netlink: add netlink_kernel_cfg parameter to netlink_kernel_create

This patch adds the following structure:

struct netlink_kernel_cfg {
        unsigned int    groups;
        void            (*input)(struct sk_buff *skb);
        struct mutex    *cb_mutex;
};

That can be passed to netlink_kernel_create to set optional configurations
for netlink kernel sockets.

I've populated this structure by looking for NULL and zero parameters at the
existing code. The remaining parameters that always need to be set are still
left in the original interface.

That includes optional parameters for the netlink socket creation. This allows
easy extensibility of this interface in the future.

This patch also adapts all callers to use this new interface.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 13 insertions, 4 deletions

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index bc8a1cdaac98..2b325c340b44 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2353,8 +2353,13 @@ static struct notifier_block rtnetlink_dev_notifier = {
 static int __net_init rtnetlink_net_init(struct net *net)
 {
         struct sock *sk;
-        sk = netlink_kernel_create(net, NETLINK_ROUTE, RTNLGRP_MAX,
-                                   rtnetlink_rcv, &rtnl_mutex, THIS_MODULE);
+        struct netlink_kernel_cfg cfg = {
+                .groups         = RTNLGRP_MAX,
+                .input          = rtnetlink_rcv,
+                .cb_mutex       = &rtnl_mutex,
+        };
+
+        sk = netlink_kernel_create(net, NETLINK_ROUTE, THIS_MODULE, &cfg);
         if (!sk)
                 return -ENOMEM;
         net->rtnl = sk;
diff --git a/net/core/sock_diag.c b/net/core/sock_diag.c
index ff2967acbfae..07a29eb34a41 100644
--- a/net/core/sock_diag.c
+++ b/net/core/sock_diag.c
@@ -171,8 +171,12 @@ EXPORT_SYMBOL_GPL(sock_diag_nlsk);
 
 static int __init sock_diag_init(void)
 {
-        sock_diag_nlsk = netlink_kernel_create(&init_net, NETLINK_SOCK_DIAG, 0,
-                                        sock_diag_rcv, NULL, THIS_MODULE);
+        struct netlink_kernel_cfg cfg = {
+                .input  = sock_diag_rcv,
+        };
+
+        sock_diag_nlsk = netlink_kernel_create(&init_net, NETLINK_SOCK_DIAG,
+                                               THIS_MODULE, &cfg);
         return sock_diag_nlsk == NULL ? -ENOMEM : 0;
 }