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Message-ID: <20070815063741.GB5175@mail.ustc.edu.cn>
Date: Wed, 15 Aug 2007 14:37:41 +0800
From: Fengguang Wu <wfg@...l.ustc.edu.cn>
To: Al Viro <viro@....linux.org.uk>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
Randy Dunlap <rddunlap@...l.org>,
Martin Bligh <mbligh@...gle.com>
Subject: Re: [patch 2/2] Sort module list by pointer address to get
coherent sleepable seq_file iterators
On Wed, Aug 15, 2007 at 05:18:45AM +0100, Al Viro wrote:
>> On Wed, Aug 15, 2007 at 11:39:45AM +0800, Fengguang Wu wrote:
>> seqfile: remove seq_file's assumption about iterators
>>
>> The seq_file implementation has some hardcoded index++/pos++ lines,
>> which assumes iterators to be *continuous* integers.
>
>What the fuck? It assumes no such thing and a lot of iterators are
>nothing like integers. What are you talking about?
Oh I used the wrong term...
Take for example this function from lwn.net:
static void *ct_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
loff_t *spos = (loff_t *) v;
*pos = ++(*spos);
return spos;
}
I mean 'pos' is sometimes increased in ct_seq_next(), and sometimes from
seq_file.c/seq_read(), too. Thus we cannot reliably do this:
*pos = (*spos) + some_variable_offset;
You are referring to spos as the iterator, are you?
Maybe I'm wrong. I'll dip more into it.
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