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Date: Fri, 21 Apr 2006 20:03:21 -0500
To: utz.bacher@de.ibm.com, Arnd Bergmann <arnd.bergmann@de.ibm.com>,
	Maxim Shchetynin <maxim@de.ibm.com>, linuxppc-dev@ozlabs.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2]: Spider ethernet driver -- protect chain head
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	<20060422001140.GA12826@gate.ebshome.net>
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From: linas@austin.ibm.com (Linas Vepstas)
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On Fri, Apr 21, 2006 at 05:11:40PM -0700, Eugene Surovegin wrote:
> On Fri, Apr 21, 2006 at 06:45:51PM -0500, Linas Vepstas wrote:
> > Prevent a potential race. If two threads are both calling
> > the transmit routine, both can potentially try to grab the
> > same dma descriptor. Serialize access to the head of the
> > tx ring with spinlocks.
> 
> Two threads cannot be in spider_net_xmit() simultaneosuly because 
> hard_start_xmit entry point is already protected by net_device 
> xmit_lock, see Documentation/net/netdevices.txt

Ahh, thank you. I was wondering why I never semmed to see this
this happen in "real life".

--linas