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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8C7E1C2BB41 for ; Tue, 16 Aug 2022 09:23:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232862AbiHPJXD (ORCPT ); Tue, 16 Aug 2022 05:23:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39252 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230481AbiHPJWi (ORCPT ); Tue, 16 Aug 2022 05:22:38 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1DB1BFAA7; Tue, 16 Aug 2022 00:37:32 -0700 (PDT) Received: from canpemm500009.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4M6NFc11jZzlVxF; Tue, 16 Aug 2022 15:34:28 +0800 (CST) Received: from [10.67.102.169] (10.67.102.169) by canpemm500009.china.huawei.com (7.192.105.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 16 Aug 2022 15:37:30 +0800 CC: , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH] drivers/perf: Change WARN_ON() to dev_err() on irq_set_affinity() failure To: Mark Rutland References: <20220815092815.11597-1-yangyicong@huawei.com> From: Yicong Yang Message-ID: <2e0c3a14-d308-dfd2-debe-8a52a3db47cc@huawei.com> Date: Tue, 16 Aug 2022 15:37:29 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.102.169] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500009.china.huawei.com (7.192.105.203) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/8/15 19:25, Mark Rutland wrote: > On Mon, Aug 15, 2022 at 05:28:15PM +0800, Yicong Yang wrote: >> From: Yicong Yang >> >> The WARN_ON() on irq_set_affinity() failure is misused according to the [1] >> and may crash people's box unintentionally. This may also be redundant since >> in the failure case we may also trigger the WARN and dump the stack in the >> perf core[2] for a second time. > > In what way do you think are these misused? I can't immediately see what you > think applies from [1]. As commented by irq_set_affinity() it "Fails if cpumask does not contain an online CPU" which means we passed an invalid input, I think which violiates the "Do not use these macros when checking for invalid external inputs". > > In perf we rely upon interrupt affinity to enforce serialization in a few > places, so if we fail to set the interrupt affinity there are a number of > things which could go wrong (e.g. memory corruption, and all the fun that could > result from that). We use WARN_ON() to catch that early. > If we'd like to catch this failure information early maybe a dev_err() should be enough to indicate this. > I can't immediately see how [2] is relevant, since that's in the context of an > IPI handler, and this patch affects the affinity of the PMU HW IRQ handler. > I think it's relevant (please correct me) as when I debug another pmu driver using MSI interrupt[*], I found I'll trigger the WARN() in [2] if the interrupt is not bind to the CPU which start trace. So I think it's required to handle the interrupt on the same CPU start the trace otherwise the "context" is mismatched. [*] https://lore.kernel.org/lkml/20220721130116.43366-3-yangyicong@huawei.com/ Thanks. > Thanks, > Mark. > >> >> So change the WARN_ON() to dev_err() to just print the failure message. >> >> [1] https://github.com/torvalds/linux/blob/master/include/asm-generic/bug.h#L74 >> [2] https://github.com/torvalds/linux/blob/master/kernel/events/core.c#L313 >> >> Suggested-by: Greg KH >> [https://lore.kernel.org/lkml/YuOi3i0XHV++z1YI@kroah.com/] >> Signed-off-by: Yicong Yang >> --- >> drivers/perf/arm-ccn.c | 5 +++-- >> drivers/perf/arm_dmc620_pmu.c | 3 ++- >> drivers/perf/arm_smmuv3_pmu.c | 6 ++++-- >> drivers/perf/fsl_imx8_ddr_perf.c | 3 ++- >> drivers/perf/hisilicon/hisi_pcie_pmu.c | 6 ++++-- >> drivers/perf/hisilicon/hisi_uncore_pmu.c | 6 ++++-- >> drivers/perf/qcom_l2_pmu.c | 8 ++++++-- >> drivers/perf/xgene_pmu.c | 6 ++++-- >> 8 files changed, 29 insertions(+), 14 deletions(-) >> >> diff --git a/drivers/perf/arm-ccn.c b/drivers/perf/arm-ccn.c >> index 728d13d8e98a..83abd909ba49 100644 >> --- a/drivers/perf/arm-ccn.c >> +++ b/drivers/perf/arm-ccn.c >> @@ -1210,8 +1210,9 @@ static int arm_ccn_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node) >> return 0; >> perf_pmu_migrate_context(&dt->pmu, cpu, target); >> dt->cpu = target; >> - if (ccn->irq) >> - WARN_ON(irq_set_affinity(ccn->irq, cpumask_of(dt->cpu))); >> + if (ccn->irq && irq_set_affinity(ccn->irq, cpumask_of(dt->cpu))) >> + dev_err(ccn->dev, "Failed to set interrupt affinity\n"); >> + >> return 0; >> } >> >> diff --git a/drivers/perf/arm_dmc620_pmu.c b/drivers/perf/arm_dmc620_pmu.c >> index 280a6ae3e27c..b59d3d9eb779 100644 >> --- a/drivers/perf/arm_dmc620_pmu.c >> +++ b/drivers/perf/arm_dmc620_pmu.c >> @@ -621,7 +621,8 @@ static int dmc620_pmu_cpu_teardown(unsigned int cpu, >> perf_pmu_migrate_context(&dmc620_pmu->pmu, irq->cpu, target); >> mutex_unlock(&dmc620_pmu_irqs_lock); >> >> - WARN_ON(irq_set_affinity(irq->irq_num, cpumask_of(target))); >> + if (irq_set_affinity(irq->irq_num, cpumask_of(target))) >> + dev_err(dmc620_pmu->pmu.dev, "Failed to set interrupt affinity\n"); >> irq->cpu = target; >> >> return 0; >> diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c >> index 00d4c45a8017..05e1b3e274d7 100644 >> --- a/drivers/perf/arm_smmuv3_pmu.c >> +++ b/drivers/perf/arm_smmuv3_pmu.c >> @@ -646,7 +646,8 @@ static int smmu_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node) >> >> perf_pmu_migrate_context(&smmu_pmu->pmu, cpu, target); >> smmu_pmu->on_cpu = target; >> - WARN_ON(irq_set_affinity(smmu_pmu->irq, cpumask_of(target))); >> + if (irq_set_affinity(smmu_pmu->irq, cpumask_of(target))) >> + dev_err(smmu_pmu->dev, "Failed to set interrupt affinity\n"); >> >> return 0; >> } >> @@ -892,7 +893,8 @@ static int smmu_pmu_probe(struct platform_device *pdev) >> >> /* Pick one CPU to be the preferred one to use */ >> smmu_pmu->on_cpu = raw_smp_processor_id(); >> - WARN_ON(irq_set_affinity(smmu_pmu->irq, cpumask_of(smmu_pmu->on_cpu))); >> + if (irq_set_affinity(smmu_pmu->irq, cpumask_of(smmu_pmu->on_cpu))) >> + dev_err(dev, "Failed to set interrupt affinity\n"); >> >> err = cpuhp_state_add_instance_nocalls(cpuhp_state_num, >> &smmu_pmu->node); >> diff --git a/drivers/perf/fsl_imx8_ddr_perf.c b/drivers/perf/fsl_imx8_ddr_perf.c >> index 8e058e08fe81..c44192e2d9db 100644 >> --- a/drivers/perf/fsl_imx8_ddr_perf.c >> +++ b/drivers/perf/fsl_imx8_ddr_perf.c >> @@ -671,7 +671,8 @@ static int ddr_perf_offline_cpu(unsigned int cpu, struct hlist_node *node) >> perf_pmu_migrate_context(&pmu->pmu, cpu, target); >> pmu->cpu = target; >> >> - WARN_ON(irq_set_affinity(pmu->irq, cpumask_of(pmu->cpu))); >> + if (irq_set_affinity(pmu->irq, cpumask_of(pmu->cpu))) >> + dev_err(pmu->dev, "Failed to set interrupt affinity\n"); >> >> return 0; >> } >> diff --git a/drivers/perf/hisilicon/hisi_pcie_pmu.c b/drivers/perf/hisilicon/hisi_pcie_pmu.c >> index 21771708597d..90aed9e51396 100644 >> --- a/drivers/perf/hisilicon/hisi_pcie_pmu.c >> +++ b/drivers/perf/hisilicon/hisi_pcie_pmu.c >> @@ -655,7 +655,8 @@ static int hisi_pcie_pmu_online_cpu(unsigned int cpu, struct hlist_node *node) >> >> if (pcie_pmu->on_cpu == -1) { >> pcie_pmu->on_cpu = cpu; >> - WARN_ON(irq_set_affinity(pcie_pmu->irq, cpumask_of(cpu))); >> + if (irq_set_affinity(pcie_pmu->irq, cpumask_of(cpu))) >> + pci_err(pcie_pmu->pdev, "Failed to set interrupt affinity\n"); >> } >> >> return 