netdev - Re: [PATCH-next v2] netfilter: don't use module

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Message-ID: <20140116192613.GA23133@d2.synalogic.ca>
Date:	Thu, 16 Jan 2014 14:26:13 -0500
From:	Benjamin Poirier <benjamin.poirier@...il.com>
To:	Paul Gortmaker <paul.gortmaker@...driver.com>
Cc:	Pablo Neira Ayuso <pablo@...filter.org>,
	Patrick McHardy <kaber@...sh.net>,
	Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
	"David S. Miller" <davem@...emloft.net>,
	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH-next v2] netfilter: don't use module_init/exit in core
 IPV4 code

On 2014/01/15 15:57, Paul Gortmaker wrote:
> The file net/ipv4/netfilter.o is created based on whether
> CONFIG_NETFILTER is set.  However that is defined as a bool, and
> hence this file with the core netfilter hooks will never be
> modular.  So using module_init as an alias for __initcall can be
> somewhat misleading.
> 
> Fix this up now, so that we can relocate module_init from
> init.h into module.h in the future.  If we don't do this, we'd
> have to add module.h to obviously non-modular code, and that
> would be a worse thing.  Also add an inclusion of init.h, as
> that was previously implicit here in the netfilter.c file.
> 
> Note that direct use of __initcall is discouraged, vs. one
> of the priority categorized subgroups.  As __initcall gets
> mapped onto device_initcall, our use of subsys_initcall (which
> seems to make sense for netfilter code) will thus change this
> registration from level 6-device to level 4-subsys (i.e. slightly
> earlier).  However no observable impact of that small difference
> has been observed during testing, or is expected. (i.e. the
> location of the netfilter messages in dmesg remains unchanged
> with respect to all the other surrounding messages.)
> 
> As for the module_exit, rather than replace it with __exitcall,
> we simply remove it, since it appears only UML does anything
> with those, and even for UML, there is no relevant cleanup
> to be done here.
> 
> Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
> ---
> 
> [v2: Drop __exitcall stuff completely, as per Eric's suggestion
>  given for patch at  http://patchwork.ozlabs.org/patch/311164/ ]
> 
>  net/ipv4/netfilter.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c
> index c3e0adea9c27..31abf9636ba7 100644
> --- a/net/ipv4/netfilter.c
> +++ b/net/ipv4/netfilter.c
> @@ -197,11 +197,4 @@ static int __init ipv4_netfilter_init(void)
>  {
>  	return nf_register_afinfo(&nf_ip_afinfo);
>  }
> -
> -static void __exit ipv4_netfilter_fini(void)
> -{
> -	nf_unregister_afinfo(&nf_ip_afinfo);
> -}
> -
> -module_init(ipv4_netfilter_init);
> -module_exit(ipv4_netfilter_fini);
> +device_initcall(ipv4_netfilter_init);

device_ vs. subsys_initcall changed from v1 of the patch and no longer
matches the description I think.

> -- 
> 1.8.5.2
> 
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