[PATCH perf/core/urgent] perf, x86: Handle in flight IRQs on P4 platform

[Don Zickus <dzickus@redhat.com>]

From: Cyrill Gorcunov <gorcunov@gmail.com>

Stephane reported we've forgot to guard the P4 platform
against spurious in-flight performance IRQs. Fix it.

[ the patch is a complement to commit 63e6be6d98e1 ]

Reported-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
CC: Robert Richter <robert.richter@amd.com>
CC: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
---
 arch/x86/kernel/cpu/perf_event_p4.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
index b560db3..2490151 100644
--- a/arch/x86/kernel/cpu/perf_event_p4.c
+++ b/arch/x86/kernel/cpu/perf_event_p4.c
@@ -660,8 +660,12 @@ static int p4_pmu_handle_irq(struct pt_regs *regs)
 	for (idx = 0; idx < x86_pmu.num_counters; idx++) {
 		int overflow;
 
-		if (!test_bit(idx, cpuc->active_mask))
+		if (!test_bit(idx, cpuc->active_mask)) {
+			/* catch in-flight IRQs */
+			if (__test_and_clear_bit(idx, cpuc->running))
+				handled++;
 			continue;
+		}
 
 		event = cpuc->events[idx];
 		hwc = &event->hw;
-- 
1.7.2.3