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Message-ID: <20241202143057.378147-38-dhowells@redhat.com>
Date: Mon, 2 Dec 2024 14:30:55 +0000
From: David Howells <dhowells@...hat.com>
To: netdev@...r.kernel.org
Cc: David Howells <dhowells@...hat.com>,
Marc Dionne <marc.dionne@...istor.com>,
Yunsheng Lin <linyunsheng@...wei.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
linux-afs@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: [PATCH net-next 37/37] rxrpc: Implement RACK/TLP to deal with transmission stalls [RFC8985]
When an rxrpc call is in its transmission phase and is sending a lot of
packets, stalls occasionally occur that cause severe performance
degradation (eg. increasing the transmission time for a 256MiB payload from
0.7s to 2.5s over a 10G link).
rxrpc already implements TCP-style congestion control [RFC5681] and this
helps mitigate the effects, but occasionally we're missing a time event
that deals with a missing ACK, leading to a stall until the RTO expires.
Fix this by implementing RACK/TLP in rxrpc.
Signed-off-by: David Howells <dhowells@...hat.com>
cc: Marc Dionne <marc.dionne@...istor.com>
cc: "David S. Miller" <davem@...emloft.net>
cc: Eric Dumazet <edumazet@...gle.com>
cc: Jakub Kicinski <kuba@...nel.org>
cc: Paolo Abeni <pabeni@...hat.com>
cc: linux-afs@...ts.infradead.org
cc: netdev@...r.kernel.org
---
include/trace/events/rxrpc.h | 342 ++++++++++++++++++++++++++--
net/rxrpc/Makefile | 1 +
net/rxrpc/ar-internal.h | 106 ++++++++-
net/rxrpc/call_event.c | 246 +++++++-------------
net/rxrpc/call_object.c | 3 +-
net/rxrpc/input.c | 117 ++++++----
net/rxrpc/input_rack.c | 422 +++++++++++++++++++++++++++++++++++
net/rxrpc/io_thread.c | 1 +
net/rxrpc/output.c | 41 +++-
9 files changed, 1044 insertions(+), 235 deletions(-)
create mode 100644 net/rxrpc/input_rack.c
diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h
index 71df5c48a413..2f119d18a061 100644
--- a/include/trace/events/rxrpc.h
+++ b/include/trace/events/rxrpc.h
@@ -305,7 +305,9 @@
#define rxrpc_txdata_traces \
EM(rxrpc_txdata_inject_loss, " *INJ-LOSS*") \
EM(rxrpc_txdata_new_data, " ") \
- E_(rxrpc_txdata_retransmit, " *RETRANS*")
+ EM(rxrpc_txdata_retransmit, " *RETRANS*") \
+ EM(rxrpc_txdata_tlp_new_data, " *TLP-NEW*") \
+ E_(rxrpc_txdata_tlp_retransmit, " *TLP-RETRANS*")
#define rxrpc_receive_traces \
EM(rxrpc_receive_end, "END") \
@@ -353,11 +355,12 @@
EM(rxrpc_timer_trace_hard, "HardLimit") \
EM(rxrpc_timer_trace_idle, "IdleLimit") \
EM(rxrpc_timer_trace_keepalive, "KeepAlive") \
- EM(rxrpc_timer_trace_lost_ack, "LostAck ") \
EM(rxrpc_timer_trace_ping, "DelayPing") \
- EM(rxrpc_timer_trace_resend, "Resend ") \
- EM(rxrpc_timer_trace_resend_reset, "ResendRst") \
- E_(rxrpc_timer_trace_resend_tx, "ResendTx ")
+ EM(rxrpc_timer_trace_rack_off, "RACK-OFF ") \
+ EM(rxrpc_timer_trace_rack_zwp, "RACK-ZWP ") \
+ EM(rxrpc_timer_trace_rack_reo, "RACK-Reo ") \
+ EM(rxrpc_timer_trace_rack_tlp_pto, "TLP-PTO ") \
+ E_(rxrpc_timer_trace_rack_rto, "RTO ")
#define rxrpc_propose_ack_traces \
EM(rxrpc_propose_ack_client_tx_end, "ClTxEnd") \
@@ -478,9 +481,9 @@
EM(rxrpc_txbuf_put_rotated, "PUT ROTATED") \
EM(rxrpc_txbuf_put_send_aborted, "PUT SEND-X ") \
EM(rxrpc_txbuf_put_trans, "PUT TRANS ") \
+ EM(rxrpc_txbuf_see_lost, "SEE LOST ") \
EM(rxrpc_txbuf_see_out_of_step, "OUT-OF-STEP") \
- EM(rxrpc_txbuf_see_send_more, "SEE SEND+ ") \
- E_(rxrpc_txbuf_see_unacked, "SEE UNACKED")
+ E_(rxrpc_txbuf_see_send_more, "SEE SEND+ ")
#define rxrpc_tq_traces \
EM(rxrpc_tq_alloc, "ALLOC") \
@@ -505,6 +508,24 @@
EM(rxrpc_rotate_trace_sack, "soft-ack") \
E_(rxrpc_rotate_trace_snak, "soft-nack")
+#define rxrpc_rack_timer_modes \
+ EM(RXRPC_CALL_RACKTIMER_OFF, "---") \
+ EM(RXRPC_CALL_RACKTIMER_RACK_REORDER, "REO") \
+ EM(RXRPC_CALL_RACKTIMER_TLP_PTO, "TLP") \
+ E_(RXRPC_CALL_RACKTIMER_RTO, "RTO")
+
+#define rxrpc_tlp_probe_traces \
+ EM(rxrpc_tlp_probe_trace_busy, "busy") \
+ EM(rxrpc_tlp_probe_trace_transmit_new, "transmit-new") \
+ E_(rxrpc_tlp_probe_trace_retransmit, "retransmit")
+
+#define rxrpc_tlp_ack_traces \
+ EM(rxrpc_tlp_ack_trace_acked, "acked") \
+ EM(rxrpc_tlp_ack_trace_dup_acked, "dup-acked") \
+ EM(rxrpc_tlp_ack_trace_hard_beyond, "hard-beyond") \
+ EM(rxrpc_tlp_ack_trace_incomplete, "incomplete") \
+ E_(rxrpc_tlp_ack_trace_new_data, "new-data")
+
/*
* Generate enums for tracing information.
*/
@@ -537,6 +558,8 @@ enum rxrpc_rtt_tx_trace { rxrpc_rtt_tx_traces } __mode(byte);
enum rxrpc_sack_trace { rxrpc_sack_traces } __mode(byte);
enum rxrpc_skb_trace { rxrpc_skb_traces } __mode(byte);
enum rxrpc_timer_trace { rxrpc_timer_traces } __mode(byte);
+enum rxrpc_tlp_ack_trace { rxrpc_tlp_ack_traces } __mode(byte);
+enum rxrpc_tlp_probe_trace { rxrpc_tlp_probe_traces } __mode(byte);
enum rxrpc_tq_trace { rxrpc_tq_traces } __mode(byte);
enum rxrpc_tx_point { rxrpc_tx_points } __mode(byte);
enum rxrpc_txbuf_trace { rxrpc_txbuf_traces } __mode(byte);
@@ -567,6 +590,7 @@ rxrpc_conn_traces;
rxrpc_local_traces;
rxrpc_pmtud_reduce_traces;
rxrpc_propose_ack_traces;
+rxrpc_rack_timer_modes;
rxrpc_receive_traces;
rxrpc_recvmsg_traces;
rxrpc_req_ack_traces;
@@ -576,6 +600,8 @@ rxrpc_rtt_tx_traces;
rxrpc_sack_traces;
rxrpc_skb_traces;
rxrpc_timer_traces;
+rxrpc_tlp_ack_traces;
+rxrpc_tlp_probe_traces;
rxrpc_tq_traces;
rxrpc_tx_points;
rxrpc_txbuf_traces;
@@ -618,6 +644,20 @@ TRACE_EVENT(rxrpc_local,
__entry->usage)
);
+TRACE_EVENT(rxrpc_iothread_rx,
+ TP_PROTO(struct rxrpc_local *local, unsigned int nr_rx),
+ TP_ARGS(local, nr_rx),
+ TP_STRUCT__entry(
+ __field(unsigned int, local)
+ __field(unsigned int, nr_rx)
+ ),
+ TP_fast_assign(
+ __entry->local = local->debug_id;
+ __entry->nr_rx = nr_rx;
+ ),
+ TP_printk("L=%08x nrx=%u", __entry->local, __entry->nr_rx)
+ );
+
TRACE_EVENT(rxrpc_peer,
TP_PROTO(unsigned int peer_debug_id, int ref, enum rxrpc_peer_trace why),
@@ -1684,16 +1724,15 @@ TRACE_EVENT(rxrpc_drop_ack,
TRACE_EVENT(rxrpc_retransmit,
TP_PROTO(struct rxrpc_call *call,
struct rxrpc_send_data_req *req,
- struct rxrpc_txbuf *txb, ktime_t expiry),
+ struct rxrpc_txbuf *txb),
- TP_ARGS(call, req, txb, expiry),
+ TP_ARGS(call, req, txb),
TP_STRUCT__entry(
__field(unsigned int, call)
__field(unsigned int, qbase)
__field(rxrpc_seq_t, seq)
__field(rxrpc_serial_t, serial)
- __field(ktime_t, expiry)
),
TP_fast_assign(
@@ -1701,15 +1740,13 @@ TRACE_EVENT(rxrpc_retransmit,
__entry->qbase = req->tq->qbase;
__entry->seq = req->seq;
__entry->serial = txb->serial;
- __entry->expiry = expiry;
),
- TP_printk("c=%08x tq=%x q=%x r=%x xp=%lld",
+ TP_printk("c=%08x tq=%x q=%x r=%x",
__entry->call,
__entry->qbase,
__entry->seq,
- __entry->serial,
- ktime_to_us(__entry->expiry))
+ __entry->serial)
);
TRACE_EVENT(rxrpc_congest,
@@ -1767,9 +1804,9 @@ TRACE_EVENT(rxrpc_congest,
);
TRACE_EVENT(rxrpc_reset_cwnd,
- TP_PROTO(struct rxrpc_call *call, ktime_t now),
+ TP_PROTO(struct rxrpc_call *call, ktime_t since_last_tx, ktime_t rtt),
- TP_ARGS(call, now),
+ TP_ARGS(call, since_last_tx, rtt),
TP_STRUCT__entry(
__field(unsigned int, call)
@@ -1779,6 +1816,7 @@ TRACE_EVENT(rxrpc_reset_cwnd,
__field(rxrpc_seq_t, hard_ack)
__field(rxrpc_seq_t, prepared)
__field(ktime_t, since_last_tx)
+ __field(ktime_t, rtt)
__field(bool, has_data)
),
@@ -1789,18 +1827,20 @@ TRACE_EVENT(rxrpc_reset_cwnd,
__entry->extra = call->cong_extra;
__entry->hard_ack = call->acks_hard_ack;
__entry->prepared = call->send_top - call->tx_bottom;
- __entry->since_last_tx = ktime_sub(now, call->tx_last_sent);
+ __entry->since_last_tx = since_last_tx;
+ __entry->rtt = rtt;
__entry->has_data = call->tx_bottom != call->tx_top;
),
- TP_printk("c=%08x q=%08x %s cw=%u+%u pr=%u tm=%llu d=%u",
+ TP_printk("c=%08x q=%08x %s cw=%u+%u pr=%u tm=%llu/%llu d=%u",
__entry->call,
__entry->hard_ack,
__print_symbolic(__entry->ca_state, rxrpc_ca_states),
__entry->cwnd,
__entry->extra,
__entry->prepared,
- ktime_to_ns(__entry->since_last_tx),
