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

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Message-ID: <5310B6BF.10604@free-electrons.com>
Date:	Fri, 28 Feb 2014 17:18:07 +0100
From:	Gregory CLEMENT <gregory.clement@...e-electrons.com>
To:	Alexandre Belloni <alexandre.belloni@...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

On 28/02/2014 16:50, Alexandre Belloni wrote:
> 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 ?

usb_gadget_remove_driver() is not the only function to use it.
usb_udc_softconn_store() can call it too and doesn't have any
debug message.


Thanks,

Gregory


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


-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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