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authorPatrick McHardy <kaber@trash.net>2008-07-08 18:36:57 -0400
committerDavid S. Miller <davem@davemloft.net>2008-07-08 18:36:57 -0400
commit11a100f844f6096787ab20e19f17d72abc957a8f (patch)
tree9dd9f8578727783dc1d321a822402ee6ca83cd10 /net/8021q
parent9bb8582efb555521c7eec595ebd34e835ddc34b8 (diff)
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>
Diffstat (limited to 'net/8021q')
-rw-r--r--net/8021q/vlan_dev.c34
1 files changed, 5 insertions, 29 deletions
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)
74static inline struct sk_buff *vlan_check_reorder_header(struct sk_buff *skb) 74static inline struct sk_buff *vlan_check_reorder_header(struct sk_buff *skb)
75{ 75{
76 if (vlan_dev_info(skb->dev)->flags & VLAN_FLAG_REORDER_HDR) { 76 if (vlan_dev_info(skb->dev)->flags & VLAN_FLAG_REORDER_HDR) {
77 if (skb_shared(skb) || skb_cloned(skb)) { 77 if (skb_cow(skb, skb_headroom(skb)) < 0)
78 struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 78 skb = NULL;
79 kfree_skb(skb);
80 skb = nskb;
81 }
82 if (skb) { 79 if (skb) {
83 /* Lifted from Gleb's VLAN code... */ 80 /* Lifted from Gleb's VLAN code... */
84 memmove(skb->data - ETH_HLEN, 81 memmove(skb->data - ETH_HLEN,
@@ -262,12 +259,14 @@ static int vlan_dev_hard_header(struct sk_buff *skb, struct net_device *dev,
262 u16 vlan_tci = 0; 259 u16 vlan_tci = 0;
263 int rc = 0; 260 int rc = 0;
264 int build_vlan_header = 0; 261 int build_vlan_header = 0;
265 struct net_device *vdev = dev;
266 262
267 pr_debug("%s: skb: %p type: %hx len: %u vlan_id: %hx, daddr: %p\n", 263 pr_debug("%s: skb: %p type: %hx len: %u vlan_id: %hx, daddr: %p\n",
268 __func__, skb, type, len, vlan_dev_info(dev)->vlan_id, 264 __func__, skb, type, len, vlan_dev_info(dev)->vlan_id,
269 daddr); 265 daddr);
270 266
267 if (WARN_ON(skb_headroom(skb) < dev->hard_header_len))
268 return -ENOSPC;
269
271 /* build vlan header only if re_order_header flag is NOT set. This 270 /* build vlan header only if re_order_header flag is NOT set. This
272 * fixes some programs that get confused when they see a VLAN device 271 * fixes some programs that get confused when they see a VLAN device
273 * sending a frame that is VLAN encoded (the consensus is that the VLAN 272 * 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,
316 315
317 dev = vlan_dev_info(dev)->real_dev; 316 dev = vlan_dev_info(dev)->real_dev;
318 317
319 /* MPLS can send us skbuffs w/out enough space. This check will grow
320 * the skb if it doesn't have enough headroom. Not a beautiful solution,
321 * so I'll tick a counter so that users can know it's happening...
322 * If they care...
323 */
324
325 /* NOTE: This may still break if the underlying device is not the final
326 * device (and thus there are more headers to add...) It should work for
327 * good-ole-ethernet though.
328 */
329 if (skb_headroom(skb) < dev->hard_header_len) {
330 struct sk_buff *sk_tmp = skb;
331 skb = skb_realloc_headroom(sk_tmp, dev->hard_header_len);
332 kfree_skb(sk_tmp);
333 if (skb == NULL) {
334 struct net_device_stats *stats = &vdev->stats;
335 stats->tx_dropped++;
336 return -ENOMEM;
337 }
338 vlan_dev_info(vdev)->cnt_inc_headroom_on_tx++;
339 pr_debug("%s: %s: had to grow skb\n", __func__, vdev->name);
340 }
341
342 if (build_vlan_header) { 318 if (build_vlan_header) {
343 /* Now make the underlying real hard header */ 319 /* Now make the underlying real hard header */
344 rc = dev_hard_header(skb, dev, ETH_P_8021Q, daddr, saddr, 320 rc = dev_hard_header(skb, dev, ETH_P_8021Q, daddr, saddr,