[NETLINK]: Make netlink_callback->done() optional

Most netlink families make no use of the done() callback, making
it optional gets rid of all unnecessary dummy implementations.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/rtnetlink.c

@@ -462,11 +462,6 @@ void rtmsg_ifinfo(int type, struct net_device *dev, unsigned change)
 	netlink_broadcast(rtnl, skb, 0, RTNLGRP_LINK, GFP_KERNEL);
 }
 
-static int rtnetlink_done(struct netlink_callback *cb)
-{
-	return 0;
-}
-
 /* Protected by RTNL sempahore.  */
 static struct rtattr **rta_buf;
 static int rtattr_max;
@@ -533,8 +528,7 @@ rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, int *errp)
 			goto err_inval;
 
 		if ((*errp = netlink_dump_start(rtnl, skb, nlh,
-						link->dumpit,
-						rtnetlink_done)) != 0) {
+						link->dumpit, NULL)) != 0) {
 			return -1;
 		}
 		rlen = NLMSG_ALIGN(nlh->nlmsg_len);

net/ipv4/inet_diag.c

@@ -724,12 +724,6 @@ static int inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	return skb->len;
 }
 
-static int inet_diag_dump_done(struct netlink_callback *cb)
-{
-	return 0;
-}
-
-
 static __inline__ int
 inet_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
@@ -760,8 +754,7 @@ inet_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 				goto err_inval;
 		}
 		return netlink_dump_start(idiagnl, skb, nlh,
-					  inet_diag_dump,
-					  inet_diag_dump_done);
+					  inet_diag_dump, NULL);
 	} else {
 		return inet_diag_get_exact(skb, nlh);
 	}

net/ipv6/route.c

@@ -1710,7 +1710,7 @@ static void fib6_dump_end(struct netlink_callback *cb)
 static int fib6_dump_done(struct netlink_callback *cb)
 {
 	fib6_dump_end(cb);
-	return cb->done(cb);
+	return cb->done ? cb->done(cb) : 0;
 }
 
 int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)

net/netlink/af_netlink.c

@@ -427,7 +427,8 @@ static int netlink_release(struct socket *sock)
 
 	spin_lock(&nlk->cb_lock);
 	if (nlk->cb) {
-		nlk->cb->done(nlk->cb);
+		if (nlk->cb->done)
+			nlk->cb->done(nlk->cb);
 		netlink_destroy_callback(nlk->cb);
 		nlk->cb = NULL;
 	}
@@ -1322,7 +1323,8 @@ static int netlink_dump(struct sock *sk)
 	skb_queue_tail(&sk->sk_receive_queue, skb);
 	sk->sk_data_ready(sk, skb->len);
 
-	cb->done(cb);
+	if (cb->done)
+		cb->done(cb);
 	nlk->cb = NULL;
 	spin_unlock(&nlk->cb_lock);
 

net/xfrm/xfrm_user.c

@@ -948,11 +948,6 @@ static struct xfrm_link {
 	[XFRM_MSG_FLUSHPOLICY - XFRM_MSG_BASE] = { .doit = xfrm_flush_policy  },
 };
 
-static int xfrm_done(struct netlink_callback *cb)
-{
-	return 0;
-}
-
 static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, int *errp)
 {
 	struct rtattr *xfrma[XFRMA_MAX];
@@ -990,8 +985,7 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, int *err
 			goto err_einval;
 
 		if ((*errp = netlink_dump_start(xfrm_nl, skb, nlh,
-						link->dump,
-						xfrm_done)) != 0) {
+						link->dump, NULL)) != 0) {
 			return -1;
 		}
 		rlen = NLMSG_ALIGN(nlh->nlmsg_len);