Re: [PATCH v3 2/2] perf/dwc_pcie: fix duplicate pci_dev devices

[Shuai Xue <xueshuai@linux.alibaba.com>]

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@bytedance.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.

Thanks.
Best Regards.
Shuai