[PATCH] ipv6: Use math to point per net sysctls into the appropriate struct net

[PATCH] ipv6: Use math to point per net sysctls into the appropriate struct net

[Cambda Zhu]

The data pointers of ipv6 sysctl are set one by one which is hard to
maintain, especially with kconfig. This patch simplifies it by using
math to point the per net sysctls into the appropriate struct net,
just like what we did for ipv4.

Signed-off-by: Cambda Zhu <cambda@linux.alibaba.com>
---
 net/ipv6/sysctl_net_ipv6.c | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index ec8fcfc60a27..cfc82cbe8e1f 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -203,6 +203,7 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
 	struct ctl_table *ipv6_table;
 	struct ctl_table *ipv6_route_table;
 	struct ctl_table *ipv6_icmp_table;
+	int i;
 	int err;
 
 	err = -ENOMEM;
@@ -210,22 +211,9 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
 			     GFP_KERNEL);
 	if (!ipv6_table)
 		goto out;
-	ipv6_table[0].data = &net->ipv6.sysctl.bindv6only;
-	ipv6_table[1].data = &net->ipv6.sysctl.anycast_src_echo_reply;
-	ipv6_table[2].data = &net->ipv6.sysctl.flowlabel_consistency;
-	ipv6_table[3].data = &net->ipv6.sysctl.auto_flowlabels;
-	ipv6_table[4].data = &net->ipv6.sysctl.fwmark_reflect;
-	ipv6_table[5].data = &net->ipv6.sysctl.idgen_retries;
-	ipv6_table[6].data = &net->ipv6.sysctl.idgen_delay;
-	ipv6_table[7].data = &net->ipv6.sysctl.flowlabel_state_ranges;
-	ipv6_table[8].data = &net->ipv6.sysctl.ip_nonlocal_bind;
-	ipv6_table[9].data = &net->ipv6.sysctl.flowlabel_reflect;
-	ipv6_table[10].data = &net->ipv6.sysctl.max_dst_opts_cnt;
-	ipv6_table[11].data = &net->ipv6.sysctl.max_hbh_opts_cnt;
-	ipv6_table[12].data = &net->ipv6.sysctl.max_dst_opts_len;
-	ipv6_table[13].data = &net->ipv6.sysctl.max_hbh_opts_len;
-	ipv6_table[14].data = &net->ipv6.sysctl.multipath_hash_policy,
-	ipv6_table[15].data = &net->ipv6.sysctl.seg6_flowlabel;
+	/* Update the variables to point into the current struct net */
+	for (i = 0; i < ARRAY_SIZE(ipv6_table_template) - 1; i++)
+		ipv6_table[i].data += (void *)net - (void *)&init_net;
 
 	ipv6_route_table = ipv6_route_sysctl_init(net);
 	if (!ipv6_route_table)
-- 
2.16.6

Re: [PATCH] ipv6: Use math to point per net sysctls into the appropriate struct net

[Eric Dumazet]

On 3/2/20 10:54 PM, Cambda Zhu wrote:
> The data pointers of ipv6 sysctl are set one by one which is hard to
> maintain, especially with kconfig. This patch simplifies it by using
> math to point the per net sysctls into the appropriate struct net,
> just like what we did for ipv4.
> 
> Signed-off-by: Cambda Zhu <cambda@linux.alibaba.com>
> ---
>  net/ipv6/sysctl_net_ipv6.c | 20 ++++----------------
>  1 file changed, 4 insertions(+), 16 deletions(-)
>


Reviewed-by: Eric Dumazet <edumazet@google.com>

Please add the intended tree (net-next in this case) for your next patches.

Documentation/networking/netdev-FAQ.rst

Re: [PATCH] ipv6: Use math to point per net sysctls into the appropriate struct net

[David Miller]

From: Cambda Zhu <cambda@linux.alibaba.com>
Date: Tue,  3 Mar 2020 14:54:34 +0800

> The data pointers of ipv6 sysctl are set one by one which is hard to
> maintain, especially with kconfig. This patch simplifies it by using
> math to point the per net sysctls into the appropriate struct net,
> just like what we did for ipv4.
> 
> Signed-off-by: Cambda Zhu <cambda@linux.alibaba.com>

Applied, thanks.