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
