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Date: Tue, 16 Aug 2022 00:25:10 +1200
From: Barry Song <21cnbao@...il.com>
To: Mark Rutland <mark.rutland@....com>
Cc: Yicong Yang <yangyicong@...wei.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, yangyicong@...ilicon.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 Tue, Aug 16, 2022 at 12:06 AM Mark Rutland <mark.rutland@....com> 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].
>
> 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.
Hi Mark,
If this is the case, is it better for us to return an ERROR after
printing a dev_err then
let the driver fail?
I really don't understand how a WARN_ON can help fix or even alert something is
wrong if we always need a successful irq_sey_affinity to make the driver work.
>
> 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.
>
> 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
> >
Thanks
Barry
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