linux-kernel - Re: [PATCH] pci: controller: pci-ftpci100: Release the clock resources

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Date:   Sat, 22 Apr 2023 17:16:57 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Junyan Ye <yejunyan@...t.edu.cn>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Wei Yongjun <weiyongjun1@...wei.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Andrew Murray <amurray@...goodpenguin.co.uk>
Cc:     hust-os-kernel-patches@...glegroups.com,
        Dongliang Mu <dzm91@...t.edu.cn>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pci: controller: pci-ftpci100: Release the clock
 resources

Le 22/04/2023 à 09:42, Junyan Ye a écrit :
> Smatch reported:
> 1. drivers/pci/controller/pci-ftpci100.c:526 faraday_pci_probe()
> warn: 'clk' from clk_prepare_enable() not released on lines:
> 442,451,462,478,512,517.
> 2. drivers/pci/controller/pci-ftpci100.c:526 faraday_pci_probe()
> warn: 'p->bus_clk' from clk_prepare_enable() not released on lines:
> 451,462,478,512,517.
> 
> The clock resource is obtained by the devm_clk_get function. The
> clk_prepare_enable function then makes the clock resource ready for use,
> notifying the system that the clock resource should be run. After that,
> the clock resource should be released when it is no longer needed. This
> includes notifying the system that the clock resource is no longer needed
> and revoking the prepared clock. The corresponding function is
> clk_disable_unprepare. However, while doing some error handling in the
> faraday_pci_probe function, the clk_disable_unprepare function is not
> called to release the clk and p->bus_clk resources.
> 
> Fix the warning by adding the clk_disable_unprepare function before
> returning the error message.
> 
> Fixes: b3c433efb8a3 ("PCI: faraday: Fix wrong pointer passed to PTR_ERR()")
> Fixes: 2eeb02b28579 ("PCI: faraday: Add clock handling")
> Fixes: 783a862563f7 ("PCI: faraday: Use pci_parse_request_of_pci_ranges()")
> Fixes: d3c68e0a7e34 ("PCI: faraday: Add Faraday Technology FTPCI100 PCI Host Bridge driver")
> Fixes: f1e8bd21e39e ("PCI: faraday: Convert IRQ masking to raw PCI config accessors")
> Signed-off-by: Junyan Ye <yejunyan@...t.edu.cn>
> Reviewed-by: Dongliang Mu <dzm91@...t.edu.cn>
> ---
> This issue is found by static analyzer.
> 
>   drivers/pci/controller/pci-ftpci100.c | 31 +++++++++++++++++++--------
>   1 file changed, 22 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-ftpci100.c b/drivers/pci/controller/pci-ftpci100.c
> index ecd3009df586..ca3ba377b3dd 100644
> --- a/drivers/pci/controller/pci-ftpci100.c
> +++ b/drivers/pci/controller/pci-ftpci100.c
> @@ -438,17 +438,21 @@ static int faraday_pci_probe(struct platform_device *pdev)
>   		return ret;
>   	}
>   	p->bus_clk = devm_clk_get(dev, "PCICLK");
> -	if (IS_ERR(p->bus_clk))
> -		return PTR_ERR(p->bus_clk);

Hi,

switching to devm_clk_get_enabled() would
   - fix the leak you reported
   - fix the same leak hapening in the (non-existent) remove() function
   - remove some lines of code, which is always great.

CJ


> +	if (IS_ERR(p->bus_clk)) {
> +		ret = PTR_ERR(p->bus_clk);
> +		goto err_release_clk;
> +	}
>   	ret = clk_prepare_enable(p->bus_clk);
>   	if (ret) {
>   		dev_err(dev, "could not prepare PCICLK\n");
> -		return ret;
> +		goto err_release_clk;
>   	}
>   
>   	p->base = devm_platform_ioremap_resource(pdev, 0);
> -	if (IS_ERR(p->base))
> -		return PTR_ERR(p->base);
> +	if (IS_ERR(p->base)) {
> +		ret = PTR_ERR(p->base);
> +		goto err_release_p_bus_clk;
> +	}
>   
>   	win = resource_list_first_type(&host->windows, IORESOURCE_IO);
>   	if (win) {
> @@ -459,7 +463,8 @@ static int faraday_pci_probe(struct platform_device *pdev)
>   			writel(val, p->base + FTPCI_IOSIZE);
>   		} else {
>   			dev_err(dev, "illegal IO mem size\n");
> -			return -EINVAL;
> +			ret = -EINVAL;
> +			goto err_release_p_bus_clk;
>   		}
>   	}
>   
> @@ -475,7 +480,7 @@ static int faraday_pci_probe(struct platform_device *pdev)
>   		ret = faraday_pci_setup_cascaded_irq(p);
>   		if (ret) {
>   			dev_err(dev, "failed to setup cascaded IRQ\n");
> -			return ret;
> +			goto err_release_p_bus_clk;
>   		}
>   	}
>   
> @@ -509,12 +514,12 @@ static int faraday_pci_probe(struct platform_device *pdev)
>   
>   	ret = faraday_pci_parse_map_dma_ranges(p);
>   	if (ret)
> -		return ret;
> +		goto err_release_p_bus_clk;
>   
>   	ret = pci_scan_root_bus_bridge(host);
>   	if (ret) {
>   		dev_err(dev, "failed to scan host: %d\n", ret);
> -		return ret;
> +		goto err_release_p_bus_clk;
>   	}
>   	p->bus = host->bus;
>   	p->bus->max_bus_speed = max_bus_speed;
> @@ -524,6 +529,14 @@ static int faraday_pci_probe(struct platform_device *pdev)
>   	pci_bus_add_devices(p->bus);
>   
>   	return 0;
> +
> +err_release_p_bus_clk:
> +	clk_disable_unprepare(p->bus_clk);
> +
> +err_release_clk:
> +	clk_disable_unprepare(clk);
> +
> +	return ret;
>   }
>   
>   /*