[PATCH v2 0/2] Fix dwc_pcie pmu driver issues

[PATCH v2 0/2] Fix dwc_pcie pmu driver issues

[Yunhui Cui]

v1:
Only sent the patch titled "fix duplicate pci_dev devices".

v2:
1. New patch: "fix the incorrect reference count".
2. The "fix duplicate pci_dev devices" change is made in two places:
One is to remove the modification of the PMU name. The other is to change
"for_each_pci_dev" to "pci_get_domain_bus_and_slot".

Yunhui Cui (2):
  perf/dwc_pcie: fix the incorrect reference count
  perf/dwc_pcie: fix duplicate pci_dev devices

 drivers/perf/dwc_pcie_pmu.c | 62 +++++++++++++++++++++++++------------
 1 file changed, 43 insertions(+), 19 deletions(-)

-- 
2.39.2

[PATCH v2 1/2] perf/dwc_pcie: fix the incorrect reference count

[Yunhui Cui]

for_each_pci_dev increments pdev refcount. Call pci_dev_put after access
to decrement it.

Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
---
 drivers/perf/dwc_pcie_pmu.c | 42 ++++++++++++++++++++++++++-----------
 1 file changed, 30 insertions(+), 12 deletions(-)

diff --git a/drivers/perf/dwc_pcie_pmu.c b/drivers/perf/dwc_pcie_pmu.c
index cccecae9823f..4ac53167d7ab 100644
--- a/drivers/perf/dwc_pcie_pmu.c
+++ b/drivers/perf/dwc_pcie_pmu.c
@@ -553,6 +553,7 @@ static u16 dwc_pcie_des_cap(struct pci_dev *pdev)
 
 static void dwc_pcie_unregister_dev(struct dwc_pcie_dev_info *dev_info)
 {
+	pci_dev_put(dev_info->pdev);
 	platform_device_unregister(dev_info->plat_dev);
 	list_del(&dev_info->dev_node);
 	kfree(dev_info);
@@ -572,8 +573,10 @@ static int dwc_pcie_register_dev(struct pci_dev *pdev)
 		return PTR_ERR(plat_dev);
 
 	dev_info = kzalloc(sizeof(*dev_info), GFP_KERNEL);
-	if (!dev_info)
+	if (!dev_info) {
+		platform_device_unregister(plat_dev);
 		return -ENOMEM;
+	}
 
 	/* Cache platform device to handle pci device hotplug */
 	dev_info->plat_dev = plat_dev;
@@ -594,8 +597,11 @@ static int dwc_pcie_pmu_notifier(struct notifier_block *nb,
 	case BUS_NOTIFY_ADD_DEVICE:
 		if (!dwc_pcie_des_cap(pdev))
 			return NOTIFY_DONE;
-		if (dwc_pcie_register_dev(pdev))
+		pci_dev_get(pdev);
+		if (dwc_pcie_register_dev(pdev)) {
+			pci_dev_put(pdev);
 			return NOTIFY_BAD;
+		}
 		break;
 	case BUS_NOTIFY_DEL_DEVICE:
 		dev_info = dwc_pcie_find_dev_info(pdev);
@@ -730,20 +736,29 @@ static struct platform_driver dwc_pcie_pmu_driver = {
 	.driver = {.name = "dwc_pcie_pmu",},
 };
 
+static void dwc_pcie_cleanup_devices(void)
+{
+	struct dwc_pcie_dev_info *dev_info, *tmp;
+
+	list_for_each_entry_safe(dev_info, tmp, &dwc_pcie_dev_info_head, dev_node) {
+		dwc_pcie_unregister_dev(dev_info);
+	}
+}
+
 static int __init dwc_pcie_pmu_init(void)
 {
 	struct pci_dev *pdev = NULL;
 	int ret;
 
 	for_each_pci_dev(pdev) {
-		if (!dwc_pcie_des_cap(pdev))
+		if (!dwc_pcie_des_cap(pdev)) {
+			pci_dev_put(pdev);
 			continue;
+		}
 
 		ret = dwc_pcie_register_dev(pdev);
-		if (ret) {
-			pci_dev_put(pdev);
-			return ret;
-		}
+		if (ret)
+			goto err_cleanup;
 	}
 
