tcp: consolidate congestion control undo functions

Most TCP congestion controls are using identical logic to undo
cwnd except BBR. This patch consolidates these similar functions
to the one used currently by Reno and others.

Suggested-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_bic.c b/net/ipv4/tcp_bic.c
index 609965f0e29836ed95605a2c7f3170e67c641058..fc36143774130c8949ecb58dc066b2c5f6271081 100644 (file)
--- a/net/ipv4/tcp_bic.c
+++ b/net/ipv4/tcp_bic.c
@@ -49,7 +49,6 @@ MODULE_PARM_DESC(smooth_part, "log(B/(B*Smin))/log(B/(B-1))+B, # of RTT from Wma
 struct bictcp {
        u32     cnt;            /* increase cwnd by 1 after ACKs */
        u32     last_max_cwnd;  /* last maximum snd_cwnd */
-       u32     loss_cwnd;      /* congestion window at last loss */
        u32     last_cwnd;      /* the last snd_cwnd */
        u32     last_time;      /* time when updated last_cwnd */
        u32     epoch_start;    /* beginning of an epoch */
@@ -72,7 +71,6 @@ static void bictcp_init(struct sock *sk)
        struct bictcp *ca = inet_csk_ca(sk);
 
        bictcp_reset(ca);
-       ca->loss_cwnd = 0;
 
        if (initial_ssthresh)
                tcp_sk(sk)->snd_ssthresh = initial_ssthresh;
@@ -172,22 +170,12 @@ static u32 bictcp_recalc_ssthresh(struct sock *sk)
        else
                ca->last_max_cwnd = tp->snd_cwnd;
 
-       ca->loss_cwnd = tp->snd_cwnd;
-
        if (tp->snd_cwnd <= low_window)
                return max(tp->snd_cwnd >> 1U, 2U);
        else
                return max((tp->snd_cwnd * beta) / BICTCP_BETA_SCALE, 2U);
 }
 
-static u32 bictcp_undo_cwnd(struct sock *sk)
-{
-       const struct tcp_sock *tp = tcp_sk(sk);
-       const struct bictcp *ca = inet_csk_ca(sk);
-
-       return max(tp->snd_cwnd, ca->loss_cwnd);
-}
-
 static void bictcp_state(struct sock *sk, u8 new_state)
 {
        if (new_state == TCP_CA_Loss)
@@ -214,7 +202,7 @@ static struct tcp_congestion_ops bictcp __read_mostly = {
        .ssthresh       = bictcp_recalc_ssthresh,
        .cong_avoid     = bictcp_cong_avoid,
        .set_state      = bictcp_state,
-       .undo_cwnd      = bictcp_undo_cwnd,
+       .undo_cwnd      = tcp_reno_undo_cwnd,
        .pkts_acked     = bictcp_acked,
        .owner          = THIS_MODULE,
        .name           = "bic",

diff --git a/net/ipv4/tcp_cdg.c b/net/ipv4/tcp_cdg.c
index 50a0f3e51d5ba3ec544674b667371d7dfb3dc1b4..66ac69f7bd1958908d6f641f2143aa0850171f04 100644 (file)
--- a/net/ipv4/tcp_cdg.c
+++ b/net/ipv4/tcp_cdg.c
@@ -85,7 +85,6 @@ struct cdg {
        u8  state;
        u8  delack;
        u32 rtt_seq;
-       u32 undo_cwnd;
        u32 shadow_wnd;
        u16 backoff_cnt;
        u16 sample_cnt;
@@ -330,8 +329,6 @@ static u32 tcp_cdg_ssthresh(struct sock *sk)
        struct cdg *ca = inet_csk_ca(sk);
        struct tcp_sock *tp = tcp_sk(sk);
 
-       ca->undo_cwnd = tp->snd_cwnd;
-
        if (ca->state == CDG_BACKOFF)
                return max(2U, (tp->snd_cwnd * min(1024U, backoff_beta)) >> 10);
 