+ ktime_to_us(__entry->since_last_tx),
+ ktime_to_us(__entry->rtt),
__entry->has_data)
);
@@ -1925,6 +1965,32 @@ TRACE_EVENT(rxrpc_resend,
__entry->transmitted)
);
+TRACE_EVENT(rxrpc_resend_lost,
+ TP_PROTO(struct rxrpc_call *call, struct rxrpc_txqueue *tq, unsigned long lost),
+
+ TP_ARGS(call, tq, lost),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, call)
+ __field(rxrpc_seq_t, qbase)
+ __field(u8, nr_rep)
+ __field(unsigned long, lost)
+ ),
+
+ TP_fast_assign(
+ __entry->call = call->debug_id;
+ __entry->qbase = tq->qbase;
+ __entry->nr_rep = tq->nr_reported_acks;
+ __entry->lost = lost;
+ ),
+
+ TP_printk("c=%08x tq=%x lost=%016lx nr=%u",
+ __entry->call,
+ __entry->qbase,
+ __entry->lost,
+ __entry->nr_rep)
+ );
+
TRACE_EVENT(rxrpc_rotate,
TP_PROTO(struct rxrpc_call *call, struct rxrpc_txqueue *tq,
struct rxrpc_ack_summary *summary, rxrpc_seq_t seq,
@@ -2363,6 +2429,244 @@ TRACE_EVENT(rxrpc_pmtud_reduce,
__entry->serial, __entry->max_data)
);
+TRACE_EVENT(rxrpc_rack,
+ TP_PROTO(struct rxrpc_call *call, ktime_t timo),
+
+ TP_ARGS(call, timo),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, call)
+ __field(rxrpc_serial_t, ack_serial)
+ __field(rxrpc_seq_t, seq)
+ __field(enum rxrpc_rack_timer_mode, mode)
+ __field(unsigned short, nr_sent)
+ __field(unsigned short, nr_lost)
+ __field(unsigned short, nr_resent)
+ __field(unsigned short, nr_sacked)
+ __field(ktime_t, timo)
+ ),
+
+ TP_fast_assign(
+ __entry->call = call->debug_id;
+ __entry->ack_serial = call->rx_serial;
+ __entry->seq = call->rack_end_seq;
+ __entry->mode = call->rack_timer_mode;
+ __entry->nr_sent = call->tx_nr_sent;
+ __entry->nr_lost = call->tx_nr_lost;
+ __entry->nr_resent = call->tx_nr_resent;
+ __entry->nr_sacked = call->acks_nr_sacks;
+ __entry->timo = timo;
+ ),
+
+ TP_printk("c=%08x r=%08x q=%08x %s slrs=%u,%u,%u,%u t=%lld",
+ __entry->call, __entry->ack_serial, __entry->seq,
+ __print_symbolic(__entry->mode, rxrpc_rack_timer_modes),
+ __entry->nr_sent, __entry->nr_lost,
+ __entry->nr_resent, __entry->nr_sacked,
+ ktime_to_us(__entry->timo))
+ );
+
+TRACE_EVENT(rxrpc_rack_update,
+ TP_PROTO(struct rxrpc_call *call, struct rxrpc_ack_summary *summary),
+
+ TP_ARGS(call, summary),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, call)
+ __field(rxrpc_serial_t, ack_serial)
+ __field(rxrpc_seq_t, seq)
+ __field(int, xmit_ts)
+ ),
+
+ TP_fast_assign(
+ __entry->call = call->debug_id;
+ __entry->ack_serial = call->rx_serial;
+ __entry->seq = call->rack_end_seq;
+ __entry->xmit_ts = ktime_sub(call->acks_latest_ts, call->rack_xmit_ts);
+ ),
+
+ TP_printk("c=%08x r=%08x q=%08x xt=%lld",
+ __entry->call, __entry->ack_serial, __entry->seq,
+ ktime_to_us(__entry->xmit_ts))
+ );
+
+TRACE_EVENT(rxrpc_rack_scan_loss,
+ TP_PROTO(struct rxrpc_call *call),
+
+ TP_ARGS(call),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, call)
+ __field(ktime_t, rack_rtt)
+ __field(ktime_t, rack_reo_wnd)
+ ),
+
+ TP_fast_assign(
+ __entry->call = call->debug_id;
+ __entry->rack_rtt = call->rack_rtt;
+ __entry->rack_reo_wnd = call->rack_reo_wnd;
+ ),
+
+ TP_printk("c=%08x rtt=%lld reow=%lld",
+ __entry->call, ktime_to_us(__entry->rack_rtt),
+ ktime_to_us(__entry->rack_reo_wnd))
+ );
+
+TRACE_EVENT(rxrpc_rack_scan_loss_tq,
+ TP_PROTO(struct rxrpc_call *call, const struct rxrpc_txqueue *tq,
+ unsigned long nacks),
+
+ TP_ARGS(call, tq, nacks),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, call)
+ __field(rxrpc_seq_t, qbase)
+ __field(unsigned long, nacks)
+ __field(unsigned long, lost)
+ __field(unsigned long, retrans)
+ ),
+
+ TP_fast_assign(
+ __entry->call = call->debug_id;
+ __entry->qbase = tq->qbase;
+ __entry->nacks = nacks;
+ __entry->lost = tq->segment_lost;
+ __entry->retrans = tq->segment_retransmitted;
+ ),
+
+ TP_printk("c=%08x q=%08x n=%lx l=%lx r=%lx",
+ __entry->call, __entry->qbase,
+ __entry->nacks, __entry->lost, __entry->retrans)
+ );
+
+TRACE_EVENT(rxrpc_rack_detect_loss,
+ TP_PROTO(struct rxrpc_call *call, struct rxrpc_ack_summary *summary,
+ rxrpc_seq_t seq),
+
+ TP_ARGS(call, summary, seq),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, call)
+ __field(rxrpc_serial_t, ack_serial)
+ __field(rxrpc_seq_t, seq)
+ ),
+
+ TP_fast_assign(
+ __entry->call = call->debug_id;
+ __entry->ack_serial = call->rx_serial;
+ __entry->seq = seq;
+ ),
+
+ TP_printk("c=%08x r=%08x q=%08x",
+ __entry->call, __entry->ack_serial, __entry->seq)
+ );
+
+TRACE_EVENT(rxrpc_rack_mark_loss_tq,
+ TP_PROTO(struct rxrpc_call *call, const struct rxrpc_txqueue *tq),
+
+ TP_ARGS(call, tq),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, call)
+ __field(rxrpc_seq_t, qbase)
+ __field(rxrpc_seq_t, trans)
+ __field(unsigned long, acked)
+ __field(unsigned long, lost)
+ __field(unsigned long, retrans)
+ ),
+
+ TP_fast_assign(
+ __entry->call = call->debug_id;
+ __entry->qbase = tq->qbase;
+ __entry->trans = call->tx_transmitted;
+ __entry->acked = tq->segment_acked;
+ __entry->lost = tq->segment_lost;
+ __entry->retrans = tq->segment_retransmitted;
+ ),
+
+ TP_printk("c=%08x tq=%08x txq=%08x a=%lx l=%lx r=%lx",
+ __entry->call, __entry->qbase, __entry->trans,
+ __entry->acked, __entry->lost, __entry->retrans)
+ );
+
+TRACE_EVENT(rxrpc_tlp_probe,
+ TP_PROTO(struct rxrpc_call *call, enum rxrpc_tlp_probe_trace trace),
+
+ TP_ARGS(call, trace),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, call)
+ __field(rxrpc_serial_t, serial)
+ __field(rxrpc_seq_t, seq)
+ __field(enum rxrpc_tlp_probe_trace, trace)
+ ),
+
+ TP_fast_assign(
+ __entry->call = call->debug_id;
+ __entry->serial = call->tlp_serial;
+ __entry->seq = call->tlp_seq;
+ __entry->trace = trace;
+ ),
+
+ TP_printk("c=%08x r=%08x pq=%08x %s",
+ __entry->call, __entry->serial, __entry->seq,
+ __print_symbolic(__entry->trace, rxrpc_tlp_probe_traces))
+ );
+
+TRACE_EVENT(rxrpc_tlp_ack,
+ TP_PROTO(struct rxrpc_call *call, struct rxrpc_ack_summary *summary,
+ enum rxrpc_tlp_ack_trace trace),
+
+ TP_ARGS(call, summary, trace),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, call)
+ __field(rxrpc_serial_t, serial)
+ __field(rxrpc_seq_t, tlp_seq)
+ __field(rxrpc_seq_t, hard_ack)
+ __field(enum rxrpc_tlp_ack_trace, trace)
+ ),
+
+ TP_fast_assign(
+ __entry->call = call->debug_id;
+ __entry->serial = call->tlp_serial;
+ __entry->tlp_seq = call->tlp_seq;
+ __entry->hard_ack = call->acks_hard_ack;
+ __entry->trace = trace;
+ ),
+
+ TP_printk("c=%08x r=%08x pq=%08x hq=%08x %s",
+ __entry->call, __entry->serial,
+ __entry->tlp_seq, __entry->hard_ack,
+ __print_symbolic(__entry->trace, rxrpc_tlp_ack_traces))
+ );
+
+TRACE_EVENT(rxrpc_rack_timer,
+ TP_PROTO(struct rxrpc_call *call, ktime_t delay, bool exp),
+
+ TP_ARGS(call, delay, exp),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, call)
+ __field(bool, exp)
+ __field(enum rxrpc_rack_timer_mode, mode)
+ __field(ktime_t, delay)
+ ),
+
+ TP_fast_assign(
+ __entry->call = call->debug_id;
+ __entry->exp = exp;
+ __entry->mode = call->rack_timer_mode;
+ __entry->delay = delay;
+ ),
+
+ TP_printk("c=%08x %s %s to=%lld",
+ __entry->call,
+ __entry->exp ? "Exp" : "Set",
+ __print_symbolic(__entry->mode, rxrpc_rack_timer_modes),
+ ktime_to_us(__entry->delay))
+ );
+
#undef EM
#undef E_
diff --git a/net/rxrpc/Makefile b/net/rxrpc/Makefile
index ac5caf5a48e1..210b75e3179e 100644
--- a/net/rxrpc/Makefile
+++ b/net/rxrpc/Makefile
@@ -16,6 +16,7 @@ rxrpc-y := \
conn_object.o \
conn_service.o \
input.o \
+ input_rack.o \
insecure.o \
io_thread.o \
key.o \
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index a48df82ef4c5..cfa063285d89 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -621,6 +621,18 @@ enum rxrpc_ca_state {
NR__RXRPC_CA_STATES
} __mode(byte);
+/*
+ * Current purpose of call RACK timer. According to the RACK-TLP protocol
+ * [RFC8985], the transmission timer (call->rack_timo_at) may only be used for
+ * one of these at once.
