[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/net/dccp/output.c b/net/dccp/output.c
index 2cc4f4b..1ae2248 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -88,11 +88,9 @@
 			return -EPROTO;
 		}
 		
-		skb->h.raw = skb_push(skb, dccp_header_size);
-		dh = dccp_hdr(skb);
 
 		/* Build DCCP header and checksum it. */
-		memset(dh, 0, dccp_header_size);
+		dh = dccp_zeroed_hdr(skb, dccp_header_size);
 		dh->dccph_type	= dcb->dccpd_type;
 		dh->dccph_sport	= inet->sport;
 		dh->dccph_dport	= inet->dport;
@@ -340,10 +338,7 @@
 		return NULL;
 	}
 
-	skb->h.raw = skb_push(skb, dccp_header_size);
-
-	dh = dccp_hdr(skb);
-	memset(dh, 0, dccp_header_size);
+	dh = dccp_zeroed_hdr(skb, dccp_header_size);
 
 	dh->dccph_sport	= inet_sk(sk)->sport;
 	dh->dccph_dport	= inet_rsk(req)->rmt_port;
@@ -392,10 +387,7 @@
 		return NULL;
 	}
 
-	skb->h.raw = skb_push(skb, dccp_header_size);
-
-	dh = dccp_hdr(skb);
-	memset(dh, 0, dccp_header_size);
+	dh = dccp_zeroed_hdr(skb, dccp_header_size);
 
 	dh->dccph_sport	= inet_sk(sk)->sport;
 	dh->dccph_dport	= inet_sk(sk)->dport;