Subject: Re: [PATCH net-next v2 06/12] netfilter: merge udpv[4,6]_net_init into udp_net_init

From: Gao feng <[email-masked]>
Date: Tue, 19 Jun 2012 16:08:31 +0800

于 2012年06月16日 19:22, Pablo Neira Ayuso 写道:
> On Sat, Jun 16, 2012 at 11:41:17AM +0800, Gao feng wrote:
>> merge udpv4_net_init and udpv6_net_init into udp_net_init to
>> reduce the redundancy codes.
>>
>> and use nf_proto_net.users to identify if it's the first time
>> we use the nf_proto_net. when it's the first time,we will
>> initialized it.
>>
>> Signed-off-by: Gao feng <[email-masked]>
>> ---
>>  net/netfilter/nf_conntrack_proto_udp.c |   56 ++++++++++---------------------
>>  1 files changed, 18 insertions(+), 38 deletions(-)
>>
>> diff --git a/net/netfilter/nf_conntrack_proto_udp.c b/net/netfilter/nf_conntrack_proto_udp.c
>> index 2b978e6..61bca4f 100644
>> --- a/net/netfilter/nf_conntrack_proto_udp.c
>> +++ b/net/netfilter/nf_conntrack_proto_udp.c
>> @@ -270,52 +270,32 @@ static int udp_kmemdup_compat_sysctl_table(struct nf_proto_net *pn)
>>  	return 0;
>>  }
>>
>> -static void udp_init_net_data(struct nf_udp_net *un)
>> +static int udp_init_net(struct net *net, u_int16_t proto)
>>  {
>> -	int i;
>> -#ifdef CONFIG_SYSCTL
>> -	if (!un->pn.ctl_table) {
>> -#else
>> -	if (!un->pn.users++) {
>> -#endif
>> +	int ret;
>> +	struct nf_udp_net *un = udp_pernet(net);
>> +	struct nf_proto_net *pn = &un->pn;
>> +
>> +	if (!pn->users) {
>> +		int i;
>>  		for (i = 0; i < UDP_CT_MAX; i++)
>>  			un->timeouts[i] = udp_timeouts[i];
>>  	}
>> -}
>> -
>> -static int udpv4_init_net(struct net *net, u_int16_t proto)
>> -{
>> -	int ret;
>> -	struct nf_udp_net *un = udp_pernet(net);
>> -	struct nf_proto_net *pn = (struct nf_proto_net *)un;
>>
>> -	udp_init_net_data(un);
>> +	if (proto == AF_INET) {
> 
> I think we can remove that u_int16_t proto that I proposed to make
> something like:
> 
> static int udp_kmemdup_compat_sysctl_table(struct nf_proto_net *pn)
> {
> #ifdef CONFIG_SYSCTL
> #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
>         struct nf_udp_net *un = (struct nf_udp_net *)pn;
> +
> +       if (pn->ctl_compat_table)
> +               return 0;
> +
>         pn->ctl_compat_table = kmemdup(udp_compat_sysctl_table,
>                                        sizeof(udp_compat_sysctl_table),
>                                        GFP_KERNEL);
>         if (!pn->ctl_compat_table)
>                 return -ENOMEM;
> 
> That should be enough to ensure that the compat is registered once. No
> matter if it's done by the IPv4 or IPv6 invocation of udp_init_net.
> 
> Thus, it will look consistent with udp_kmemdup_sysctl_table.

yes, but this will be very terrible to unregister compat sysctl
and free compat sysctl table.

thinking about, we may insmod nf_conntrack_ipv6 only, as your idea,
we will allocate compat_sysctl_table.so we have to free it when
rmmod nf_conntrack_ipv6.

in order to implement it, we have to change the logic of
nf_ct_l4proto_unregister_sysctl and nf_ct_unregister_sysctl. because we
only free the sysctl table when we unregister the proto.