+ */
+enum rxrpc_rack_timer_mode {
+ RXRPC_CALL_RACKTIMER_OFF, /* Timer not running */
+ RXRPC_CALL_RACKTIMER_RACK_REORDER, /* RACK reordering timer */
+ RXRPC_CALL_RACKTIMER_TLP_PTO, /* TLP timeout */
+ RXRPC_CALL_RACKTIMER_RTO, /* Retransmission timeout */
+} __mode(byte);
+
/*
* RxRPC call definition
* - matched by { connection, call_id }
@@ -638,8 +650,7 @@ struct rxrpc_call {
struct mutex user_mutex; /* User access mutex */
struct sockaddr_rxrpc dest_srx; /* Destination address */
ktime_t delay_ack_at; /* When DELAY ACK needs to happen */
- ktime_t ack_lost_at; /* When ACK is figured as lost */
- ktime_t resend_at; /* When next resend needs to happen */
+ ktime_t rack_timo_at; /* When ACK is figured as lost */
ktime_t ping_at; /* When next to send a ping */
ktime_t keepalive_at; /* When next to send a keepalive ping */
ktime_t expect_rx_by; /* When we expect to get a packet by */
@@ -695,8 +706,12 @@ struct rxrpc_call {
rxrpc_seq_t tx_bottom; /* First packet in buffer */
rxrpc_seq_t tx_transmitted; /* Highest packet transmitted */
rxrpc_seq_t tx_top; /* Highest Tx slot allocated. */
+ rxrpc_serial_t tx_last_serial; /* Serial of last DATA transmitted */
u16 tx_backoff; /* Delay to insert due to Tx failure (ms) */
- u8 tx_winsize; /* Maximum size of Tx window */
+ u16 tx_nr_sent; /* Number of packets sent, but unacked */
+ u16 tx_nr_lost; /* Number of packets marked lost */
+ u16 tx_nr_resent; /* Number of packets resent, but unacked */
+ u16 tx_winsize; /* Maximum size of Tx window */
#define RXRPC_TX_MAX_WINDOW 128
u8 tx_jumbo_max; /* Maximum subpkts peer will accept */
u8 tx_jumbo_limit; /* Maximum subpkts in a jumbo packet */
@@ -726,6 +741,25 @@ struct rxrpc_call {
u16 cong_cumul_acks; /* Cumulative ACK count */
ktime_t cong_tstamp; /* Last time cwnd was changed */
+ /* RACK-TLP [RFC8985] state. */
+ ktime_t rack_xmit_ts; /* Latest transmission timestamp */
+ ktime_t rack_rtt; /* RTT of most recently ACK'd segment */
+ ktime_t rack_rtt_ts; /* Timestamp of rack_rtt */
+ ktime_t rack_reo_wnd; /* Reordering window */
+ unsigned int rack_reo_wnd_mult; /* Multiplier applied to rack_reo_wnd */
+ int rack_reo_wnd_persist; /* Num loss recoveries before reset reo_wnd */
+ rxrpc_seq_t rack_fack; /* Highest sequence so far ACK'd */
+ rxrpc_seq_t rack_end_seq; /* Highest sequence seen */
+ rxrpc_seq_t rack_dsack_round; /* DSACK opt recv'd in latest roundtrip */
+ bool rack_dsack_round_none; /* T if dsack_round is "None" */
+ bool rack_reordering_seen; /* T if detected reordering event */
+ enum rxrpc_rack_timer_mode rack_timer_mode; /* Current mode of RACK timer */
+ bool tlp_is_retrans; /* T if unacked TLP retransmission */
+ rxrpc_serial_t tlp_serial; /* Serial of TLP probe (or 0 if none in progress) */
+ rxrpc_seq_t tlp_seq; /* Sequence of TLP probe */
+ unsigned int tlp_rtt_taken; /* Last time RTT taken */
+ ktime_t tlp_max_ack_delay; /* Sender budget for max delayed ACK interval */
+
/* Receive-phase ACK management (ACKs we send). */
u8 ackr_reason; /* reason to ACK */
u16 ackr_sack_base; /* Starting slot in SACK table ring */
@@ -784,6 +818,9 @@ struct rxrpc_ack_summary {
bool retrans_timeo:1; /* T if reTx due to timeout happened */
bool need_retransmit:1; /* T if we need transmission */
bool rtt_sample_avail:1; /* T if RTT sample available */
+ bool in_fast_or_rto_recovery:1;
+ bool exiting_fast_or_rto_recovery:1;
+ bool tlp_probe_acked:1; /* T if the TLP probe seq was acked */
u8 /*enum rxrpc_congest_change*/ change;
};
@@ -865,6 +902,7 @@ struct rxrpc_txqueue {
unsigned long segment_lost; /* Bit-per-buf: Set if declared lost */
unsigned long segment_retransmitted; /* Bit-per-buf: Set if retransmitted */
unsigned long rtt_samples; /* Bit-per-buf: Set if available for RTT */
+ unsigned long ever_retransmitted; /* Bit-per-buf: Set if ever retransmitted */
/* The arrays we want to pack into as few cache lines as possible. */
struct {
@@ -884,7 +922,9 @@ struct rxrpc_send_data_req {
struct rxrpc_txqueue *tq; /* Tx queue segment holding first DATA */
rxrpc_seq_t seq; /* Sequence of first data */
int n; /* Number of DATA packets to glue into jumbo */
+ bool retrans; /* T if this is a retransmission */
bool did_send; /* T if did actually send */
+ bool tlp_probe; /* T if this is a TLP probe */
int /* enum rxrpc_txdata_trace */ trace;
};
@@ -944,8 +984,9 @@ void rxrpc_propose_ping(struct rxrpc_call *call, u32 serial,
enum rxrpc_propose_ack_trace why);
void rxrpc_propose_delay_ACK(struct rxrpc_call *, rxrpc_serial_t,
enum rxrpc_propose_ack_trace);
-void rxrpc_resend(struct rxrpc_call *call, rxrpc_serial_t ack_serial, bool ping_response);
-
+void rxrpc_resend_tlp(struct rxrpc_call *call);
+void rxrpc_transmit_some_data(struct rxrpc_call *call, unsigned int limit,
+ enum rxrpc_txdata_trace trace);
bool rxrpc_input_call_event(struct rxrpc_call *call);
/*
@@ -1124,6 +1165,32 @@ void rxrpc_congestion_degrade(struct rxrpc_call *);
void rxrpc_input_call_packet(struct rxrpc_call *, struct sk_buff *);
void rxrpc_implicit_end_call(struct rxrpc_call *, struct sk_buff *);
+/*
+ * input_rack.c
+ */
+void rxrpc_input_rack_one(struct rxrpc_call *call,
+ struct rxrpc_ack_summary *summary,
+ struct rxrpc_txqueue *tq,
+ unsigned int ix);
+void rxrpc_input_rack(struct rxrpc_call *call,
+ struct rxrpc_ack_summary *summary,
+ struct rxrpc_txqueue *tq,
+ unsigned long new_acks);
+void rxrpc_rack_detect_loss_and_arm_timer(struct rxrpc_call *call,
+ struct rxrpc_ack_summary *summary);
+ktime_t rxrpc_tlp_calc_pto(struct rxrpc_call *call, ktime_t now);
+void rxrpc_tlp_send_probe(struct rxrpc_call *call);
+void rxrpc_tlp_process_ack(struct rxrpc_call *call, struct rxrpc_ack_summary *summary);
+void rxrpc_rack_timer_expired(struct rxrpc_call *call, ktime_t overran_by);
+
+/* Initialise TLP state [RFC8958 7.1]. */
+static inline void rxrpc_tlp_init(struct rxrpc_call *call)
+{
+ call->tlp_serial = 0;
+ call->tlp_seq = call->acks_hard_ack;
+ call->tlp_is_retrans = false;
+}
+
/*
* io_thread.c
*/
@@ -1400,6 +1467,10 @@ static inline u32 latest(u32 seq1, u32 seq2)
{
return after(seq1, seq2) ? seq1 : seq2;
}
+static inline bool rxrpc_seq_in_txq(const struct rxrpc_txqueue *tq, rxrpc_seq_t seq)
+{
+ return (seq & (RXRPC_NR_TXQUEUE - 1)) == tq->qbase;
+}
static inline void rxrpc_queue_rx_call_packet(struct rxrpc_call *call, struct sk_buff *skb)
{
@@ -1408,6 +1479,31 @@ static inline void rxrpc_queue_rx_call_packet(struct rxrpc_call *call, struct sk
rxrpc_poke_call(call, rxrpc_call_poke_rx_packet);
}
+/*
+ * Calculate how much space there is for transmitting more DATA packets.
