rxrpc: Implement slow-start
Implement RxRPC slow-start, which is similar to RFC 5681 for TCP. A
tracepoint is added to log the state of the congestion management algorithm
and the decisions it makes.
Notes:
(1) Since we send fixed-size DATA packets (apart from the final packet in
each phase), counters and calculations are in terms of packets rather
than bytes.
(2) The ACK packet carries the equivalent of TCP SACK.
(3) The FLIGHT_SIZE calculation in RFC 5681 doesn't seem particularly
suited to SACK of a small number of packets. It seems that, almost
inevitably, by the time three 'duplicate' ACKs have been seen, we have
narrowed the loss down to one or two missing packets, and the
FLIGHT_SIZE calculation ends up as 2.
(4) In rxrpc_resend(), if there was no data that apparently needed
retransmission, we transmit a PING ACK to ask the peer to tell us what
its Rx window state is.
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h
index 5647549..ada12d0 100644
--- a/include/trace/events/rxrpc.h
+++ b/include/trace/events/rxrpc.h
@@ -570,6 +570,51 @@
__entry->expiry)
);
+TRACE_EVENT(rxrpc_congest,
+ TP_PROTO(struct rxrpc_call *call, struct rxrpc_ack_summary *summary,
+ rxrpc_serial_t ack_serial, enum rxrpc_congest_change change),
+
+ TP_ARGS(call, summary, ack_serial, change),
+
+ TP_STRUCT__entry(
+ __field(struct rxrpc_call *, call )
+ __field(enum rxrpc_congest_change, change )
+ __field(rxrpc_seq_t, hard_ack )
+ __field(rxrpc_seq_t, top )
+ __field(rxrpc_seq_t, lowest_nak )
+ __field(rxrpc_serial_t, ack_serial )
+ __field_struct(struct rxrpc_ack_summary, sum )
+ ),
+
+ TP_fast_assign(
+ __entry->call = call;
+ __entry->change = change;
+ __entry->hard_ack = call->tx_hard_ack;
+ __entry->top = call->tx_top;
+ __entry->lowest_nak = call->acks_lowest_nak;
+ __entry->ack_serial = ack_serial;
+ memcpy(&__entry->sum, summary, sizeof(__entry->sum));
+ ),
+
+ TP_printk("c=%p %08x %s %08x %s cw=%u ss=%u nr=%u,%u nw=%u,%u r=%u b=%u u=%u d=%u l=%x%s%s%s",
+ __entry->call,
+ __entry->ack_serial,
+ rxrpc_ack_names[__entry->sum.ack_reason],
+ __entry->hard_ack,
+ rxrpc_congest_modes[__entry->sum.mode],
+ __entry->sum.cwnd,
+ __entry->sum.ssthresh,
+ __entry->sum.nr_acks, __entry->sum.nr_nacks,
+ __entry->sum.nr_new_acks, __entry->sum.nr_new_nacks,
+ __entry->sum.nr_rot_new_acks,
+ __entry->top - __entry->hard_ack,
+ __entry->sum.cumulative_acks,
+ __entry->sum.dup_acks,
+ __entry->lowest_nak, __entry->sum.new_low_nack ? "!" : "",
+ rxrpc_congest_changes[__entry->change],
+ __entry->sum.retrans_timeo ? " rTxTo" : "")
+ );
+
#endif /* _TRACE_RXRPC_H */
/* This part must be outside protection */
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index b1e697f..ca96e54 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -402,6 +402,7 @@
RXRPC_CALL_RX_LAST, /* Received the last packet (at rxtx_top) */
RXRPC_CALL_TX_LAST, /* Last packet in Tx buffer (at rxtx_top) */
RXRPC_CALL_PINGING, /* Ping in process */
+ RXRPC_CALL_RETRANS_TIMEOUT, /* Retransmission due to timeout occurred */
};
/*
@@ -447,6 +448,17 @@
};
/*
+ * Call Tx congestion management modes.
