[PATCH 10/11] CCID2: Add helper functions for changing important CCID2 state

[Andrea Bittau <a.bittau@cs.ucl.ac.uk>]

Introduce methods which manipulate interesting congestion control state such as
pipe and rtt estimate.  This is useful for people wishing to monitor the
variables of CCID and instrument the code [perhaps using Kprobes].  Personally,
I am a fan of encapsulation---that justifies this change =D.

Signed-off-by: Andrea Bittau <a.bittau@cs.ucl.ac.uk>

---

diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index db0f1f1..b6f6681 100644
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -199,6 +199,21 @@ static void ccid2_change_cwnd(struct cci
 	hctx->ccid2hctx_cwnd = val;
 }
 
+static void ccid2_change_srtt(struct ccid2_hc_tx_sock *hctx, long val)
+{
+	ccid2_pr_debug("change SRTT to %ld\n", val);
+ 
+	if (hctx->ccid2hctx_srtt = val)
+		return;
+ 
+	hctx->ccid2hctx_srtt = val;
+}
+ 
+static void ccid2_change_pipe(struct ccid2_hc_tx_sock *hctx, long val)
+{
+	hctx->ccid2hctx_pipe = val;
+}
+
 static void ccid2_start_rto_timer(struct sock *sk);
 
 static void ccid2_hc_tx_rto_expire(unsigned long data)
@@ -228,7 +243,7 @@ static void ccid2_hc_tx_rto_expire(unsig
 	ccid2_start_rto_timer(sk);
 
 	/* adjust pipe, cwnd etc */
-	hctx->ccid2hctx_pipe = 0;
+	ccid2_change_pipe(hctx, 0);
 	hctx->ccid2hctx_ssthresh = hctx->ccid2hctx_cwnd >> 1;
 	if (hctx->ccid2hctx_ssthresh < 2)
 		hctx->ccid2hctx_ssthresh = 2;
@@ -274,7 +289,7 @@ static void ccid2_hc_tx_packet_sent(stru
 
 	BUG_ON(!hctx->ccid2hctx_sendwait);
 	hctx->ccid2hctx_sendwait = 0;
-	hctx->ccid2hctx_pipe++;
+	ccid2_change_pipe(hctx, hctx->ccid2hctx_pipe+1);
 	BUG_ON(hctx->ccid2hctx_pipe < 0);
 
 	/* There is an issue.  What if another packet is sent between
@@ -471,11 +486,13 @@ static inline void ccid2_new_ack(struct 
 		if (hctx->ccid2hctx_srtt = -1) {
 			ccid2_pr_debug("R: %lu Time=%lu seq=%llu\n",
 			       	       r, jiffies, seqp->ccid2s_seq);
-			hctx->ccid2hctx_srtt = r;
+			ccid2_change_srtt(hctx, r);
 			hctx->ccid2hctx_rttvar = r >> 1;
 		} else {
 			/* RTTVAR */
 			long tmp = hctx->ccid2hctx_srtt - r;
+			long srtt;
+
 			if (tmp < 0)
 				tmp *= -1;
 
@@ -485,10 +502,12 @@ static inline void ccid2_new_ack(struct 
 			hctx->ccid2hctx_rttvar += tmp;
 
 			/* SRTT */
-			hctx->ccid2hctx_srtt *= 7;
-			hctx->ccid2hctx_srtt >>= 3;
+			srtt = hctx->ccid2hctx_srtt;
+			srtt *= 7;
+			srtt >>= 3;
 			tmp = r >> 3;
-			hctx->ccid2hctx_srtt += tmp;
+			srtt += tmp;
+			ccid2_change_srtt(hctx, srtt);
 		}
 		s = hctx->ccid2hctx_rttvar << 2;
 		/* clock granularity is 1 when based on jiffies */
@@ -524,7 +543,7 @@ static void ccid2_hc_tx_dec_pipe(struct 
 {
 	struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
 
-	hctx->ccid2hctx_pipe--;
+	ccid2_change_pipe(hctx, hctx->ccid2hctx_pipe-1);
 	BUG_ON(hctx->ccid2hctx_pipe < 0);
 
 	if (hctx->ccid2hctx_pipe = 0)
@@ -746,7 +765,7 @@ static int ccid2_hc_tx_init(struct ccid 
 
 	hctx->ccid2hctx_sent	 = 0;
 	hctx->ccid2hctx_rto	 = 3 * HZ;
-	hctx->ccid2hctx_srtt	 = -1;
+	ccid2_change_srtt(hctx, -1);
 	hctx->ccid2hctx_rttvar	 = -1;
 	hctx->ccid2hctx_lastrtt  = 0;
 	hctx->ccid2hctx_rpdupack = -1;