> -----Original Message----- > From: Robin Murphy [mailto:robin.murphy@xxxxxxx] > Sent: 03 October 2018 11:37 > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx>; > lorenzo.pieralisi@xxxxxxx > Cc: will.deacon@xxxxxxx; mark.rutland@xxxxxxx; Guohanjun (Hanjun Guo) > <guohanjun@xxxxxxxxxx>; John Garry <john.garry@xxxxxxxxxx>; > pabba@xxxxxxxxxxxxxx; vkilari@xxxxxxxxxxxxxx; rruigrok@xxxxxxxxxxxxxx; > linux-acpi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm- > kernel@xxxxxxxxxxxxxxxxxxx; Linuxarm <linuxarm@xxxxxxxxxx>; > neil.m.leeder@xxxxxxxxx > Subject: Re: [PATCH v3 2/3] perf: add arm64 smmuv3 pmu driver > > On 21/09/18 16:08, Shameer Kolothum wrote: > [...] > > + > > + err = cpuhp_state_add_instance_nocalls(cpuhp_state_num, > > + &smmu_pmu->node); > > In theory a hotplug event could happen as soon as the instance is > registered... > > > + if (err) { > > + dev_err(dev, "Error %d registering hotplug, PMU @%pa\n", > > + err, &res_0->start); > > + return err; > > + } > > + > > + /* Pick one CPU to be the preferred one to use */ > > + smmu_pmu->on_cpu = get_cpu(); > > ...so this looks too late, i.e. a race here can result in a bogus call > to perf_pmu_migrate_context() with an uninitialised pmu. Thanks Robin. I will reorder them. Shameer > Robin. > > + WARN_ON(irq_set_affinity(smmu_pmu->irq, cpumask_of(smmu_pmu- > >on_cpu))); > > + > > + err = perf_pmu_register(&smmu_pmu->pmu, name, -1); > > + if (err) { > > + dev_err(dev, "Error %d registering PMU @%pa\n", > > + err, &res_0->start); > > + goto out_unregister; > > + } > > + > > + put_cpu();