+ */
+static inline unsigned int rxrpc_tx_window_space(const struct rxrpc_call *call)
+{
+ int winsize = umin(call->tx_winsize, call->cong_cwnd + call->cong_extra);
+ int transmitted = call->tx_top - call->tx_bottom;
+
+ return max(winsize - transmitted, 0);
+}
+
+static inline unsigned int rxrpc_left_out(const struct rxrpc_call *call)
+{
+ return call->acks_nr_sacks + call->tx_nr_lost;
+}
+
+/*
+ * Calculate the number of transmitted DATA packets assumed to be in flight
+ * [approx RFC6675].
+ */
+static inline unsigned int rxrpc_tx_in_flight(const struct rxrpc_call *call)
+{
+ return call->tx_nr_sent - rxrpc_left_out(call) + call->tx_nr_resent;
+}
+
/*
* debug tracing
*/
diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
index 82db8bc664ac..95fc27047c3d 100644
--- a/net/rxrpc/call_event.c
+++ b/net/rxrpc/call_event.c
@@ -54,35 +54,21 @@ void rxrpc_propose_delay_ACK(struct rxrpc_call *call, rxrpc_serial_t serial,
trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_delayed_ack);
}
-/*
- * Handle congestion being detected by the retransmit timeout.
- */
-static void rxrpc_congestion_timeout(struct rxrpc_call *call)
-{
- set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
-}
-
/*
* Retransmit one or more packets.
*/
static bool rxrpc_retransmit_data(struct rxrpc_call *call,
- struct rxrpc_send_data_req *req,
- ktime_t rto, bool skip_too_young)
+ struct rxrpc_send_data_req *req)
{
struct rxrpc_txqueue *tq = req->tq;
unsigned int ix = req->seq & RXRPC_TXQ_MASK;
struct rxrpc_txbuf *txb = tq->bufs[ix];
- ktime_t xmit_ts, resend_at;
_enter("%x,%x,%x,%px", tq->qbase, req->seq, ix, txb);
- xmit_ts = ktime_add_us(tq->xmit_ts_base, tq->segment_xmit_ts[ix]);
- resend_at = ktime_add(xmit_ts, rto);
- trace_rxrpc_retransmit(call, req, txb, ktime_sub(resend_at, req->now));
- if (skip_too_young && ktime_after(resend_at, req->now))
- return false;
+ req->retrans = true;
+ trace_rxrpc_retransmit(call, req, txb);
- __set_bit(ix, &tq->segment_retransmitted);
txb->flags |= RXRPC_TXBUF_RESENT;
rxrpc_send_data_packet(call, req);
rxrpc_inc_stat(call->rxnet, stat_tx_data_retrans);
@@ -97,132 +83,76 @@ static bool rxrpc_retransmit_data(struct rxrpc_call *call,
/*
* Perform retransmission of NAK'd and unack'd packets.
*/
-void rxrpc_resend(struct rxrpc_call *call, rxrpc_serial_t ack_serial, bool ping_response)
+static void rxrpc_resend(struct rxrpc_call *call)
{
struct rxrpc_send_data_req req = {
.now = ktime_get_real(),
.trace = rxrpc_txdata_retransmit,
};
- struct rxrpc_txqueue *tq = call->tx_queue;
- ktime_t lowest_xmit_ts = KTIME_MAX;
- ktime_t rto = rxrpc_get_rto_backoff(call, false);
- bool unacked = false;
+ struct rxrpc_txqueue *tq;
_enter("{%d,%d}", call->tx_bottom, call->tx_top);
- if (call->tx_bottom == call->tx_top) {
- call->resend_at = KTIME_MAX;
- trace_rxrpc_timer_can(call, rxrpc_timer_trace_resend);
- return;
- }
+ trace_rxrpc_resend(call, call->acks_highest_serial);
- trace_rxrpc_resend(call, ack_serial);
-
- /* Scan the transmission queue, looking for explicitly NAK'd packets. */
- do {
- unsigned long naks = ~tq->segment_acked;
- rxrpc_seq_t tq_top = tq->qbase + RXRPC_NR_TXQUEUE - 1;
+ /* Scan the transmission queue, looking for lost packets. */
+ for (tq = call->tx_queue; tq; tq = tq->next) {
+ unsigned long lost = tq->segment_lost;
if (after(tq->qbase, call->tx_transmitted))
break;
- if (tq->nr_reported_acks < RXRPC_NR_TXQUEUE)
- naks &= (1UL << tq->nr_reported_acks) - 1;
-
_debug("retr %16lx %u c=%08x [%x]",
tq->segment_acked, tq->nr_reported_acks, call->debug_id, tq->qbase);
- _debug("nack %16lx", naks);
+ _debug("lost %16lx", lost);
- while (naks) {
- unsigned int ix = __ffs(naks);
+ trace_rxrpc_resend_lost(call, tq, lost);
+ while (lost) {
+ unsigned int ix = __ffs(lost);
struct rxrpc_txbuf *txb = tq->bufs[ix];
- __clear_bit(ix, &naks);
- if (after(txb->serial, call->acks_highest_serial))
- continue; /* Ack point not yet reached */
-
- rxrpc_see_txbuf(txb, rxrpc_txbuf_see_unacked);
+ __clear_bit(ix, &lost);
+ rxrpc_see_txbuf(txb, rxrpc_txbuf_see_lost);
req.tq = tq;
req.seq = tq->qbase + ix;
req.n = 1;
- rxrpc_retransmit_data(call, &req, rto, false);
- }
-
- /* Anything after the soft-ACK table up to and including
- * ack.previousPacket will get ACK'd or NACK'd in due course,
- * so don't worry about those here. We do, however, need to
- * consider retransmitting anything beyond that point.
- */
- if (tq->nr_reported_acks < RXRPC_NR_TXQUEUE &&
- after(tq_top, call->acks_prev_seq)) {
- rxrpc_seq_t start = latest(call->acks_prev_seq,
- tq->qbase + tq->nr_reported_acks);
- rxrpc_seq_t stop = earliest(tq_top, call->tx_transmitted);
-
- _debug("unrep %x-%x", start, stop);
- for (rxrpc_seq_t seq = start; before_eq(seq, stop); seq++) {
- rxrpc_serial_t serial = tq->segment_serial[seq & RXRPC_TXQ_MASK];
-
- if (ping_response &&
- before(serial, call->acks_highest_serial))
- break; /* Wasn't accounted for by a more recent ping. */
- req.tq = tq;
- req.seq = seq;
- req.n = 1;
- if (rxrpc_retransmit_data(call, &req, rto, true))
- unacked = true;
- }
+ rxrpc_retransmit_data(call, &req);
}
-
- /* Work out the next retransmission timeout. */
- if (ktime_before(tq->xmit_ts_base, lowest_xmit_ts)) {
- unsigned int lowest_us = UINT_MAX;
-
- for (int i = 0; i < RXRPC_NR_TXQUEUE; i++)
- if (!test_bit(i, &tq->segment_acked) &&
- tq->segment_xmit_ts[i] < lowest_us)
- lowest_us = tq->segment_xmit_ts[i];
- _debug("lowest[%x] %llx %u", tq->qbase, tq->xmit_ts_base, lowest_us);
-
- if (lowest_us != UINT_MAX) {
- ktime_t lowest_ns = ktime_add_us(tq->xmit_ts_base, lowest_us);
- if (ktime_before(lowest_ns, lowest_xmit_ts))
- lowest_xmit_ts = lowest_ns;
- }
- }
- } while ((tq = tq->next));
-
- if (lowest_xmit_ts < KTIME_MAX) {
- ktime_t delay = rxrpc_get_rto_backoff(call, req.did_send);
- ktime_t resend_at = ktime_add(lowest_xmit_ts, delay);
-
- _debug("delay %llu %lld", delay, ktime_sub(resend_at, req.now));
- call->resend_at = resend_at;
- trace_rxrpc_timer_set(call, ktime_sub(resend_at, req.now),
- rxrpc_timer_trace_resend_reset);
- } else {
- call->resend_at = KTIME_MAX;
- trace_rxrpc_timer_can(call, rxrpc_timer_trace_resend);
}
- if (unacked)
- rxrpc_congestion_timeout(call);
+ rxrpc_get_rto_backoff(call, req.did_send);
+ _leave("");
+}
- /* If there was nothing that needed retransmission then it's likely
- * that an ACK got lost somewhere. Send a ping to find out instead of
- * retransmitting data.
- */
- if (!req.did_send) {
- ktime_t next_ping = ktime_add_us(call->acks_latest_ts,
- call->srtt_us >> 3);
+/*
+ * Resend the highest-seq DATA packet so far transmitted for RACK-TLP [RFC8985 7.3].
+ */
+void rxrpc_resend_tlp(struct rxrpc_call *call)
+{
+ struct rxrpc_send_data_req req = {
+ .now = ktime_get_real(),
+ .seq = call->tx_transmitted,
+ .n = 1,
+ .tlp_probe = true,
+ .trace = rxrpc_txdata_tlp_retransmit,
+ };
- if (ktime_sub(next_ping, req.now) <= 0)
- rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
- rxrpc_propose_ack_ping_for_0_retrans);
+ /* There's a chance it'll be on the tail segment of the queue. */
+ req.tq = READ_ONCE(call->tx_qtail);
+ if (req.tq &&
+ before(call->tx_transmitted, req.tq->qbase + RXRPC_NR_TXQUEUE)) {
+ rxrpc_retransmit_data(call, &req);
+ return;
}
- _leave("");
+ for (req.tq = call->tx_queue; req.tq; req.tq = req.tq->next) {
+ if (after_eq(call->tx_transmitted, req.tq->qbase) &&
+ before(call->tx_transmitted, req.tq->qbase + RXRPC_NR_TXQUEUE)) {
+ rxrpc_retransmit_data(call, &req);
+ return;
+ }
+ }
}
/*
@@ -258,18 +188,10 @@ static void rxrpc_close_tx_phase(struct rxrpc_call *call)
}
}
-static unsigned int rxrpc_tx_window_space(struct rxrpc_call *call)
-{
- int winsize = umin(call->tx_winsize, call->cong_cwnd + call->cong_extra);
- int in_flight = call->tx_top - call->tx_bottom;
-
- return max(winsize - in_flight, 0);
-}
-
/*
- * Transmit some as-yet untransmitted data.