@@ -344,13 +341,6 @@ static u32 tcp_cdg_ssthresh(struct sock *sk)
        return max(2U, tp->snd_cwnd >> 1);
 }
 
-static u32 tcp_cdg_undo_cwnd(struct sock *sk)
-{
-       struct cdg *ca = inet_csk_ca(sk);
-
-       return max(tcp_sk(sk)->snd_cwnd, ca->undo_cwnd);
-}
-
 static void tcp_cdg_cwnd_event(struct sock *sk, const enum tcp_ca_event ev)
 {
        struct cdg *ca = inet_csk_ca(sk);
@@ -403,7 +393,7 @@ struct tcp_congestion_ops tcp_cdg __read_mostly = {
        .cong_avoid = tcp_cdg_cong_avoid,
        .cwnd_event = tcp_cdg_cwnd_event,
        .pkts_acked = tcp_cdg_acked,
-       .undo_cwnd = tcp_cdg_undo_cwnd,
+       .undo_cwnd = tcp_reno_undo_cwnd,
        .ssthresh = tcp_cdg_ssthresh,
        .release = tcp_cdg_release,
        .init = tcp_cdg_init,

diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c
index 57ae5b5ae643efad106f5d6ac224ca54a52f9689..78bfadfcf342695ed2e7f02626ddd1fda7d4d543 100644 (file)
--- a/net/ipv4/tcp_cubic.c
+++ b/net/ipv4/tcp_cubic.c
@@ -83,7 +83,6 @@ MODULE_PARM_DESC(hystart_ack_delta, "spacing between ack's indicating train (mse
 struct bictcp {
        u32     cnt;            /* increase cwnd by 1 after ACKs */
        u32     last_max_cwnd;  /* last maximum snd_cwnd */
-       u32     loss_cwnd;      /* congestion window at last loss */
        u32     last_cwnd;      /* the last snd_cwnd */
        u32     last_time;      /* time when updated last_cwnd */
        u32     bic_origin_point;/* origin point of bic function */
@@ -142,7 +141,6 @@ static void bictcp_init(struct sock *sk)
        struct bictcp *ca = inet_csk_ca(sk);
 
        bictcp_reset(ca);
-       ca->loss_cwnd = 0;
 
        if (hystart)
                bictcp_hystart_reset(sk);
@@ -366,18 +364,9 @@ static u32 bictcp_recalc_ssthresh(struct sock *sk)
        else
                ca->last_max_cwnd = tp->snd_cwnd;
 
-       ca->loss_cwnd = tp->snd_cwnd;
-
        return max((tp->snd_cwnd * beta) / BICTCP_BETA_SCALE, 2U);
 }
 
-static u32 bictcp_undo_cwnd(struct sock *sk)
-{
-       struct bictcp *ca = inet_csk_ca(sk);
-
-       return max(tcp_sk(sk)->snd_cwnd, ca->loss_cwnd);
-}
-
 static void bictcp_state(struct sock *sk, u8 new_state)
 {
        if (new_state == TCP_CA_Loss) {
@@ -470,7 +459,7 @@ static struct tcp_congestion_ops cubictcp __read_mostly = {
        .ssthresh       = bictcp_recalc_ssthresh,
        .cong_avoid     = bictcp_cong_avoid,
        .set_state      = bictcp_state,
-       .undo_cwnd      = bictcp_undo_cwnd,
+       .undo_cwnd      = tcp_reno_undo_cwnd,
        .cwnd_event     = bictcp_cwnd_event,
        .pkts_acked     = bictcp_acked,
        .owner          = THIS_MODULE,

diff --git a/net/ipv4/tcp_highspeed.c b/net/ipv4/tcp_highspeed.c
index 6d9879e93648a0c60579586242643ba364f4e506..d1c33c91eadc34f187f59f583f21b41f243ab171 100644 (file)
--- a/net/ipv4/tcp_highspeed.c
+++ b/net/ipv4/tcp_highspeed.c
@@ -94,7 +94,6 @@ static const struct hstcp_aimd_val {
 
 struct hstcp {
        u32     ai;
-       u32     loss_cwnd;
 };
 
 static void hstcp_init(struct sock *sk)
@@ -153,22 +152,14 @@ static u32 hstcp_ssthresh(struct sock *sk)
        const struct tcp_sock *tp = tcp_sk(sk);
        struct hstcp *ca = inet_csk_ca(sk);
 
