[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>

76 files changed, 257 insertions, 241 deletions

diff --git a/net/atm/lec.c b/net/atm/lec.c
index d339645dc79..a8c6b285e06 100644
--- a/net/atm/lec.c
+++ b/net/atm/lec.c
@@ -283,7 +283,7 @@ static int lec_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	}
 
 	DPRINTK("skbuff head:%lx data:%lx tail:%lx end:%lx\n",
-		(long)skb->head, (long)skb->data, (long)skb->tail,
+		(long)skb->head, (long)skb->data, (long)skb_tail_pointer(skb),
 		(long)skb->end);
 #if defined(CONFIG_BRIDGE) || defined(CONFIG_BRIDGE_MODULE)
 	if (memcmp(skb->data, bridge_ula_lec, sizeof(bridge_ula_lec)) == 0)
diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
index 94f45736056..10cc13cfae6 100644
--- a/net/bluetooth/rfcomm/core.c
+++ b/net/bluetooth/rfcomm/core.c
@@ -1567,7 +1567,7 @@ static int rfcomm_recv_frame(struct rfcomm_session *s, struct sk_buff *skb)
 
 	/* Trim FCS */
 	skb->len--; skb->tail--;
-	fcs = *(u8 *) skb->tail;
+	fcs = *(u8 *)skb_tail_pointer(skb);
 
 	if (__check_fcs(skb->data, type, fcs)) {
 		BT_ERR("bad checksum in packet");
diff --git a/net/core/dev.c b/net/core/dev.c
index 6562e5736e2..86dc9f693f6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1069,7 +1069,7 @@ static void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
 			skb_reset_mac_header(skb2);
 
 			if (skb_network_header(skb2) < skb2->data ||
-			    skb_network_header(skb2) > skb2->tail) {
+			    skb2->network_header > skb2->tail) {
 				if (net_ratelimit())
 					printk(KERN_CRIT "protocol %04x is "
 					       "buggy, dev %s\n",
@@ -1175,7 +1175,7 @@ int skb_checksum_help(struct sk_buff *skb)
 	BUG_ON(offset > (int)skb->len);
 	csum = skb_checksum(skb, offset, skb->len-offset, 0);
 
-	offset = skb->tail - skb_transport_header(skb);
+	offset = skb->tail - skb->transport_header;
 	BUG_ON(offset <= 0);
 	BUG_ON(skb->csum_offset + 2 > offset);
 
diff --git a/net/core/filter.c b/net/core/filter.c
index d2358a5e633..bd903aaf7aa 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -46,7 +46,7 @@ static void *__load_pointer(struct sk_buff *skb, int k)
 	else if (k >= SKF_LL_OFF)
 		ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
 
-	if (ptr >= skb->head && ptr < skb->tail)
+	if (ptr >= skb->head && ptr < skb_tail_pointer(skb))
 		return ptr;
 	return NULL;
 }
diff --git a/net/core/gen_stats.c b/net/core/gen_stats.c
index 259473d0559..bcc25591d8a 100644
--- a/net/core/gen_stats.c
+++ b/net/core/gen_stats.c
@@ -61,7 +61,7 @@ gnet_stats_start_copy_compat(struct sk_buff *skb, int type, int tc_stats_type,
 	spin_lock_bh(lock);
 	d->lock = lock;
 	if (type)
-		d->tail = (struct rtattr *) skb->tail;
+		d->tail = (struct rtattr *)skb_tail_pointer(skb);
 	d->skb = skb;
 	d->compat_tc_stats = tc_stats_type;
 	d->compat_xstats = xstats_type;
@@ -212,7 +212,7 @@ int
 gnet_stats_finish_copy(struct gnet_dump *d)
 {
 	if (d->tail)
-		d->tail->rta_len = d->skb->tail - (u8 *) d->tail;
+		d->tail->rta_len = skb_tail_pointer(d->skb) - (u8 *)d->tail;
 
 	if (d->compat_tc_stats)
 		if (gnet_stats_copy(d, d->compat_tc_stats, &d->tc_stats,
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 9da8357addc..f9469ea530c 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2357,7 +2357,7 @@ static struct sk_buff *fill_packet_ipv4(struct net_device *odev,
 		*vlan_encapsulated_proto = htons(ETH_P_IP);
 	}
 
-	skb_set_network_header(skb, skb->tail - skb->data);
+	skb->network_header = skb->tail;
 	skb->transport_header = skb->network_header + sizeof(struct iphdr);
 	skb_put(skb, sizeof(struct iphdr) + sizeof(struct udphdr));
 
@@ -2696,7 +2696,7 @@ static struct sk_buff *fill_packet_ipv6(struct net_device *odev,
 		*vlan_encapsulated_proto = htons(ETH_P_IPV6);
 	}
 
