powerpc/perf: Convert book3s notifier to state machine callbacks

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153334.345786236@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/powerpc/perf/core-book3s.c

@@ -2158,31 +2158,15 @@ static void perf_event_interrupt(struct pt_regs *regs)
 		irq_exit();
 }
 
-static void power_pmu_setup(int cpu)
+int power_pmu_prepare_cpu(unsigned int cpu)
 {
 	struct cpu_hw_events *cpuhw = &per_cpu(cpu_hw_events, cpu);
 
-	if (!ppmu)
-		return;
-	memset(cpuhw, 0, sizeof(*cpuhw));
-	cpuhw->mmcr[0] = MMCR0_FC;
-}
-
-static int
-power_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu)
-{
-	unsigned int cpu = (long)hcpu;
-
-	switch (action & ~CPU_TASKS_FROZEN) {
-	case CPU_UP_PREPARE:
-		power_pmu_setup(cpu);
-		break;
-
-	default:
-		break;
+	if (ppmu) {
+		memset(cpuhw, 0, sizeof(*cpuhw));
+		cpuhw->mmcr[0] = MMCR0_FC;
 	}
-
-	return NOTIFY_OK;
+	return 0;
 }
 
 int register_power_pmu(struct power_pmu *pmu)
@@ -2205,7 +2189,7 @@ int register_power_pmu(struct power_pmu *pmu)
 #endif /* CONFIG_PPC64 */
 
 	perf_pmu_register(&power_pmu, "cpu", PERF_TYPE_RAW);
-	perf_cpu_notifier(power_pmu_notifier);
-
+	cpuhp_setup_state(CPUHP_PERF_POWER, "PERF_POWER",
+			  power_pmu_prepare_cpu, NULL);
 	return 0;
 }

include/linux/cpuhotplug.h

@@ -10,6 +10,7 @@ enum cpuhp_state {
 	CPUHP_PERF_X86_AMD_UNCORE_PREP,
 	CPUHP_PERF_X86_RAPL_PREP,
 	CPUHP_PERF_BFIN,
+	CPUHP_PERF_POWER,
 	CPUHP_NOTIFY_PREPARE,
 	CPUHP_BRINGUP_CPU,
 	CPUHP_AP_IDLE_DEAD,