[PATCH v2 bluetooth-next] Simplify lowpan receive path so skb is freed in lowpan_rcv when dropped.

[Martin Townsend <martin.townsend@xsilon.com>]

Signed-off-by: Martin Townsend<martin.townsend@xsilon.com>
---
  include/net/6lowpan.h         |  2 +-
  net/6lowpan/iphc.c            | 29 ++++++++++++++++-------------
  net/bluetooth/6lowpan.c       | 12 ++++++++----
  net/ieee802154/6lowpan_rtnl.c | 12 ++++++------
  4 files changed, 31 insertions(+), 24 deletions(-)

diff --git a/include/net/6lowpan.h b/include/net/6lowpan.h
index d7e9169..aa0381e 100644
--- a/include/net/6lowpan.h
+++ b/include/net/6lowpan.h
@@ -374,7 +374,7 @@ lowpan_uncompress_size(const struct sk_buff *skb, u16 *dgram_offset)
  
  typedef int (*skb_delivery_cb)(struct sk_buff *skb);
  
-int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
+int lowpan_process_data(struct sk_buff **skb_inout, struct net_device *dev,
  		const u8 *saddr, const u8 saddr_type, const u8 saddr_len,
  		const u8 *daddr, const u8 daddr_type, const u8 daddr_len,
  		u8 iphc0, u8 iphc1, skb_delivery_cb skb_deliver);
diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c
index 92eed6d..18dac0a 100644
--- a/net/6lowpan/iphc.c
+++ b/net/6lowpan/iphc.c
@@ -179,11 +179,11 @@ static int skb_deliver(struct sk_buff *skb, struct ipv6hdr *hdr,
  
  	new = skb_copy_expand(skb, sizeof(struct ipv6hdr), skb_tailroom(skb),
  			      GFP_ATOMIC);
-	kfree_skb(skb);
-
  	if (!new)
  		return -ENOMEM;
  
+	kfree_skb(skb);
+
  	skb_push(new, sizeof(struct ipv6hdr));
  	skb_reset_network_header(new);
  	skb_copy_to_linear_data(new, hdr, sizeof(struct ipv6hdr));
@@ -196,6 +196,8 @@ static int skb_deliver(struct sk_buff *skb, struct ipv6hdr *hdr,
  		       new->data, new->len);
  
  	stat = deliver_skb(new);
+	if (stat < 0)
+		stat = NET_RX_DROP;
  
  	kfree_skb(new);
  
@@ -333,7 +335,7 @@ err:
  /* TTL uncompression values */
  static const u8 lowpan_ttl_values[] = { 0, 1, 64, 255 };
  
-int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
+int lowpan_process_data(struct sk_buff **skb_inout, struct net_device *dev,
  			const u8 *saddr, const u8 saddr_type, const u8 saddr_len,
  			const u8 *daddr, const u8 daddr_type, const u8 daddr_len,
  			u8 iphc0, u8 iphc1, skb_delivery_cb deliver_skb)
@@ -341,6 +343,8 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
  	struct ipv6hdr hdr = {};
  	u8 tmp, num_context = 0;
  	int err;
+	int err_ret = -EINVAL;
+	struct sk_buff *skb = *skb_inout;
  
  	raw_dump_table(__func__, "raw skb data dump uncompressed",
  		       skb->data, skb->len);
@@ -461,7 +465,6 @@ 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;
@@ -469,14 +472,15 @@ 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 = skb_copy_expand(skb, sizeof(struct udphdr),
  				      skb_tailroom(skb), GFP_ATOMIC);
-		kfree_skb(skb);
-
-		if (!new)
-			return -ENOMEM;
-
-		skb = new;
+		if (!skb) {
+			err_ret = -ENOMEM;
+			goto drop;
+		}
+		
+		kfree_skb(*skb_inout);
+		*skb_inout = skb;
  
  		skb_push(skb, sizeof(struct udphdr));
  		skb_reset_transport_header(skb);
@@ -503,8 +507,7 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
  	return skb_deliver(skb, &hdr, dev, deliver_skb);
  
  drop:
-	kfree_skb(skb);
-	return -EINVAL;
+	return err_ret;
  }
  EXPORT_SYMBOL_GPL(lowpan_process_data);
  
diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
index f5df93f..38a2987 100644
--- a/net/bluetooth/6lowpan.c
+++ b/net/bluetooth/6lowpan.c
@@ -215,7 +215,7 @@ static int give_skb_to_upper(struct sk_buff *skb)
  	return ret;
  }
  
