tcp: replace cnt & rtt with struct in pkts_acked()

Replace 2 arguments (cnt and rtt) in the congestion control modules'
pkts_acked() function with a struct. This will allow adding more
information without having to modify existing congestion control
modules (tcp_nv in particular needs bytes in flight when packet
was sent).

As proposed by Neal Cardwell in his comments to the tcp_nv patch.

Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

13 files changed, 60 insertions, 47 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 4775a1bba7f7..c9ab561387c4 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -854,6 +854,11 @@ enum tcp_ca_ack_event_flags {
 
 union tcp_cc_info;
 
+struct ack_sample {
+        u32 pkts_acked;
+        s32 rtt_us;
+};
+
 struct tcp_congestion_ops {
         struct list_head        list;
         u32 key;
@@ -877,7 +882,7 @@ struct tcp_congestion_ops {
         /* new value of cwnd after loss (optional) */
         u32  (*undo_cwnd)(struct sock *sk);
         /* hook for packet ack accounting (optional) */
-        void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
+        void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
         /* get info for inet_diag (optional) */
         size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
                            union tcp_cc_info *info);
diff --git a/net/ipv4/tcp_bic.c b/net/ipv4/tcp_bic.c
index fd1405d37c14..36087bca9f48 100644
--- a/net/ipv4/tcp_bic.c
+++ b/net/ipv4/tcp_bic.c
@@ -197,15 +197,15 @@ static void bictcp_state(struct sock *sk, u8 new_state)
 /* Track delayed acknowledgment ratio using sliding window
  * ratio = (15*ratio + sample) / 16
  */
-static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt)
+static void bictcp_acked(struct sock *sk, const struct ack_sample *sample)
 {
         const struct inet_connection_sock *icsk = inet_csk(sk);
 
         if (icsk->icsk_ca_state == TCP_CA_Open) {
                 struct bictcp *ca = inet_csk_ca(sk);
 
-                cnt -= ca->delayed_ack >> ACK_RATIO_SHIFT;
-                ca->delayed_ack += cnt;
+                ca->delayed_ack += sample->pkts_acked -
+                        (ca->delayed_ack >> ACK_RATIO_SHIFT);
         }
 }
 
diff --git a/net/ipv4/tcp_cdg.c b/net/ipv4/tcp_cdg.c
index ccce8a55f1e1..03725b294286 100644
--- a/net/ipv4/tcp_cdg.c
+++ b/net/ipv4/tcp_cdg.c
@@ -294,12 +294,12 @@ static void tcp_cdg_cong_avoid(struct sock *sk, u32 ack, u32 acked)
         ca->shadow_wnd = max(ca->shadow_wnd, ca->shadow_wnd + incr);
 }
 
-static void tcp_cdg_acked(struct sock *sk, u32 num_acked, s32 rtt_us)
+static void tcp_cdg_acked(struct sock *sk, const struct ack_sample *sample)
 {
         struct cdg *ca = inet_csk_ca(sk);
         struct tcp_sock *tp = tcp_sk(sk);
 
-        if (rtt_us <= 0)
+        if (sample->rtt_us <= 0)
                 return;
 
         /* A heuristic for filtering delayed ACKs, adapted from:
@@ -307,20 +307,20 @@ static void tcp_cdg_acked(struct sock *sk, u32 num_acked, s32 rtt_us)
          * delay and rate based TCP mechanisms." TR 100219A. CAIA, 2010.
          */
         if (tp->sacked_out == 0) {
-                if (num_acked == 1 && ca->delack) {
+                if (sample->pkts_acked == 1 && ca->delack) {
                         /* A delayed ACK is only used for the minimum if it is
                          * provenly lower than an existing non-zero minimum.
                          */
-                        ca->rtt.min = min(ca->rtt.min, rtt_us);
+                        ca->rtt.min = min(ca->rtt.min, sample->rtt_us);
                         ca->delack--;
                         return;
-                } else if (num_acked > 1 && ca->delack < 5) {
+                } else if (sample->pkts_acked > 1 && ca->delack < 5) {
                         ca->delack++;
                 }
         }
 
