From: Will Deacon <will@kernel.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: mark.rutland@arm.com, john.garry@huawei.com,
linux-kernel@vger.kernel.org, linuxarm@huawei.com,
zhangshaokun@hisilicon.com, wang.wanghaifeng@huawei.com,
Qi Liu <liuqi115@huawei.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] drivers/perf: Fix kernel panic when rmmod PMU modules during perf sampling
Date: Thu, 16 Jul 2020 11:30:59 +0100 [thread overview]
Message-ID: <20200716103058.GE7036@willie-the-truck> (raw)
In-Reply-To: <a0f3d0c2-6a08-16a5-f7e9-42ac1d96ea11@arm.com>
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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next prev parent reply other threads:[~2020-07-16 10:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-16 9:19 [PATCH] drivers/perf: Fix kernel panic when rmmod PMU modules during perf sampling Qi Liu
2020-07-16 9:41 ` Will Deacon
2020-07-16 10:21 ` John Garry
2020-07-16 10:26 ` Robin Murphy
2020-07-16 10:30 ` Will Deacon [this message]
2020-07-16 10:36 ` John Garry
2020-07-16 10:44 ` Will Deacon
2020-07-16 11:09 ` John Garry
2020-07-16 12:00 ` Will Deacon
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