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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>
This commit is contained in:
Michael Ellerman 2013-06-28 18:15:14 +10:00 committed by Benjamin Herrenschmidt
parent 0a48843d6c
commit 4ea355b536
1 changed files with 5 additions and 2 deletions
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7
arch/powerpc/perf/core-book3s.c
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@ -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;
}