-        ca->rtt.min = min_not_zero(ca->rtt.min, rtt_us);
-        ca->rtt.max = max(ca->rtt.max, rtt_us);
+        ca->rtt.min = min_not_zero(ca->rtt.min, sample->rtt_us);
+        ca->rtt.max = max(ca->rtt.max, sample->rtt_us);
 }
 
 static u32 tcp_cdg_ssthresh(struct sock *sk)
diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c
index 0ce946e395e1..c99230efcd52 100644
--- a/net/ipv4/tcp_cubic.c
+++ b/net/ipv4/tcp_cubic.c
@@ -437,21 +437,21 @@ static void hystart_update(struct sock *sk, u32 delay)
 /* Track delayed acknowledgment ratio using sliding window
  * ratio = (15*ratio + sample) / 16
  */
-static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt_us)
+static void bictcp_acked(struct sock *sk, const struct ack_sample *sample)
 {
         const struct tcp_sock *tp = tcp_sk(sk);
         struct bictcp *ca = inet_csk_ca(sk);
         u32 delay;
 
         /* Some calls are for duplicates without timetamps */
-        if (rtt_us < 0)
+        if (sample->rtt_us < 0)
                 return;
 
         /* Discard delay samples right after fast recovery */
         if (ca->epoch_start && (s32)(tcp_time_stamp - ca->epoch_start) < HZ)
                 return;
 
-        delay = (rtt_us << 3) / USEC_PER_MSEC;
+        delay = (sample->rtt_us << 3) / USEC_PER_MSEC;
         if (delay == 0)
                 delay = 1;
 
diff --git a/net/ipv4/tcp_htcp.c b/net/ipv4/tcp_htcp.c
index 82f0d9ed60f5..4a4d8e76738f 100644
--- a/net/ipv4/tcp_htcp.c
+++ b/net/ipv4/tcp_htcp.c
@@ -99,7 +99,7 @@ static inline void measure_rtt(struct sock *sk, u32 srtt)
 }
 
 static void measure_achieved_throughput(struct sock *sk,
-                                        u32 pkts_acked, s32 rtt)
+                                        const struct ack_sample *sample)
 {
         const struct inet_connection_sock *icsk = inet_csk(sk);
         const struct tcp_sock *tp = tcp_sk(sk);
@@ -107,10 +107,10 @@ static void measure_achieved_throughput(struct sock *sk,
         u32 now = tcp_time_stamp;
 
         if (icsk->icsk_ca_state == TCP_CA_Open)
-                ca->pkts_acked = pkts_acked;
+                ca->pkts_acked = sample->pkts_acked;
 
-        if (rtt > 0)
-                measure_rtt(sk, usecs_to_jiffies(rtt));
+        if (sample->rtt_us > 0)
+                measure_rtt(sk, usecs_to_jiffies(sample->rtt_us));
 
         if (!use_bandwidth_switch)
                 return;
@@ -122,7 +122,7 @@ static void measure_achieved_throughput(struct sock *sk,
                 return;
         }
 
-        ca->packetcount += pkts_acked;
+        ca->packetcount += sample->pkts_acked;
 
         if (ca->packetcount >= tp->snd_cwnd - (ca->alpha >> 7 ? : 1) &&
             now - ca->lasttime >= ca->minRTT &&
diff --git a/net/ipv4/tcp_illinois.c b/net/ipv4/tcp_illinois.c
index 2ab9bbb6faff..c8e6d86be114 100644
--- a/net/ipv4/tcp_illinois.c
+++ b/net/ipv4/tcp_illinois.c
@@ -82,30 +82,31 @@ static void tcp_illinois_init(struct sock *sk)
 }
 
 /* Measure RTT for each ack. */
-static void tcp_illinois_acked(struct sock *sk, u32 pkts_acked, s32 rtt)
+static void tcp_illinois_acked(struct sock *sk, const struct ack_sample *sample)
 {
         struct illinois *ca = inet_csk_ca(sk);
+        s32 rtt_us = sample->rtt_us;
 
