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Subject[patch 21/66] bus: arm-cci: convert to hotplug statemachine
From: Sebastian Andrzej Siewior <bigeasy@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 <bigeasy@linutronix.de>
Cc: "Suzuki K. Poulose" <suzuki.poulose@arm.com>
Cc: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: Anna-Maria Gleixner <anna-maria@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,

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