[CCID2]: Replace read-only variable with constant

This replaces the field member `numdupack', which was used as a read-only
constant in the code, with a #define.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/ccids/ccid2.c

@@ -586,8 +586,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 			hctx->ccid2hctx_rpdupack++;
 
 			/* check if we got enough dupacks */
-			if (hctx->ccid2hctx_rpdupack >=
-			    hctx->ccid2hctx_numdupack) {
+			if (hctx->ccid2hctx_rpdupack >= NUMDUPACK) {
 				hctx->ccid2hctx_rpdupack = -1; /* XXX lame */
 				hctx->ccid2hctx_rpseq = 0;
 
@@ -708,7 +707,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 	while (1) {
 		if (seqp->ccid2s_acked) {
 			done++;
-			if (done == hctx->ccid2hctx_numdupack)
+			if (done == NUMDUPACK)
 				break;
 		}
 		if (seqp == hctx->ccid2hctx_seqt)
@@ -719,7 +718,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 	/* If there are at least 3 acknowledgements, anything unacknowledged
 	 * below the last sequence number is considered lost
 	 */
-	if (done == hctx->ccid2hctx_numdupack) {
+	if (done == NUMDUPACK) {
 		struct ccid2_seq *last_acked = seqp;
 
 		/* check for lost packets */
@@ -761,7 +760,6 @@ static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
 
 	/* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
 	hctx->ccid2hctx_ssthresh  = ~0;
-	hctx->ccid2hctx_numdupack = 3;
 
 	/*
 	 * RFC 4341, 5: "The cwnd parameter is initialized to at most four

net/dccp/ccids/ccid2.h

@@ -24,6 +24,8 @@
 #include <linux/timer.h>
 #include <linux/types.h>
 #include "../ccid.h"
+/* NUMDUPACK parameter from RFC 4341, p. 6 */
+#define NUMDUPACK	3
 
 struct sock;
 
@@ -52,7 +54,6 @@ struct ccid2_hc_tx_sock {
 	int			ccid2hctx_acks;
 	unsigned int		ccid2hctx_ssthresh;
 	int			ccid2hctx_pipe;
-	int			ccid2hctx_numdupack;
 	struct ccid2_seq	*ccid2hctx_seqbuf[CCID2_SEQBUF_MAX];
 	int			ccid2hctx_seqbufc;
 	struct ccid2_seq	*ccid2hctx_seqh;