 	ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
@@ -751,24 +766,27 @@ static int __init dwc_pcie_pmu_init(void)
 				      dwc_pcie_pmu_online_cpu,
 				      dwc_pcie_pmu_offline_cpu);
 	if (ret < 0)
-		return ret;
+		goto err_cleanup;
 
 	dwc_pcie_pmu_hp_state = ret;
 
 	ret = platform_driver_register(&dwc_pcie_pmu_driver);
 	if (ret)
-		goto platform_driver_register_err;
+		goto err_remove_cpuhp;
 
 	ret = bus_register_notifier(&pci_bus_type, &dwc_pcie_pmu_nb);
 	if (ret)
-		goto platform_driver_register_err;
+		goto err_unregister_driver;
 	notify = true;
 
 	return 0;
 
-platform_driver_register_err:
+err_unregister_driver:
+	platform_driver_unregister(&dwc_pcie_pmu_driver);
+err_remove_cpuhp:
 	cpuhp_remove_multi_state(dwc_pcie_pmu_hp_state);
-
+err_cleanup:
+	dwc_pcie_cleanup_devices();
 	return ret;
 }
 
-- 
2.39.2

Re: [PATCH v2 1/2] perf/dwc_pcie: fix the incorrect reference count

[Shuai Xue]

在 2025/2/5 11:14, Yunhui Cui 写道:
> for_each_pci_dev increments pdev refcount. Call pci_dev_put after access
> to decrement it.
> 
> Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
> ---
>   drivers/perf/dwc_pcie_pmu.c | 42 ++++++++++++++++++++++++++-----------
>   1 file changed, 30 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/perf/dwc_pcie_pmu.c b/drivers/perf/dwc_pcie_pmu.c
> index cccecae9823f..4ac53167d7ab 100644
> --- a/drivers/perf/dwc_pcie_pmu.c
> +++ b/drivers/perf/dwc_pcie_pmu.c
> @@ -553,6 +553,7 @@ static u16 dwc_pcie_des_cap(struct pci_dev *pdev)
>   
>   static void dwc_pcie_unregister_dev(struct dwc_pcie_dev_info *dev_info)
>   {
> +	pci_dev_put(dev_info->pdev);
>   	platform_device_unregister(dev_info->plat_dev);
>   	list_del(&dev_info->dev_node);
>   	kfree(dev_info);
> @@ -572,8 +573,10 @@ static int dwc_pcie_register_dev(struct pci_dev *pdev)
>   		return PTR_ERR(plat_dev);
>   
>   	dev_info = kzalloc(sizeof(*dev_info), GFP_KERNEL);
> -	if (!dev_info)
> +	if (!dev_info) {
> +		platform_device_unregister(plat_dev);
>   		return -ENOMEM;
> +	}
>   
>   	/* Cache platform device to handle pci device hotplug */
>   	dev_info->plat_dev = plat_dev;
> @@ -594,8 +597,11 @@ static int dwc_pcie_pmu_notifier(struct notifier_block *nb,
>   	case BUS_NOTIFY_ADD_DEVICE:
>   		if (!dwc_pcie_des_cap(pdev))
>   			return NOTIFY_DONE;
> -		if (dwc_pcie_register_dev(pdev))
> +		pci_dev_get(pdev);
> +		if (dwc_pcie_register_dev(pdev)) {
> +			pci_dev_put(pdev);
>   			return NOTIFY_BAD;
> +		}
>   		break;
>   	case BUS_NOTIFY_DEL_DEVICE:
>   		dev_info = dwc_pcie_find_dev_info(pdev);
> @@ -730,20 +736,29 @@ static struct platform_driver dwc_pcie_pmu_driver = {
>   	.driver = {.name = "dwc_pcie_pmu",},
>   };
>   
> +static void dwc_pcie_cleanup_devices(void)
> +{
> +	struct dwc_pcie_dev_info *dev_info, *tmp;
> +
> +	list_for_each_entry_safe(dev_info, tmp, &dwc_pcie_dev_info_head, dev_node) {
> +		dwc_pcie_unregister_dev(dev_info);
> +	}
> +}
> +
>   static int __init dwc_pcie_pmu_init(void)
>   {
>   	struct pci_dev *pdev = NULL;
>   	int ret;
>   
>   	for_each_pci_dev(pdev) {
> -		if (!dwc_pcie_des_cap(pdev))
> +		if (!dwc_pcie_des_cap(pdev)) {
> +			pci_dev_put(pdev);

If the pdev has no RAS cap, we do not need to put the device.

