linux-kernel - Re: [External] Re: [PATCH v3 2/2] perf/dwc_pcie: fix duplicate pci

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Message-ID: <CAEEQ3wk5AhHK5cbZ-m1ibz93qqGJ1OPXM_NE_6rWjkuPM=Gw=g@mail.gmail.com>
Date: Tue, 18 Feb 2025 16:46:08 +0800
From: yunhui cui <cuiyunhui@...edance.com>
To: Shuai Xue <xueshuai@...ux.alibaba.com>
Cc: renyu.zj@...ux.alibaba.com, will@...nel.org, mark.rutland@....com, 
	linux-arm-kernel@...ts.infradead.org, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Jonathan Cameron <Jonathan.Cameron@...wei.com>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org
Subject: Re: [External] Re: [PATCH v3 2/2] perf/dwc_pcie: fix duplicate
 pci_dev devices

Hi Shuai,

On Tue, Feb 11, 2025 at 4:02 PM Shuai Xue <xueshuai@...ux.alibaba.com> wrote:
>
>
>
> 在 2025/2/8 18:40, Yunhui Cui 写道:
> > During platform_device_register, wrongly using struct device
> > pci_dev as platform_data caused a kmemdup copy of pci_dev. Worse
> > still, accessing the duplicated device leads to list corruption as its
> > mutex content (e.g., list, magic) remains the same as the original.
> >
> > Signed-off-by: Yunhui Cui <cuiyunhui@...edance.com>
> > ---
> >   drivers/perf/dwc_pcie_pmu.c | 20 +++++++++++++-------
> >   1 file changed, 13 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/perf/dwc_pcie_pmu.c b/drivers/perf/dwc_pcie_pmu.c
> > index 19fa2ba8dd67..4f6599e32bba 100644
> > --- a/drivers/perf/dwc_pcie_pmu.c
> > +++ b/drivers/perf/dwc_pcie_pmu.c
> > @@ -565,9 +565,7 @@ static int dwc_pcie_register_dev(struct pci_dev *pdev)
> >       u32 sbdf;
> >
> >       sbdf = (pci_domain_nr(pdev->bus) << 16) | PCI_DEVID(pdev->bus->number, pdev->devfn);
> > -     plat_dev = platform_device_register_data(NULL, "dwc_pcie_pmu", sbdf,
> > -                                              pdev, sizeof(*pdev));
> > -
> > +     plat_dev = platform_device_register_simple("platform_dwc_pcie", sbdf, NULL, 0);
> >       if (IS_ERR(plat_dev))
> >               return PTR_ERR(plat_dev);
> >
> > @@ -616,18 +614,26 @@ static struct notifier_block dwc_pcie_pmu_nb = {
> >
> >   static int dwc_pcie_pmu_probe(struct platform_device *plat_dev)
> >   {
> > -     struct pci_dev *pdev = plat_dev->dev.platform_data;
> > +     struct pci_dev *pdev;
> >       struct dwc_pcie_pmu *pcie_pmu;
> >       char *name;
> >       u32 sbdf;
> >       u16 vsec;
> >       int ret;
> >
> > +     sbdf = plat_dev->id;
> > +     pdev = pci_get_domain_bus_and_slot(sbdf >> 16, PCI_BUS_NUM(sbdf & 0xffff),
> > +                                        sbdf & 0xff);
> > +     if (!pdev) {
> > +             pr_err("No pdev found for the sbdf 0x%x\n", sbdf);
> > +             return -ENODEV;
> > +     }
> > +
> >       vsec = dwc_pcie_des_cap(pdev);
> >       if (!vsec)
> >               return -ENODEV;
>
> pci_dev_put(pdev) should move ahead to aovid return here.
>
> >
> > -     sbdf = plat_dev->id;
> > +     pci_dev_put(pdev);
> >       name = devm_kasprintf(&plat_dev->dev, GFP_KERNEL, "dwc_rootport_%x", sbdf);
> >       if (!name)
> >               return -ENOMEM;
> > @@ -642,7 +648,7 @@ static int dwc_pcie_pmu_probe(struct platform_device *plat_dev)
> >       pcie_pmu->on_cpu = -1;
> >       pcie_pmu->pmu = (struct pmu){
> >               .name           = name,
> > -             .parent         = &pdev->dev,
> > +             .parent         = &plat_dev->dev,
> >               .module         = THIS_MODULE,
> >               .attr_groups    = dwc_pcie_attr_groups,
> >               .capabilities   = PERF_PMU_CAP_NO_EXCLUDE,
> > @@ -729,7 +735,7 @@ static int dwc_pcie_pmu_offline_cpu(unsigned int cpu, struct hlist_node *cpuhp_n
> >
> >   static struct platform_driver dwc_pcie_pmu_driver = {
> >       .probe = dwc_pcie_pmu_probe,
> > -     .driver = {.name = "dwc_pcie_pmu",},
> > +     .driver = {.name = "platform_dwc_pcie",},
>
> Aha, it is very difficult to come up with a name that satisfies everyone. The
> original name uses the '_pmu' suffix to follow the unwritten convention of
> other PMU drivers.
>
> Personally, I think the original name is more appropriate, but I'll leave the
> decision to @Will.

Since Will hasn't replied, I'll update to the next version to keep the
original name.

>
> Thanks.
> Best Regards.
> Shuai

Thanks,
Yunhui