[patch 21/66] bus: arm-cci: convert to hotplug statemachine

[Anna-Maria Gleixner]

From: Sebastian Andrzej Siewior <bige...@linutronix.de>

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

Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
Cc: "Suzuki K. Poulose" <suzuki.poul...@arm.com>
Cc: Punit Agrawal <punit.agra...@arm.com>
Signed-off-by: Anna-Maria Gleixner <anna-ma...@linutronix.de>
---
 drivers/bus/arm-cci.c      |   54 +++++++++++++++------------------------------
 include/linux/cpuhotplug.h |    1 
 2 files changed, 20 insertions(+), 35 deletions(-)

--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -144,7 +144,6 @@ struct cci_pmu {
        int num_cntrs;
        atomic_t active_events;
        struct mutex reserve_mutex;
-       struct notifier_block cpu_nb;
        cpumask_t cpus;
 };
 
@@ -1503,31 +1502,22 @@ static int cci_pmu_init(struct cci_pmu *
        return perf_pmu_register(&cci_pmu->pmu, name, -1);
 }
 
-static int cci_pmu_cpu_notifier(struct notifier_block *self,
-                               unsigned long action, void *hcpu)
+static struct cci_pmu *cpuhp_cci_pmu;
+static int cci_pmu_offline_cpu(unsigned int cpu)
 {
-       struct cci_pmu *cci_pmu = container_of(self,
-                                       struct cci_pmu, cpu_nb);
-       unsigned int cpu = (long)hcpu;
        unsigned int target;
 
-       switch (action & ~CPU_TASKS_FROZEN) {
-       case CPU_DOWN_PREPARE:
-               if (!cpumask_test_and_clear_cpu(cpu, &cci_pmu->cpus))
-                       break;
-               target = cpumask_any_but(cpu_online_mask, cpu);
-               if (target >= nr_cpu_ids) // UP, last CPU
-                       break;
-               /*
-                * TODO: migrate context once core races on event->ctx have
-                * been fixed.
-                */
-               cpumask_set_cpu(target, &cci_pmu->cpus);
-       default:
-               break;
-       }
-
-       return NOTIFY_OK;
+       if (!cpumask_test_and_clear_cpu(cpu, &cpuhp_cci_pmu->cpus))
+               return 0;
+       target = cpumask_any_but(cpu_online_mask, cpu);
+       if (target >= nr_cpu_ids) // UP, last CPU
+               return 0;
+       /*
+        * TODO: migrate context once core races on event->ctx have
+        * been fixed.
+        */
+       cpumask_set_cpu(target, &cpuhp_cci_pmu->cpus);
+       return 0;
 }
 
 static struct cci_pmu_model cci_pmu_models[] = {
@@ -1765,23 +1755,17 @@ static int cci_pmu_probe(struct platform
        mutex_init(&cci_pmu->reserve_mutex);
        atomic_set(&cci_pmu->active_events, 0);
        cpumask_set_cpu(smp_processor_id(), &cci_pmu->cpus);
-
-       cci_pmu->cpu_nb = (struct notifier_block) {
-               .notifier_call  = cci_pmu_cpu_notifier,
-               /*
-                * to migrate uncore events, our notifier should be executed
-                * before perf core's notifier.
-                */
-               .priority       = CPU_PRI_PERF + 1,
-       };
-
-       ret = register_cpu_notifier(&cci_pmu->cpu_nb);
+       cpuhp_cci_pmu = cci_pmu;
+       ret = cpuhp_setup_state(CPUHP_AP_PERF_ARM_CCI_ONLINE,
+                               "AP_PERF_ARM_CCI_ONLINE", NULL,
+                               cci_pmu_offline_cpu);
        if (ret)
                return ret;
 
        ret = cci_pmu_init(cci_pmu, pdev);
        if (ret) {
-               unregister_cpu_notifier(&cci_pmu->cpu_nb);
+               cpuhp_remove_state_nocalls(CPUHP_AP_PERF_ARM_CCI_ONLINE);
+               cpuhp_cci_pmu = NULL;
                return ret;
        }
 
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -45,6 +45,7 @@ enum cpuhp_state {
        CPUHP_AP_PERF_X86_CSTATE_ONLINE,
        CPUHP_AP_PERF_S390_CF_ONLINE,
        CPUHP_AP_PERF_S390_SF_ONLINE,
+       CPUHP_AP_PERF_ARM_CCI_ONLINE,
        CPUHP_AP_NOTIFY_ONLINE,
        CPUHP_AP_ONLINE_DYN,
        CPUHP_AP_ONLINE_DYN_END         = CPUHP_AP_ONLINE_DYN + 30,