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

Yunhui Cui posted 2 patches 1 year ago
There is a newer version of this series
[PATCH v2 1/2] perf/dwc_pcie: fix the incorrect reference count
Posted by Yunhui Cui 1 year ago 
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
Posted by Shuai Xue 1 year ago 

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
Posted by yunhui cui 1 year ago 
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

Patchew 2.1-devel-b67e4c2

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