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Date: Thu, 19 Aug 2004 16:50:52 -0600
From: Scott Long <scottl@samsco.org>
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To: Roman Kurakin <rik@cronyx.ru>
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cc: freebsd-current@freebsd.org
Subject: Re: Tracking down LORs
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Roman Kurakin wrote:
> Hi,
> 
>     Currently I am trying to track down a couple of LORS
> in my code. But it seems that I do not undestand smth or all
> things id realy so bad.
> 
>     So I want to ask some questions to find out if my thoughts
> correct or wrong.
> 
> 1. If I am right LOR means that we have at least two mutexs.
> Lets call them a and b. If we set a, then b in first case
> and b then a in second we could get dead loop, and thus LOR.

Correct.

> 
> 2. If I have some driver that have mutex a, and we have some
> sytem code that could call this driver with Giant (b), we would
> get LOR if driver lock a and some other part of system will
> try to lock Giant?

The general rule is that NO other locks should be held when Giant
is grabbed.

Scott