[tip:perf/pebs] perf, x86: Fix PEBS enable/disable vs cpuc->enabled

[tip-bot for Peter Zijlstra]

Commit-ID:  4807e3d5dc7bb7057dd6ca3abb09f3da2eb8c323
Gitweb:     http://git.kernel.org/tip/4807e3d5dc7bb7057dd6ca3abb09f3da2eb8c323
Author:     Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Sat, 6 Mar 2010 13:47:07 +0100
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 10 Mar 2010 13:23:36 +0100

perf, x86: Fix PEBS enable/disable vs cpuc->enabled

We should never call ->enable with the pmu enabled, and we _can_ have
->disable called with the pmu enabled.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxx>
Cc: paulus@xxxxxxxxx
Cc: eranian@xxxxxxxxxx
Cc: robert.richter@xxxxxxx
Cc: fweisbec@xxxxxxxxx
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 arch/x86/kernel/cpu/perf_event_intel_ds.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 66c6962..9ad0e67 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -338,7 +338,7 @@ static void intel_pmu_pebs_enable(struct perf_event *event)
 	hwc->config &= ~ARCH_PERFMON_EVENTSEL_INT;
 
 	val |= 1ULL << hwc->idx;
-	wrmsrl(MSR_IA32_PEBS_ENABLE, val);
+	WARN_ON_ONCE(cpuc->enabled);
 
 	if (x86_pmu.intel_cap.pebs_trap)
 		intel_pmu_lbr_enable(event);
@@ -351,7 +351,8 @@ static void intel_pmu_pebs_disable(struct perf_event *event)
 	u64 val = cpuc->pebs_enabled;
 
 	val &= ~(1ULL << hwc->idx);
-	wrmsrl(MSR_IA32_PEBS_ENABLE, val);
+	if (cpuc->enabled)
+		wrmsrl(MSR_IA32_PEBS_ENABLE, val);
 
 	hwc->config |= ARCH_PERFMON_EVENTSEL_INT;
 
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