linux-kernel - Re: [PATCH 1/3] PCI/pwrctrl: Fix device leak at registration

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Message-ID: <20250722110526.00002a60@huawei.com>
Date: Tue, 22 Jul 2025 11:05:26 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Johan Hovold <johan+linaro@...nel.org>
CC: Bjorn Helgaas <bhelgaas@...gle.com>, Manivannan Sadhasivam
	<mani@...nel.org>, <linux-pci@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>
Subject: Re: [PATCH 1/3] PCI/pwrctrl: Fix device leak at registration

On Mon, 21 Jul 2025 17:36:07 +0200
Johan Hovold <johan+linaro@...nel.org> wrote:

> Make sure to drop the reference to the pwrctrl device taken by
> of_find_device_by_node() when registering a PCI device.
> 
> Fixes: b458ff7e8176 ("PCI/pwrctl: Ensure that pwrctl drivers are probed before PCI client drivers")
> Cc: stable@...r.kernel.org	# 6.13
> Cc: Manivannan Sadhasivam <mani@...nel.org>
> Signed-off-by: Johan Hovold <johan+linaro@...nel.org>

Hi Johan,

Perhaps time for 
DEFINE_FREE(put_pdev, struct platform_device *, if (_T) put_device(&_T->dev));

then...

> ---
>  drivers/pci/bus.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
> index 69048869ef1c..0394a9c77b38 100644
> --- a/drivers/pci/bus.c
> +++ b/drivers/pci/bus.c
> @@ -362,11 +362,15 @@ void pci_bus_add_device(struct pci_dev *dev)
>  	 * before PCI client drivers.
>  	 */
>  	pdev = of_find_device_by_node(dn);
> -	if (pdev && of_pci_supply_present(dn)) {
> -		if (!device_link_add(&dev->dev, &pdev->dev,
> -				     DL_FLAG_AUTOREMOVE_CONSUMER))
> -			pci_err(dev, "failed to add device link to power control device %s\n",
> -				pdev->name);

	struct platform_device *pdev __free(put_pdev) =
		of_find_device_by_node(dn);
> +	if (pdev) {
> +		if (of_pci_supply_present(dn)) {
> +			if (!device_link_add(&dev->dev, &pdev->dev,
> +					     DL_FLAG_AUTOREMOVE_CONSUMER)) {
> +				pci_err(dev, "failed to add device link to power control device %s\n",
> +					pdev->name);
> +			}
> +		}
> +		put_device(&pdev->dev);

and no need for any explicit put.

We already do this extensively in some subsystems (e.g. CXL) and it
greatly simplifies code.

>  	}
>  
>  	if (!dn || of_device_is_available(dn))