From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965087AbbJ0Qr0 (ORCPT ); Tue, 27 Oct 2015 12:47:26 -0400 Received: from foss.arm.com ([217.140.101.70]:57564 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965050AbbJ0QrY (ORCPT ); Tue, 27 Oct 2015 12:47:24 -0400 Date: Tue, 27 Oct 2015 16:47:20 +0000 From: Will Deacon To: roy.qing.li@gmail.com Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] ARM: perf: ensure the cpu is available to scheduler when set irq affinity Message-ID: <20151027164720.GH20208@arm.com> References: <1445414162-12414-1-git-send-email-roy.qing.li@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1445414162-12414-1-git-send-email-roy.qing.li@gmail.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 21, 2015 at 03:56:02PM +0800, roy.qing.li@gmail.com wrote: > From: Li RongQing > > when there are 4 cpus, but only one is available to schedule, the warning > will be generated when run the below command: > # perf record -g -e cpu-clock -- find / -name "*.ko" > CPU PMU: unable to set irq affinity (irq=28, cpu=1) > CPU PMU: unable to set irq affinity (irq=29, cpu=2) > CPU PMU: unable to set irq affinity (irq=30, cpu=3) > > so ensure the cpu is available to scheduler when set irq affinity > > Signed-off-by: Li RongQing > --- > drivers/perf/arm_pmu.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c > index 2365a32..9401aa8 100644 > --- a/drivers/perf/arm_pmu.c > +++ b/drivers/perf/arm_pmu.c > @@ -619,6 +619,9 @@ static void cpu_pmu_free_irq(struct arm_pmu *cpu_pmu) > if (cpu_pmu->irq_affinity) > cpu = cpu_pmu->irq_affinity[i]; > > + if (!cpu_online(cpu)) > + continue; > + > if (!cpumask_test_and_clear_cpu(cpu, &cpu_pmu->active_irqs)) > continue; > irq = platform_get_irq(pmu_device, i); > @@ -665,6 +668,9 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler) > if (cpu_pmu->irq_affinity) > cpu = cpu_pmu->irq_affinity[i]; > > + if (!cpu_online(cpu)) > + continue; > + Isn't this all racy against concurrent hotplug events? We're probably better off requesting the IRQs at PMU probe time, since we no longer have to worry about sharing the IRQ lines with other subsystems such as oprofile, which is why it was designed this way originally. Will