linux-kernel - Re: [PATCH v2] misc: rp1: Fix a reference leak

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Message-ID: <a2fc02e2-d75a-43ed-8057-9b3860873ebb@kernel.org>
Date: Sat, 25 Oct 2025 13:33:03 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>,
 Andrea della Porta <andrea.porta@...e.com>, Arnd Bergmann <arnd@...db.de>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Bjorn Helgaas <bhelgaas@...gle.com>,
 Florian Fainelli <florian.fainelli@...adcom.com>
Cc: linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
 Dan Carpenter <dan.carpenter@...aro.org>
Subject: Re: [PATCH v2] misc: rp1: Fix a reference leak

On 24/10/2025 21:36, Christophe JAILLET wrote:
> The reference taken by of_find_node_by_name() in the probe is not released
> in the remove function.
> 
> In order to avoid a reference leak, use cleanup.h to automatically
> release the reference at the end of the probe when it is not needed
> anymore.
> 
> In order to do so, a reference also needs to be taken when DT is not used.
> 
> This simplifies the error handling path and makes direct returns possible
> in several places.
> 
> While at it, also add a missing \n at the end of an error message.
> 
> Fixes: 49d63971f963 ("misc: rp1: RaspberryPi RP1 misc driver")
> Suggested-by: Dan Carpenter <dan.carpenter@...aro.org>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
> This patch is compile tested only.
> 
> This change is speculative. Review with care.
> 
> Changes in v2:
>   - implement Dan's suggestions
> 
> v1: https://lore.kernel.org/lkml/4e92a271fdb98560c4e659556a1f3e99e7d0d38e.1760987458.git.christophe.jaillet@wanadoo.fr/
> ---
>  drivers/misc/rp1/rp1_pci.c | 42 ++++++++++++++++----------------------
>  1 file changed, 18 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/misc/rp1/rp1_pci.c b/drivers/misc/rp1/rp1_pci.c
> index 803832006ec8..0abfeb4a28e3 100644
> --- a/drivers/misc/rp1/rp1_pci.c
> +++ b/drivers/misc/rp1/rp1_pci.c
> @@ -5,6 +5,7 @@
>   * All rights reserved.
>   */
>  
> +#include <linux/cleanup.h>
>  #include <linux/err.h>
>  #include <linux/interrupt.h>
>  #include <linux/irq.h>
> @@ -185,9 +186,9 @@ static void rp1_unregister_interrupts(struct pci_dev *pdev)
>  static int rp1_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  {
>  	u32 dtbo_size = __dtbo_rp1_pci_end - __dtbo_rp1_pci_begin;
> +	struct device_node *rp1_node __free(device_node) = NULL;

This is not recommended way of using cleanup. You should declare it with
constructor.... if you cannot that's strong indication you are not
suppose to use cleanup.

>  	void *dtbo_start = __dtbo_rp1_pci_begin;
>  	struct device *dev = &pdev->dev;
> -	struct device_node *rp1_node;
>  	bool skip_ovl = true;
>  	struct rp1_dev *rp1;
>  	int err = 0;
> @@ -200,42 +201,40 @@ static int rp1_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	rp1_node = of_find_node_by_name(NULL, "rp1_nexus");
>  	if (!rp1_node) {
>  		rp1_node = dev_of_node(dev);
> +		/*
> +		 * Take a reference to match of_find_node_by_name()
> +		 * behavior. This makes cleanup.h usable in both cases.
> +		 */
> +		of_node_get(rp1_node);
>  		skip_ovl = false;
>  	}
>  
>  	if (!rp1_node) {
>  		dev_err(dev, "Missing of_node for device\n");
> -		err = -EINVAL;
> -		goto err_put_node;
> +		return -EINVAL;
>  	}
>  
>  	rp1 = devm_kzalloc(&pdev->dev, sizeof(*rp1), GFP_KERNEL);
> -	if (!rp1) {
> -		err = -ENOMEM;
> -		goto err_put_node;
> -	}
> +	if (!rp1)
> +		return -ENOMEM;
>  
>  	rp1->pdev = pdev;
>  
>  	if (pci_resource_len(pdev, 1) <= 0x10000) {
>  		dev_err(&pdev->dev,
>  			"Not initialized - is the firmware running?\n");
> -		err = -EINVAL;
> -		goto err_put_node;
> +		return -EINVAL;
>  	}
>  
>  	err = pcim_enable_device(pdev);
> -	if (err < 0) {
> -		err = dev_err_probe(&pdev->dev, err,
> -				    "Enabling PCI device has failed");
> -		goto err_put_node;
> -	}
> +	if (err < 0)
> +		return dev_err_probe(&pdev->dev, err,
> +				     "Enabling PCI device has failed\n");
>  
>  	rp1->bar1 = pcim_iomap(pdev, 1, 0);
>  	if (!rp1->bar1) {
>  		dev_err(&pdev->dev, "Cannot map PCI BAR\n");
> -		err = -EIO;
> -		goto err_put_node;
> +		return -EIO;
>  	}
>  
>  	pci_set_master(pdev);
> @@ -243,13 +242,11 @@ static int rp1_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	err = pci_alloc_irq_vectors(pdev, RP1_INT_END, RP1_INT_END,
>  				    PCI_IRQ_MSIX);
>  	if (err < 0) {
> -		err = dev_err_probe(&pdev->dev, err,
> -				    "Failed to allocate MSI-X vectors\n");
> -		goto err_put_node;
> +		return dev_err_probe(&pdev->dev, err,
> +				     "Failed to allocate MSI-X vectors\n");
>  	} else if (err != RP1_INT_END) {
>  		dev_err(&pdev->dev, "Cannot allocate enough interrupts\n");
> -		err = -EINVAL;
> -		goto err_put_node;
> +		return -EINVAL;
>  	}
>  
>  	pci_set_drvdata(pdev, rp1);
> @@ -295,9 +292,6 @@ static int rp1_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	of_overlay_remove(&rp1->ovcs_id);
>  err_unregister_interrupts:

And gotos is another strong indication that you should not use
cleanup.h. See cleanup.h for further explanations.



Best regards,
Krzysztof