-	skb_set_network_header(skb, skb->tail - skb->data);
+	skb->network_header = skb->tail;
 	skb->transport_header = skb->network_header + sizeof(struct ipv6hdr);
 	skb_put(skb, sizeof(struct ipv6hdr) + sizeof(struct udphdr));
 
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a48b0868126..ddcbc4d10da 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -87,8 +87,9 @@ static struct kmem_cache *skbuff_fclone_cache __read_mostly;
 void skb_over_panic(struct sk_buff *skb, int sz, void *here)
 {
 	printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
-			  "data:%p tail:%p end:%p dev:%s\n",
-	       here, skb->len, sz, skb->head, skb->data, skb->tail, skb->end,
+			  "data:%p tail:%#lx end:%p dev:%s\n",
+	       here, skb->len, sz, skb->head, skb->data,
+	       (unsigned long)skb->tail, skb->end,
 	       skb->dev ? skb->dev->name : "<NULL>");
 	BUG();
 }
@@ -105,8 +106,9 @@ void skb_over_panic(struct sk_buff *skb, int sz, void *here)
 void skb_under_panic(struct sk_buff *skb, int sz, void *here)
 {
 	printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
-			  "data:%p tail:%p end:%p dev:%s\n",
-	       here, skb->len, sz, skb->head, skb->data, skb->tail, skb->end,
+			  "data:%p tail:%#lx end:%p dev:%s\n",
+	       here, skb->len, sz, skb->head, skb->data,
+	       (unsigned long)skb->tail, skb->end,
 	       skb->dev ? skb->dev->name : "<NULL>");
 	BUG();
 }
@@ -167,7 +169,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
 	atomic_set(&skb->users, 1);
 	skb->head = data;
 	skb->data = data;
-	skb->tail = data;
+	skb_reset_tail_pointer(skb);
 	skb->end  = data + size;
 	/* make sure we initialize shinfo sequentially */
 	shinfo = skb_shinfo(skb);
@@ -629,7 +631,12 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
 
 	/* Copy only real data... and, alas, header. This should be
 	 * optimized for the cases when header is void. */
-	memcpy(data + nhead, skb->head, skb->tail - skb->head);
+	memcpy(data + nhead, skb->head,
+		skb->tail
+#ifndef NET_SKBUFF_DATA_USES_OFFSET
+		- skb->head
+#endif
+		);
 	memcpy(data + size, skb->end, sizeof(struct skb_shared_info));
 
 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
@@ -645,9 +652,9 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
 	skb->head     = data;
 	skb->end      = data + size;
 	skb->data    += off;
-	skb->tail    += off;
 #ifndef NET_SKBUFF_DATA_USES_OFFSET
-	/* {transport,network,mac}_header are relative to skb->head */
+	/* {transport,network,mac}_header and tail are relative to skb->head */
+	skb->tail	      += off;
 	skb->transport_header += off;
 	skb->network_header   += off;
 	skb->mac_header	      += off;
@@ -762,7 +769,7 @@ int skb_pad(struct sk_buff *skb, int pad)
 		return 0;
 	}
 
-	ntail = skb->data_len + pad - (skb->end - skb->tail);
+	ntail = skb->data_len + pad - (skb->end - skb_tail_pointer(skb));
 	if (likely(skb_cloned(skb) || ntail > 0)) {
 		err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
 		if (unlikely(err))
@@ -863,7 +870,7 @@ done:
 	} else {
 		skb->len       = len;
 		skb->data_len  = 0;
-		skb->tail      = skb->data + len;
+		skb_set_tail_pointer(skb, len);
 	}
 
 	return 0;
@@ -900,7 +907,7 @@ unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
 	 * plus 128 bytes for future expansions. If we have enough
 	 * room at tail, reallocate without expansion only if skb is cloned.
 	 */
-	int i, k, eat = (skb->tail + delta) - skb->end;
+	int i, k, eat = (skb_tail_pointer(skb) + delta) - skb->end;
 
 	if (eat > 0 || skb_cloned(skb)) {
 		if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
@@ -908,7 +915,7 @@ unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
 			return NULL;
 	}
 
-	if (skb_copy_bits(skb, skb_headlen(skb), skb->tail, delta))
+	if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
 		BUG();
 
 	/* Optimization: no fragments, no reasons to preestimate
@@ -1004,7 +1011,7 @@ pull_pages:
 	skb->tail     += delta;
 	skb->data_len -= delta;
 
