From 37b502f121adab26ccc2769c3063f0e1272be7de Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 20 Jul 2016 09:51:11 +0200 Subject: [PATCH] arm/perf: Fix hotplug state machine conversion Mark Rutland pointed out that this commit is incomplete: 7d88eb695a1f ("arm/perf: Convert to hotplug state machine") The problem is that: > We may have multiple PMUs (e.g. two in big.LITTLE systems), and > __oprofile_cpu_pmu only contains one of these. So this conversion is not > correct. > > We were relying on the notifier list implicitly containing a list of > those PMUs. It seems like we need an explicit list here. > > We keep __oprofile_cpu_pmu around for legacy 32-bit users of OProfile > (on non-hetereogeneous systems), and that's all that the variable should > be used for. Introduce arm_pmu_list to correctly handle multiple PMUs in the system. Signed-off-by: Sebastian Andrzej Siewior Acked-by: Mark Rutland Cc: Anna-Maria Gleixner Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Cc: linux-tip-commits@vger.kernel.org Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160719111733.GA22911@linutronix.de Signed-off-by: Ingo Molnar --- drivers/perf/arm_pmu.c | 53 +++++++++++++++++++++++++----------- include/linux/perf/arm_pmu.h | 1 + 2 files changed, 38 insertions(+), 16 deletions(-) diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c index ae9fc6c6add3..f6ab4f7f75bf 100644 --- a/drivers/perf/arm_pmu.c +++ b/drivers/perf/arm_pmu.c @@ -685,6 +685,9 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler) return 0; } +static DEFINE_MUTEX(arm_pmu_mutex); +static LIST_HEAD(arm_pmu_list); + /* * PMU hardware loses all context when a CPU goes offline. * When a CPU is hotplugged back in, since some hardware registers are @@ -693,12 +696,17 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler) */ static int arm_perf_starting_cpu(unsigned int cpu) { - if (!__oprofile_cpu_pmu) - return 0; - if (!cpumask_test_cpu(cpu, &__oprofile_cpu_pmu->supported_cpus)) - return 0; - if (__oprofile_cpu_pmu->reset) - __oprofile_cpu_pmu->reset(__oprofile_cpu_pmu); + struct arm_pmu *pmu; + + mutex_lock(&arm_pmu_mutex); + list_for_each_entry(pmu, &arm_pmu_list, entry) { + + if (!cpumask_test_cpu(cpu, &pmu->supported_cpus)) + continue; + if (pmu->reset) + pmu->reset(pmu); + } + mutex_unlock(&arm_pmu_mutex); return 0; } @@ -810,11 +818,9 @@ static int cpu_pmu_init(struct arm_pmu *cpu_pmu) if (!cpu_hw_events) return -ENOMEM; - err = cpuhp_setup_state_nocalls(CPUHP_AP_PERF_ARM_STARTING, - "AP_PERF_ARM_STARTING", - arm_perf_starting_cpu, NULL); - if (err) - goto out_hw_events; + mutex_lock(&arm_pmu_mutex); + list_add_tail(&cpu_pmu->entry, &arm_pmu_list); + mutex_unlock(&arm_pmu_mutex); err = cpu_pm_pmu_register(cpu_pmu); if (err) @@ -850,8 +856,9 @@ static int cpu_pmu_init(struct arm_pmu *cpu_pmu) return 0; out_unregister: - cpuhp_remove_state_nocalls(CPUHP_AP_PERF_ARM_STARTING); -out_hw_events: + mutex_lock(&arm_pmu_mutex); + list_del(&cpu_pmu->entry); + mutex_unlock(&arm_pmu_mutex); free_percpu(cpu_hw_events); return err; } @@ -859,7 +866,9 @@ out_hw_events: static void cpu_pmu_destroy(struct arm_pmu *cpu_pmu) { cpu_pm_pmu_unregister(cpu_pmu); - cpuhp_remove_state_nocalls(CPUHP_AP_PERF_ARM_STARTING); + mutex_lock(&arm_pmu_mutex); + list_del(&cpu_pmu->entry); + mutex_unlock(&arm_pmu_mutex); free_percpu(cpu_pmu->hw_events); } @@ -1019,8 +1028,6 @@ int arm_pmu_device_probe(struct platform_device *pdev, if (ret) goto out_destroy; - WARN(__oprofile_cpu_pmu, "%s(): missing PMU strucure for CPU-hotplug\n", - __func__); if (!__oprofile_cpu_pmu) __oprofile_cpu_pmu = pmu; @@ -1038,3 +1045,17 @@ out_free: kfree(pmu); return ret; } + +static int arm_pmu_hp_init(void) +{ + int ret; + + ret = cpuhp_setup_state_nocalls(CPUHP_AP_PERF_ARM_STARTING, + "AP_PERF_ARM_STARTING", + arm_perf_starting_cpu, NULL); + if (ret) + pr_err("CPU hotplug notifier for ARM PMU could not be registered: %d\n", + ret); + return ret; +} +subsys_initcall(arm_pmu_hp_init); diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h index e6ed34eb2b2b..e18843809eec 100644 --- a/include/linux/perf/arm_pmu.h +++ b/include/linux/perf/arm_pmu.h @@ -109,6 +109,7 @@ struct arm_pmu { DECLARE_BITMAP(pmceid_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS); struct platform_device *plat_device; struct pmu_hw_events __percpu *hw_events; + struct list_head entry; struct notifier_block cpu_pm_nb; };