linux-kernel - Re: [PATCH] usb: ohci-spear: fix call balance of sohci

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Message-ID: <81c02947-5617-4ab5-a8bd-56349b9929f4@rowland.harvard.edu>
Date: Thu, 5 Dec 2024 10:12:20 -0500
From: Alan Stern <stern@...land.harvard.edu>
To: Vitalii Mordan <mordan@...ras.ru>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Deepak Saxena <dsaxena@...aro.org>,
	Manjunath Goudar <manjunath.goudar@...aro.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Fedor Pchelkin <pchelkin@...ras.ru>,
	Alexey Khoroshilov <khoroshilov@...ras.ru>,
	Vadim Mutilin <mutilin@...ras.ru>, stable@...r.kernel.org
Subject: Re: [PATCH] usb: ohci-spear: fix call balance of sohci_p->clk
 handling routines

On Thu, Dec 05, 2024 at 04:33:00PM +0300, Vitalii Mordan wrote:
> If the clock sohci_p->clk was not enabled in spear_ohci_hcd_drv_probe,
> it should not be disabled in any path.
> 
> Conversely, if it was enabled in spear_ohci_hcd_drv_probe, it must be disabled
> in all error paths to ensure proper cleanup.
> 
> The check inside spear_ohci_hcd_drv_resume() actually doesn't prevent
> the clock to be unconditionally disabled later during the driver removal but
> it is still good to have the check at least so that the PM core would duly
> print the errors in the system log. This would also be consistent with
> the similar code paths in ->resume() functions of other usb drivers, e.g. in
> exynos_ehci_resume().
> 
> Found by Linux Verification Center (linuxtesting.org) with Klever.
> 
> Fixes: 1cc6ac59ffaa ("USB: OHCI: make ohci-spear a separate driver")
> Cc: stable@...r.kernel.org
> Signed-off-by: Vitalii Mordan <mordan@...ras.ru>
> ---

Acked-by: Alan Stern <stern@...land.harvard.edu>

>  drivers/usb/host/ohci-spear.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/host/ohci-spear.c b/drivers/usb/host/ohci-spear.c
> index 993f347c5c28..6f6ae6fadfe5 100644
> --- a/drivers/usb/host/ohci-spear.c
> +++ b/drivers/usb/host/ohci-spear.c
> @@ -80,7 +80,9 @@ static int spear_ohci_hcd_drv_probe(struct platform_device *pdev)
>  	sohci_p = to_spear_ohci(hcd);
>  	sohci_p->clk = usbh_clk;
>  
> -	clk_prepare_enable(sohci_p->clk);
> +	retval = clk_prepare_enable(sohci_p->clk);
> +	if (retval)
> +		goto err_put_hcd;
>  
>  	retval = usb_add_hcd(hcd, irq, 0);
>  	if (retval == 0) {
> @@ -103,8 +105,7 @@ static void spear_ohci_hcd_drv_remove(struct platform_device *pdev)
>  	struct spear_ohci *sohci_p = to_spear_ohci(hcd);
>  
>  	usb_remove_hcd(hcd);
> -	if (sohci_p->clk)
> -		clk_disable_unprepare(sohci_p->clk);
> +	clk_disable_unprepare(sohci_p->clk);
>  
>  	usb_put_hcd(hcd);
>  }
> @@ -137,12 +138,15 @@ static int spear_ohci_hcd_drv_resume(struct platform_device *dev)
>  	struct usb_hcd *hcd = platform_get_drvdata(dev);
>  	struct ohci_hcd	*ohci = hcd_to_ohci(hcd);
>  	struct spear_ohci *sohci_p = to_spear_ohci(hcd);
> +	int ret;
>  
>  	if (time_before(jiffies, ohci->next_statechange))
>  		msleep(5);
>  	ohci->next_statechange = jiffies;
>  
> -	clk_prepare_enable(sohci_p->clk);
> +	ret = clk_prepare_enable(sohci_p->clk);
> +	if (ret)
> +		return ret;
>  	ohci_resume(hcd, false);
>  	return 0;
>  }
> -- 
> 2.25.1
>