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Commit 03057f26 authored by Robin Murphy's avatar Robin Murphy Committed by Arnd Bergmann
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perf/arm-cci: Simplify CPU hotplug 



Realistically, systems with multiple CCIs are unlikely to ever exist,
and since the driver only actually supports a single instance anyway
there's really no need to do the multi-instance hotplug state dance.

Take the opportunity to simplify the hotplug-related code all over,
addressing the context-migration TODO in the process for good measure.

Acked-by: default avatarPunit Agrawal <punit.agrawal@arm.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
parent 3de6be7a

drivers/perf/arm-cci.c

+19 −37
Original line number Diff line number Diff line
@@ -90,6 +90,7 @@ static struct cci_pmu_model cci_pmu_models[]; 
struct cci_pmu {

	void __iomem *base;

	struct pmu pmu;

	int cpu;

	int nr_irqs;

	int *irqs;

	unsigned long active_irqs;
@@ -99,12 +100,12 @@ struct cci_pmu { 
	int num_cntrs;

	atomic_t active_events;

	struct mutex reserve_mutex;

	struct hlist_node node;

	cpumask_t cpus;

};



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



static struct cci_pmu *g_cci_pmu;



enum cci_models {

#ifdef CONFIG_ARM_CCI400_PMU

	CCI400_R0,
@@ -1325,7 +1326,6 @@ static int cci_pmu_event_init(struct perf_event *event) 
	struct cci_pmu *cci_pmu = to_cci_pmu(event->pmu);

	atomic_t *active_events = &cci_pmu->active_events;

	int err = 0;

	int cpu;



	if (event->attr.type != event->pmu->type)

		return -ENOENT;
@@ -1352,10 +1352,9 @@ static int cci_pmu_event_init(struct perf_event *event) 
	 * the event being installed into its context, so the PMU's CPU can't

	 * change under our feet.

	 */

	cpu = cpumask_first(&cci_pmu->cpus);

	if (event->cpu < 0 || cpu < 0)

	if (event->cpu < 0)

		return -EINVAL;

	event->cpu = cpu;

	event->cpu = cci_pmu->cpu;



	event->destroy = hw_perf_event_destroy;

	if (!atomic_inc_not_zero(active_events)) {
@@ -1382,11 +1381,7 @@ static ssize_t pmu_cpumask_attr_show(struct device *dev, 
	struct pmu *pmu = dev_get_drvdata(dev);

	struct cci_pmu *cci_pmu = to_cci_pmu(pmu);



	int n = scnprintf(buf, PAGE_SIZE - 1, "%*pbl",

			  cpumask_pr_args(&cci_pmu->cpus));

	buf[n++] = '\n';

	buf[n] = '\0';

	return n;

	return cpumap_print_to_pagebuf(true, buf, cpumask_of(cci_pmu->cpu));

}



static struct device_attribute pmu_cpumask_attr =
@@ -1455,21 +1450,19 @@ static int cci_pmu_init(struct cci_pmu *cci_pmu, struct platform_device *pdev) 
	return perf_pmu_register(&cci_pmu->pmu, name, -1);

}



static int cci_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)

static int cci_pmu_offline_cpu(unsigned int cpu)

{

	struct cci_pmu *cci_pmu = hlist_entry_safe(node, struct cci_pmu, node);

	unsigned int target;

	int target;



	if (!cpumask_test_and_clear_cpu(cpu, &cci_pmu->cpus))

	if (!g_cci_pmu || cpu != g_cci_pmu->cpu)

		return 0;



	target = cpumask_any_but(cpu_online_mask, cpu);

	if (target >= nr_cpu_ids)

		return 0;

	/*

	 * TODO: migrate context once core races on event->ctx have

	 * been fixed.

	 */

	cpumask_set_cpu(target, &cci_pmu->cpus);



	perf_pmu_migrate_context(&g_cci_pmu->pmu, cpu, target);

	g_cci_pmu->cpu = target;

	return 0;

}
@@ -1706,7 +1699,7 @@ static int cci_pmu_probe(struct platform_device *pdev) 
	raw_spin_lock_init(&cci_pmu->hw_events.pmu_lock);

	mutex_init(&cci_pmu->reserve_mutex);

	atomic_set(&cci_pmu->active_events, 0);

	cpumask_set_cpu(get_cpu(), &cci_pmu->cpus);

	cci_pmu->cpu = get_cpu();



	ret = cci_pmu_init(cci_pmu, pdev);

	if (ret) {
@@ -1714,9 +1707,11 @@ static int cci_pmu_probe(struct platform_device *pdev) 
		return ret;

	}



	cpuhp_state_add_instance_nocalls(CPUHP_AP_PERF_ARM_CCI_ONLINE,

					 &cci_pmu->node);

	cpuhp_setup_state_nocalls(CPUHP_AP_PERF_ARM_CCI_ONLINE,

				  "perf/arm/cci:online", NULL,

				  cci_pmu_offline_cpu);

	put_cpu();

	g_cci_pmu = cci_pmu;

	pr_info("ARM %s PMU driver probed", cci_pmu->model->name);

	return 0;

}
@@ -1729,19 +1724,6 @@ static struct platform_driver cci_pmu_driver = { 
	.probe = cci_pmu_probe,

};



static int __init cci_platform_init(void)

{

	int ret;



	ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_CCI_ONLINE,

				      "perf/arm/cci:online", NULL,

				      cci_pmu_offline_cpu);

	if (ret)

		return ret;



	return platform_driver_register(&cci_pmu_driver);

}



device_initcall(cci_platform_init);

builtin_platform_driver(cci_pmu_driver);

MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("ARM CCI PMU support");