netdev - Re: [PATCH nf-next] ipt_LOG: add bufferisation to call printk() once

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Message-ID: <4CAA23CF.80904@trash.net>
Date:	Mon, 04 Oct 2010 20:58:23 +0200
From:	Patrick McHardy <kaber@...sh.net>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	netdev <netdev@...r.kernel.org>,
	Netfilter Development Mailinglist 
	<netfilter-devel@...r.kernel.org>
Subject: Re: [PATCH nf-next] ipt_LOG: add bufferisation to call printk() once

Am 02.10.2010 17:07, schrieb Eric Dumazet:
> ipt_LOG & ip6t_LOG use lot of calls to printk() and use a lock in a hope
> several cpus wont mix their output in syslog.
> 
> printk() being very expensive [1], its better to call it once, on a
> prebuilt and complete line. Also, with mixed IPv4 and IPv6 trafic,
> separate IPv4/IPv6 locks dont avoid garbage.
> 
> I used an allocation of a 1024 bytes structure, sort of seq_printf() but
> with a fixed size limit.
> Use a static buffer if dynamic allocation failed.
> 
> Emit a once time alert if buffer size happens to be too short.
> 
> [1]: printk() has various features like printk_delay()...

Nice work, applied, thanks Eric.

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