[NET]: Treat CHECKSUM_PARTIAL as CHECKSUM_UNNECESSARY

When a transmitted packet is looped back directly, CHECKSUM_PARTIAL
maps to the semantics of CHECKSUM_UNNECESSARY.  Therefore we should
treat it as such in the stack.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 13 insertions, 7 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 910560e85561..c413afbe0b9c 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -32,10 +32,11 @@
 #define HAVE_ALLOC_SKB          /* For the drivers to know */
 #define HAVE_ALIGNABLE_SKB      /* Ditto 8)                */
 
+/* Don't change this without changing skb_csum_unnecessary! */
 #define CHECKSUM_NONE 0
-#define CHECKSUM_PARTIAL 1
-#define CHECKSUM_UNNECESSARY 2
-#define CHECKSUM_COMPLETE 3
+#define CHECKSUM_UNNECESSARY 1
+#define CHECKSUM_COMPLETE 2
+#define CHECKSUM_PARTIAL 3
 
 #define SKB_DATA_ALIGN(X)       (((X) + (SMP_CACHE_BYTES - 1)) & \
                                  ~(SMP_CACHE_BYTES - 1))
@@ -1572,6 +1573,11 @@ static inline void __net_timestamp(struct sk_buff *skb)
 extern __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
 extern __sum16 __skb_checksum_complete(struct sk_buff *skb);
 
+static inline int skb_csum_unnecessary(const struct sk_buff *skb)
+{
+        return skb->ip_summed & CHECKSUM_UNNECESSARY;
+}
+
 /**
  *      skb_checksum_complete - Calculate checksum of an entire packet
  *      @skb: packet to process
@@ -1590,8 +1596,8 @@ extern __sum16 __skb_checksum_complete(struct sk_buff *skb);
  */
 static inline unsigned int skb_checksum_complete(struct sk_buff *skb)
 {
-        return skb->ip_summed != CHECKSUM_UNNECESSARY &&
-                __skb_checksum_complete(skb);
+        return skb_csum_unnecessary(skb) ?
+               0 : __skb_checksum_complete(skb);
 }
 
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index af9273204cfd..07f724e02f84 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -818,7 +818,7 @@ static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
 
 static inline int tcp_checksum_complete(struct sk_buff *skb)
 {
-        return skb->ip_summed != CHECKSUM_UNNECESSARY &&
+        return !skb_csum_unnecessary(skb) &&
                 __tcp_checksum_complete(skb);
 }
 
diff --git a/include/net/udp.h b/include/net/udp.h
index 4906ed7113e7..98755ebaf163 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -77,7 +77,7 @@ static inline __sum16 __udp_lib_checksum_complete(struct sk_buff *skb)
 
 static inline int udp_lib_checksum_complete(struct sk_buff *skb)
 {
-        return skb->ip_summed != CHECKSUM_UNNECESSARY &&
+        return !skb_csum_unnecessary(skb) &&
                 __udp_lib_checksum_complete(skb);
 }