-       ca->loss_cwnd = tp->snd_cwnd;
        /* Do multiplicative decrease */
        return max(tp->snd_cwnd - ((tp->snd_cwnd * hstcp_aimd_vals[ca->ai].md) >> 8), 2U);
 }
 
-static u32 hstcp_cwnd_undo(struct sock *sk)
-{
-       const struct hstcp *ca = inet_csk_ca(sk);
-
-       return max(tcp_sk(sk)->snd_cwnd, ca->loss_cwnd);
-}
-
 static struct tcp_congestion_ops tcp_highspeed __read_mostly = {
        .init           = hstcp_init,
        .ssthresh       = hstcp_ssthresh,
-       .undo_cwnd      = hstcp_cwnd_undo,
+       .undo_cwnd      = tcp_reno_undo_cwnd,
        .cong_avoid     = hstcp_cong_avoid,
 
        .owner          = THIS_MODULE,

diff --git a/net/ipv4/tcp_illinois.c b/net/ipv4/tcp_illinois.c
index 60352ff4f5a85f065793a5fb21c0d69713a0453a..7c843578f2333db58100cedbc2a9d0784f72d861 100644 (file)
--- a/net/ipv4/tcp_illinois.c
+++ b/net/ipv4/tcp_illinois.c
@@ -48,7 +48,6 @@ struct illinois {
        u32     end_seq;        /* right edge of current RTT */
        u32     alpha;          /* Additive increase */
        u32     beta;           /* Muliplicative decrease */
-       u32     loss_cwnd;      /* cwnd on loss */
        u16     acked;          /* # packets acked by current ACK */
        u8      rtt_above;      /* average rtt has gone above threshold */
        u8      rtt_low;        /* # of rtts measurements below threshold */
@@ -297,18 +296,10 @@ static u32 tcp_illinois_ssthresh(struct sock *sk)
        struct tcp_sock *tp = tcp_sk(sk);
        struct illinois *ca = inet_csk_ca(sk);
 
-       ca->loss_cwnd = tp->snd_cwnd;
        /* Multiplicative decrease */
        return max(tp->snd_cwnd - ((tp->snd_cwnd * ca->beta) >> BETA_SHIFT), 2U);
 }
 
-static u32 tcp_illinois_cwnd_undo(struct sock *sk)
-{
-       const struct illinois *ca = inet_csk_ca(sk);
-
-       return max(tcp_sk(sk)->snd_cwnd, ca->loss_cwnd);
-}
-
 /* Extract info for Tcp socket info provided via netlink. */
 static size_t tcp_illinois_info(struct sock *sk, u32 ext, int *attr,
                                union tcp_cc_info *info)
@@ -336,7 +327,7 @@ static size_t tcp_illinois_info(struct sock *sk, u32 ext, int *attr,
 static struct tcp_congestion_ops tcp_illinois __read_mostly = {
        .init           = tcp_illinois_init,
        .ssthresh       = tcp_illinois_ssthresh,
-       .undo_cwnd      = tcp_illinois_cwnd_undo,
+       .undo_cwnd      = tcp_reno_undo_cwnd,
        .cong_avoid     = tcp_illinois_cong_avoid,
        .set_state      = tcp_illinois_state,
        .get_info       = tcp_illinois_info,