-        ca->acked = pkts_acked;
+        ca->acked = sample->pkts_acked;
 
         /* dup ack, no rtt sample */
-        if (rtt < 0)
+        if (rtt_us < 0)
                 return;
 
         /* ignore bogus values, this prevents wraparound in alpha math */
-        if (rtt > RTT_MAX)
-                rtt = RTT_MAX;
+        if (rtt_us > RTT_MAX)
+                rtt_us = RTT_MAX;
 
         /* keep track of minimum RTT seen so far */
-        if (ca->base_rtt > rtt)
-                ca->base_rtt = rtt;
+        if (ca->base_rtt > rtt_us)
+                ca->base_rtt = rtt_us;
 
         /* and max */
-        if (ca->max_rtt < rtt)
-                ca->max_rtt = rtt;
+        if (ca->max_rtt < rtt_us)
+                ca->max_rtt = rtt_us;
 
         ++ca->cnt_rtt;
-        ca->sum_rtt += rtt;
+        ca->sum_rtt += rtt_us;
 }
 
 /* Maximum queuing delay */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a914e0607895..d6c8f4cd0800 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3248,8 +3248,12 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
                 tcp_rearm_rto(sk);
         }
 
-        if (icsk->icsk_ca_ops->pkts_acked)
-                icsk->icsk_ca_ops->pkts_acked(sk, pkts_acked, ca_rtt_us);
+        if (icsk->icsk_ca_ops->pkts_acked) {
+                struct ack_sample sample = { .pkts_acked = pkts_acked,
+                                             .rtt_us = ca_rtt_us };
+
+                icsk->icsk_ca_ops->pkts_acked(sk, &sample);
+        }
 
 #if FASTRETRANS_DEBUG > 0
         WARN_ON((int)tp->sacked_out < 0);
diff --git a/net/ipv4/tcp_lp.c b/net/ipv4/tcp_lp.c
index 1e70fa8fa793..c67ece1390c2 100644
--- a/net/ipv4/tcp_lp.c
+++ b/net/ipv4/tcp_lp.c
@@ -260,13 +260,13 @@ static void tcp_lp_rtt_sample(struct sock *sk, u32 rtt)
  * newReno in increase case.
  * We work it out by following the idea from TCP-LP's paper directly
  */
-static void tcp_lp_pkts_acked(struct sock *sk, u32 num_acked, s32 rtt_us)
+static void tcp_lp_pkts_acked(struct sock *sk, const struct ack_sample *sample)
 {
         struct tcp_sock *tp = tcp_sk(sk);
         struct lp *lp = inet_csk_ca(sk);
 
-        if (rtt_us > 0)
-                tcp_lp_rtt_sample(sk, rtt_us);
+        if (sample->rtt_us > 0)
+                tcp_lp_rtt_sample(sk, sample->rtt_us);
 
         /* calc inference */
         if (tcp_time_stamp > tp->rx_opt.rcv_tsecr)
diff --git a/net/ipv4/tcp_vegas.c b/net/ipv4/tcp_vegas.c
index 13951c4087d4..4c4bac1b5eab 100644
--- a/net/ipv4/tcp_vegas.c
+++ b/net/ipv4/tcp_vegas.c
@@ -107,16 +107,16 @@ EXPORT_SYMBOL_GPL(tcp_vegas_init);
  *   o min-filter RTT samples from a much longer window (forever for now)
  *     to find the propagation delay (baseRTT)
  */
-void tcp_vegas_pkts_acked(struct sock *sk, u32 cnt, s32 rtt_us)
+void tcp_vegas_pkts_acked(struct sock *sk, const struct ack_sample *sample)
 {
         struct vegas *vegas = inet_csk_ca(sk);
         u32 vrtt;
 
-        if (rtt_us < 0)
+        if (sample->rtt_us < 0)
                 return;
 
         /* Never allow zero rtt or baseRTT */
-        vrtt = rtt_us + 1;
+        vrtt = sample->rtt_us + 1;
 
