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>

6 files changed, 29 insertions, 5 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 1f659e8c2b88..1fbab2ae613c 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -421,6 +421,7 @@ extern void skb_dma_unmap(struct device *dev, struct sk_buff *skb,
 #endif
 
 extern void kfree_skb(struct sk_buff *skb);
+extern void consume_skb(struct sk_buff *skb);
 extern void            __kfree_skb(struct sk_buff *skb);
 extern struct sk_buff *__alloc_skb(unsigned int size,
                                    gfp_t priority, int fclone, int node);
@@ -459,7 +460,8 @@ extern int	       skb_to_sgvec(struct sk_buff *skb,
 extern int             skb_cow_data(struct sk_buff *skb, int tailbits,
                                     struct sk_buff **trailer);
 extern int             skb_pad(struct sk_buff *skb, int pad);
-#define dev_kfree_skb(a)        kfree_skb(a)
+#define dev_kfree_skb(a)        consume_skb(a)
+#define dev_consume_skb(a)      kfree_skb_clean(a)
 extern void           skb_over_panic(struct sk_buff *skb, int len,
                                      void *here);
 extern void           skb_under_panic(struct sk_buff *skb, int len,
diff --git a/net/core/datagram.c b/net/core/datagram.c
index 5e2ac0c4b07c..d0de644b378d 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 e5e2111a397d..6acbf9e79eb1 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
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 3d67d1ffed77..9c220323f353 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -892,7 +892,7 @@ static int arp_process(struct sk_buff *skb)
 out:
         if (in_dev)
                 in_dev_put(in_dev);
-        kfree_skb(skb);
+        consume_skb(skb);
         return 0;
 }
 
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 4bd178a111d5..05b7abb99f69 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1184,7 +1184,7 @@ static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
                         sk = sknext;
                 } while (sknext);
         } else
-                kfree_skb(skb);
+                consume_skb(skb);
         spin_unlock(&hslot->lock);
         return 0;
 }
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index d8cc006fac45..74776de523ec 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -584,7 +584,7 @@ drop_n_restore:
                 skb->len = skb_len;
         }
 drop:
-        kfree_skb(skb);
+        consume_skb(skb);
         return 0;
 }