[TCP] TCP Yeah: cleanup

Eliminate need for full 6/4/64 divide to compute queue.
Variable maxqueue was really a constant.
Fix indentation.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_yeah.c b/net/ipv4/tcp_yeah.c
index 18355a2608e193011c736b517a20fb013db729ff..46dd1bee583af9a8a408c0210ea4ce8259e9f611 100644 (file)
--- a/net/ipv4/tcp_yeah.c
+++ b/net/ipv4/tcp_yeah.c
@@ -74,7 +74,7 @@ static void tcp_yeah_pkts_acked(struct sock *sk, u32 pkts_acked)
 }
 
 static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack,
-                                u32 seq_rtt, u32 in_flight, int flag)
+                               u32 seq_rtt, u32 in_flight, int flag)
 {
        struct tcp_sock *tp = tcp_sk(sk);
        struct yeah *yeah = inet_csk_ca(sk);
@@ -142,8 +142,8 @@ static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack,
                 */
 
                if (yeah->cntRTT > 2) {
-                       u32 rtt;
-                       u32 queue, maxqueue;
+                       u32 rtt, queue;
+                       u64 bw;
 
                        /* We have enough RTT samples, so, using the Vegas
                         * algorithm, we determine if we should increase or
@@ -158,32 +158,36 @@ static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack,
                         */
                        rtt = yeah->minRTT;
 
-                       queue = (u32)div64_64((u64)tp->snd_cwnd * (rtt - yeah->baseRTT), rtt);
-
-                       maxqueue = TCP_YEAH_ALPHA;
-
-                       if (queue > maxqueue ||
-                                   rtt - yeah->baseRTT > (yeah->baseRTT / TCP_YEAH_PHY)) {
-
-                               if (queue > maxqueue && tp->snd_cwnd > yeah->reno_count) {
-                                       u32 reduction = min( queue / TCP_YEAH_GAMMA ,
-                                                        tp->snd_cwnd >> TCP_YEAH_EPSILON );
+                       /* Compute excess number of packets above bandwidth
+                        * Avoid doing full 64 bit divide.
+                        */
+                       bw = tp->snd_cwnd;
+                       bw *= rtt - yeah->baseRTT;
+                       do_div(bw, rtt);
+                       queue = bw;
+
+                       if (queue > TCP_YEAH_ALPHA ||
+                           rtt - yeah->baseRTT > (yeah->baseRTT / TCP_YEAH_PHY)) {
+                               if (queue > TCP_YEAH_ALPHA
+                                   && tp->snd_cwnd > yeah->reno_count) {
+                                       u32 reduction = min(queue / TCP_YEAH_GAMMA ,
+                                                           tp->snd_cwnd >> TCP_YEAH_EPSILON);
 
                                        tp->snd_cwnd -= reduction;
 
-                                       tp->snd_cwnd = max( tp->snd_cwnd, yeah->reno_count);
+                                       tp->snd_cwnd = max(tp->snd_cwnd,
+                                                          yeah->reno_count);
 
                                        tp->snd_ssthresh = tp->snd_cwnd;
-                       }
+                               }
 
                                if (yeah->reno_count <= 2)
-                                       yeah->reno_count = max( tp->snd_cwnd>>1, 2U);
+                                       yeah->reno_count = max(tp->snd_cwnd>>1, 2U);
                                else
                                        yeah->reno_count++;
 
-                               yeah->doing_reno_now =
-                                                  min_t( u32, yeah->doing_reno_now + 1 , 0xffffff);
-
+                               yeah->doing_reno_now = min(yeah->doing_reno_now + 1,
+                                                          0xffffffU);
                        } else {
                                yeah->fast_count++;