ipv6: Remove all uses of LL_ALLOCATED_SPACE

ipv6: Remove all uses of LL_ALLOCATED_SPACE

The macro LL_ALLOCATED_SPACE was ill-conceived.  It applies the
alignment to the sum of needed_headroom and needed_tailroom.  As
the amount that is then reserved for head room is needed_headroom
with alignment, this means that the tail room left may be too small.

This patch replaces all uses of LL_ALLOCATED_SPACE in net/ipv6
with the macro LL_RESERVED_SPACE and direct reference to
needed_tailroom.

This also fixes the problem with needed_headroom changing between
allocating the skb and reserving the head room.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 4a20982..d699ddc 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -446,6 +446,8 @@
 	struct sock *sk = net->ipv6.ndisc_sk;
 	struct sk_buff *skb;
 	struct icmp6hdr *hdr;
+	int hlen = LL_RESERVED_SPACE(dev);
+	int tlen = dev->needed_tailroom;
 	int len;
 	int err;
 	u8 *opt;
@@ -459,7 +461,7 @@
 
 	skb = sock_alloc_send_skb(sk,
 				  (MAX_HEADER + sizeof(struct ipv6hdr) +
-				   len + LL_ALLOCATED_SPACE(dev)),
+				   len + hlen + tlen),
 				  1, &err);
 	if (!skb) {
 		ND_PRINTK0(KERN_ERR
@@ -468,7 +470,7 @@
 		return NULL;
 	}
 
-	skb_reserve(skb, LL_RESERVED_SPACE(dev));
+	skb_reserve(skb, hlen);
 	ip6_nd_hdr(sk, skb, dev, saddr, daddr, IPPROTO_ICMPV6, len);
 
 	skb->transport_header = skb->tail;
@@ -1533,6 +1535,7 @@
 	struct inet6_dev *idev;
 	struct flowi6 fl6;
 	u8 *opt;
+	int hlen, tlen;
 	int rd_len;
 	int err;
 	u8 ha_buf[MAX_ADDR_LEN], *ha = NULL;
@@ -1590,9 +1593,11 @@
 	rd_len &= ~0x7;
 	len += rd_len;
 
+	hlen = LL_RESERVED_SPACE(dev);
+	tlen = dev->needed_tailroom;
 	buff = sock_alloc_send_skb(sk,
 				   (MAX_HEADER + sizeof(struct ipv6hdr) +
-				    len + LL_ALLOCATED_SPACE(dev)),
+				    len + hlen + tlen),
 				   1, &err);
 	if (buff == NULL) {
 		ND_PRINTK0(KERN_ERR
@@ -1601,7 +1606,7 @@
 		goto release;
 	}
 
-	skb_reserve(buff, LL_RESERVED_SPACE(dev));
+	skb_reserve(buff, hlen);
 	ip6_nd_hdr(sk, buff, dev, &saddr_buf, &ipv6_hdr(skb)->saddr,
 		   IPPROTO_ICMPV6, len);