[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>
diff --git a/drivers/s390/net/netiucv.c b/drivers/s390/net/netiucv.c
index 82edf20..cd42bd5 100644
--- a/drivers/s390/net/netiucv.c
+++ b/drivers/s390/net/netiucv.c
@@ -689,7 +689,8 @@
msg->length, conn->max_buffsize);
return;
}
- conn->rx_buff->data = conn->rx_buff->tail = conn->rx_buff->head;
+ conn->rx_buff->data = conn->rx_buff->head;
+ skb_reset_tail_pointer(conn->rx_buff);
conn->rx_buff->len = 0;
rc = iucv_message_receive(conn->path, msg, 0, conn->rx_buff->data,
msg->length, NULL);
@@ -735,7 +736,8 @@
}
}
}
- conn->tx_buff->data = conn->tx_buff->tail = conn->tx_buff->head;
+ conn->tx_buff->data = conn->tx_buff->head;
+ skb_reset_tail_pointer(conn->tx_buff);
conn->tx_buff->len = 0;
spin_lock_irqsave(&conn->collect_lock, saveflags);
while ((skb = skb_dequeue(&conn->collect_queue))) {
@@ -1164,8 +1166,8 @@
* Copy the skb to a new allocated skb in lowmem only if the
* data is located above 2G in memory or tailroom is < 2.
*/
- unsigned long hi =
- ((unsigned long)(skb->tail + NETIUCV_HDRLEN)) >> 31;
+ unsigned long hi = ((unsigned long)(skb_tail_pointer(skb) +
+ NETIUCV_HDRLEN)) >> 31;
int copied = 0;
if (hi || (skb_tailroom(skb) < 2)) {
nskb = alloc_skb(skb->len + NETIUCV_HDRLEN +