Network Drop Monitor: Adding kfree_skb_clean for non-drops and modifying end-of-line points for skbs

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>

 include/linux/skbuff.h |    4 +++-
 net/core/datagram.c    |    2 +-
 net/core/skbuff.c      |   22 ++++++++++++++++++++++
 net/ipv4/arp.c         |    2 +-
 net/ipv4/udp.c         |    2 +-
 net/packet/af_packet.c |    2 +-
 6 files changed, 29 insertions(+), 5 deletions(-)
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 23 insertions, 1 deletions

diff --git a/net/core/datagram.c b/net/core/datagram.c
index 5e2ac0c..d0de644 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -208,7 +208,7 @@ struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
 
 void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
 {
-	kfree_skb(skb);
+	consume_skb(skb);
 	sk_mem_reclaim_partial(sk);
 }
 
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index e5e2111..6acbf9e 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -65,6 +65,7 @@
 
 #include <asm/uaccess.h>
 #include <asm/system.h>
+#include <trace/skb.h>
 
 #include "kmap_skb.h"
 
@@ -442,11 +443,32 @@ void kfree_skb(struct sk_buff *skb)
 		smp_rmb();
 	else if (likely(!atomic_dec_and_test(&skb->users)))
 		return;
+	trace_kfree_skb(skb, __builtin_return_address(0));
 	__kfree_skb(skb);
 }
 EXPORT_SYMBOL(kfree_skb);
 
 /**
+ *	consume_skb - free an skbuff
+ *	@skb: buffer to free
+ *
+ *	Drop a ref to the buffer and free it if the usage count has hit zero
+ *	Functions identically to kfree_skb, but kfree_skb assumes that the frame
+ *	is being dropped after a failure and notes that
+ */
+void consume_skb(struct sk_buff *skb)
+{
+	if (unlikely(!skb))
+		return;
+	if (likely(atomic_read(&skb->users) == 1))
+		smp_rmb();
+	else if (likely(!atomic_dec_and_test(&skb->users)))
+		return;
+	__kfree_skb(skb);
+}
+EXPORT_SYMBOL(consume_skb);
+
+/**
  *	skb_recycle_check - check if skb can be reused for receive
  *	@skb: buffer
  *	@skb_size: minimum receive buffer size