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Subject[patch V2 22/67] 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: Andrzej Hajda <a.hajda@samsung.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Punit Agrawal <punit.agrawal@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Suzuki K. Poulose <suzuki.poulose@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
drivers/bus/arm-cci.c | 53 +++++++++++++++++++--------------------------
include/linux/cpuhotplug.h | 1
2 files changed, 24 insertions(+), 30 deletions(-)

--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -144,12 +144,15 @@ struct cci_pmu {
int num_cntrs;
atomic_t active_events;
struct mutex reserve_mutex;
- struct notifier_block cpu_nb;
+ struct list_head entry;
cpumask_t cpus;
};

#define to_cci_pmu(c) (container_of(c, struct cci_pmu, pmu))

+static DEFINE_MUTEX(cci_pmu_mutex);
+static LIST_HEAD(cci_pmu_list);
+
enum cci_models {
#ifdef CONFIG_ARM_CCI400_PMU
CCI400_R0,
@@ -1503,31 +1506,26 @@ 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 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;
+ struct cci_pmu *cci_pmu;
unsigned int target;

- switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_DOWN_PREPARE:
+ mutex_lock(&cci_pmu_mutex);
+ list_for_each_entry(cci_pmu, &cci_pmu_list, entry) {
if (!cpumask_test_and_clear_cpu(cpu, &cci_pmu->cpus))
- break;
+ continue;
target = cpumask_any_but(cpu_online_mask, cpu);
- if (target >= nr_cpu_ids) // UP, last CPU
- break;
+ if (target >= nr_cpu_ids)
+ continue;
/*
* TODO: migrate context once core races on event->ctx have
* been fixed.
*/
cpumask_set_cpu(target, &cci_pmu->cpus);
- default:
- break;
}
-
- return NOTIFY_OK;
+ mutex_unlock(&cci_pmu_mutex);
+ return 0;
}

static struct cci_pmu_model cci_pmu_models[] = {
@@ -1766,24 +1764,13 @@ static int cci_pmu_probe(struct platform
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);
+ ret = cci_pmu_init(cci_pmu, pdev);
if (ret)
return ret;

- ret = cci_pmu_init(cci_pmu, pdev);
- if (ret) {
- unregister_cpu_notifier(&cci_pmu->cpu_nb);
- return ret;
- }
+ mutex_lock(&cci_pmu_mutex);
+ list_add(&cci_pmu->entry, &cci_pmu_list);
+ mutex_unlock(&cci_pmu_mutex);

pr_info("ARM %s PMU driver probed", cci_pmu->model->name);
return 0;
@@ -1817,6 +1804,12 @@ static int __init cci_platform_init(void
{
int ret;

+ ret = cpuhp_setup_state_nocalls(CPUHP_AP_PERF_ARM_CCI_ONLINE,
+ "AP_PERF_ARM_CCI_ONLINE", NULL,
+ cci_pmu_offline_cpu);
+ if (ret)
+ return ret;
+
ret = platform_driver_register(&cci_pmu_driver);
if (ret)
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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