> The reference count for @from is
> always decremented if it is not %NULL.

Please see comments from pci_get_device() for more details.

Shuai

Re: [External] Re: [PATCH v2 1/2] perf/dwc_pcie: fix the incorrect reference count

[yunhui cui]

Hi Shuai,


On Fri, Feb 7, 2025 at 10:20 AM Shuai Xue <xueshuai@linux.alibaba.com> wrote:
>
>
>
> 在 2025/2/5 11:14, Yunhui Cui 写道:
> > for_each_pci_dev increments pdev refcount. Call pci_dev_put after access
> > to decrement it.
> >
> > Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
> > ---
> >   drivers/perf/dwc_pcie_pmu.c | 42 ++++++++++++++++++++++++++-----------
> >   1 file changed, 30 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/perf/dwc_pcie_pmu.c b/drivers/perf/dwc_pcie_pmu.c
> > index cccecae9823f..4ac53167d7ab 100644
> > --- a/drivers/perf/dwc_pcie_pmu.c
> > +++ b/drivers/perf/dwc_pcie_pmu.c
> > @@ -553,6 +553,7 @@ static u16 dwc_pcie_des_cap(struct pci_dev *pdev)
> >
> >   static void dwc_pcie_unregister_dev(struct dwc_pcie_dev_info *dev_info)
> >   {
> > +     pci_dev_put(dev_info->pdev);
> >       platform_device_unregister(dev_info->plat_dev);
> >       list_del(&dev_info->dev_node);
> >       kfree(dev_info);
> > @@ -572,8 +573,10 @@ static int dwc_pcie_register_dev(struct pci_dev *pdev)
> >               return PTR_ERR(plat_dev);
> >
> >       dev_info = kzalloc(sizeof(*dev_info), GFP_KERNEL);
> > -     if (!dev_info)
> > +     if (!dev_info) {
> > +             platform_device_unregister(plat_dev);
> >               return -ENOMEM;
> > +     }
> >
> >       /* Cache platform device to handle pci device hotplug */
> >       dev_info->plat_dev = plat_dev;
> > @@ -594,8 +597,11 @@ static int dwc_pcie_pmu_notifier(struct notifier_block *nb,
> >       case BUS_NOTIFY_ADD_DEVICE:
> >               if (!dwc_pcie_des_cap(pdev))
> >                       return NOTIFY_DONE;
> > -             if (dwc_pcie_register_dev(pdev))
> > +             pci_dev_get(pdev);
> > +             if (dwc_pcie_register_dev(pdev)) {
> > +                     pci_dev_put(pdev);
> >                       return NOTIFY_BAD;
> > +             }
> >               break;
> >       case BUS_NOTIFY_DEL_DEVICE:
> >               dev_info = dwc_pcie_find_dev_info(pdev);
> > @@ -730,20 +736,29 @@ static struct platform_driver dwc_pcie_pmu_driver = {
> >       .driver = {.name = "dwc_pcie_pmu",},
> >   };
> >
> > +static void dwc_pcie_cleanup_devices(void)
> > +{
> > +     struct dwc_pcie_dev_info *dev_info, *tmp;
> > +
> > +     list_for_each_entry_safe(dev_info, tmp, &dwc_pcie_dev_info_head, dev_node) {
> > +             dwc_pcie_unregister_dev(dev_info);
> > +     }
> > +}
> > +
> >   static int __init dwc_pcie_pmu_init(void)
> >   {
> >       struct pci_dev *pdev = NULL;
> >       int ret;
> >
> >       for_each_pci_dev(pdev) {
> > -             if (!dwc_pcie_des_cap(pdev))
> > +             if (!dwc_pcie_des_cap(pdev)) {
> > +                     pci_dev_put(pdev);
>
> If the pdev has no RAS cap, we do not need to put the device.
>
> > The reference count for @from is
> > always decremented if it is not %NULL.
>
> Please see comments from pci_get_device() for more details.
Oh, yes. If that's the case, I'll update to v3.


