linux-kernel - Re: [PATCH] Support single byte reads from integers published in procfs by kernel/sysctl.c

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Date:	Mon, 23 Jan 2012 08:47:51 -0800
From:	Earl Chew <echew@...acom.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Eric Paris <eparis@...hat.com>,
	"Serge E. Hallyn" <serge.hallyn@...onical.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	<adobriyan@...il.com>
Subject: Re: [PATCH] Support single byte reads from integers published in
 procfs by kernel/sysctl.c

On 23/01/2012 8:35 AM, Eric W. Biederman wrote:
> read X < file seems like a reasonable case to support.
> Bash doesn't have that problem so presumably BusyBox is simply
> inefficient.

I think you are correct. In BusyBox, I believe there is a conscious
design decision to favour minimum size over maximum speed where it makes sense.

> If you are interested in fixing this properly with a tiny buffer
> reachable from struct file I think this can be worth fixing.  I think
> this is doable by using seq_file in proc_sys_read.

I did think about using seq_file, but my initial thoughts were that it
would end up being a much bigger change and I was reluctant to take that
on without some indication that it would be a more acceptable approach.

> Rereading different bytes of the integer multiple times when the integer
> may be changing does not seem like a reasonable implementation.

Yes. I agree with you. I shall re-work the patch as per your suggestion.

Earl

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