From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57FF0C10F14 for ; Tue, 16 Apr 2019 16:26:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 32A7C2087C for ; Tue, 16 Apr 2019 16:26:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729321AbfDPQ0t (ORCPT ); Tue, 16 Apr 2019 12:26:49 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:59180 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726230AbfDPQ0t (ORCPT ); Tue, 16 Apr 2019 12:26:49 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9E4D980D; Tue, 16 Apr 2019 09:26:48 -0700 (PDT) Received: from [10.37.12.3] (unknown [10.37.12.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 52A753F59C; Tue, 16 Apr 2019 09:26:46 -0700 (PDT) Subject: Re: [PATCH v3 2/2] perf/arm-ccn: Clean up CPU hotplug handling To: robin.murphy@arm.com, will.deacon@arm.com Cc: mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, bigeasy@linutronix.de, peterz@infradead.org, clabbe.montjoie@gmail.com, Meng.Li@windriver.com References: <918d9bb287b1086d62415030139204aab44c2221.1555427430.git.robin.murphy@arm.com> From: Suzuki K Poulose Message-ID: Date: Tue, 16 Apr 2019 17:29:06 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <918d9bb287b1086d62415030139204aab44c2221.1555427430.git.robin.murphy@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/16/2019 04:24 PM, Robin Murphy wrote: > Like arm-cci, arm-ccn has the same issue of disabling preemption around > operations which can take mutexes. Again, remove the definite bug by > simply not trying to fight the theoretical races. And since we are > touching the hotplug handling code, take the opportunity to streamline > it, as there's really no need to store a full-sized cpumask to keep > track of a single CPU ID. > > Signed-off-by: Robin Murphy > --- > drivers/perf/arm-ccn.c | 25 +++++++++++++------------ > 1 file changed, 13 insertions(+), 12 deletions(-) > > diff --git a/drivers/perf/arm-ccn.c b/drivers/perf/arm-ccn.c > index 2ae76026e947..0bb52d9bdcf7 100644 > --- a/drivers/perf/arm-ccn.c > +++ b/drivers/perf/arm-ccn.c > @@ -167,7 +167,7 @@ struct arm_ccn_dt { > > struct hrtimer hrtimer; > > - cpumask_t cpu; > + unsigned int cpu; > struct hlist_node node; > > struct pmu pmu; > @@ -559,7 +559,7 @@ static ssize_t arm_ccn_pmu_cpumask_show(struct device *dev, > { > struct arm_ccn *ccn = pmu_to_arm_ccn(dev_get_drvdata(dev)); > > - return cpumap_print_to_pagebuf(true, buf, &ccn->dt.cpu); > + return cpumap_print_to_pagebuf(true, buf, cpumask_of(ccn->dt.cpu)); > } > > static struct device_attribute arm_ccn_pmu_cpumask_attr = > @@ -759,7 +759,7 @@ static int arm_ccn_pmu_event_init(struct perf_event *event) > * mitigate this, we enforce CPU assignment to one, selected > * processor (the one described in the "cpumask" attribute). > */ > - event->cpu = cpumask_first(&ccn->dt.cpu); > + event->cpu = ccn->dt.cpu; > > node_xp = CCN_CONFIG_NODE(event->attr.config); > type = CCN_CONFIG_TYPE(event->attr.config); > @@ -1215,15 +1215,15 @@ static int arm_ccn_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node) > struct arm_ccn *ccn = container_of(dt, struct arm_ccn, dt); > unsigned int target; > > - if (!cpumask_test_and_clear_cpu(cpu, &dt->cpu)) > + if (cpu != dt->cpu) > return 0; > target = cpumask_any_but(cpu_online_mask, cpu); > if (target >= nr_cpu_ids) > return 0; > perf_pmu_migrate_context(&dt->pmu, cpu, target); > - cpumask_set_cpu(target, &dt->cpu); > + dt->cpu = target; > if (ccn->irq) > - WARN_ON(irq_set_affinity_hint(ccn->irq, &dt->cpu) != 0); > + WARN_ON(irq_set_affinity_hint(ccn->irq, cpumask_of(dt->cpu))); > return 0; > } > > @@ -1299,29 +1299,30 @@ static int arm_ccn_pmu_init(struct arm_ccn *ccn) > } > > /* Pick one CPU which we will use to collect data from CCN... */ > - cpumask_set_cpu(get_cpu(), &ccn->dt.cpu); > + ccn->dt.cpu = raw_smp_processor_id(); > > /* Also make sure that the overflow interrupt is handled by this CPU */ > if (ccn->irq) { > - err = irq_set_affinity_hint(ccn->irq, &ccn->dt.cpu); > + err = irq_set_affinity_hint(ccn->irq, cpumask_of(ccn->dt.cpu)); > if (err) { > dev_err(ccn->dev, "Failed to set interrupt affinity!\n"); > goto error_set_affinity; > } > } > > + cpuhp_state_add_instance_nocalls(CPUHP_AP_PERF_ARM_CCN_ONLINE, > + &ccn->dt.node); > + > err = perf_pmu_register(&ccn->dt.pmu, name, -1); > if (err) > goto error_pmu_register; > > - cpuhp_state_add_instance_nocalls(CPUHP_AP_PERF_ARM_CCN_ONLINE, > - &ccn->dt.node); > - put_cpu(); > return 0; > > error_pmu_register: > + cpuhp_state_remove_instance_nocalls(CPUHP_AP_PERF_ARM_CCN_ONLINE, > + &ccn->dt.node); > error_set_affinity: > - put_cpu(); Super minor nit: We don't need the error_set_affinity label anymore, as we don't do anything here. Otherwise: Reviewed-by: Suzuki K Poulose