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Date: Fri, 26 Aug 2011 14:06:10 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Greg KH <gregkh@suse.de>, Kay Sievers <kay.sievers@vrfy.org>,
        Alan Cox <alan@lxorguk.ukuu.org.uk>, linux-kernel@vger.kernel.org,
        Nick Piggin <npiggin@kernel.dk>, Al Viro <viro@zeniv.linux.org.uk>,
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        David Howells <dhowells@redhat.com>,
        "Serge E. Hallyn" <serge.hallyn@canonical.com>,
        Daniel Lezcano <daniel.lezcano@free.fr>, Jiri Slaby <jslaby@suse.cz>,
        James Morris <jmorris@namei.org>, neilb@suse.de
Subject: Re: [PATCH] sysctl: add support for poll()
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On Thu,  4 Aug 2011 15:57:18 -0300
Lucas De Marchi <lucas.demarchi@profusion.mobi> wrote:

> Adding support for poll() in sysctl fs allows userspace to receive
> notifications of changes in sysctl entries. This adds a infrastructure
> to allow files in sysctl fs to be pollable and implements it for
> hostname and domainname.
> 

Seems reasonable.  One slight nit:

> +#define __CTL_TABLE_POLL_INITIALIZER(name) {				\
> +	.event = ATOMIC_INIT(0),					\
> +	.wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
> +
> +#define DECLARE_CTL_TABLE_POLL(name)					\
> +	struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)

This macro is used to define an instance of ctl_table_poll.  Hence it
should be called DEFINE_CTL_TABLE_POLL, not DECLARE_*.

declaration: "one of these exists"
definition: "here it is".

This matters a bit, because sometimes we'll have separate macros for
declaring and defining.