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Date: Thu, 8 Aug 2013 17:18:02 -0700
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Subject: Re: [net] protecting interfaces from races between control and data ?
From: Adrian Chadd <adrian@freebsd.org>
To: Scott Long <scott4long@yahoo.com>
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Cc: current@freebsd.org, Bryan Venteicher <bryanv@daemoninthecloset.org>,
 Navdeep Parhar <np@freebsd.org>, net@freebsd.org,
 Giuseppe Lettieri <g.lettieri@iet.unipi.it>, Luigi Rizzo <rizzo@iet.unipi.it>,
 Warner Losh <imp@bsdimp.com>
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.. and it's not just about "saturate the port" with traffic.

It's also about "what happens if I shut down the MAC whilst I'm in the
process of programming in new RX/TX descriptors?"

The ath(4) driver had a spectacular behaviour where if you mess things
up the wrong way it will quite happily DMA crap all over the memory of
your running system, leading to quite hilarious bugs.



-adrian