+ * Transmit some as-yet untransmitted data, to a maximum of the supplied limit.
*/
-static void rxrpc_transmit_fresh_data(struct rxrpc_call *call,
+static void rxrpc_transmit_fresh_data(struct rxrpc_call *call, unsigned int limit,
enum rxrpc_txdata_trace trace)
{
int space = rxrpc_tx_window_space(call);
@@ -334,8 +256,8 @@ static void rxrpc_transmit_fresh_data(struct rxrpc_call *call,
}
}
-static void rxrpc_transmit_some_data(struct rxrpc_call *call,
- enum rxrpc_txdata_trace trace)
+void rxrpc_transmit_some_data(struct rxrpc_call *call, unsigned int limit,
+ enum rxrpc_txdata_trace trace)
{
switch (__rxrpc_call_state(call)) {
case RXRPC_CALL_SERVER_ACK_REQUEST:
@@ -352,7 +274,7 @@ static void rxrpc_transmit_some_data(struct rxrpc_call *call,
rxrpc_inc_stat(call->rxnet, stat_tx_data_underflow);
return;
}
- rxrpc_transmit_fresh_data(call, trace);
+ rxrpc_transmit_fresh_data(call, limit, trace);
break;
default:
return;
@@ -379,7 +301,7 @@ bool rxrpc_input_call_event(struct rxrpc_call *call)
{
struct sk_buff *skb;
ktime_t now, t;
- bool resend = false, did_receive = false, saw_ack = false;
+ bool did_receive = false, saw_ack = false;
s32 abort_code;
rxrpc_see_call(call, rxrpc_call_see_input);
@@ -397,21 +319,33 @@ bool rxrpc_input_call_event(struct rxrpc_call *call)
goto out;
}
- while ((skb = __skb_dequeue(&call->rx_queue))) {
- struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+ do {
+ skb = __skb_dequeue(&call->rx_queue);
+ if (skb) {
+ struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+
+ if (__rxrpc_call_is_complete(call) ||
+ skb->mark == RXRPC_SKB_MARK_ERROR) {
+ rxrpc_free_skb(skb, rxrpc_skb_put_call_rx);
+ goto out;
+ }
- if (__rxrpc_call_is_complete(call) ||
- skb->mark == RXRPC_SKB_MARK_ERROR) {
+ saw_ack |= sp->hdr.type == RXRPC_PACKET_TYPE_ACK;
+
+ rxrpc_input_call_packet(call, skb);
rxrpc_free_skb(skb, rxrpc_skb_put_call_rx);
- goto out;
+ did_receive = true;
}
- saw_ack |= sp->hdr.type == RXRPC_PACKET_TYPE_ACK;
+ t = ktime_sub(call->rack_timo_at, ktime_get_real());
+ if (t <= 0) {
+ trace_rxrpc_timer_exp(call, t,
+ rxrpc_timer_trace_rack_off + call->rack_timer_mode);
+ call->rack_timo_at = KTIME_MAX;
+ rxrpc_rack_timer_expired(call, t);
+ }
- rxrpc_input_call_packet(call, skb);
- rxrpc_free_skb(skb, rxrpc_skb_put_call_rx);
- did_receive = true;
- }
+ } while (!skb_queue_empty(&call->rx_queue));
/* If we see our async-event poke, check for timeout trippage. */
now = ktime_get_real();
@@ -444,13 +378,6 @@ bool rxrpc_input_call_event(struct rxrpc_call *call)
rxrpc_propose_ack_delayed_ack);
}
- t = ktime_sub(call->ack_lost_at, now);
- if (t <= 0) {
- trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_lost_ack);
- call->ack_lost_at = KTIME_MAX;
- set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
- }
-
t = ktime_sub(call->ping_at, now);
if (t <= 0) {
trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_ping);
@@ -459,15 +386,6 @@ bool rxrpc_input_call_event(struct rxrpc_call *call)
rxrpc_propose_ack_ping_for_keepalive);
}
- t = ktime_sub(call->resend_at, now);
- if (t <= 0) {
- trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_resend);
- call->resend_at = KTIME_MAX;
- resend = true;
- }
-
- rxrpc_transmit_some_data(call, rxrpc_txdata_new_data);
-
now = ktime_get_real();
t = ktime_sub(call->keepalive_at, now);
if (t <= 0) {
@@ -477,21 +395,30 @@ bool rxrpc_input_call_event(struct rxrpc_call *call)
rxrpc_propose_ack_ping_for_keepalive);
}
+ if (test_and_clear_bit(RXRPC_CALL_EV_INITIAL_PING, &call->events))
+ rxrpc_send_initial_ping(call);
+
+ rxrpc_transmit_some_data(call, UINT_MAX, rxrpc_txdata_new_data);
+
if (saw_ack)
rxrpc_congestion_degrade(call);
- if (test_and_clear_bit(RXRPC_CALL_EV_INITIAL_PING, &call->events))
- rxrpc_send_initial_ping(call);
+ if (did_receive &&
+ (__rxrpc_call_state(call) == RXRPC_CALL_CLIENT_SEND_REQUEST ||
+ __rxrpc_call_state(call) == RXRPC_CALL_SERVER_SEND_REPLY)) {
+ t = ktime_sub(call->rack_timo_at, ktime_get_real());
+ trace_rxrpc_rack(call, t);
+ }
/* Process events */
if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events))
rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
rxrpc_propose_ack_ping_for_lost_ack);
- if (resend &&
+ if (call->tx_nr_lost > 0 &&
__rxrpc_call_state(call) != RXRPC_CALL_CLIENT_RECV_REPLY &&
!test_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags))
- rxrpc_resend(call, 0, false);
+ rxrpc_resend(call);
if (test_and_clear_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags))
rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
@@ -519,8 +446,7 @@ bool rxrpc_input_call_event(struct rxrpc_call *call)
set(call->expect_req_by);
set(call->expect_rx_by);
set(call->delay_ack_at);
- set(call->ack_lost_at);
- set(call->resend_at);
+ set(call->rack_timo_at);
set(call->keepalive_at);
set(call->ping_at);
diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c
index 2405b8a4d69d..f5104b6e655e 100644
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -161,8 +161,7 @@ struct rxrpc_call *rxrpc_alloc_call(struct rxrpc_sock *rx, gfp_t gfp,
call->ackr_window = 1;
call->ackr_wtop = 1;
call->delay_ack_at = KTIME_MAX;
- call->ack_lost_at = KTIME_MAX;
- call->resend_at = KTIME_MAX;
+ call->rack_timo_at = KTIME_MAX;
call->ping_at = KTIME_MAX;
call->keepalive_at = KTIME_MAX;
call->expect_rx_by = KTIME_MAX;
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index cdfabfbc1a38..8fb32e9926a0 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -27,13 +27,13 @@ static void rxrpc_proto_abort(struct rxrpc_call *call, rxrpc_seq_t seq,
}
/*
- * Do TCP-style congestion management [RFC 5681].
+ * Do TCP-style congestion management [RFC5681].