diff --git a/net/ipv4/tcp_nv.c b/net/ipv4/tcp_nv.c
index 6d650ed3cb598c0027b1c25e75f115b01402da31..1ff73982e28c58ecd0faa787e5ee30793e30dea8 100644 (file)
--- a/net/ipv4/tcp_nv.c
+++ b/net/ipv4/tcp_nv.c
@@ -86,7 +86,6 @@ struct tcpnv {
                                 * < 0 => less than 1 packet/RTT */
        u8  available8;
        u16 available16;
-       u32 loss_cwnd;  /* cwnd at last loss */
        u8  nv_allow_cwnd_growth:1, /* whether cwnd can grow */
                nv_reset:1,         /* whether to reset values */
                nv_catchup:1;       /* whether we are growing because
@@ -121,7 +120,6 @@ static inline void tcpnv_reset(struct tcpnv *ca, struct sock *sk)
        struct tcp_sock *tp = tcp_sk(sk);
 
        ca->nv_reset = 0;
-       ca->loss_cwnd = 0;
        ca->nv_no_cong_cnt = 0;
        ca->nv_rtt_cnt = 0;
        ca->nv_last_rtt = 0;
@@ -177,19 +175,10 @@ static void tcpnv_cong_avoid(struct sock *sk, u32 ack, u32 acked)
 static u32 tcpnv_recalc_ssthresh(struct sock *sk)
 {
        const struct tcp_sock *tp = tcp_sk(sk);
-       struct tcpnv *ca = inet_csk_ca(sk);
 
-       ca->loss_cwnd = tp->snd_cwnd;
        return max((tp->snd_cwnd * nv_loss_dec_factor) >> 10, 2U);
 }
 
-static u32 tcpnv_undo_cwnd(struct sock *sk)
-{
-       struct tcpnv *ca = inet_csk_ca(sk);
-
-       return max(tcp_sk(sk)->snd_cwnd, ca->loss_cwnd);
-}
-
 static void tcpnv_state(struct sock *sk, u8 new_state)
 {
        struct tcpnv *ca = inet_csk_ca(sk);
@@ -446,7 +435,7 @@ static struct tcp_congestion_ops tcpnv __read_mostly = {
        .ssthresh       = tcpnv_recalc_ssthresh,
        .cong_avoid     = tcpnv_cong_avoid,
        .set_state      = tcpnv_state,
-       .undo_cwnd      = tcpnv_undo_cwnd,
+       .undo_cwnd      = tcp_reno_undo_cwnd,
        .pkts_acked     = tcpnv_acked,
        .get_info       = tcpnv_get_info,
 

diff --git a/net/ipv4/tcp_scalable.c b/net/ipv4/tcp_scalable.c
index f2123075ce6e1be4753e26bb1db81423e272caef..addc122f88186fb04579e0ee60fd4a7adad9f97d 100644 (file)
--- a/net/ipv4/tcp_scalable.c
+++ b/net/ipv4/tcp_scalable.c
@@ -15,10 +15,6 @@
 #define TCP_SCALABLE_AI_CNT    50U
 #define TCP_SCALABLE_MD_SCALE  3
 
-struct scalable {
-       u32 loss_cwnd;
-};
-
 static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked)
 {
        struct tcp_sock *tp = tcp_sk(sk);
@@ -36,23 +32,13 @@ static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked)
 static u32 tcp_scalable_ssthresh(struct sock *sk)
 {
        const struct tcp_sock *tp = tcp_sk(sk);
-       struct scalable *ca = inet_csk_ca(sk);
-
-       ca->loss_cwnd = tp->snd_cwnd;
 
        return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
 }
 
-static u32 tcp_scalable_cwnd_undo(struct sock *sk)
-{
-       const struct scalable *ca = inet_csk_ca(sk);
-
-       return max(tcp_sk(sk)->snd_cwnd, ca->loss_cwnd);
-}
-
 static struct tcp_congestion_ops tcp_scalable __read_mostly = {
        .ssthresh       = tcp_scalable_ssthresh,
-       .undo_cwnd      = tcp_scalable_cwnd_undo,
+       .undo_cwnd      = tcp_reno_undo_cwnd,
        .cong_avoid     = tcp_scalable_cong_avoid,
 
