[SK_BUFF]: Convert skb->tail to sk_buff_data_t

So that it is also an offset from skb->head, reduces its size from 8 to 4 bytes
on 64bit architectures, allowing us to combine the 4 bytes hole left by the
layer headers conversion, reducing struct sk_buff size to 256 bytes, i.e. 4
64byte cachelines, and since the sk_buff slab cache is SLAB_HWCACHE_ALIGN...
:-)

Many calculations that previously required that skb->{transport,network,
mac}_header be first converted to a pointer now can be done directly, being
meaningful as offsets or pointers.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 8 insertions, 7 deletions

diff --git a/net/ipv4/netfilter/arpt_mangle.c b/net/ipv4/netfilter/arpt_mangle.c
index b4450f1ccc1..6298d404e7c 100644
--- a/net/ipv4/netfilter/arpt_mangle.c
+++ b/net/ipv4/netfilter/arpt_mangle.c
@@ -37,28 +37,28 @@ target(struct sk_buff **pskb,
 	/* We assume that pln and hln were checked in the match */
 	if (mangle->flags & ARPT_MANGLE_SDEV) {
 		if (ARPT_DEV_ADDR_LEN_MAX < hln ||
-		   (arpptr + hln > (**pskb).tail))
+		   (arpptr + hln > skb_tail_pointer(*pskb)))
 			return NF_DROP;
 		memcpy(arpptr, mangle->src_devaddr, hln);
 	}
 	arpptr += hln;
 	if (mangle->flags & ARPT_MANGLE_SIP) {
 		if (ARPT_MANGLE_ADDR_LEN_MAX < pln ||
-		   (arpptr + pln > (**pskb).tail))
+		   (arpptr + pln > skb_tail_pointer(*pskb)))
 			return NF_DROP;
 		memcpy(arpptr, &mangle->u_s.src_ip, pln);
 	}
 	arpptr += pln;
 	if (mangle->flags & ARPT_MANGLE_TDEV) {
 		if (ARPT_DEV_ADDR_LEN_MAX < hln ||
-		   (arpptr + hln > (**pskb).tail))
+		   (arpptr + hln > skb_tail_pointer(*pskb)))
 			return NF_DROP;
 		memcpy(arpptr, mangle->tgt_devaddr, hln);
 	}
 	arpptr += hln;
 	if (mangle->flags & ARPT_MANGLE_TIP) {
 		if (ARPT_MANGLE_ADDR_LEN_MAX < pln ||
-		   (arpptr + pln > (**pskb).tail))
+		   (arpptr + pln > skb_tail_pointer(*pskb)))
 			return NF_DROP;
 		memcpy(arpptr, &mangle->u_t.tgt_ip, pln);
 	}
diff --git a/net/ipv4/netfilter/ip_queue.c b/net/ipv4/netfilter/ip_queue.c
index 5842f1aa973..15e0d200223 100644
--- a/net/ipv4/netfilter/ip_queue.c
+++ b/net/ipv4/netfilter/ip_queue.c
@@ -191,7 +191,7 @@ ipq_flush(int verdict)
 static struct sk_buff *
 ipq_build_packet_message(struct ipq_queue_entry *entry, int *errp)
 {
-	unsigned char *old_tail;
+	sk_buff_data_t old_tail;
 	size_t size = 0;
 	size_t data_len = 0;
 	struct sk_buff *skb;
@@ -235,7 +235,7 @@ ipq_build_packet_message(struct ipq_queue_entry *entry, int *errp)
 	if (!skb)
 		goto nlmsg_failure;
 
-	old_tail= skb->tail;
+	old_tail = skb->tail;
 	nlh = NLMSG_PUT(skb, 0, 0, IPQM_PACKET, size - sizeof(*nlh));
 	pmsg = NLMSG_DATA(nlh);
 	memset(pmsg, 0, sizeof(*pmsg));
diff --git a/net/ipv4/netfilter/nf_nat_helper.c b/net/ipv4/netfilter/nf_nat_helper.c
index c2c92ff1278..8a40fbe842b 100644
--- a/net/ipv4/netfilter/nf_nat_helper.c
+++ b/net/ipv4/netfilter/nf_nat_helper.c
@@ -92,7 +92,8 @@ static void mangle_contents(struct sk_buff *skb,
 	/* move post-replacement */
 	memmove(data + match_offset + rep_len,
 		data + match_offset + match_len,
-		skb->tail - (data + match_offset + match_len));
+		skb->tail - (skb->network_header + dataoff +
+			     match_offset + match_len));
 
 	/* insert data from buffer */
 	memcpy(data + match_offset, rep_buffer, rep_len);