Messages in this thread | | | Date | Thu, 16 Jul 2020 11:30:59 +0100 | From | Will Deacon <> | Subject | Re: [PATCH] drivers/perf: Fix kernel panic when rmmod PMU modules during perf sampling |
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On Thu, Jul 16, 2020 at 11:26:25AM +0100, Robin Murphy wrote: > On 2020-07-16 10:41, Will Deacon wrote: > > On Thu, Jul 16, 2020 at 05:19:25PM +0800, Qi Liu wrote: > > > Kernel panic will also happen when users try to unbind PMU drivers with > > > device. This unbind issue could be solved by another patch latter. > > > > > > drivers/perf/arm_smmuv3_pmu.c | 1 + > > > drivers/perf/fsl_imx8_ddr_perf.c | 1 + > > > drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c | 1 + > > > drivers/perf/hisilicon/hisi_uncore_hha_pmu.c | 1 + > > > drivers/perf/hisilicon/hisi_uncore_l3c_pmu.c | 1 + > > > 5 files changed, 5 insertions(+) > > > > > > diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c > > > index 48e28ef..90caba56 100644 > > > --- a/drivers/perf/arm_smmuv3_pmu.c > > > +++ b/drivers/perf/arm_smmuv3_pmu.c > > > @@ -742,6 +742,7 @@ static int smmu_pmu_probe(struct platform_device *pdev) > > > platform_set_drvdata(pdev, smmu_pmu); > > > > > > smmu_pmu->pmu = (struct pmu) { > > > + .module = THIS_MODULE, > > > > I thought platform_driver_register() did this automatically? > > For the platform device itself, yes, but this is for the PMU device - perf > needs to take a reference to the module, otherwise the platform device can > still be pulled out from under its feet.
Urgh, gross.
> I can't remember if we ever discussed making perf_pmu_register() do the same > trick as platform_device_register() and friends, but obviously it's a > possibility.
Yeah, but I suppose this patch is the right thing to do for now. I'll queue it as a fix.
Will
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