netlink: add netlink_dump_control structure for netlink_dump_start()

Davem considers that the argument list of this interface is getting
out of control. This patch tries to address this issue following
his proposal:

struct netlink_dump_control c = { .dump = dump, .done = done, ... };

netlink_dump_start(..., &c);

Suggested by David S. Miller.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index a390e9d..1f8c1a9 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -248,11 +248,15 @@
 #define NLMSG_PUT(skb, pid, seq, type, len) \
 	NLMSG_NEW(skb, pid, seq, type, len, 0)
 
+struct netlink_dump_control {
+	int (*dump)(struct sk_buff *skb, struct netlink_callback *);
+	int (*done)(struct netlink_callback*);
+	u16 min_dump_alloc;
+};
+
 extern int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 			      const struct nlmsghdr *nlh,
-			      int (*dump)(struct sk_buff *skb, struct netlink_callback*),
-			      int (*done)(struct netlink_callback*),
-			      u16 min_dump_alloc);
+			      struct netlink_dump_control *control);
 
 
 #define NL_NONROOT_RECV 0x1