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Commit 11e3ff70 authored by Martin Townsend's avatar Martin Townsend Committed by Marcel Holtmann
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6lowpan: Use skb_cow in IPHC decompression. 



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: default avatarMartin Townsend <martin.townsend@xsilon.com>
Acked-by: default avatarAlexander Aring <alex.aring@gmail.com>
Acked-by: default avatarJukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: default avatarMarcel Holtmann <marcel@holtmann.org>
parent 4456c50d

net/6lowpan/iphc.c

+21 −26
Original line number Diff line number Diff line
@@ -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);

		err = skb_cow(skb, needed);

		if (unlikely(err)) {

			kfree_skb(skb);



		if (!new)

			return -ENOMEM;



		skb = new;

			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);

net/bluetooth/6lowpan.c

+4 −0
Original line number Diff line number Diff line
@@ -309,6 +309,10 @@ 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