[NET]: Annotate skb_checksum() and callers.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -1334,8 +1334,8 @@ extern int	       skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
 extern void	       skb_free_datagram(struct sock *sk, struct sk_buff *skb);
 extern void	       skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
 					 unsigned int flags);
-extern unsigned int    skb_checksum(const struct sk_buff *skb, int offset,
-				    int len, unsigned int csum);
+extern __wsum	       skb_checksum(const struct sk_buff *skb, int offset,
+				    int len, __wsum csum);
 extern int	       skb_copy_bits(const struct sk_buff *skb, int offset,
 				     void *to, int len);
 extern int	       skb_store_bits(const struct sk_buff *skb, int offset,

net/core/skbuff.c

@@ -1240,8 +1240,8 @@ EXPORT_SYMBOL(skb_store_bits);
 
 /* Checksum skb data. */
 
-unsigned int skb_checksum(const struct sk_buff *skb, int offset,
-			  int len, unsigned int csum)
+__wsum skb_checksum(const struct sk_buff *skb, int offset,
+			  int len, __wsum csum)
 {
 	int start = skb_headlen(skb);
 	int i, copy = start - offset;