[patch 18/66] s390: perf: Convert the hotplug notifier to state machine callbacks (Counter)

[Anna-Maria Gleixner]

From: Thomas Gleixner <t...@linutronix.de>

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

Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Cc: Martin Schwidefsky <schwidef...@de.ibm.com>
Cc: Heiko Carstens <heiko.carst...@de.ibm.com>
Cc: linux-s...@vger.kernel.org
Reviewed-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-ma...@linutronix.de>
---
 arch/s390/kernel/perf_cpum_cf.c |   44 ++++++++++++++++------------------------
 include/linux/cpuhotplug.h      |    1 
 2 files changed, 19 insertions(+), 26 deletions(-)

--- a/arch/s390/kernel/perf_cpum_cf.c
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -664,30 +664,22 @@ static struct pmu cpumf_pmu = {
        .cancel_txn   = cpumf_pmu_cancel_txn,
 };
 
-static int cpumf_pmu_notifier(struct notifier_block *self, unsigned long 
action,
-                             void *hcpu)
+static int cpumf_pmf_setup(unsigned int cpu, int flags)
 {
-       int flags;
+       local_irq_disable();
+       setup_pmc_cpu(&flags);
+       local_irq_enable();
+       return 0;
+}
 
-       switch (action & ~CPU_TASKS_FROZEN) {
-       case CPU_ONLINE:
-       case CPU_DOWN_FAILED:
-               flags = PMC_INIT;
-               local_irq_disable();
-               setup_pmc_cpu(&flags);
-               local_irq_enable();
-               break;
-       case CPU_DOWN_PREPARE:
-               flags = PMC_RELEASE;
-               local_irq_disable();
-               setup_pmc_cpu(&flags);
-               local_irq_enable();
-               break;
-       default:
-               break;
-       }
+static int s390_pmu_online_cpu(unsigned int cpu)
+{
+       return cpumf_pmf_setup(cpu, PMC_INIT);
+}
 
-       return NOTIFY_OK;
+static int s390_pmu_offline_cpu(unsigned int cpu)
+{
+       return cpumf_pmf_setup(cpu, PMC_RELEASE);
 }
 
 static int __init cpumf_pmu_init(void)
@@ -707,7 +699,7 @@ static int __init cpumf_pmu_init(void)
        if (rc) {
                pr_err("Registering for CPU-measurement alerts "
                       "failed with rc=%i\n", rc);
-               goto out;
+               return rc;
        }
 
        cpumf_pmu.attr_groups = cpumf_cf_event_group();
@@ -716,10 +708,10 @@ static int __init cpumf_pmu_init(void)
                pr_err("Registering the cpum_cf PMU failed with rc=%i\n", rc);
                unregister_external_irq(EXT_IRQ_MEASURE_ALERT,
                                        cpumf_measurement_alert);
-               goto out;
+               return rc;
        }
-       perf_cpu_notifier(cpumf_pmu_notifier);
-out:
-       return rc;
+       return cpuhp_setup_state(CPUHP_AP_PERF_S390_CF_ONLINE,
+                                "AP_PERF_S390_CF_ONLINE",
+                                s390_pmu_online_cpu, s390_pmu_offline_cpu);
 }
 early_initcall(cpumf_pmu_init);
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -42,6 +42,7 @@ enum cpuhp_state {
        CPUHP_AP_PERF_X86_RAPL_ONLINE,
        CPUHP_AP_PERF_X86_CQM_ONLINE,
        CPUHP_AP_PERF_X86_CSTATE_ONLINE,
+       CPUHP_AP_PERF_S390_CF_ONLINE,
        CPUHP_AP_NOTIFY_ONLINE,
        CPUHP_AP_ONLINE_DYN,
        CPUHP_AP_ONLINE_DYN_END         = CPUHP_AP_ONLINE_DYN + 30,