From 03057f2626e955ebea88a668a6d7d699f836e5c0 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Thu, 15 Feb 2018 18:51:43 +0000 Subject: [PATCH] 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: Punit Agrawal Acked-by: Will Deacon Signed-off-by: Robin Murphy Signed-off-by: Arnd Bergmann --- drivers/perf/arm-cci.c | 56 ++++++++++++++---------------------------- 1 file changed, 19 insertions(+), 37 deletions(-) diff --git a/drivers/perf/arm-cci.c b/drivers/perf/arm-cci.c index d5f8c750fd41..242623fbce1f 100644 --- a/drivers/perf/arm-cci.c +++ b/drivers/perf/arm-cci.c @@ -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"); -- 2.45.2