Currently there are potentially 2 skb_copy_expand calls in IPHC
decompression. This patch replaces this with one call to
skb_cow which will check to see if there is enough headroom
first to ensure it's only done if necessary and will handle
alignment issues for cache.
As skb_cow uses pskb_expand_head we ensure the skb isn't shared from
bluetooth and ieee802.15.4 code that use the IPHC decompression.
Signed-off-by: Martin Townsend <martin.townsend@xxxxxxxxxx>
---
net/6lowpan/iphc.c | 47 +++++++++++++++++++++--------------------------
net/bluetooth/6lowpan.c | 4 ++++
2 files changed, 25 insertions(+), 26 deletions(-)
diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c
index 142eef5..747b3cc 100644
--- a/net/6lowpan/iphc.c
+++ b/net/6lowpan/iphc.c
@@ -174,30 +174,22 @@ static int uncompress_context_based_src_addr(struct sk_buff *skb,
static int skb_deliver(struct sk_buff *skb, struct ipv6hdr *hdr,
struct net_device *dev, skb_delivery_cb deliver_skb)
{
- struct sk_buff *new;
int stat;
- new = skb_copy_expand(skb, sizeof(struct ipv6hdr), skb_tailroom(skb),
- GFP_ATOMIC);
- kfree_skb(skb);
-
- if (!new)
- return -ENOMEM;
-
- skb_push(new, sizeof(struct ipv6hdr));
- skb_reset_network_header(new);
- skb_copy_to_linear_data(new, hdr, sizeof(struct ipv6hdr));
+ skb_push(skb, sizeof(struct ipv6hdr));
+ skb_reset_network_header(skb);
+ skb_copy_to_linear_data(skb, hdr, sizeof(struct ipv6hdr));
- new->protocol = htons(ETH_P_IPV6);
- new->pkt_type = PACKET_HOST;
- new->dev = dev;
+ skb->protocol = htons(ETH_P_IPV6);
+ skb->pkt_type = PACKET_HOST;
+ skb->dev = dev;
raw_dump_table(__func__, "raw skb data dump before receiving",
- new->data, new->len);
+ skb->data, skb->len);
- stat = deliver_skb(new, dev);
+ stat = deliver_skb(skb, dev);
- kfree_skb(new);
+ consume_skb(skb);
return stat;
}
@@ -460,7 +452,7 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
/* UDP data uncompression */
if (iphc0 & LOWPAN_IPHC_NH_C) {
struct udphdr uh;
- struct sk_buff *new;
+ const int needed = sizeof(struct udphdr) + sizeof(hdr);
if (uncompress_udp_header(skb, &uh))
goto drop;
@@ -468,14 +460,11 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
/* replace the compressed UDP head by the uncompressed UDP
* header
*/
- new = skb_copy_expand(skb, sizeof(struct udphdr),
- skb_tailroom(skb), GFP_ATOMIC);
- kfree_skb(skb);
-
- if (!new)
- return -ENOMEM;
-
- skb = new;
+ err = skb_cow(skb, needed);
+ if (unlikely(err)) {
+ kfree_skb(skb);
+ return err;
+ }
skb_push(skb, sizeof(struct udphdr));
skb_reset_transport_header(skb);
@@ -485,6 +474,12 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
(u8 *)&uh, sizeof(uh));
hdr.nexthdr = UIP_PROTO_UDP;
+ } else {
+ err = skb_cow(skb, sizeof(hdr));
+ if (unlikely(err)) {
+ kfree_skb(skb);
+ return err;
+ }
}
hdr.payload_len = htons(skb->len);
diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
index c2e0d14..4ebc806 100644
--- a/net/bluetooth/6lowpan.c
+++ b/net/bluetooth/6lowpan.c
@@ -316,6 +316,10 @@ static int recv_pkt(struct sk_buff *skb, struct net_device *dev,
if (dev->type != ARPHRD_6LOWPAN)
goto drop;
+ skb = skb_share_check(skb, GFP_ATOMIC);
+ if (!skb)
+ goto drop;
+
/* check that it's our buffer */
if (skb->data[0] == LOWPAN_DISPATCH_IPV6) {
/* Copy the packet so that the IPv6 header is
--
1.9.1
--
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