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authorFlorian Westphal <fw@strlen.de>2016-11-21 14:18:38 +0100
committerDavid S. Miller <davem@davemloft.net>2016-11-21 13:20:17 -0500
commite97991832a4ea4a5f47d65f068a4c966a2eb5730 (patch)
tree870e5c09c37890d286872c9ae22382d6bf336b37
parent85f7e7508a1d288b513493196ef406c6c06134e1 (diff)
downloadlinux-e97991832a4ea4a5f47d65f068a4c966a2eb5730.tar.bz2
tcp: make undo_cwnd mandatory for congestion modules
The undo_cwnd fallback in the stack doubles cwnd based on ssthresh, which un-does reno halving behaviour. It seems more appropriate to let congctl algorithms pair .ssthresh and .undo_cwnd properly. Add a 'tcp_reno_undo_cwnd' function and wire it up for all congestion algorithms that used to rely on the fallback. Cc: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/tcp.h1
-rw-r--r--net/ipv4/tcp_cong.c14
-rw-r--r--net/ipv4/tcp_dctcp.c1
-rw-r--r--net/ipv4/tcp_hybla.c1
-rw-r--r--net/ipv4/tcp_input.c5
-rw-r--r--net/ipv4/tcp_lp.c1
-rw-r--r--net/ipv4/tcp_vegas.c1
-rw-r--r--net/ipv4/tcp_westwood.c1
8 files changed, 19 insertions, 6 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 123979fe12bf..7de80739adab 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -958,6 +958,7 @@ u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
u32 tcp_reno_ssthresh(struct sock *sk);
+u32 tcp_reno_undo_cwnd(struct sock *sk);
void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
extern struct tcp_congestion_ops tcp_reno;
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 1294af4e0127..38905ec5f508 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -68,8 +68,9 @@ int tcp_register_congestion_control(struct tcp_congestion_ops *ca)
{
int ret = 0;
- /* all algorithms must implement ssthresh and cong_avoid ops */
- if (!ca->ssthresh || !(ca->cong_avoid || ca->cong_control)) {
+ /* all algorithms must implement these */
+ if (!ca->ssthresh || !ca->undo_cwnd ||
+ !(ca->cong_avoid || ca->cong_control)) {
pr_err("%s does not implement required ops\n", ca->name);
return -EINVAL;
}
@@ -441,10 +442,19 @@ u32 tcp_reno_ssthresh(struct sock *sk)
}
EXPORT_SYMBOL_GPL(tcp_reno_ssthresh);
+u32 tcp_reno_undo_cwnd(struct sock *sk)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+
+ return max(tp->snd_cwnd, tp->snd_ssthresh << 1);
+}
+EXPORT_SYMBOL_GPL(tcp_reno_undo_cwnd);
+
struct tcp_congestion_ops tcp_reno = {
.flags = TCP_CONG_NON_RESTRICTED,
.name = "reno",
.owner = THIS_MODULE,
.ssthresh = tcp_reno_ssthresh,
.cong_avoid = tcp_reno_cong_avoid,
+ .undo_cwnd = tcp_reno_undo_cwnd,
};
diff --git a/net/ipv4/tcp_dctcp.c b/net/ipv4/tcp_dctcp.c
index 51139175bf61..bde22ebb92a8 100644
--- a/net/ipv4/tcp_dctcp.c
+++ b/net/ipv4/tcp_dctcp.c
@@ -342,6 +342,7 @@ static struct tcp_congestion_ops dctcp __read_mostly = {
static struct tcp_congestion_ops dctcp_reno __read_mostly = {
.ssthresh = tcp_reno_ssthresh,
.cong_avoid = tcp_reno_cong_avoid,
+ .undo_cwnd = tcp_reno_undo_cwnd,
.get_info = dctcp_get_info,
.owner = THIS_MODULE,
.name = "dctcp-reno",
diff --git a/net/ipv4/tcp_hybla.c b/net/ipv4/tcp_hybla.c
index 083831e359df..0f7175c3338e 100644
--- a/net/ipv4/tcp_hybla.c
+++ b/net/ipv4/tcp_hybla.c
@@ -166,6 +166,7 @@ static void hybla_cong_avoid(struct sock *sk, u32 ack, u32 acked)
static struct tcp_congestion_ops tcp_hybla __read_mostly = {
.init = hybla_init,
.ssthresh = tcp_reno_ssthresh,
+ .undo_cwnd = tcp_reno_undo_cwnd,
.cong_avoid = hybla_cong_avoid,
.set_state = hybla_state,
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a70046fea0e8..22e6a2097ff6 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2394,10 +2394,7 @@ static void tcp_undo_cwnd_reduction(struct sock *sk, bool unmark_loss)
if (tp->prior_ssthresh) {
const struct inet_connection_sock *icsk = inet_csk(sk);
- if (icsk->icsk_ca_ops->undo_cwnd)
- tp->snd_cwnd = icsk->icsk_ca_ops->undo_cwnd(sk);
- else
- tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh << 1);
+ tp->snd_cwnd = icsk->icsk_ca_ops->undo_cwnd(sk);
if (tp->prior_ssthresh > tp->snd_ssthresh) {
tp->snd_ssthresh = tp->prior_ssthresh;
diff --git a/net/ipv4/tcp_lp.c b/net/ipv4/tcp_lp.c
index c67ece1390c2..046fd3910873 100644
--- a/net/ipv4/tcp_lp.c
+++ b/net/ipv4/tcp_lp.c
@@ -316,6 +316,7 @@ static void tcp_lp_pkts_acked(struct sock *sk, const struct ack_sample *sample)
static struct tcp_congestion_ops tcp_lp __read_mostly = {
.init = tcp_lp_init,
.ssthresh = tcp_reno_ssthresh,
+ .undo_cwnd = tcp_reno_undo_cwnd,
.cong_avoid = tcp_lp_cong_avoid,
.pkts_acked = tcp_lp_pkts_acked,
diff --git a/net/ipv4/tcp_vegas.c b/net/ipv4/tcp_vegas.c
index 4c4bac1b5eab..218cfcc77650 100644
--- a/net/ipv4/tcp_vegas.c
+++ b/net/ipv4/tcp_vegas.c
@@ -307,6 +307,7 @@ EXPORT_SYMBOL_GPL(tcp_vegas_get_info);
static struct tcp_congestion_ops tcp_vegas __read_mostly = {
.init = tcp_vegas_init,
.ssthresh = tcp_reno_ssthresh,
+ .undo_cwnd = tcp_reno_undo_cwnd,
.cong_avoid = tcp_vegas_cong_avoid,
.pkts_acked = tcp_vegas_pkts_acked,
.set_state = tcp_vegas_state,
diff --git a/net/ipv4/tcp_westwood.c b/net/ipv4/tcp_westwood.c
index 4b03a2e2a050..fed66dc0e0f5 100644
--- a/net/ipv4/tcp_westwood.c
+++ b/net/ipv4/tcp_westwood.c
@@ -278,6 +278,7 @@ static struct tcp_congestion_ops tcp_westwood __read_mostly = {
.init = tcp_westwood_init,
.ssthresh = tcp_reno_ssthresh,
.cong_avoid = tcp_reno_cong_avoid,
+ .undo_cwnd = tcp_reno_undo_cwnd,
.cwnd_event = tcp_westwood_event,
.in_ack_event = tcp_westwood_ack,
.get_info = tcp_westwood_info,