[NET]: Move netfilter checksum helpers to net/core/utils.c

This allows to get rid of the CONFIG_NETFILTER dependency of NET_ACT_NAT.
This patch redefines the old names to keep the noise low, the next patch
converts all users.

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

Author: kaber

include/linux/netfilter.h

@@ -298,27 +298,10 @@ extern void nf_invalidate_cache(int pf);
    Returns true or false. */
 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 
-static inline void nf_csum_replace4(__sum16 *sum, __be32 from, __be32 to)
-{
-	__be32 diff[] = { ~from, to };
-
-	*sum = csum_fold(csum_partial((char *)diff, sizeof(diff), ~csum_unfold(*sum)));
-}
-
-static inline void nf_csum_replace2(__sum16 *sum, __be16 from, __be16 to)
-{
-	nf_csum_replace4(sum, (__force __be32)from, (__force __be32)to);
-}
-
-extern void nf_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
-				      __be32 from, __be32 to, int pseudohdr);
-
-static inline void nf_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
-				      __be16 from, __be16 to, int pseudohdr)
-{
-	nf_proto_csum_replace4(sum, skb, (__force __be32)from,
-				(__force __be32)to, pseudohdr);
-}
+#define nf_csum_replace4	csum_replace4
+#define nf_csum_replace2	csum_replace2
+#define nf_proto_csum_replace4	inet_proto_csum_replace4
+#define nf_proto_csum_replace2	inet_proto_csum_replace2
 
 struct nf_afinfo {
 	unsigned short	family;

include/net/checksum.h

@@ -93,4 +93,29 @@ static inline __wsum csum_unfold(__sum16 n)
 }
 
 #define CSUM_MANGLED_0 ((__force __sum16)0xffff)
+
+static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
+{
+	__be32 diff[] = { ~from, to };
+
+	*sum = csum_fold(csum_partial((char *)diff, sizeof(diff), ~csum_unfold(*sum)));
+}
+
+static inline void csum_replace2(__sum16 *sum, __be16 from, __be16 to)
+{
+	csum_replace4(sum, (__force __be32)from, (__force __be32)to);
+}
+
+struct sk_buff;
+extern void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
+				     __be32 from, __be32 to, int pseudohdr);
+
+static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
+					    __be16 from, __be16 to,
+					    int pseudohdr)
+{
+	inet_proto_csum_replace4(sum, skb, (__force __be32)from,
+				 (__force __be32)to, pseudohdr);
+}
+
 #endif

net/core/utils.c

@@ -293,3 +293,19 @@ int in6_pton(const char *src, int srclen,
 }
 
 EXPORT_SYMBOL(in6_pton);
+
+void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
+			      __be32 from, __be32 to, int pseudohdr)
+{
+	__be32 diff[] = { ~from, to };
+	if (skb->ip_summed != CHECKSUM_PARTIAL) {
+		*sum = csum_fold(csum_partial(diff, sizeof(diff),
+				~csum_unfold(*sum)));
+		if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
+			skb->csum = ~csum_partial(diff, sizeof(diff),
+						~skb->csum);
+	} else if (pseudohdr)
+		*sum = ~csum_fold(csum_partial(diff, sizeof(diff),
+				csum_unfold(*sum)));
+}
+EXPORT_SYMBOL(inet_proto_csum_replace4);

net/netfilter/core.c

@@ -217,22 +217,6 @@ int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
 }
 EXPORT_SYMBOL(skb_make_writable);
 
-void nf_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
-			    __be32 from, __be32 to, int pseudohdr)
-{
-	__be32 diff[] = { ~from, to };
-	if (skb->ip_summed != CHECKSUM_PARTIAL) {
-		*sum = csum_fold(csum_partial(diff, sizeof(diff),
-				~csum_unfold(*sum)));
-		if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
-			skb->csum = ~csum_partial(diff, sizeof(diff),
-						~skb->csum);
-	} else if (pseudohdr)
-		*sum = ~csum_fold(csum_partial(diff, sizeof(diff),
-				csum_unfold(*sum)));
-}
-EXPORT_SYMBOL(nf_proto_csum_replace4);
-
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 /* This does not belong here, but locally generated errors need it if connection
    tracking in use: without this, connection may not be in hash table, and hence