vlan: avoid header copying and linearisation where possible
- vlan_dev_reorder_header() is only called on the receive path after
calling skb_share_check(). This means we can use skb_cow() since
all we need is a writable header.
- vlan_dev_hard_header() includes a work-around for some apparently
broken out of tree MPLS code. The hard_header functions can expect
to always have a headroom of at least there own hard_header_len
available, so the reallocation check is unnecessary.
- __vlan_put_tag() can use skb_cow_head() to avoid the skb_unshare()
copy when the header is writable.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index d36515d..93f5d9b 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -185,22 +185,10 @@
{
struct vlan_ethhdr *veth;
- if (skb_headroom(skb) < VLAN_HLEN) {
- struct sk_buff *sk_tmp = skb;
- skb = skb_realloc_headroom(sk_tmp, VLAN_HLEN);
- kfree_skb(sk_tmp);
- if (!skb) {
- printk(KERN_ERR "vlan: failed to realloc headroom\n");
- return NULL;
- }
- } else {
- skb = skb_unshare(skb, GFP_ATOMIC);
- if (!skb) {
- printk(KERN_ERR "vlan: failed to unshare skbuff\n");
- return NULL;
- }
+ if (skb_cow_head(skb, VLAN_HLEN) < 0) {
+ kfree_skb(skb);
+ return NULL;
}
-
veth = (struct vlan_ethhdr *)skb_push(skb, VLAN_HLEN);
/* Move the mac addresses to the beginning of the new header. */