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From: =?utf-8?Q?Bj=C3=B8rn_Mork?= <bjorn@mork.no>
To: Oliver Neukum <oliver@neukum.org>
Cc: wangbiao <biao.wang@intel.com>, netdev@vger.kernel.org,
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        william.douglas@intel.com, di.zhang@intel.com
Subject: Re: [PATCH V3] usbnet: fix race condition caused spinlock bad magic issue
Organization: m
References: <1384394595.4229.24.camel@wangbiao>
	<1384415082.18291.8.camel@linux-fkkt.site>
Date: Thu, 14 Nov 2013 10:18:05 +0100
In-Reply-To: <1384415082.18291.8.camel@linux-fkkt.site> (Oliver Neukum's
	message of "Thu, 14 Nov 2013 08:44:42 +0100")
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Oliver Neukum <oliver@neukum.org> writes:

> On Thu, 2013-11-14 at 10:03 +0800, wangbiao wrote:
>> From: wang, biao <biao.wang@intel.com>
>> Date: Mon, 11 Nov 2013 10:23:40 +0800
>> Subject: [PATCH] usbnet: fix race condition caused spinlock bad magic issue
>> 
>> there is race between usbnet_terminate_urbs and usbnet_bh.
>> for example:
>>     cpu 0                                     cpu 1
>>                                           usbnet_suspend
>> usbnet_bh {                               ->usbnet_terminate_urbs {
>>                                               dev->wait = &unlink_wakeup;
>>                                               while(....){..}//break
>>     if(dev->wait) is true
>>                        		              dev->wait=NULL
>>                                           }//unlink_wakeup is invalid
>>     __wake_up(dev->wait)//garbage value
>> }
>> 
>> the race is due to unprotection of dev->wait, so this patch involves a
>> spinlock to avoid it.
>> 
>> Signed-off-by: wang, biao <biao.wang@intel.com>
>> Signed-off-by: Zhang, Di <di.zhang@intel.com>
> Acked-by: Oliver Neukum <oliver@neukum.org>


Really?  Serializing the suspend of all usbnet devices seems like a good
idea?


Bjørn