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-rw-r--r--include/linux/tcp.h1
-rw-r--r--include/net/tcp.h7
-rw-r--r--net/ipv4/tcp_input.c36
-rw-r--r--net/ipv4/tcp_recovery.c41
4 files changed, 50 insertions, 35 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index fc5848dad7a4..1255c592719c 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -207,6 +207,7 @@ struct tcp_sock {
/* Information of the most recently (s)acked skb */
struct tcp_rack {
struct skb_mstamp mstamp; /* (Re)sent time of the skb */
+ u32 rtt_us; /* Associated RTT */
u8 advanced; /* mstamp advanced since last lost marking */
u8 reord; /* reordering detected */
} rack;
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 51183bba3835..1439107658c2 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1863,9 +1863,10 @@ extern int sysctl_tcp_recovery;
/* Use TCP RACK to detect (some) tail and retransmit losses */
#define TCP_RACK_LOST_RETRANS 0x1
-extern void tcp_rack_mark_lost(struct sock *sk);
-extern void tcp_rack_advance(struct tcp_sock *tp,
- const struct skb_mstamp *xmit_time, u8 sacked);
+extern void tcp_rack_mark_lost(struct sock *sk, const struct skb_mstamp *now);
+extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked,
+ const struct skb_mstamp *xmit_time,
+ const struct skb_mstamp *ack_time);
/*
* Save and compile IPv4 options, return a pointer to it
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index bb24b93e64bc..8ccd171999bf 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1135,6 +1135,7 @@ struct tcp_sacktag_state {
*/
struct skb_mstamp first_sackt;
struct skb_mstamp last_sackt;
+ struct skb_mstamp ack_time; /* Timestamp when the S/ACK was received */
struct rate_sample *rate;
int flag;
};
@@ -1217,7 +1218,7 @@ static u8 tcp_sacktag_one(struct sock *sk,
return sacked;
if (!(sacked & TCPCB_SACKED_ACKED)) {
- tcp_rack_advance(tp, xmit_time, sacked);
+ tcp_rack_advance(tp, sacked, xmit_time, &state->ack_time);
if (sacked & TCPCB_SACKED_RETRANS) {
/* If the segment is not tagged as lost,
@@ -2813,7 +2814,8 @@ static bool tcp_try_undo_partial(struct sock *sk, const int acked)
* tcp_xmit_retransmit_queue().
*/
static void tcp_fastretrans_alert(struct sock *sk, const int acked,
- bool is_dupack, int *ack_flag, int *rexmit)
+ bool is_dupack, int *ack_flag, int *rexmit,
+ const struct skb_mstamp *ack_time)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
@@ -2868,7 +2870,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const int acked,
if (sysctl_tcp_recovery & TCP_RACK_LOST_RETRANS) {
u32 prior_retrans = tp->retrans_out;
- tcp_rack_mark_lost(sk);
+ tcp_rack_mark_lost(sk, ack_time);
if (prior_retrans > tp->retrans_out) {
flag |= FLAG_LOST_RETRANS;
*ack_flag |= FLAG_LOST_RETRANS;
@@ -3105,11 +3107,11 @@ static void tcp_ack_tstamp(struct sock *sk, struct sk_buff *skb,
*/
static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
u32 prior_snd_una, int *acked,
- struct tcp_sacktag_state *sack,
- struct skb_mstamp *now)
+ struct tcp_sacktag_state *sack)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
struct skb_mstamp first_ackt, last_ackt;
+ struct skb_mstamp *now = &sack->ack_time;
struct tcp_sock *tp = tcp_sk(sk);
u32 prior_sacked = tp->sacked_out;
u32 reord = tp->packets_out;
@@ -3169,7 +3171,9 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
} else if (tcp_is_sack(tp)) {
tp->delivered += acked_pcount;
if (!tcp_skb_spurious_retrans(tp, skb))
- tcp_rack_advance(tp, &skb->skb_mstamp, sacked);
+ tcp_rack_advance(tp, sacked,
+ &skb->skb_mstamp,
+ &sack->ack_time);
}
if (sacked & TCPCB_LOST)
tp->lost_out -= acked_pcount;
@@ -3599,7 +3603,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
u32 lost = tp->lost;
int acked = 0; /* Number of packets newly acked */
int rexmit = REXMIT_NONE; /* Flag to (re)transmit to recover losses */
- struct skb_mstamp now;
sack_state.first_sackt.v64 = 0;
sack_state.rate = &rs;
@@ -3625,7 +3628,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
if (after(ack, tp->snd_nxt))
goto invalid_ack;
- skb_mstamp_get(&now);
+ skb_mstamp_get(&sack_state.ack_time);
if (icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)
@@ -3693,11 +3696,12 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
/* See if we can take anything off of the retransmit queue. */
flag |= tcp_clean_rtx_queue(sk, prior_fackets, prior_snd_una, &acked,
- &sack_state, &now);
+ &sack_state);
if (tcp_ack_is_dubious(sk, flag)) {
is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP));
- tcp_fastretrans_alert(sk, acked, is_dupack, &flag, &rexmit);
+ tcp_fastretrans_alert(sk, acked, is_dupack, &flag, &rexmit,
+ &sack_state.ack_time);
}
if (tp->tlp_high_seq)
tcp_process_tlp_ack(sk, ack, flag);
@@ -3712,15 +3716,17 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
tcp_schedule_loss_probe(sk);
delivered = tp->delivered - delivered; /* freshly ACKed or SACKed */
lost = tp->lost - lost; /* freshly marked lost */
- tcp_rate_gen(sk, delivered, lost, &now, &rs);
- tcp_cong_control(sk, ack, delivered, flag, &rs);
+ tcp_rate_gen(sk, delivered, lost, &sack_state.ack_time,
+ sack_state.rate);
+ tcp_cong_control(sk, ack, delivered, flag, sack_state.rate);
tcp_xmit_recovery(sk, rexmit);
return 1;
no_queue:
/* If data was DSACKed, see if we can undo a cwnd reduction. */
if (flag & FLAG_DSACKING_ACK)
- tcp_fastretrans_alert(sk, acked, is_dupack, &flag, &rexmit);
+ tcp_fastretrans_alert(sk, acked, is_dupack, &flag, &rexmit,
+ &sack_state.ack_time);
/* If this ack opens up a zero window, clear backoff. It was
* being used to time the probes, and is probably far higher than
* it needs to be for normal retransmission.