> Shuai
>

Thanks，
Yunhui

[PATCH v2 2/2] perf/dwc_pcie: fix duplicate pci_dev devices

[Yunhui Cui]

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 4ac53167d7ab..fd9d87b4f201 100644
--- a/drivers/perf/dwc_pcie_pmu.c
+++ b/drivers/perf/dwc_pcie_pmu.c
@@ -566,9 +566,7 @@ 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);
 
@@ -620,18 +618,26 @@ 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");
+		return -ENODEV;
+	}
+
 	vsec = dwc_pcie_des_cap(pdev);
 	if (!vsec)
 		return -ENODEV;
 
-	sbdf = plat_dev->id;
+	pci_dev_put(pdev);
 	name = devm_kasprintf(&plat_dev->dev, GFP_KERNEL, "dwc_rootport_%x", sbdf);
 	if (!name)
 		return -ENOMEM;
@@ -646,7 +652,7 @@ 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,
@@ -733,7 +739,7 @@ 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",},
 };
 
 static void dwc_pcie_cleanup_devices(void)
-- 
2.39.2

Re: [PATCH v2 2/2] perf/dwc_pcie: fix duplicate pci_dev devices

[Shuai Xue]

在 2025/2/5 11:14, 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 4ac53167d7ab..fd9d87b4f201 100644
> --- a/drivers/perf/dwc_pcie_pmu.c
> +++ b/drivers/perf/dwc_pcie_pmu.c
> @@ -566,9 +566,7 @@ 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);
>   
> @@ -620,18 +618,26 @@ 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");

How about also adding the sbdf to print?

> +		return -ENODEV;
> +	}
> +
>   	vsec = dwc_pcie_des_cap(pdev);
>   	if (!vsec)
>   		return -ENODEV;
>   
> -	sbdf = plat_dev->id;
> +	pci_dev_put(pdev);
>   	name = devm_kasprintf(&plat_dev->dev, GFP_KERNEL, "dwc_rootport_%x", sbdf);
>   	if (!name)
>   		return -ENOMEM;
> @@ -646,7 +652,7 @@ 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,
> @@ -733,7 +739,7 @@ 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",},
>   };
>   
>   static void dwc_pcie_cleanup_devices(void)

Re: [External] Re: [PATCH v2 2/2] perf/dwc_pcie: fix duplicate pci_dev devices

[yunhui cui]

Hi Shuai,

On Fri, Feb 7, 2025 at 10:36 AM Shuai Xue <xueshuai@linux.alibaba.com> wrote:
>
>
>
> 在 2025/2/5 11:14, 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 4ac53167d7ab..fd9d87b4f201 100644
> > --- a/drivers/perf/dwc_pcie_pmu.c
> > +++ b/drivers/perf/dwc_pcie_pmu.c
> > @@ -566,9 +566,7 @@ 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);
> >
> > @@ -620,18 +618,26 @@ 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");
>
> How about also adding the sbdf to print?
OK, I'll update to v3.

>
> > +             return -ENODEV;
> > +     }
> > +
> >       vsec = dwc_pcie_des_cap(pdev);
> >       if (!vsec)
> >               return -ENODEV;
> >
> > -     sbdf = plat_dev->id;
> > +     pci_dev_put(pdev);
> >       name = devm_kasprintf(&plat_dev->dev, GFP_KERNEL, "dwc_rootport_%x", sbdf);
> >       if (!name)
> >               return -ENOMEM;
> > @@ -646,7 +652,7 @@ 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,
> > @@ -733,7 +739,7 @@ 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",},
> >   };
> >
> >   static void dwc_pcie_cleanup_devices(void)
>

Thanks,
Yunhui