[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, 10 insertions, 10 deletions

diff --git a/net/irda/ircomm/ircomm_param.c b/net/irda/ircomm/ircomm_param.c
index 01d7c9c..e5e4792 100644
--- a/net/irda/ircomm/ircomm_param.c
+++ b/net/irda/ircomm/ircomm_param.c
@@ -133,8 +133,8 @@ int ircomm_param_request(struct ircomm_tty_cb *self, __u8 pi, int flush)
 	 * Inserting is a little bit tricky since we don't know how much
 	 * room we will need. But this should hopefully work OK
 	 */
-	count = irda_param_insert(self, pi, skb->tail, skb_tailroom(skb),
-				  &ircomm_param_info);
+	count = irda_param_insert(self, pi, skb_tail_pointer(skb),
+				  skb_tailroom(skb), &ircomm_param_info);
 	if (count < 0) {
 		IRDA_WARNING("%s(), no room for parameter!\n", __FUNCTION__);
 		spin_unlock_irqrestore(&self->spinlock, flags);
diff --git a/net/irda/irlan/irlan_common.c b/net/irda/irlan/irlan_common.c
index fcf9d65..ed69773 100644
--- a/net/irda/irlan/irlan_common.c
+++ b/net/irda/irlan/irlan_common.c
@@ -1039,7 +1039,7 @@ static int __irlan_insert_param(struct sk_buff *skb, char *param, int type,
 	}
 
 	/* Insert at end of sk-buffer */
-	frame = skb->tail;
+	frame = skb_tail_pointer(skb);
 
 	/* Make space for data */
 	if (skb_tailroom(skb) < (param_len+value_len+3)) {
diff --git a/net/irda/qos.c b/net/irda/qos.c
index 349012c..aeb18cf 100644
--- a/net/irda/qos.c
+++ b/net/irda/qos.c
@@ -469,49 +469,49 @@ int irlap_insert_qos_negotiation_params(struct irlap_cb *self,
 	int ret;
 
 	/* Insert data rate */
-	ret = irda_param_insert(self, PI_BAUD_RATE, skb->tail,
+	ret = irda_param_insert(self, PI_BAUD_RATE, skb_tail_pointer(skb),
 				skb_tailroom(skb), &irlap_param_info);
 	if (ret < 0)
 		return ret;
 	skb_put(skb, ret);
 
 	/* Insert max turnaround time */
-	ret = irda_param_insert(self, PI_MAX_TURN_TIME, skb->tail,
+	ret = irda_param_insert(self, PI_MAX_TURN_TIME, skb_tail_pointer(skb),
 				skb_tailroom(skb), &irlap_param_info);
 	if (ret < 0)
 		return ret;
 	skb_put(skb, ret);
 
 	/* Insert data size */
-	ret = irda_param_insert(self, PI_DATA_SIZE, skb->tail,
+	ret = irda_param_insert(self, PI_DATA_SIZE, skb_tail_pointer(skb),
 				skb_tailroom(skb), &irlap_param_info);
 	if (ret < 0)
 		return ret;
 	skb_put(skb, ret);
 
 	/* Insert window size */
-	ret = irda_param_insert(self, PI_WINDOW_SIZE, skb->tail,
+	ret = irda_param_insert(self, PI_WINDOW_SIZE, skb_tail_pointer(skb),
 				skb_tailroom(skb), &irlap_param_info);
 	if (ret < 0)
 		return ret;
 	skb_put(skb, ret);
 
 	/* Insert additional BOFs */
-	ret = irda_param_insert(self, PI_ADD_BOFS, skb->tail,
+	ret = irda_param_insert(self, PI_ADD_BOFS, skb_tail_pointer(skb),
 				skb_tailroom(skb), &irlap_param_info);
 	if (ret < 0)
 		return ret;
 	skb_put(skb, ret);
 
 	/* Insert minimum turnaround time */
-	ret = irda_param_insert(self, PI_MIN_TURN_TIME, skb->tail,
+	ret = irda_param_insert(self, PI_MIN_TURN_TIME, skb_tail_pointer(skb),
 				skb_tailroom(skb), &irlap_param_info);
 	if (ret < 0)
 		return ret;
 	skb_put(skb, ret);
 
 	/* Insert link disconnect/threshold time */
-	ret = irda_param_insert(self, PI_LINK_DISC, skb->tail,
+	ret = irda_param_insert(self, PI_LINK_DISC, skb_tail_pointer(skb),
 				skb_tailroom(skb), &irlap_param_info);
 	if (ret < 0)
 		return ret;