         /* Filter to find propagation delay: */
         if (vrtt < vegas->baseRTT)
diff --git a/net/ipv4/tcp_vegas.h b/net/ipv4/tcp_vegas.h
index ef9da5306c68..248cfc0ff9ae 100644
--- a/net/ipv4/tcp_vegas.h
+++ b/net/ipv4/tcp_vegas.h
@@ -17,7 +17,7 @@ struct vegas {
 
 void tcp_vegas_init(struct sock *sk);
 void tcp_vegas_state(struct sock *sk, u8 ca_state);
-void tcp_vegas_pkts_acked(struct sock *sk, u32 cnt, s32 rtt_us);
+void tcp_vegas_pkts_acked(struct sock *sk, const struct ack_sample *sample);
 void tcp_vegas_cwnd_event(struct sock *sk, enum tcp_ca_event event);
 size_t tcp_vegas_get_info(struct sock *sk, u32 ext, int *attr,
                           union tcp_cc_info *info);
diff --git a/net/ipv4/tcp_veno.c b/net/ipv4/tcp_veno.c
index 0d094b995cd9..40171e163cff 100644
--- a/net/ipv4/tcp_veno.c
+++ b/net/ipv4/tcp_veno.c
@@ -69,16 +69,17 @@ static void tcp_veno_init(struct sock *sk)
 }
 
 /* Do rtt sampling needed for Veno. */
-static void tcp_veno_pkts_acked(struct sock *sk, u32 cnt, s32 rtt_us)
+static void tcp_veno_pkts_acked(struct sock *sk,
+                                const struct ack_sample *sample)
 {
         struct veno *veno = inet_csk_ca(sk);
         u32 vrtt;
 
-        if (rtt_us < 0)
+        if (sample->rtt_us < 0)
                 return;
 
         /* Never allow zero rtt or baseRTT */
-        vrtt = rtt_us + 1;
+        vrtt = sample->rtt_us + 1;
 
         /* Filter to find propagation delay: */
         if (vrtt < veno->basertt)
diff --git a/net/ipv4/tcp_westwood.c b/net/ipv4/tcp_westwood.c
index c10732e39837..4b03a2e2a050 100644
--- a/net/ipv4/tcp_westwood.c
+++ b/net/ipv4/tcp_westwood.c
@@ -99,12 +99,13 @@ static void westwood_filter(struct westwood *w, u32 delta)
  * Called after processing group of packets.
  * but all westwood needs is the last sample of srtt.
  */
-static void tcp_westwood_pkts_acked(struct sock *sk, u32 cnt, s32 rtt)
+static void tcp_westwood_pkts_acked(struct sock *sk,
+                                    const struct ack_sample *sample)
 {
         struct westwood *w = inet_csk_ca(sk);
 
-        if (rtt > 0)
-                w->rtt = usecs_to_jiffies(rtt);
+        if (sample->rtt_us > 0)
+                w->rtt = usecs_to_jiffies(sample->rtt_us);
 }
 
 /*
diff --git a/net/ipv4/tcp_yeah.c b/net/ipv4/tcp_yeah.c
index 3e6a472e6b88..028eb046ea40 100644
--- a/net/ipv4/tcp_yeah.c
+++ b/net/ipv4/tcp_yeah.c
@@ -56,15 +56,16 @@ static void tcp_yeah_init(struct sock *sk)
         tp->snd_cwnd_clamp = min_t(u32, tp->snd_cwnd_clamp, 0xffffffff/128);
 }
 
-static void tcp_yeah_pkts_acked(struct sock *sk, u32 pkts_acked, s32 rtt_us)
+static void tcp_yeah_pkts_acked(struct sock *sk,
+                                const struct ack_sample *sample)
 {
         const struct inet_connection_sock *icsk = inet_csk(sk);
         struct yeah *yeah = inet_csk_ca(sk);
 
         if (icsk->icsk_ca_state == TCP_CA_Open)
-                yeah->pkts_acked = pkts_acked;
+                yeah->pkts_acked = sample->pkts_acked;
 
-        tcp_vegas_pkts_acked(sk, pkts_acked, rtt_us);
+        tcp_vegas_pkts_acked(sk, sample);
 }
 
 static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack, u32 acked)