*/
static void rxrpc_congestion_management(struct rxrpc_call *call,
struct rxrpc_ack_summary *summary)
{
summary->change = rxrpc_cong_no_change;
- summary->in_flight = (call->tx_top - call->tx_bottom) - call->acks_nr_sacks;
+ summary->in_flight = rxrpc_tx_in_flight(call);
if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
summary->retrans_timeo = true;
@@ -106,9 +106,12 @@ static void rxrpc_congestion_management(struct rxrpc_call *call,
call->cong_extra = 0;
call->cong_dup_acks = 0;
summary->need_retransmit = true;
+ summary->in_fast_or_rto_recovery = true;
goto out;
case RXRPC_CA_FAST_RETRANSMIT:
+ rxrpc_tlp_init(call);
+ summary->in_fast_or_rto_recovery = true;
if (!summary->new_low_snack) {
if (summary->nr_new_sacks == 0)
call->cong_cwnd += 1;
@@ -121,8 +124,10 @@ static void rxrpc_congestion_management(struct rxrpc_call *call,
} else {
summary->change = rxrpc_cong_progress;
call->cong_cwnd = call->cong_ssthresh;
- if (call->acks_nr_snacks == 0)
+ if (call->acks_nr_snacks == 0) {
+ summary->exiting_fast_or_rto_recovery = true;
goto resume_normality;
+ }
}
goto out;
@@ -171,7 +176,7 @@ static void rxrpc_congestion_management(struct rxrpc_call *call,
*/
void rxrpc_congestion_degrade(struct rxrpc_call *call)
{
- ktime_t rtt, now;
+ ktime_t rtt, now, time_since;
if (call->cong_ca_state != RXRPC_CA_SLOW_START &&
call->cong_ca_state != RXRPC_CA_CONGEST_AVOIDANCE)
@@ -181,10 +186,11 @@ void rxrpc_congestion_degrade(struct rxrpc_call *call)
rtt = ns_to_ktime(call->srtt_us * (NSEC_PER_USEC / 8));
now = ktime_get_real();
- if (!ktime_before(ktime_add(call->tx_last_sent, rtt), now))
+ time_since = ktime_sub(now, call->tx_last_sent);
+ if (ktime_before(time_since, rtt))
return;
- trace_rxrpc_reset_cwnd(call, now);
+ trace_rxrpc_reset_cwnd(call, time_since, rtt);
rxrpc_inc_stat(call->rxnet, stat_tx_data_cwnd_reset);
call->tx_last_sent = now;
call->cong_ca_state = RXRPC_CA_SLOW_START;
@@ -200,11 +206,11 @@ static void rxrpc_add_data_rtt_sample(struct rxrpc_call *call,
struct rxrpc_txqueue *tq,
int ix)
{
+ ktime_t xmit_ts = ktime_add_us(tq->xmit_ts_base, tq->segment_xmit_ts[ix]);
+
rxrpc_call_add_rtt(call, rxrpc_rtt_rx_data_ack, -1,
summary->acked_serial, summary->ack_serial,
- ktime_add_us(tq->xmit_ts_base, tq->segment_xmit_ts[ix]),
- call->acks_latest_ts);
- summary->rtt_sample_avail = false;
+ xmit_ts, call->acks_latest_ts);
__clear_bit(ix, &tq->rtt_samples); /* Prevent repeat RTT sample */
}
@@ -216,7 +222,7 @@ static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
{
struct rxrpc_txqueue *tq = call->tx_queue;
rxrpc_seq_t seq = call->tx_bottom + 1;
- bool rot_last = false;
+ bool rot_last = false, trace = false;
_enter("%x,%x", call->tx_bottom, to);
@@ -250,14 +256,16 @@ static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
rot_last = true;
}
- if (summary->rtt_sample_avail &&
- summary->acked_serial == tq->segment_serial[ix] &&
+ if (summary->acked_serial == tq->segment_serial[ix] &&
test_bit(ix, &tq->rtt_samples))
rxrpc_add_data_rtt_sample(call, summary, tq, ix);
if (ix == tq->nr_reported_acks) {
/* Packet directly hard ACK'd. */
tq->nr_reported_acks++;
+ rxrpc_input_rack_one(call, summary, tq, ix);
+ if (seq == call->tlp_seq)
+ summary->tlp_probe_acked = true;
summary->nr_new_hacks++;
__set_bit(ix, &tq->segment_acked);
trace_rxrpc_rotate(call, tq, summary, seq, rxrpc_rotate_trace_hack);
@@ -268,11 +276,21 @@ static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
} else {
/* Soft NAK -> hard ACK. */
call->acks_nr_snacks--;
+ rxrpc_input_rack_one(call, summary, tq, ix);
+ if (seq == call->tlp_seq)
+ summary->tlp_probe_acked = true;
summary->nr_new_hacks++;
__set_bit(ix, &tq->segment_acked);
trace_rxrpc_rotate(call, tq, summary, seq, rxrpc_rotate_trace_snak);
}
+ call->tx_nr_sent--;
+ if (__test_and_clear_bit(ix, &tq->segment_lost))
+ call->tx_nr_lost--;
+ if (__test_and_clear_bit(ix, &tq->segment_retransmitted))
+ call->tx_nr_resent--;
+ __clear_bit(ix, &tq->ever_retransmitted);
+
rxrpc_put_txbuf(tq->bufs[ix], rxrpc_txbuf_put_rotated);
tq->bufs[ix] = NULL;
@@ -282,7 +300,10 @@ static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
rxrpc_txqueue_rotate));
seq++;
+ trace = true;
if (!(seq & RXRPC_TXQ_MASK)) {
+ trace_rxrpc_rack_update(call, summary);
+ trace = false;
prefetch(tq->next);
if (tq != call->tx_qtail) {
call->tx_qbase += RXRPC_NR_TXQUEUE;
@@ -299,6 +320,9 @@ static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
} while (before_eq(seq, to));
+ if (trace)
+ trace_rxrpc_rack_update(call, summary);
+
if (rot_last) {
set_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags);
if (tq) {
@@ -325,8 +349,10 @@ static void rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
{
ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
- call->resend_at = KTIME_MAX;
- trace_rxrpc_timer_can(call, rxrpc_timer_trace_resend);
+ call->rack_timer_mode = RXRPC_CALL_RACKTIMER_OFF;
+ call->rack_timo_at = KTIME_MAX;
+ trace_rxrpc_rack_timer(call, 0, false);
+ trace_rxrpc_timer_can(call, rxrpc_timer_trace_rack_off + call->rack_timer_mode);
switch (__rxrpc_call_state(call)) {
case RXRPC_CALL_CLIENT_SEND_REQUEST:
@@ -842,10 +868,13 @@ static void rxrpc_input_soft_ack_tq(struct rxrpc_call *call,
rxrpc_seq_t seq,
rxrpc_seq_t *lowest_nak)
{
- unsigned long old_reported, flipped, new_acks, a_to_n, n_to_a;
+ unsigned long old_reported = 0, flipped, new_acks = 0;
+ unsigned long a_to_n, n_to_a = 0;
int new, a, n;
- old_reported = ~0UL >> (RXRPC_NR_TXQUEUE - tq->nr_reported_acks);
+ if (tq->nr_reported_acks > 0)
+ old_reported = ~0UL >> (RXRPC_NR_TXQUEUE - tq->nr_reported_acks);
+
_enter("{%x,%lx,%d},%lx,%d,%x",
tq->qbase, tq->segment_acked, tq->nr_reported_acks,
extracted_acks, nr_reported, seq);
@@ -898,6 +927,18 @@ static void rxrpc_input_soft_ack_tq(struct rxrpc_call *call,
if (before(lowest, *lowest_nak))
*lowest_nak = lowest;
}
+
+ if (summary->acked_serial)
+ rxrpc_input_soft_rtt(call, summary, tq);
+
+ new_acks |= n_to_a;
+ if (new_acks)
+ rxrpc_input_rack(call, summary, tq, new_acks);
+
+ if (call->tlp_serial &&
+ rxrpc_seq_in_txq(tq, call->tlp_seq) &&
+ test_bit(call->tlp_seq - tq->qbase, &new_acks))
+ summary->tlp_probe_acked = true;
}
/*
@@ -940,8 +981,6 @@ static void rxrpc_input_soft_acks(struct rxrpc_call *call,
_debug("bound %16lx %u", extracted, nr);
- if (summary->rtt_sample_avail)
- rxrpc_input_soft_rtt(call, summary, tq);
rxrpc_input_soft_ack_tq(call, summary, tq, extracted, RXRPC_NR_TXQUEUE,
seq - RXRPC_NR_TXQUEUE, &lowest_nak);
extracted = ~0UL;
@@ -1063,7 +1102,7 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
/* Discard any out-of-order or duplicate ACKs (outside lock). */
if (!rxrpc_is_ack_valid(call, hard_ack, prev_pkt)) {
trace_rxrpc_rx_discard_ack(call, summary.ack_serial, hard_ack, prev_pkt);
- goto send_response;
+ goto send_response; /* Still respond if requested. */
}
trailer.maxMTU = 0;
@@ -1079,14 +1118,19 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
call->acks_hard_ack = hard_ack;
call->acks_prev_seq = prev_pkt;
- switch (summary.ack_reason) {
- case RXRPC_ACK_PING:
- break;
- default:
- if (summary.acked_serial &&
- after(summary.acked_serial, call->acks_highest_serial))
- call->acks_highest_serial = summary.acked_serial;
- break;
+ if (summary.acked_serial) {
+ switch (summary.ack_reason) {
+ case RXRPC_ACK_PING_RESPONSE:
+ rxrpc_complete_rtt_probe(call, call->acks_latest_ts,
+ summary.acked_serial, summary.ack_serial,
+ rxrpc_rtt_rx_ping_response);
+ break;
+ default:
+ if (after(summary.acked_serial, call->acks_highest_serial))
+ call->acks_highest_serial = summary.acked_serial;
+ summary.rtt_sample_avail = true;
+ break;
+ }
}
/* Parse rwind and mtu sizes if provided. */
@@ -1096,15 +1140,6 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
if (hard_ack + 1 == 0)
return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_zero);
- if (summary.acked_serial) {
- if (summary.ack_reason == RXRPC_ACK_PING_RESPONSE)
- rxrpc_complete_rtt_probe(call, call->acks_latest_ts,
- summary.acked_serial, summary.ack_serial,
- rxrpc_rtt_rx_ping_response);
- else
- summary.rtt_sample_avail = true;
- }
-
/* Ignore ACKs unless we are or have just been transmitting. */
switch (__rxrpc_call_state(call)) {
case RXRPC_CALL_CLIENT_SEND_REQUEST:
@@ -1141,10 +1176,14 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
rxrpc_propose_ping(call, summary.ack_serial,
rxrpc_propose_ack_ping_for_lost_reply);
+ /* Drive the congestion management algorithm first and then RACK-TLP as
+ * the latter depends on the state/change in state in the former.
+ */
rxrpc_congestion_management(call, &summary);
- if (summary.need_retransmit)
- rxrpc_resend(call, summary.ack_serial,
- summary.ack_reason == RXRPC_ACK_PING_RESPONSE);
+ rxrpc_rack_detect_loss_and_arm_timer(call, &summary);
+ rxrpc_tlp_process_ack(call, &summary);
+ if (call->tlp_serial && after_eq(summary.acked_serial, call->tlp_serial))
+ call->tlp_serial = 0;
send_response:
if (summary.ack_reason == RXRPC_ACK_PING)
diff --git a/net/rxrpc/input_rack.c b/net/rxrpc/input_rack.c
new file mode 100644
index 000000000000..b5d7a8d69c76
--- /dev/null
+++ b/net/rxrpc/input_rack.c
@@ -0,0 +1,422 @@
+/* RACK-TLP [RFC8958] Implementation
+ *
+ * Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@...hat.com)
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include "ar-internal.h"
+
+static inline ktime_t us_to_ktime(u64 us)
+{
+ return us * NSEC_PER_USEC;
+}
+
+static bool rxrpc_rack_sent_after(ktime_t t1, rxrpc_seq_t seq1,
+ ktime_t t2, rxrpc_seq_t seq2)
+{
+ if (ktime_after(t1, t2))
+ return true;
+ return t1 == t2 && after(seq1, seq2);
+}
+
+/*
+ * Mark a packet lost.
+ */
+static void rxrpc_rack_mark_lost(struct rxrpc_call *call,
+ struct rxrpc_txqueue *tq, unsigned int ix)
+{
+ if (__test_and_set_bit(ix, &tq->segment_lost)) {
+ if (__test_and_clear_bit(ix, &tq->segment_retransmitted))
+ call->tx_nr_resent--;
+ } else {
+ call->tx_nr_lost++;
+ }
+ tq->segment_xmit_ts[ix] = UINT_MAX;
+}
+
+/*
+ * Get the transmission time of a packet in the Tx queue.
