On Tue, Aug 16, 2022 at 12:06 AM Mark Rutland <mark.rutland@xxxxxxx> wrote: > > On Mon, Aug 15, 2022 at 05:28:15PM +0800, Yicong Yang wrote: > > From: Yicong Yang <yangyicong@xxxxxxxxxxxxx> > > > > 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@xxxxxxxxxxxxxxxxxxx> > > [https://lore.kernel.org/lkml/YuOi3i0XHV++z1YI@xxxxxxxxx/] > > Signed-off-by: Yicong Yang <yangyicong@xxxxxxxxxxxxx> > > --- > > 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
