/trunk/arch/x86/kernel/cpu/perf_counter.c
+++ b/trunk/arch/x86/kernel/cpu/perf_counter.c
@@ -783,6 +783,10 @@ static int amd_pmu_handle_irq(struct pt_regs *regs, int nmi)
 
 		counter = cpuc->counters[idx];
 		hwc = &counter->hw;
+
+		if (counter->hw_event.nmi != nmi)
+			goto next;
+
 		val = x86_perf_counter_update(counter, hwc, idx);
 		if (val & (1ULL << (x86_pmu.counter_bits - 1)))
 			goto next;
@@ -869,7 +873,6 @@ perf_counter_nmi_handler(struct notifier_block *self,
 {
 	struct die_args *args = __args;
 	struct pt_regs *regs;
-	int ret;
 
 	if (!atomic_read(&active_counters))
 		return NOTIFY_DONE;
@@ -886,9 +889,16 @@ perf_counter_nmi_handler(struct notifier_block *self,
 	regs = args->regs;
 
 	apic_write(APIC_LVTPC, APIC_DM_NMI);
-	ret = x86_pmu.handle_irq(regs, 1);
+	/*
+	 * Can't rely on the handled return value to say it was our NMI, two
+	 * counters could trigger 'simultaneously' raising two back-to-back NMIs.
+	 *
+	 * If the first NMI handles both, the latter will be empty and daze
+	 * the CPU.
+	 */
+	x86_pmu.handle_irq(regs, 1);
 
-	return ret ? NOTIFY_STOP : NOTIFY_OK;
+	return NOTIFY_STOP;
 }
 
 static __read_mostly struct notifier_block perf_counter_nmi_notifier = {