-	return skb->tail;
+	return skb_tail_pointer(skb);
 }
 
 /* Copy some data bits from skb to kernel buffer. */
@@ -1539,7 +1546,7 @@ static inline void skb_split_inside_header(struct sk_buff *skb,
 	skb1->len		   += skb1->data_len;
 	skb->data_len		   = 0;
 	skb->len		   = len;
-	skb->tail		   = skb->data + len;
+	skb_set_tail_pointer(skb, len);
 }
 
 static inline void skb_split_no_header(struct sk_buff *skb,
diff --git a/net/core/wireless.c b/net/core/wireless.c
index 7c6a5db544f..4a777b68e3b 100644
--- a/net/core/wireless.c
+++ b/net/core/wireless.c
@@ -1938,7 +1938,7 @@ static inline int rtnetlink_fill_iwinfo(struct sk_buff *	skb,
 {
 	struct ifinfomsg *r;
 	struct nlmsghdr  *nlh;
-	unsigned char	 *b = skb->tail;
+	unsigned char	 *b = skb_tail_pointer(skb);
 
 	nlh = NLMSG_PUT(skb, 0, 0, type, sizeof(*r));
 	r = NLMSG_DATA(nlh);
@@ -1952,7 +1952,7 @@ static inline int rtnetlink_fill_iwinfo(struct sk_buff *	skb,
 	/* Add the wireless events in the netlink packet */
 	RTA_PUT(skb, IFLA_WIRELESS, event_len, event);
 
-	nlh->nlmsg_len = skb->tail - b;
+	nlh->nlmsg_len = skb_tail_pointer(skb) - b;
 	return skb->len;
 
 nlmsg_failure:
diff --git a/net/decnet/dn_nsp_out.c b/net/decnet/dn_nsp_out.c
index 84b8c5b45fe..7404653880b 100644
--- a/net/decnet/dn_nsp_out.c
+++ b/net/decnet/dn_nsp_out.c
@@ -681,8 +681,10 @@ void dn_nsp_send_conninit(struct sock *sk, unsigned char msgflg)
 	if (scp->peer.sdn_objnum)
 		type = 0;
 
-	skb_put(skb, dn_sockaddr2username(&scp->peer, skb->tail, type));
-	skb_put(skb, dn_sockaddr2username(&scp->addr, skb->tail, 2));
+	skb_put(skb, dn_sockaddr2username(&scp->peer,
+					  skb_tail_pointer(skb), type));
+	skb_put(skb, dn_sockaddr2username(&scp->addr,
+					  skb_tail_pointer(skb), 2));
 
 	menuver = DN_MENUVER_ACC | DN_MENUVER_USR;
 	if (scp->peer.sdn_flags & SDF_PROXY)
diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index bb73bf16630..9678b096b84 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -1468,7 +1468,7 @@ static int dn_rt_fill_info(struct sk_buff *skb, u32 pid, u32 seq,
 	struct dn_route *rt = (struct dn_route *)skb->dst;
 	struct rtmsg *r;
 	struct nlmsghdr *nlh;
-	unsigned char *b = skb->tail;
+	unsigned char *b = skb_tail_pointer(skb);
 	long expires;
 
 	nlh = NLMSG_NEW(skb, pid, seq, event, sizeof(*r), flags);
@@ -1509,7 +1509,7 @@ static int dn_rt_fill_info(struct sk_buff *skb, u32 pid, u32 seq,
 	if (rt->fl.iif)
 		RTA_PUT(skb, RTA_IIF, sizeof(int), &rt->fl.iif);
 
-	nlh->nlmsg_len = skb->tail - b;
+	nlh->nlmsg_len = skb_tail_pointer(skb) - b;
 	return skb->len;
 
 nlmsg_failure:
diff --git a/net/decnet/dn_table.c b/net/decnet/dn_table.c
index 780a141f834..544c4554074 100644
--- a/net/decnet/dn_table.c
+++ b/net/decnet/dn_table.c
@@ -295,7 +295,7 @@ static int dn_fib_dump_info(struct sk_buff *skb, u32 pid, u32 seq, int event,
 {
 	struct rtmsg *rtm;
 	struct nlmsghdr *nlh;
-	unsigned char *b = skb->tail;
+	unsigned char *b = skb_tail_pointer(skb);
 
 	nlh = NLMSG_NEW(skb, pid, seq, event, sizeof(*rtm), flags);
 	rtm = NLMSG_DATA(nlh);
@@ -337,13 +337,13 @@ static int dn_fib_dump_info(struct sk_buff *skb, u32 pid, u32 seq, int event,
 			nhp->rtnh_ifindex = nh->nh_oif;
 			if (nh->nh_gw)
 				RTA_PUT(skb, RTA_GATEWAY, 2, &nh->nh_gw);
-			nhp->rtnh_len = skb->tail - (unsigned char *)nhp;
+			nhp->rtnh_len = skb_tail_pointer(skb) - (unsigned char *)nhp;
 		} endfor_nexthops(fi);
 		mp_head->rta_type = RTA_MULTIPATH;
-		mp_head->rta_len = skb->tail - (u8*)mp_head;
+		mp_head->rta_len = skb_tail_pointer(skb) - (u8 *)mp_head;
 	}
 