+ */
+static ktime_t rxrpc_get_xmit_ts(const struct rxrpc_txqueue *tq, unsigned int ix)
+{
+ if (tq->segment_xmit_ts[ix] == UINT_MAX)
+ return KTIME_MAX;
+ return ktime_add_us(tq->xmit_ts_base, tq->segment_xmit_ts[ix]);
+}
+
+/*
+ * Get a bitmask of nack bits for a queue segment and mask off any that aren't
+ * yet reported.
+ */
+static unsigned long rxrpc_tq_nacks(const struct rxrpc_txqueue *tq)
+{
+ unsigned long nacks = ~tq->segment_acked;
+
+ if (tq->nr_reported_acks < RXRPC_NR_TXQUEUE)
+ nacks &= (1UL << tq->nr_reported_acks) - 1;
+ return nacks;
+}
+
+/*
+ * Update the RACK state for the most recently sent packet that has been
+ * delivered [RFC8958 6.2 Step 2].
+ */
+static void rxrpc_rack_update(struct rxrpc_call *call,
+ struct rxrpc_ack_summary *summary,
+ struct rxrpc_txqueue *tq,
+ unsigned int ix)
+{
+ rxrpc_seq_t seq = tq->qbase + ix;
+ ktime_t xmit_ts = rxrpc_get_xmit_ts(tq, ix);
+ ktime_t rtt = ktime_sub(call->acks_latest_ts, xmit_ts);
+
+ if (__test_and_clear_bit(ix, &tq->segment_lost))
+ call->tx_nr_lost--;
+
+ if (test_bit(ix, &tq->segment_retransmitted)) {
+ /* Use Rx.serial instead of TCP.ACK.ts_option.echo_reply. */
+ if (before(call->acks_highest_serial, tq->segment_serial[ix]))
+ return;
+ if (rtt < minmax_get(&call->min_rtt))
+ return;
+ }
+
+ /* The RACK algorithm requires the segment ACKs to be traversed in
+ * order of segment transmission - but the only thing this seems to
+ * matter for is that RACK.rtt is set to the rtt of the most recently
+ * transmitted segment. We should be able to achieve the same by only
+ * setting RACK.rtt if the xmit time is greater.
+ */
+ if (ktime_after(xmit_ts, call->rack_rtt_ts)) {
+ call->rack_rtt = rtt;
+ call->rack_rtt_ts = xmit_ts;
+ }
+
+ if (rxrpc_rack_sent_after(xmit_ts, seq, call->rack_xmit_ts, call->rack_end_seq)) {
+ call->rack_rtt = rtt;
+ call->rack_xmit_ts = xmit_ts;
+ call->rack_end_seq = seq;
+ }
+}
+
+/*
+ * Detect data segment reordering [RFC8958 6.2 Step 3].
+ */
+static void rxrpc_rack_detect_reordering(struct rxrpc_call *call,
+ struct rxrpc_ack_summary *summary,
+ struct rxrpc_txqueue *tq,
+ unsigned int ix)
+{
+ rxrpc_seq_t seq = tq->qbase + ix;
+
+ /* Track the highest sequence number so far ACK'd. This is not
+ * necessarily the same as ack.firstPacket + ack.nAcks - 1 as the peer
+ * could put a NACK in the last SACK slot.
+ */
+ if (after(seq, call->rack_fack))
+ call->rack_fack = seq;
+ else if (before(seq, call->rack_fack) &&
+ test_bit(ix, &tq->segment_retransmitted))
+ call->rack_reordering_seen = true;
+}
+
+void rxrpc_input_rack_one(struct rxrpc_call *call,
+ struct rxrpc_ack_summary *summary,
+ struct rxrpc_txqueue *tq,
+ unsigned int ix)
+{
+ rxrpc_rack_update(call, summary, tq, ix);
+ rxrpc_rack_detect_reordering(call, summary, tq, ix);
+}
+
+void rxrpc_input_rack(struct rxrpc_call *call,
+ struct rxrpc_ack_summary *summary,
+ struct rxrpc_txqueue *tq,
+ unsigned long new_acks)
+{
+ while (new_acks) {
+ unsigned int ix = __ffs(new_acks);
+
+ __clear_bit(ix, &new_acks);
+ rxrpc_input_rack_one(call, summary, tq, ix);
+ }
+
+ trace_rxrpc_rack_update(call, summary);
+}
+
+/*
+ * Update the reordering window [RFC8958 6.2 Step 4]. Returns the updated
+ * duration of the reordering window.
+ *
+ * Note that the Rx protocol doesn't have a 'DSACK option' per se, but ACKs can
+ * be given a 'DUPLICATE' reason with the serial number referring to the
+ * duplicated DATA packet. Rx does not inform as to whether this was a
+ * reception of the same packet twice or of a retransmission of a packet we
+ * already received (though this could be determined by the transmitter based
+ * on the serial number).
+ */
+static ktime_t rxrpc_rack_update_reo_wnd(struct rxrpc_call *call,
+ struct rxrpc_ack_summary *summary)
+{
+ rxrpc_seq_t snd_una = call->acks_lowest_nak; /* Lowest unack'd seq */
+ rxrpc_seq_t snd_nxt = call->tx_transmitted + 1; /* Next seq to be sent */
+ bool have_dsack_option = summary->ack_reason == RXRPC_ACK_DUPLICATE;
+ int dup_thresh = 3;
+
+ /* DSACK-based reordering window adaptation */
+ if (!call->rack_dsack_round_none &&
+ after_eq(snd_una, call->rack_dsack_round))
+ call->rack_dsack_round_none = true;
+
+ /* Grow the reordering window per round that sees DSACK. Reset the
+ * window after 16 DSACK-free recoveries.
+ */
+ if (call->rack_dsack_round_none && have_dsack_option) {
+ call->rack_dsack_round_none = false;
+ call->rack_dsack_round = snd_nxt;
+ call->rack_reo_wnd_mult++;
+ call->rack_reo_wnd_persist = 16;
+ } else if (summary->exiting_fast_or_rto_recovery) {
+ call->rack_reo_wnd_persist--;
+ if (call->rack_reo_wnd_persist <= 0)
+ call->rack_reo_wnd_mult = 1;
+ }
+
+ if (!call->rack_reordering_seen) {
+ if (summary->in_fast_or_rto_recovery)
+ return 0;
+ if (call->acks_nr_sacks >= dup_thresh)
+ return 0;
+ }
+
+ return us_to_ktime(umin(call->rack_reo_wnd_mult * minmax_get(&call->min_rtt) / 4,
+ call->srtt_us >> 3));
+}
+
+/*
+ * Detect losses [RFC8958 6.2 Step 5].
+ */
+static ktime_t rxrpc_rack_detect_loss(struct rxrpc_call *call,
+ struct rxrpc_ack_summary *summary)
+{
+ struct rxrpc_txqueue *tq;
+ ktime_t timeout = 0, lost_after, now = ktime_get_real();
+
+ call->rack_reo_wnd = rxrpc_rack_update_reo_wnd(call, summary);
+ lost_after = ktime_add(call->rack_rtt, call->rack_reo_wnd);
+ trace_rxrpc_rack_scan_loss(call);
+
+ for (tq = call->tx_queue; tq; tq = tq->next) {
+ unsigned long nacks = rxrpc_tq_nacks(tq);
+
+ if (after(tq->qbase, call->tx_transmitted))
+ break;
+ trace_rxrpc_rack_scan_loss_tq(call, tq, nacks);
+
+ /* Skip ones marked lost but not yet retransmitted */
+ nacks &= ~tq->segment_lost | tq->segment_retransmitted;
+
+ while (nacks) {
+ unsigned int ix = __ffs(nacks);
+ rxrpc_seq_t seq = tq->qbase + ix;
+ ktime_t remaining;
+ ktime_t xmit_ts = rxrpc_get_xmit_ts(tq, ix);
+
+ __clear_bit(ix, &nacks);
+
+ if (rxrpc_rack_sent_after(call->rack_xmit_ts, call->rack_end_seq,
+ xmit_ts, seq)) {
+ remaining = ktime_sub(ktime_add(xmit_ts, lost_after), now);
+ if (remaining <= 0) {
+ rxrpc_rack_mark_lost(call, tq, ix);
+ trace_rxrpc_rack_detect_loss(call, summary, seq);
+ } else {
+ timeout = max(remaining, timeout);
+ }
+ }
+ }
+ }
+
+ return timeout;
+}
+
+/*
+ * Detect losses and set a timer to retry the detection [RFC8958 6.2 Step 5].
+ */
+void rxrpc_rack_detect_loss_and_arm_timer(struct rxrpc_call *call,
+ struct rxrpc_ack_summary *summary)
+{
+ ktime_t timeout = rxrpc_rack_detect_loss(call, summary);
+
+ if (timeout) {
+ call->rack_timer_mode = RXRPC_CALL_RACKTIMER_RACK_REORDER;
+ call->rack_timo_at = ktime_add(ktime_get_real(), timeout);
+ trace_rxrpc_rack_timer(call, timeout, false);
+ trace_rxrpc_timer_set(call, timeout, rxrpc_timer_trace_rack_reo);
+ }
+}
+
+/*
+ * Handle RACK-TLP RTO expiration [RFC8958 6.3].
+ */
+static void rxrpc_rack_mark_losses_on_rto(struct rxrpc_call *call)
+{
+ struct rxrpc_txqueue *tq;
+ rxrpc_seq_t snd_una = call->acks_lowest_nak; /* Lowest unack'd seq */
+ ktime_t lost_after = ktime_add(call->rack_rtt, call->rack_reo_wnd);
+ ktime_t deadline = ktime_sub(ktime_get_real(), lost_after);
+
+ for (tq = call->tx_queue; tq; tq = tq->next) {
+ unsigned long unacked = ~tq->segment_acked;
+
+ trace_rxrpc_rack_mark_loss_tq(call, tq);
+ while (unacked) {
+ unsigned int ix = __ffs(unacked);
+ rxrpc_seq_t seq = tq->qbase + ix;
+ ktime_t xmit_ts = rxrpc_get_xmit_ts(tq, ix);
+
+ if (after(seq, call->tx_transmitted))
+ return;
+ __clear_bit(ix, &unacked);
+
+ if (seq == snd_una ||
+ ktime_before(xmit_ts, deadline))
+ rxrpc_rack_mark_lost(call, tq, ix);
+ }
+ }
+}
+
+/*
+ * Calculate the TLP loss probe timeout (PTO) [RFC8958 7.2].
