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Date: Thu, 10 Apr 2003 14:40:09 +0200 (CEST)
From: Harti Brandt <brandt@fokus.fraunhofer.de>
To: Jeffrey Hsu <hsu@FreeBSD.org>
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Subject: Re: LOR in if_detach
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On Thu, 10 Apr 2003, Jeffrey Hsu wrote:

JH>  > is there any insight on how to avoid an LOR in if_detach?
JH>
JH>Call if_detach() before you acquire the driver lock.

I must stop the interface before calling if_detach. To stop it I need the
lock. If I unlock after stoping before detaching, I get a race window
where somebody could just UP the interface.

While thinking about, it seems, that having a lock in struct ifnet would
make sense in the long run. How can we otherwise ensure, that nobody is
calling if_ioctl while we are detaching the interface? Hmmm...

harti
-- 
harti brandt,
http://www.fokus.fraunhofer.de/research/cc/cats/employees/hartmut.brandt/private
brandt@fokus.fraunhofer.de, harti@freebsd.org