-static int process_data(struct sk_buff *skb, struct net_device *netdev,
+static int process_data(struct sk_buff **skb_inout, struct net_device *netdev,
  			struct l2cap_chan *chan)
  {
  	const u8 *saddr, *daddr;
@@ -223,6 +223,7 @@ static int process_data(struct sk_buff *skb, struct net_device *netdev,
  	struct lowpan_dev *dev;
  	struct lowpan_peer *peer;
  	unsigned long flags;
+	struct sk_buff *skb = *skb_inout;
  
  	dev = lowpan_dev(netdev);
  
@@ -245,13 +246,12 @@ static int process_data(struct sk_buff *skb, struct net_device *netdev,
  	if (lowpan_fetch_skb_u8(skb, &iphc1))
  		goto drop;
  
-	return lowpan_process_data(skb, netdev,
+	return lowpan_process_data(skb_inout, netdev,
  				   saddr, IEEE802154_ADDR_LONG, EUI64_ADDR_LEN,
  				   daddr, IEEE802154_ADDR_LONG, EUI64_ADDR_LEN,
  				   iphc0, iphc1, give_skb_to_upper);
  
  drop:
-	kfree_skb(skb);
  	return -EINVAL;
  }
  
@@ -300,7 +300,11 @@ static int recv_pkt(struct sk_buff *skb, struct net_device *dev,
  			if (!local_skb)
  				goto drop;
  
-			ret = process_data(local_skb, dev, chan);
+			ret = process_data(&local_skb, dev, chan);
+			if (ret < 0) {
+				kfree_skb(local_skb);
+				goto drop;
+			}
  			if (ret != NET_RX_SUCCESS)
  				goto drop;
  
diff --git a/net/ieee802154/6lowpan_rtnl.c b/net/ieee802154/6lowpan_rtnl.c
index 3154775..3ae7646 100644
--- a/net/ieee802154/6lowpan_rtnl.c
+++ b/net/ieee802154/6lowpan_rtnl.c
@@ -166,11 +166,12 @@ static int lowpan_give_skb_to_devices(struct sk_buff *skb)
  	return stat;
  }
  
-static int process_data(struct sk_buff *skb, const struct ieee802154_hdr *hdr)
+static int process_data(struct sk_buff **skb_inout, const struct ieee802154_hdr *hdr)
  {
  	u8 iphc0, iphc1;
  	struct ieee802154_addr_sa sa, da;
  	void *sap, *dap;
+	struct sk_buff *skb = *skb_inout;
  
  	raw_dump_table(__func__, "raw skb data dump", skb->data, skb->len);
  	/* at least two bytes will be used for the encoding */
@@ -196,13 +197,12 @@ static int process_data(struct sk_buff *skb, const struct ieee802154_hdr *hdr)
  	else
  		dap = &da.hwaddr;
  
-	return lowpan_process_data(skb, skb->dev, sap, sa.addr_type,
+	return lowpan_process_data(skb_inout, skb->dev, sap, sa.addr_type,
  				   IEEE802154_ADDR_LEN, dap, da.addr_type,
  				   IEEE802154_ADDR_LEN, iphc0, iphc1,
  				   lowpan_give_skb_to_devices);
  
  drop:
-	kfree_skb(skb);
  	return -EINVAL;
  }
  
@@ -485,14 +485,14 @@ static int lowpan_rcv(struct sk_buff *skb, struct net_device *dev,
  	} else {
  		switch (skb->data[0] & 0xe0) {
  		case LOWPAN_DISPATCH_IPHC:	/* ipv6 datagram */
-			ret = process_data(skb, &hdr);
+			ret = process_data(&skb, &hdr);
  			if (ret == NET_RX_DROP)
  				goto drop;
  			break;
  		case LOWPAN_DISPATCH_FRAG1:	/* first fragment header */
  			ret = lowpan_frag_rcv(skb, LOWPAN_DISPATCH_FRAG1);
  			if (ret == 1) {
-				ret = process_data(skb, &hdr);
+				ret = process_data(&skb, &hdr);
  				if (ret == NET_RX_DROP)
  					goto drop;
  			}
@@ -500,7 +500,7 @@ static int lowpan_rcv(struct sk_buff *skb, struct net_device *dev,
  		case LOWPAN_DISPATCH_FRAGN:	/* next fragments headers */
  			ret = lowpan_frag_rcv(skb, LOWPAN_DISPATCH_FRAGN);
  			if (ret == 1) {
-				ret = process_data(skb, &hdr);
+				ret = process_data(&skb, &hdr);
  				if (ret == NET_RX_DROP)
  					goto drop;
  			}
-- 
1.8.1.2