I should also mention this has only been compile tested as I currently don't have a way of testing it easily. So I would appreciate any testing on real HW.
Jukka, I would be very interested to see if you see that locking error message you were seeing previously.
- Martin.
On 07/10/14 16:33, Martin Townsend wrote:
> Currently there are potentially 2 skb_copy_expand calls in IPHC
> decompression. This patch replaces this with one call to
> pskb_expand_head. It also checks to see if there is enough headroom
> first to ensure it's only done if necessary.
> As pskb_expand_head must only have one reference the calling code
> now ensures this.
>
> Signed-off-by: Martin Townsend <martin.townsend@xxxxxxxxxx>
> ---
> net/6lowpan/iphc.c | 53 ++++++++++++++++++++++---------------------
> net/bluetooth/6lowpan.c | 19 ++++++++++++----
> net/ieee802154/6lowpan_rtnl.c | 13 +++++++++++
> 3 files changed, 55 insertions(+), 30 deletions(-)
>
> diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c
> index 142eef5..fa8f348 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);
> + kfree_skb(skb);
>
> return stat;
> }
> @@ -460,7 +452,6 @@ 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;
>
> if (uncompress_udp_header(skb, &uh))
> goto drop;
> @@ -468,14 +459,15 @@ 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;
> + if (skb_headroom(skb) < sizeof(struct udphdr) + sizeof(hdr)) {
> + int n = sizeof(struct udphdr) + sizeof(hdr);
> +
> + err = pskb_expand_head(skb, n, 0, GFP_ATOMIC);
> + if (unlikely(err)) {
> + kfree_skb(skb);
> + return err;
> + }
> + }
>
> skb_push(skb, sizeof(struct udphdr));
> skb_reset_transport_header(skb);
> @@ -485,6 +477,15 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
> (u8 *)&uh, sizeof(uh));
>
> hdr.nexthdr = UIP_PROTO_UDP;
> + } else {
> + if (skb_headroom(skb) < sizeof(hdr)) {
> + err = pskb_expand_head(skb, sizeof(hdr), 0, GFP_ATOMIC);
> +
> + 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..ab51e16 100644
> --- a/net/bluetooth/6lowpan.c
> +++ b/net/bluetooth/6lowpan.c
> @@ -343,13 +343,24 @@ static int recv_pkt(struct sk_buff *skb, struct net_device *dev,
> kfree_skb(local_skb);
> kfree_skb(skb);
> } else {
> + /* Decompression may use pskb_expand_head, ensure skb unique */
> + if (skb_cloned(skb)) {
> + struct sk_buff *new;
> + int new_headroom = sizeof(struct ipv6hdr) +
> + sizeof(struct udphdr);
> +
> + new = skb_copy_expand(skb, new_headroom,
> + skb_tailroom(skb), GFP_ATOMIC);
> + if (!new)
> + goto drop;
> + consume_skb(skb);
> + skb = new;
> + }
> +
> switch (skb->data[0] & 0xe0) {
> case LOWPAN_DISPATCH_IPHC: /* ipv6 datagram */
> - local_skb = skb_clone(skb, GFP_ATOMIC);
> - if (!local_skb)
> - goto drop;
>
> - ret = process_data(local_skb, dev, chan);
> + ret = process_data(skb, dev, chan);
> if (ret != NET_RX_SUCCESS)
> goto drop;
>
> diff --git a/net/ieee802154/6lowpan_rtnl.c b/net/ieee802154/6lowpan_rtnl.c
> index c7e07b8..2ccea84 100644
> --- a/net/ieee802154/6lowpan_rtnl.c
> +++ b/net/ieee802154/6lowpan_rtnl.c
> @@ -537,6 +537,19 @@ static int lowpan_rcv(struct sk_buff *skb, struct net_device *dev,
> if (ret == NET_RX_DROP)
> goto drop;
> } else {
> + /* Decompression may use pskb_expand_head, ensure skb unique */
> + if (skb_cloned(skb)) {
> + struct sk_buff *new;
> + int new_headroom = sizeof(struct ipv6hdr) +
> + sizeof(struct udphdr);
> +
> + new = skb_copy_expand(skb, new_headroom,
> + skb_tailroom(skb), GFP_ATOMIC);
> + if (!new)
> + goto drop_skb;
> + consume_skb(skb);
> + skb = new;
> + }
> switch (skb->data[0] & 0xe0) {
> case LOWPAN_DISPATCH_IPHC: /* ipv6 datagram */
> ret = process_data(skb, &hdr);
--
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