From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Wed, 17 Oct 2012 16:33:42 +0100 Subject: [PATCH 5/7] ARM: perf: register cpu_notifier at driver init In-Reply-To: <1350488024-3224-1-git-send-email-will.deacon@arm.com> References: <1350488024-3224-1-git-send-email-will.deacon@arm.com> Message-ID: <1350488024-3224-6-git-send-email-will.deacon@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Mark Rutland The current practice of registering the cpu hotplug notifier at PMU registration time won't be safe with multiple PMUs, as we'll repeatedly attempt to register the notifier. This has the unfortunate effect of silently corrupting the notifier list, leading to boot stalling. Instead, register the notifier at init time. Its sanity checks will prevent anything bad from happening if the notifier is called before we have any PMUs registered. Signed-off-by: Mark Rutland Signed-off-by: Will Deacon --- arch/arm/kernel/perf_event_cpu.c | 13 +++++++++++-- 1 files changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c index 02244fa..71c824c 100644 --- a/arch/arm/kernel/perf_event_cpu.c +++ b/arch/arm/kernel/perf_event_cpu.c @@ -285,7 +285,6 @@ static int __devinit cpu_pmu_device_probe(struct platform_device *pdev) cpu_pmu = pmu; cpu_pmu->plat_device = pdev; cpu_pmu_init(cpu_pmu); - register_cpu_notifier(&cpu_pmu_hotplug_notifier); armpmu_register(cpu_pmu, cpu_pmu->name, PERF_TYPE_RAW); return 0; @@ -303,6 +302,16 @@ static struct platform_driver cpu_pmu_driver = { static int __init register_pmu_driver(void) { - return platform_driver_register(&cpu_pmu_driver); + int err; + + err = register_cpu_notifier(&cpu_pmu_hotplug_notifier); + if (err) + return err; + + err = platform_driver_register(&cpu_pmu_driver); + if (err) + unregister_cpu_notifier(&cpu_pmu_hotplug_notifier); + + return err; } device_initcall(register_pmu_driver); -- 1.7.4.1