ipv4: Remove all uses of LL_ALLOCATED_SPACE

ipv4: 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/ipv4
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>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index d732827..5c29ac5 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -592,16 +592,18 @@ struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
 	struct sk_buff *skb;
 	struct arphdr *arp;
 	unsigned char *arp_ptr;
+	int hlen = LL_RESERVED_SPACE(dev);
+	int tlen = dev->needed_tailroom;
 
 	/*
 	 *	Allocate a buffer
 	 */
 
-	skb = alloc_skb(arp_hdr_len(dev) + LL_ALLOCATED_SPACE(dev), GFP_ATOMIC);
+	skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
 	if (skb == NULL)
 		return NULL;
 
-	skb_reserve(skb, LL_RESERVED_SPACE(dev));
+	skb_reserve(skb, hlen);
 	skb_reset_network_header(skb);
 	arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
 	skb->dev = dev;