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Message-ID: <2e0c3a14-d308-dfd2-debe-8a52a3db47cc@huawei.com>
Date: Tue, 16 Aug 2022 15:37:29 +0800
From: Yicong Yang <yangyicong@...wei.com>
To: Mark Rutland <mark.rutland@....com>
CC: <yangyicong@...ilicon.com>, <will@...nel.org>, <Frank.li@....com>,
<shawnguo@...nel.org>, <s.hauer@...gutronix.de>,
<kernel@...gutronix.de>, <festevam@...il.com>, <linux-imx@....com>,
<zhangshaokun@...ilicon.com>, <agross@...nel.org>,
<bjorn.andersson@...aro.org>, <konrad.dybcio@...ainline.org>,
<khuong@...amperecomputing.com>, <john.garry@...wei.com>,
<jonathan.cameron@...wei.com>, <gregkh@...uxfoundation.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH] drivers/perf: Change WARN_ON() to dev_err() on
irq_set_affinity() failure
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 <yangyicong@...ilicon.com>
>>
>> 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 <gregkh@...uxfoundation.org>
>> [https://lore.kernel.org/lkml/YuOi3i0XHV++z1YI@kroah.com/]
>> Signed-off-by: Yicong Yang <yangyicong@...ilicon.com>
>> ---
>> 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
>>
> .
>
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