-	nlh->nlmsg_len = skb->tail - b;
+	nlh->nlmsg_len = skb_tail_pointer(skb) - b;
 	return skb->len;
 
 
diff --git a/net/decnet/netfilter/dn_rtmsg.c b/net/decnet/netfilter/dn_rtmsg.c
index 0e62def05a5..ceefd9dd0c9 100644
--- a/net/decnet/netfilter/dn_rtmsg.c
+++ b/net/decnet/netfilter/dn_rtmsg.c
@@ -33,7 +33,7 @@ static struct sk_buff *dnrmg_build_message(struct sk_buff *rt_skb, int *errp)
 {
 	struct sk_buff *skb = NULL;
 	size_t size;
-	unsigned char *old_tail;
+	sk_buff_data_t old_tail;
 	struct nlmsghdr *nlh;
 	unsigned char *ptr;
 	struct nf_dn_rtmsg *rtm;
diff --git a/net/econet/af_econet.c b/net/econet/af_econet.c
index 78993dadb53..b5524f32ac2 100644
--- a/net/econet/af_econet.c
+++ b/net/econet/af_econet.c
@@ -366,7 +366,7 @@ static int econet_sendmsg(struct kiocb *iocb, struct socket *sock,
 			fh->cb = cb;
 			fh->port = port;
 			if (sock->type != SOCK_DGRAM) {
-				skb->tail = skb->data;
+				skb_reset_tail_pointer(skb);
 				skb->len = 0;
 			} else if (res < 0)
 				goto out_free;
diff --git a/net/ieee80211/ieee80211_rx.c b/net/ieee80211/ieee80211_rx.c
index 59a765c49cf..2b854941e06 100644
--- a/net/ieee80211/ieee80211_rx.c
+++ b/net/ieee80211/ieee80211_rx.c
@@ -595,7 +595,7 @@ int ieee80211_rx(struct ieee80211_device *ieee, struct sk_buff *skb,
 		if (frag != 0)
 			flen -= hdrlen;
 
-		if (frag_skb->tail + flen > frag_skb->end) {
+		if (skb_tail_pointer(frag_skb) + flen > frag_skb->end) {
 			printk(KERN_WARNING "%s: host decrypted and "
 			       "reassembled frame did not fit skb\n",
 			       dev->name);
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index de019f9fbfe..5e5613930ff 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -21,6 +21,7 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
 	struct blkcipher_desc desc;
 	struct esp_data *esp;
 	struct sk_buff *trailer;
+	u8 *tail;
 	int blksize;
 	int clen;
 	int alen;
@@ -49,12 +50,13 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
 		goto error;
 
 	/* Fill padding... */
+	tail = skb_tail_pointer(trailer);
 	do {
 		int i;
 		for (i=0; i<clen-skb->len - 2; i++)
-			*(u8*)(trailer->tail + i) = i+1;
+			tail[i] = i + 1;
 	} while (0);
-	*(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2;
+	tail[clen - skb->len - 2] = (clen - skb->len) - 2;
 	pskb_put(skb, trailer, clen - skb->len);
 
 	__skb_push(skb, skb->data - skb_network_header(skb));
@@ -62,7 +64,7 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
 	esph = (struct ip_esp_hdr *)(skb_network_header(skb) +
 				     top_iph->ihl * 4);
 	top_iph->tot_len = htons(skb->len + alen);
-	*(u8*)(trailer->tail - 1) = top_iph->protocol;
+	*(skb_tail_pointer(skb) - 1) = top_iph->protocol;
 
 	/* this is non-NULL only with UDP Encapsulation */
 	if (x->encap) {
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 8372f8b8f0c..d38cbba92a4 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -450,7 +450,8 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 	 */
 	iph = ip_hdr(skb_in);
 
-	if ((u8 *)iph < skb_in->head || (u8 *)(iph + 1) > skb_in->tail)
+	if ((u8 *)iph < skb_in->head ||
+	    (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
 		goto out;
 
 	/*
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 1fc637fb675..2506021c293 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -348,8 +348,8 @@ static int igmpv3_sendpack(struct sk_buff *skb)
 {
 	struct iphdr *pip = ip_hdr(skb);
 	struct igmphdr *pig = igmp_hdr(skb);
-	const int iplen = skb->tail - skb_network_header(skb);
-	const int igmplen = skb->tail - skb_transport_header(skb);
+	const int iplen = skb->tail - skb->network_header;
+	const int igmplen = skb->tail - skb->transport_header;
 
 	pip->tot_len = htons(iplen);
 	ip_send_check(pip);
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 5df71cd08da..37362cd1d07 100644
--- a/