powerpc/perf: Don't enable if we have zero events
Michael Ellerman [Fri, 28 Jun 2013 08:15:14 +0000 (18:15 +1000)]
commit 4ea355b5368bde0574c12430df53334c4be3bdcf upstream.

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>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/powerpc/perf/core-book3s.c

index af4b4b1..d3ee2e5 100644 (file)
@@ -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;
        }