Return-Path: From: Martin Townsend To: linux-bluetooth@vger.kernel.org, linux-wpan@vger.kernel.org Cc: marcel@holtmann.org, alex.aring@gmail.com, jukka.rissanen@linux.intel.com, Martin Townsend Subject: [PATCH v6 bluetooth-next] 6lowpan: Use skb_cow in IPHC decompression. Date: Mon, 13 Oct 2014 11:00:56 +0100 Message-Id: <1413194456-26351-2-git-send-email-martin.townsend@xsilon.com> In-Reply-To: <1413194456-26351-1-git-send-email-martin.townsend@xsilon.com> References: <1413194456-26351-1-git-send-email-martin.townsend@xsilon.com> List-ID: 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 --- 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