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authorPatrick McHardy <kaber@trash.net>2008-07-08 15:36:57 -0700
committerDavid S. Miller <davem@davemloft.net>2008-07-08 15:36:57 -0700
commit11a100f844f6096787ab20e19f17d72abc957a8f (patch)
tree9dd9f8578727783dc1d321a822402ee6ca83cd10
parent9bb8582efb555521c7eec595ebd34e835ddc34b8 (diff)
downloadlinux-11a100f844f6096787ab20e19f17d72abc957a8f.tar.bz2
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>
-rw-r--r--include/linux/if_vlan.h18
-rw-r--r--net/8021q/vlan_dev.c34
2 files changed, 8 insertions, 44 deletions
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index d36515dae62f..93f5d9b0e9f9 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -185,22 +185,10 @@ static inline struct sk_buff *__vlan_put_tag(struct sk_buff *skb, u16 vlan_tci)
{
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. */
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 2ccac6bea57e..b6e52c025fd8 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -74,11 +74,8 @@ static int vlan_dev_rebuild_header(struct sk_buff *skb)
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 @@ static int vlan_dev_hard_header(struct sk_buff *skb, struct net_device *dev,
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 @@ static int vlan_dev_hard_header(struct sk_buff *skb, struct net_device *dev,
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,