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/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 2ccac6b..b6e52c0 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -74,11 +74,8 @@
static inline struct sk_buff *vlan_check_reorder_header(struct sk_buff *skb)
{
if (vlan_dev_info(skb->dev)->flags & VLAN_FLAG_REORDER_HDR) {
- if (skb_shared(skb) || skb_cloned(skb)) {
- struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC);
- kfree_skb(skb);
- skb = nskb;
- }
+ if (skb_cow(skb, skb_headroom(skb)) < 0)
+ skb = NULL;
if (skb) {
/* Lifted from Gleb's VLAN code... */
memmove(skb->data - ETH_HLEN,
@@ -262,12 +259,14 @@
u16 vlan_tci = 0;
int rc = 0;
int build_vlan_header = 0;
- struct net_device *vdev = dev;
pr_debug("%s: skb: %p type: %hx len: %u vlan_id: %hx, daddr: %p\n",
__func__, skb, type, len, vlan_dev_info(dev)->vlan_id,
daddr);
+ if (WARN_ON(skb_headroom(skb) < dev->hard_header_len))
+ return -ENOSPC;
+
/* build vlan header only if re_order_header flag is NOT set. This
* fixes some programs that get confused when they see a VLAN device
* sending a frame that is VLAN encoded (the consensus is that the VLAN
@@ -316,29 +315,6 @@
dev = vlan_dev_info(dev)->real_dev;
- /* MPLS can send us skbuffs w/out enough space. This check will grow
- * the skb if it doesn't have enough headroom. Not a beautiful solution,
- * so I'll tick a counter so that users can know it's happening...
- * If they care...
- */
-
- /* NOTE: This may still break if the underlying device is not the final
- * device (and thus there are more headers to add...) It should work for
- * good-ole-ethernet though.
- */
- if (skb_headroom(skb) < dev->hard_header_len) {
- struct sk_buff *sk_tmp = skb;
- skb = skb_realloc_headroom(sk_tmp, dev->hard_header_len);
- kfree_skb(sk_tmp);
- if (skb == NULL) {
- struct net_device_stats *stats = &vdev->stats;
- stats->tx_dropped++;
- return -ENOMEM;
- }
- vlan_dev_info(vdev)->cnt_inc_headroom_on_tx++;
- pr_debug("%s: %s: had to grow skb\n", __func__, vdev->name);
- }
-
if (build_vlan_header) {
/* Now make the underlying real hard header */
rc = dev_hard_header(skb, dev, ETH_P_8021Q, daddr, saddr,