+ */
+ktime_t rxrpc_tlp_calc_pto(struct rxrpc_call *call, ktime_t now)
+{
+ unsigned int flight_size = rxrpc_tx_in_flight(call);
+ ktime_t rto_at = ktime_add(call->tx_last_sent,
+ rxrpc_get_rto_backoff(call, false));
+ ktime_t pto;
+
+ if (call->rtt_count > 0) {
+ /* Use 2*SRTT as the timeout. */
+ pto = ns_to_ktime(call->srtt_us * NSEC_PER_USEC / 4);
+ if (flight_size)
+ pto = ktime_add(pto, call->tlp_max_ack_delay);
+ } else {
+ pto = NSEC_PER_SEC;
+ }
+
+ if (ktime_after(ktime_add(now, pto), rto_at))
+ pto = ktime_sub(rto_at, now);
+ return pto;
+}
+
+/*
+ * Send a TLP loss probe on PTO expiration [RFC8958 7.3].
+ */
+void rxrpc_tlp_send_probe(struct rxrpc_call *call)
+{
+ unsigned int in_flight = rxrpc_tx_in_flight(call);
+
+ if (after_eq(call->acks_hard_ack, call->tx_transmitted))
+ return; /* Everything we transmitted has been acked. */
+
+ /* There must be no other loss probe still in flight and we need to
+ * have taken a new RTT sample since last probe or the start of
+ * connection.
+ */
+ if (!call->tlp_serial &&
+ call->tlp_rtt_taken != call->rtt_taken) {
+ call->tlp_is_retrans = false;
+ if (after(call->send_top, call->tx_transmitted) &&
+ rxrpc_tx_window_space(call) > 0) {
+ /* Transmit the lowest-sequence unsent DATA */
+ call->tx_last_serial = 0;
+ rxrpc_transmit_some_data(call, 1, rxrpc_txdata_tlp_new_data);
+ call->tlp_serial = call->tx_last_serial;
+ call->tlp_seq = call->tx_transmitted;
+ trace_rxrpc_tlp_probe(call, rxrpc_tlp_probe_trace_transmit_new);
+ in_flight = rxrpc_tx_in_flight(call);
+ } else {
+ /* Retransmit the highest-sequence DATA sent */
+ call->tx_last_serial = 0;
+ rxrpc_resend_tlp(call);
+ call->tlp_is_retrans = true;
+ trace_rxrpc_tlp_probe(call, rxrpc_tlp_probe_trace_retransmit);
+ }
+ } else {
+ trace_rxrpc_tlp_probe(call, rxrpc_tlp_probe_trace_busy);
+ }
+
+ if (in_flight != 0) {
+ ktime_t rto = rxrpc_get_rto_backoff(call, false);
+
+ call->rack_timer_mode = RXRPC_CALL_RACKTIMER_RTO;
+ call->rack_timo_at = ktime_add(ktime_get_real(), rto);
+ trace_rxrpc_rack_timer(call, rto, false);
+ trace_rxrpc_timer_set(call, rto, rxrpc_timer_trace_rack_rto);
+ }
+}
+
+/*
+ * Detect losses using the ACK of a TLP loss probe [RFC8958 7.4].
+ */
+void rxrpc_tlp_process_ack(struct rxrpc_call *call, struct rxrpc_ack_summary *summary)
+{
+ if (!call->tlp_serial || after(call->tlp_seq, call->acks_hard_ack))
+ return;
+
+ if (!call->tlp_is_retrans) {
+ /* TLP of new data delivered */
+ trace_rxrpc_tlp_ack(call, summary, rxrpc_tlp_ack_trace_new_data);
+ call->tlp_serial = 0;
+ } else if (summary->ack_reason == RXRPC_ACK_DUPLICATE &&
+ summary->acked_serial == call->tlp_serial) {
+ /* General Case: Detected packet losses using RACK [7.4.1] */
+ trace_rxrpc_tlp_ack(call, summary, rxrpc_tlp_ack_trace_dup_acked);
+ call->tlp_serial = 0;
+ } else if (after(call->acks_hard_ack, call->tlp_seq)) {
+ /* Repaired the single loss */
+ trace_rxrpc_tlp_ack(call, summary, rxrpc_tlp_ack_trace_hard_beyond);
+ call->tlp_serial = 0;
+ // TODO: Invoke congestion control to react to the loss
+ // event the probe has repaired
+ } else if (summary->tlp_probe_acked) {
+ trace_rxrpc_tlp_ack(call, summary, rxrpc_tlp_ack_trace_acked);
+ /* Special Case: Detected a single loss repaired by the loss
+ * probe [7.4.2]
+ */
+ call->tlp_serial = 0;
+ } else {
+ trace_rxrpc_tlp_ack(call, summary, rxrpc_tlp_ack_trace_incomplete);
+ }
+}
+
+/*
+ * Handle RACK timer expiration; returns true to request a resend.
+ */
+void rxrpc_rack_timer_expired(struct rxrpc_call *call, ktime_t overran_by)
+{
+ struct rxrpc_ack_summary summary = {};
+ enum rxrpc_rack_timer_mode mode = call->rack_timer_mode;
+
+ trace_rxrpc_rack_timer(call, overran_by, true);
+ call->rack_timer_mode = RXRPC_CALL_RACKTIMER_OFF;
+
+ switch (mode) {
+ case RXRPC_CALL_RACKTIMER_RACK_REORDER:
+ rxrpc_rack_detect_loss_and_arm_timer(call, &summary);
+ break;
+ case RXRPC_CALL_RACKTIMER_TLP_PTO:
+ rxrpc_tlp_send_probe(call);
+ break;
+ case RXRPC_CALL_RACKTIMER_RTO:
+ // Might need to poke the congestion algo in some way
+ rxrpc_rack_mark_losses_on_rto(call);
+ break;
+ //case RXRPC_CALL_RACKTIMER_ZEROWIN:
+ default:
+ pr_warn("Unexpected rack timer %u", call->rack_timer_mode);
+ }
+}
diff --git a/net/rxrpc/io_thread.c b/net/rxrpc/io_thread.c
index 86a746f54851..44612980b60a 100644
--- a/net/rxrpc/io_thread.c
+++ b/net/rxrpc/io_thread.c
@@ -470,6 +470,7 @@ int rxrpc_io_thread(void *data)
spin_lock_irq(&local->rx_queue.lock);
skb_queue_splice_tail_init(&local->rx_queue, &rx_queue);
spin_unlock_irq(&local->rx_queue.lock);
+ trace_rxrpc_iothread_rx(local, skb_queue_len(&rx_queue));
}
/* Distribute packets and errors. */
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index c8ae59103c21..56ae207e4f3a 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -541,12 +541,14 @@ static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call, struct rxrpc_se
unsigned int xmit_ts;
rxrpc_seq_t seq = req->seq;
size_t len = 0;
+ bool start_tlp = false;
trace_rxrpc_tq(call, tq, seq, rxrpc_tq_transmit);
/* Each transmission of a Tx packet needs a new serial number */
serial = rxrpc_get_next_serials(call->conn, req->n);
+ call->tx_last_serial = serial + req->n - 1;
call->tx_last_sent = req->now;
xmit_ts = rxrpc_prepare_txqueue(tq, req);
prefetch(tq->next);
@@ -556,6 +558,18 @@ static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call, struct rxrpc_se
struct rxrpc_txbuf *txb = tq->bufs[seq & RXRPC_TXQ_MASK];
_debug("prep[%u] tq=%x q=%x", i, tq->qbase, seq);
+
+ /* Record (re-)transmission for RACK [RFC8985 6.1]. */
+ if (__test_and_clear_bit(ix, &tq->segment_lost))
+ call->tx_nr_lost--;
+ if (req->retrans) {
+ __set_bit(ix, &tq->ever_retransmitted);
+ __set_bit(ix, &tq->segment_retransmitted);
+ call->tx_nr_resent++;
+ } else {
+ call->tx_nr_sent++;
+ start_tlp = true;
+ }
tq->segment_xmit_ts[ix] = xmit_ts;
tq->segment_serial[ix] = serial;
if (i + 1 == req->n)
@@ -575,11 +589,24 @@ static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call, struct rxrpc_se
}
/* Set timeouts */
- if (call->rtt_count > 1) {
- ktime_t delay = rxrpc_get_rto_backoff(call, false);
+ if (req->tlp_probe) {
+ /* Sending TLP loss probe [RFC8985 7.3]. */
+ call->tlp_serial = serial - 1;
+ call->tlp_seq = seq - 1;
+ } else if (start_tlp) {
+ /* Schedule TLP loss probe [RFC8985 7.2]. */
+ ktime_t pto;
+
+ if (!test_bit(RXRPC_CALL_BEGAN_RX_TIMER, &call->flags))
+ pto = NSEC_PER_SEC; /* The first packet may take longer
+ * to elicit a response. */
+ else
+ pto = rxrpc_tlp_calc_pto(call, req->now);
- call->ack_lost_at = ktime_add(req->now, delay);
- trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_lost_ack);
+ call->rack_timer_mode = RXRPC_CALL_RACKTIMER_TLP_PTO;
+ call->rack_timo_at = ktime_add(req->now, pto);
+ trace_rxrpc_rack_timer(call, pto, false);
+ trace_rxrpc_timer_set(call, pto, rxrpc_timer_trace_rack_tlp_pto);
}
if (!test_and_set_bit(RXRPC_CALL_BEGAN_RX_TIMER, &call->flags)) {
@@ -588,12 +615,6 @@ static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call, struct rxrpc_se
call->expect_rx_by = ktime_add(req->now, delay);
trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_expect_rx);
}
- if (call->resend_at == KTIME_MAX) {
- ktime_t delay = rxrpc_get_rto_backoff(call, false);
-
- call->resend_at = ktime_add(req->now, delay);
- trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_resend);
- }
rxrpc_set_keepalive(call, req->now);
return len;
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