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Date: Thu, 13 Nov 2014 00:59:06 -0800
From: Alfred Perlstein <alfred@freebsd.org>
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To: freebsd-arch@freebsd.org, Adrian Chadd <adrian@freebsd.org>
Subject: Re: Questions about locking; turnstiles and sleeping threads
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On 11/12/14, 11:25 PM, Adrian Chadd wrote:
> On 12 November 2014 19:48, Adrian Chadd <adrian@freebsd.org> wrote:
>> kan pointed out that we should likely do a WITNESS_WARN() in the
>> relevant spots in the callout code so we catch these before it
>> happens.
>>
>> I'll see what we can add to -HEAD to be pro-active about it.
> Amusingly, I tried adding it and it made my laptop turn to soup very
> quickly - among other things, the TCP timer callouts are all setup
> with non sleep locks held.
>

Howso?  You only have to worry about callout_drain(), most other callout 
functions should be safe-ish....

-Alfred