linux-kernel - Re: [PATCH v2 1/5] usb: gadget: lpc32xx_udc: fix clock imbalance in error path

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Message-ID: <6355f7da-9b60-4e71-8ea0-da76ed4c0330@mleia.com>
Date: Fri, 19 Dec 2025 02:11:41 +0200
From: Vladimir Zapolskiy <vz@...ia.com>
To: Johan Hovold <johan@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Piotr Wojtaszczyk <piotr.wojtaszczyk@...esys.com>,
 Alan Stern <stern@...land.harvard.edu>, Ma Ke <make24@...as.ac.cn>,
 linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH v2 1/5] usb: gadget: lpc32xx_udc: fix clock imbalance in
 error path

Hi Johan,

thank you for looking at the issue.

On 12/18/25 17:35, Johan Hovold wrote:
> A recent change fixing a device reference leak introduced a clock
> imbalance by reusing an error path so that the clock may be disabled
> before having been enabled.
> 
> Note that the clock framework allows for passing in NULL clocks so there
> is no risk for a NULL pointer dereference.
> 
> Also drop the bogus I2C client NULL check added by the offending commit
> as the pointer has already been verified to be non-NULL.
> 
> Fixes: c84117912bdd ("USB: lpc32xx_udc: Fix error handling in probe")

This commit didn't get a proper review, and it is broken in so many ways,
that I'd say it has to be reverted.

> Cc: stable@...r.kernel.org
> Cc: Ma Ke <make24@...as.ac.cn>
> Signed-off-by: Johan Hovold <johan@...nel.org>
> ---
>   drivers/usb/gadget/udc/lpc32xx_udc.c | 20 ++++++++++----------
>   1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/lpc32xx_udc.c b/drivers/usb/gadget/udc/lpc32xx_udc.c
> index 73c0f28a8585..a962d4294fbe 100644
> --- a/drivers/usb/gadget/udc/lpc32xx_udc.c
> +++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
> @@ -3020,7 +3020,7 @@ static int lpc32xx_udc_probe(struct platform_device *pdev)
>   	pdev->dev.dma_mask = &lpc32xx_usbd_dmamask;
>   	retval = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
>   	if (retval)
> -		goto i2c_fail;
> +		goto err_put_client;
>   
>   	udc->board = &lpc32xx_usbddata;
>   
> @@ -3040,7 +3040,7 @@ static int lpc32xx_udc_probe(struct platform_device *pdev)
>   		udc->udp_irq[i] = platform_get_irq(pdev, i);
>   		if (udc->udp_irq[i] < 0) {
>   			retval = udc->udp_irq[i];
> -			goto i2c_fail;
> +			goto err_put_client;
>   		}
>   	}
>   
> @@ -3048,7 +3048,7 @@ static int lpc32xx_udc_probe(struct platform_device *pdev)
>   	if (IS_ERR(udc->udp_baseaddr)) {
>   		dev_err(udc->dev, "IO map failure\n");
>   		retval = PTR_ERR(udc->udp_baseaddr);
> -		goto i2c_fail;
> +		goto err_put_client;
>   	}
>   
>   	/* Get USB device clock */
> @@ -3056,14 +3056,14 @@ static int lpc32xx_udc_probe(struct platform_device *pdev)
>   	if (IS_ERR(udc->usb_slv_clk)) {
>   		dev_err(udc->dev, "failed to acquire USB device clock\n");
>   		retval = PTR_ERR(udc->usb_slv_clk);
> -		goto i2c_fail;
> +		goto err_put_client;
>   	}
>   
>   	/* Enable USB device clock */
>   	retval = clk_prepare_enable(udc->usb_slv_clk);
>   	if (retval < 0) {
>   		dev_err(udc->dev, "failed to start USB device clock\n");
> -		goto i2c_fail;
> +		goto err_put_client;
>   	}
>   
>   	/* Setup deferred workqueue data */
> @@ -3165,9 +3165,10 @@ static int lpc32xx_udc_probe(struct platform_device *pdev)
>   	dma_free_coherent(&pdev->dev, UDCA_BUFF_SIZE,
>   			  udc->udca_v_base, udc->udca_p_base);
>   i2c_fail:
> -	if (udc->isp1301_i2c_client)
> -		put_device(&udc->isp1301_i2c_client->dev);
>   	clk_disable_unprepare(udc->usb_slv_clk);
> +err_put_client:
> +	put_device(&udc->isp1301_i2c_client->dev);
> +
>   	dev_err(udc->dev, "%s probe failed, %d\n", driver_name, retval);
>   
>   	return retval;
> @@ -3195,10 +3196,9 @@ static void lpc32xx_udc_remove(struct platform_device *pdev)
>   	dma_free_coherent(&pdev->dev, UDCA_BUFF_SIZE,
>   			  udc->udca_v_base, udc->udca_p_base);
>   
> -	if (udc->isp1301_i2c_client)
> -		put_device(&udc->isp1301_i2c_client->dev);
> -
>   	clk_disable_unprepare(udc->usb_slv_clk);
> +
> +	put_device(&udc->isp1301_i2c_client->dev);
>   }
>   
>   #ifdef CONFIG_PM

Reviewed-by: Vladimir Zapolskiy <vz@...ia.com>

-- 
Best wishes,
Vladimir