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Date:      Sun, 14 Jul 2002 11:57:29 +0200
From:      Poul-Henning Kamp <phk@critter.freebsd.dk>
To:        Don Lewis <dl-freebsd@catspoiler.org>
Cc:        arch@FreeBSD.ORG
Subject:   Re: wiring the sysctl output buffer 
Message-ID:  <56792.1026640649@critter.freebsd.dk>
In-Reply-To: Your message of "Sun, 14 Jul 2002 02:54:11 PDT." <200207140954.g6E9sBwr020599@gw.catspoiler.org> 

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In message <200207140954.g6E9sBwr020599@gw.catspoiler.org>, Don Lewis writes:
>On 14 Jul, Poul-Henning Kamp wrote:
>> In message <200207140916.g6E9Ghwr020552@gw.catspoiler.org>, Don Lewis writes:
>> 
>>>I think the best solution to this problem is to add a sysctl system API
>>>to prewire the output buffer that can be called before grabbing the
>>>locks.  Doing so allows the existing code to operate properly with only
>>>minimal changes.
>> 
>> It used to be that sysctl unconditionally wired the output buffer,
>> but that gave rise to a host of other problems.
>
>Anything specific that I should be aware of?

No, just bad deadlocks and such.

You may also want to restrict the amount of buffer you pin
if I hand the kernel a 2G buffer for a 4 byte sysctl integer
you wouldn't want to pin it all.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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