From 4ea355b5368bde0574c12430df53334c4be3bdcf Mon Sep 17 00:00:00 2001
From: Michael Ellerman <michael@ellerman.id.au>
Date: Fri, 28 Jun 2013 18:15:14 +1000
Subject: [PATCH] powerpc/perf: Don't enable if we have zero events
In power_pmu_enable() we still enable the PMU even if we have zero
events. This should have no effect but doesn't make much sense. Instead
just return after telling the hypervisor that we are not using the PMCs.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
CC: <stable@vger.kernel.org> [v3.10]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
arch/powerpc/perf/core-book3s.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 1bb26d586e3c7a..c91dc43e04de2d 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -926,6 +926,11 @@ static void power_pmu_enable(struct pmu *pmu)
if (!cpuhw->disabled)
goto out;
+ if (cpuhw->n_events == 0) {
+ ppc_set_pmu_inuse(0);
+ goto out;
+ }
+
cpuhw->disabled = 0;
/*
@@ -937,8 +942,6 @@ static void power_pmu_enable(struct pmu *pmu)
if (!cpuhw->n_added) {
mtspr(SPRN_MMCRA, cpuhw->mmcr[2] & ~MMCRA_SAMPLE_ENABLE);
mtspr(SPRN_MMCR1, cpuhw->mmcr[1]);
- if (cpuhw->n_events == 0)
- ppc_set_pmu_inuse(0);
goto out_enable;
}
--
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