From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ben Greear <greearb@candelatech.com>
Subject: Re: RFR: new SiS gige driver
Date: Sat, 09 Aug 2003 11:10:45 -0700
Sender: netdev-bounce@oss.sgi.com
Message-ID: <3F353925.3030106@candelatech.com>
References: <20030808173932.GA4077@gtf.org> <20030809141533.GB4539@wotan.suse.de> <3F350CC8.3090605@pobox.com>
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Cc: Andi Kleen <ak@suse.de>, netdev@oss.sgi.com
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To: Jeff Garzik <jgarzik@pobox.com>
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Jeff Garzik wrote:
> Andi Kleen wrote:
> 
>> * netif_stop_queue in hard_start_xmit is not protected against the 
>> interrupt by the spinlock. That's racy, isn't it?
> 
> 
> Shouldn't be, if done right.  If the interrupt runs a TX completion 
> cycle, it will run the code
>     if (work_done && netif_queue_stopped(dev))
>         netif_wake_queue(dev)
> 

> Since ->hard_start_xmit is guaranteed never to be called if the queue is 
> stopped, you also guaranteed that netif_wake_queue and ->hard_start_xmit 
> are mutually exclusive.

Is this really guaranteed?  What if the queue is stopped between the check
to see if it's stopped and the call to hard_start_xmit?

Ben


-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com