0; >> @@ -681,7 +682,8 @@ static int hisi_pcie_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node) >> perf_pmu_migrate_context(&pcie_pmu->pmu, cpu, target); >> /* Use this CPU for event counting */ >> pcie_pmu->on_cpu = target; >> - WARN_ON(irq_set_affinity(pcie_pmu->irq, cpumask_of(target))); >> + if (irq_set_affinity(pcie_pmu->irq, cpumask_of(target))) >> + pci_err(pcie_pmu->pdev, "Failed to set interrupt affinity\n"); >> >> return 0; >> } >> diff --git a/drivers/perf/hisilicon/hisi_uncore_pmu.c b/drivers/perf/hisilicon/hisi_uncore_pmu.c >> index fbc8a93d5eac..74397b5ec889 100644 >> --- a/drivers/perf/hisilicon/hisi_uncore_pmu.c >> +++ b/drivers/perf/hisilicon/hisi_uncore_pmu.c >> @@ -492,7 +492,8 @@ int hisi_uncore_pmu_online_cpu(unsigned int cpu, struct hlist_node *node) >> hisi_pmu->on_cpu = cpu; >> >> /* Overflow interrupt also should use the same CPU */ >> - WARN_ON(irq_set_affinity(hisi_pmu->irq, cpumask_of(cpu))); >> + if (irq_set_affinity(hisi_pmu->irq, cpumask_of(cpu))) >> + dev_err(hisi_pmu->dev, "Failed to set interrupt affinity\n"); >> >> return 0; >> } >> @@ -525,7 +526,8 @@ int hisi_uncore_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node) >> perf_pmu_migrate_context(&hisi_pmu->pmu, cpu, target); >> /* Use this CPU for event counting */ >> hisi_pmu->on_cpu = target; >> - WARN_ON(irq_set_affinity(hisi_pmu->irq, cpumask_of(target))); >> + if (irq_set_affinity(hisi_pmu->irq, cpumask_of(target))) >> + dev_err(hisi_pmu->dev, "Failed to set interrupt affinity\n"); >> >> return 0; >> } >> diff --git a/drivers/perf/qcom_l2_pmu.c b/drivers/perf/qcom_l2_pmu.c >> index 30234c261b05..c6fe01c7e637 100644 >> --- a/drivers/perf/qcom_l2_pmu.c >> +++ b/drivers/perf/qcom_l2_pmu.c >> @@ -793,7 +793,9 @@ static int l2cache_pmu_online_cpu(unsigned int cpu, struct hlist_node *node) >> cpumask_set_cpu(cpu, &l2cache_pmu->cpumask); >> cluster_pmu_reset(); >> >> - WARN_ON(irq_set_affinity(cluster->irq, cpumask_of(cpu))); >> + if (irq_set_affinity(cluster->irq, cpumask_of(cpu))) >> + dev_err(&l2cache_pmu->pdev->dev, >> + "Failed to set interrupt affinity\n"); >> enable_irq(cluster->irq); >> >> return 0; >> @@ -831,7 +833,9 @@ static int l2cache_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node) >> perf_pmu_migrate_context(&l2cache_pmu->pmu, cpu, target); >> cluster->on_cpu = target; >> cpumask_set_cpu(target, &l2cache_pmu->cpumask); >> - WARN_ON(irq_set_affinity(cluster->irq, cpumask_of(target))); >> + if (irq_set_affinity(cluster->irq, cpumask_of(target))) >> + dev_err(&l2cache_pmu->pdev->dev, >> + "Failed to set interrupt affinity\n"); >> >> return 0; >> } >> diff --git a/drivers/perf/xgene_pmu.c b/drivers/perf/xgene_pmu.c >> index 0c32dffc7ede..f31e678fdb69 100644 >> --- a/drivers/perf/xgene_pmu.c >> +++ b/drivers/perf/xgene_pmu.c >> @@ -1790,7 +1790,8 @@ static int xgene_pmu_online_cpu(unsigned int cpu, struct hlist_node *node) >> cpumask_set_cpu(cpu, &xgene_pmu->cpu); >> >> /* Overflow interrupt also should use the same CPU */ >> - WARN_ON(irq_set_affinity(xgene_pmu->irq, &xgene_pmu->cpu)); >> + if (irq_set_affinity(xgene_pmu->irq, &xgene_pmu->cpu)) >> + dev_err(xgene_pmu->dev, "Failed to set interrupt affinity\n"); >> >> return 0; >> } >> @@ -1823,7 +1824,8 @@ static int xgene_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node) >> >> cpumask_set_cpu(target, &xgene_pmu->cpu); >> /* Overflow interrupt also should use the same CPU */ >> - WARN_ON(irq_set_affinity(xgene_pmu->irq, &xgene_pmu->cpu)); >> + if (irq_set_affinity(xgene_pmu->irq, &xgene_pmu->cpu)) >> + dev_err(xgene_pmu->dev, "Failed to set interrupt affinity\n"); >> >> return 0; >> } >> -- >> 2.24.0 >> > . >