        .owner          = THIS_MODULE,

diff --git a/net/ipv4/tcp_veno.c b/net/ipv4/tcp_veno.c
index 76005d4b8dfc2287009628aa07912e0183ea2f05..6fcf482d611ba16e667d8b8024ac97658d45f84f 100644 (file)
--- a/net/ipv4/tcp_veno.c
+++ b/net/ipv4/tcp_veno.c
@@ -30,7 +30,6 @@ struct veno {
        u32 basertt;            /* the min of all Veno rtt measurements seen (in usec) */
        u32 inc;                /* decide whether to increase cwnd */
        u32 diff;               /* calculate the diff rate */
-       u32 loss_cwnd;          /* cwnd when loss occured */
 };
 
 /* There are several situations when we must "re-start" Veno:
@@ -194,7 +193,6 @@ static u32 tcp_veno_ssthresh(struct sock *sk)
        const struct tcp_sock *tp = tcp_sk(sk);
        struct veno *veno = inet_csk_ca(sk);
 
-       veno->loss_cwnd = tp->snd_cwnd;
        if (veno->diff < beta)
                /* in "non-congestive state", cut cwnd by 1/5 */
                return max(tp->snd_cwnd * 4 / 5, 2U);
@@ -203,17 +201,10 @@ static u32 tcp_veno_ssthresh(struct sock *sk)
                return max(tp->snd_cwnd >> 1U, 2U);
 }
 
-static u32 tcp_veno_cwnd_undo(struct sock *sk)
-{
-       const struct veno *veno = inet_csk_ca(sk);
-
-       return max(tcp_sk(sk)->snd_cwnd, veno->loss_cwnd);
-}
-
 static struct tcp_congestion_ops tcp_veno __read_mostly = {
        .init           = tcp_veno_init,
        .ssthresh       = tcp_veno_ssthresh,
-       .undo_cwnd      = tcp_veno_cwnd_undo,
+       .undo_cwnd      = tcp_reno_undo_cwnd,
        .cong_avoid     = tcp_veno_cong_avoid,
        .pkts_acked     = tcp_veno_pkts_acked,
        .set_state      = tcp_veno_state,

diff --git a/net/ipv4/tcp_yeah.c b/net/ipv4/tcp_yeah.c
index e6ff99c4bd3b6914a6e79dc3bb94aa45176dae9e..96e829b2e2fcb8f4539a5b7591a558828feeafbd 100644 (file)
--- a/net/ipv4/tcp_yeah.c
+++ b/net/ipv4/tcp_yeah.c
@@ -37,7 +37,6 @@ struct yeah {
        u32 fast_count;
 
        u32 pkts_acked;
-       u32 loss_cwnd;
 };
 
 static void tcp_yeah_init(struct sock *sk)
@@ -220,22 +219,14 @@ static u32 tcp_yeah_ssthresh(struct sock *sk)
 
        yeah->fast_count = 0;
        yeah->reno_count = max(yeah->reno_count>>1, 2U);
-       yeah->loss_cwnd = tp->snd_cwnd;
 
        return max_t(int, tp->snd_cwnd - reduction, 2);
 }
 
-static u32 tcp_yeah_cwnd_undo(struct sock *sk)
-{
-       const struct yeah *yeah = inet_csk_ca(sk);
-
-       return max(tcp_sk(sk)->snd_cwnd, yeah->loss_cwnd);
-}
-
 static struct tcp_congestion_ops tcp_yeah __read_mostly = {
        .init           = tcp_yeah_init,
        .ssthresh       = tcp_yeah_ssthresh,
-       .undo_cwnd      = tcp_yeah_cwnd_undo,
+       .undo_cwnd      = tcp_reno_undo_cwnd,
        .cong_avoid     = tcp_yeah_cong_avoid,
        .set_state      = tcp_vegas_state,
        .cwnd_event     = tcp_vegas_cwnd_event,