@@ -3741,9 +3747,11 @@ old_ack:
* If data was DSACKed, see if we can undo a cwnd reduction.
*/
if (TCP_SKB_CB(skb)->sacked) {
+ skb_mstamp_get(&sack_state.ack_time);
flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una,
&sack_state);
- tcp_fastretrans_alert(sk, acked, is_dupack, &flag, &rexmit);
+ tcp_fastretrans_alert(sk, acked, is_dupack, &flag, &rexmit,
+ &sack_state.ack_time);
tcp_xmit_recovery(sk, rexmit);
}
diff --git a/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c
index 7ea0377229c0..557363cde58a 100644
--- a/net/ipv4/tcp_recovery.c
+++ b/net/ipv4/tcp_recovery.c
@@ -32,7 +32,7 @@ static void tcp_rack_mark_skb_lost(struct sock *sk, struct sk_buff *skb)
* The current version is only used after recovery starts but can be
* easily extended to detect the first loss.
*/
-static void tcp_rack_detect_loss(struct sock *sk)
+static void tcp_rack_detect_loss(struct sock *sk, const struct skb_mstamp *now)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
@@ -62,13 +62,14 @@ static void tcp_rack_detect_loss(struct sock *sk)
continue;
if (skb_mstamp_after(&tp->rack.mstamp, &skb->skb_mstamp)) {
-
- if (skb_mstamp_us_delta(&tp->rack.mstamp,
- &skb->skb_mstamp) <= reo_wnd)
- continue;
-
- /* skb is lost if packet sent later is sacked */
- tcp_rack_mark_skb_lost(sk, skb);
+ /* Step 3 in draft-cheng-tcpm-rack-00.txt:
+ * A packet is lost if its elapsed time is beyond
+ * the recent RTT plus the reordering window.
+ */
+ if (skb_mstamp_us_delta(now, &skb->skb_mstamp) >
+ tp->rack.rtt_us + reo_wnd) {
+ tcp_rack_mark_skb_lost(sk, skb);
+ }
} else if (!(scb->sacked & TCPCB_RETRANS)) {
/* Original data are sent sequentially so stop early
* b/c the rest are all sent after rack_sent
@@ -78,7 +79,7 @@ static void tcp_rack_detect_loss(struct sock *sk)
}
}
-void tcp_rack_mark_lost(struct sock *sk)
+void tcp_rack_mark_lost(struct sock *sk, const struct skb_mstamp *now)
{
struct tcp_sock *tp = tcp_sk(sk);
@@ -86,20 +87,25 @@ void tcp_rack_mark_lost(struct sock *sk)
return;
/* Reset the advanced flag to avoid unnecessary queue scanning */
tp->rack.advanced = 0;
- tcp_rack_detect_loss(sk);
+ tcp_rack_detect_loss(sk, now);
}
-/* Record the most recently (re)sent time among the (s)acked packets */
-void tcp_rack_advance(struct tcp_sock *tp,
- const struct skb_mstamp *xmit_time, u8 sacked)
+/* Record the most recently (re)sent time among the (s)acked packets
+ * This is "Step 3: Advance RACK.xmit_time and update RACK.RTT" from
+ * draft-cheng-tcpm-rack-00.txt
+ */
+void tcp_rack_advance(struct tcp_sock *tp, u8 sacked,
+ const struct skb_mstamp *xmit_time,
+ const struct skb_mstamp *ack_time)
{
+ u32 rtt_us;
+
if (tp->rack.mstamp.v64 &&
!skb_mstamp_after(xmit_time, &tp->rack.mstamp))
return;
+ rtt_us = skb_mstamp_us_delta(ack_time, xmit_time);
if (sacked & TCPCB_RETRANS) {
- struct skb_mstamp now;
-
/* If the sacked packet was retransmitted, it's ambiguous
* whether the retransmission or the original (or the prior
* retransmission) was sacked.
@@ -110,11 +116,10 @@ void tcp_rack_advance(struct tcp_sock *tp,
* so it's at least one RTT (i.e., retransmission is at least
* an RTT later).
*/
- skb_mstamp_get(&now);
- if (skb_mstamp_us_delta(&now, xmit_time) < tcp_min_rtt(tp))
+ if (rtt_us < tcp_min_rtt(tp))
return;
}
-
+ tp->rack.rtt_us = rtt_us;
tp->rack.mstamp = *xmit_time;
tp->rack.advanced = 1;
}
generated by cgit v1.2.3 (git 2.39.0) at 2025-01-14 05:45:49 +0300