bus/arm-cci: Convert to hotplug statemachine

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>
Signed-off-by: Anna-Maria Gleixner <anna-maria@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: Pawel Moll <pawel.moll@arm.com>
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: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153334.679142601@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index a49b28378d5994851d7e217c42738a0a7584e50d..5755907f836f8d7a6aa5c892e8eef542e6e9c678 100644 (file)
--- 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 *cci_pmu, struct platform_device *pdev)
        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_device *pdev)
        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;

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 16ab41779ca74b736ed9827a797c0bb6cb224c0b..0f2f727594fa3d140af35dd2eab0f0f43f4b2c83 100644 (file)
--- 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,