linux-kernel - Re: [PATCH] usb: gadget: atmel_usba: Fix crashed during stopping when DEBUG is enabled

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Message-ID: <20140228155027.GC2974@piout.net>
Date:	Fri, 28 Feb 2014 16:50:28 +0100
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Gregory CLEMENT <gregory.clement@...e-electrons.com>
Cc:	Nicolas Ferre <nicolas.ferre@...el.com>,
	Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-arm-kernel@...ts.infradead.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] usb: gadget: atmel_usba: Fix crashed during stopping
 when DEBUG is enabled

Hi Gregory,

On 28/02/2014 at 15:34:01 +0100, Gregory CLEMENT wrote :
> The debug trace in the atmel_usba_stop function made the assumption
> that the driver pointer passed in parameter was not NULL. Since the
> commit "usb: gadget: udc-core: fix a regression during gadget driver
> unbinding", it was no more always true. This lead to a kernel crash.
> 
> This commit now use the driver pointer stored in udc which fixes this
> issue.
> 
> Since the commit which have triggered this issue was backported to the
> 3.2 stable branch, then this one should also be backported to the same
> kernel.
> 
> Cc: stable@...r.kernel.org # v3.2+
> Fixes: 511f3c5326ea (usb: gadget: udc-core: fix a regression during gadget driver unbinding)
> ---
>  drivers/usb/gadget/atmel_usba_udc.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/gadget/atmel_usba_udc.c b/drivers/usb/gadget/atmel_usba_udc.c
> index 52771d4c44bc..167843de2d8a 100644
> --- a/drivers/usb/gadget/atmel_usba_udc.c
> +++ b/drivers/usb/gadget/atmel_usba_udc.c
> @@ -1827,12 +1827,12 @@ static int atmel_usba_stop(struct usb_gadget *gadget,
>  	toggle_bias(0);
>  	usba_writel(udc, CTRL, USBA_DISABLE_MASK);
>  
> -	udc->driver = NULL;
> -
>  	clk_disable_unprepare(udc->hclk);
>  	clk_disable_unprepare(udc->pclk);
>  
> -	DBG(DBG_GADGET, "unregistered driver `%s'\n", driver->driver.name);
> +	DBG(DBG_GADGET, "unregistered driver `%s'\n", udc->driver->driver.name);
> +
> +	udc->driver = NULL;

Shouldn't we get rid of that assignment as it is done in
usb_gadget_remove_driver() anyway ?

>  
>  	return 0;
>  }
> -- 
> 1.8.1.2
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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