Message-ID: <41F84313.4030509@osdl.org>
Date: Wed, 26 Jan 2005 17:25:39 -0800
From: "Randy.Dunlap" <rddunlap@osdl.org>
Organization: OSDL
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To: John Richard Moser <nigelenki@comcast.net>
CC: linux-kernel@vger.kernel.org
Subject: Re: /proc parent &proc_root == NULL?
References: <41F82218.1080705@comcast.net>
In-Reply-To: <41F82218.1080705@comcast.net>
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John Richard Moser wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> proc_misc_init() has both these lines in it:
> 
> entry = create_proc_entry("kmsg", S_IRUSR, &proc_root);
> proc_root_kcore = create_proc_entry("kcore", S_IRUSR, NULL);
> 
> Both entries show up in /proc, as /proc/kmsg and /proc/kcore.  So I ask,
> as I can't see after several minutes of examination, what's the
> difference?  Why is NULL used for some and &proc_root used for others?
> 
> I'm looking at 2.6.10

create_proc_entry() passes &parent to proc_create().
See proc_create():
...
This is an error path:
	if (!(*parent) && xlate_proc_name(name, parent, &fn) != 0)
		goto out;
but xlate_proc_name() searches for a /proc/.... and returns the 
all-but-final-part-of-name *parent (hope that makes some sense,
see the comments above the function), so it returns &proc_root.

HTH.  If not, fire back.
-- 
~Randy
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