[DCCP]: Combine allocating & zeroing header space on skb

This is a code simplification:
it combines three often recurring operations into one inline function,

        * allocate `len' bytes header space in skb
        * fill these `len' bytes with zeroes
        * cast the start of this header space as dccp_hdr

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 53553c9..90d04ff 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -256,6 +256,13 @@
 	return (struct dccp_hdr *)skb->h.raw;
 }
 
+static inline struct dccp_hdr *dccp_zeroed_hdr(struct sk_buff *skb, int headlen)
+{
+	skb->h.raw = skb_push(skb, headlen);
+	memset(skb->h.raw, 0, headlen);
+	return dccp_hdr(skb);
+}
+
 static inline struct dccp_hdr_ext *dccp_hdrx(const struct sk_buff *skb)
 {
 	return (struct dccp_hdr_ext *)(skb->h.raw + sizeof(struct dccp_hdr));