+ */
+enum rxrpc_congest_mode {
+ RXRPC_CALL_SLOW_START,
+ RXRPC_CALL_CONGEST_AVOIDANCE,
+ RXRPC_CALL_PACKET_LOSS,
+ RXRPC_CALL_FAST_RETRANSMIT,
+ NR__RXRPC_CONGEST_MODES
+};
+
+/*
* RxRPC call definition
* - matched by { connection, call_id }
*/
@@ -518,6 +530,20 @@
* not hard-ACK'd packet follows this.
*/
rxrpc_seq_t tx_top; /* Highest Tx slot allocated. */
+
+ /* TCP-style slow-start congestion control [RFC5681]. Since the SMSS
+ * is fixed, we keep these numbers in terms of segments (ie. DATA
+ * packets) rather than bytes.
+ */
+#define RXRPC_TX_SMSS RXRPC_JUMBO_DATALEN
+ u8 cong_cwnd; /* Congestion window size */
+ u8 cong_extra; /* Extra to send for congestion management */
+ u8 cong_ssthresh; /* Slow-start threshold */
+ enum rxrpc_congest_mode cong_mode:8; /* Congestion management mode */
+ u8 cong_dup_acks; /* Count of ACKs showing missing packets */
+ u8 cong_cumul_acks; /* Cumulative ACK count */
+ ktime_t cong_tstamp; /* Last time cwnd was changed */
+
rxrpc_seq_t rx_hard_ack; /* Dead slot in buffer; the first received but not
* consumed packet follows this.
*/
@@ -539,12 +565,13 @@
ktime_t ackr_ping_time; /* Time last ping sent */
/* transmission-phase ACK management */
+ ktime_t acks_latest_ts; /* Timestamp of latest ACK received */
rxrpc_serial_t acks_latest; /* serial number of latest ACK received */
rxrpc_seq_t acks_lowest_nak; /* Lowest NACK in the buffer (or ==tx_hard_ack) */
};
/*
- * Summary of a new ACK and the changes it made.
+ * Summary of a new ACK and the changes it made to the Tx buffer packet states.
*/
struct rxrpc_ack_summary {
u8 ack_reason;
@@ -554,6 +581,14 @@
u8 nr_new_nacks; /* Number of new NACKs in packet */
u8 nr_rot_new_acks; /* Number of rotated new ACKs */
bool new_low_nack; /* T if new low NACK found */
+ bool retrans_timeo; /* T if reTx due to timeout happened */
+ u8 flight_size; /* Number of unreceived transmissions */
+ /* Place to stash values for tracing */
+ enum rxrpc_congest_mode mode:8;
+ u8 cwnd;
+ u8 ssthresh;
+ u8 dup_acks;
+ u8 cumulative_acks;
};
enum rxrpc_skb_trace {
@@ -709,6 +744,7 @@
enum rxrpc_propose_ack_trace {
rxrpc_propose_ack_client_tx_end,
rxrpc_propose_ack_input_data,
+ rxrpc_propose_ack_ping_for_lost_ack,
rxrpc_propose_ack_ping_for_lost_reply,
rxrpc_propose_ack_ping_for_params,
rxrpc_propose_ack_respond_to_ack,
@@ -729,6 +765,21 @@
extern const char rxrpc_propose_ack_traces[rxrpc_propose_ack__nr_trace][8];
extern const char *const rxrpc_propose_ack_outcomes[rxrpc_propose_ack__nr_outcomes];
+enum rxrpc_congest_change {
+ rxrpc_cong_begin_retransmission,
+ rxrpc_cong_cleared_nacks,
+ rxrpc_cong_new_low_nack,
+ rxrpc_cong_no_change,
+ rxrpc_cong_progress,
+ rxrpc_cong_retransmit_again,
+ rxrpc_cong_rtt_window_end,
+ rxrpc_cong_saw_nack,
+ rxrpc_congest__nr_change
+};
+
+extern const char rxrpc_congest_modes[NR__RXRPC_CONGEST_MODES][10];
+extern const char rxrpc_congest_changes[rxrpc_congest__nr_change][9];
+
extern const char *const rxrpc_pkts[];
extern const char const rxrpc_ack_names[RXRPC_ACK__INVALID + 1][4];
diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
index 05b94d1..0e84780 100644
--- a/net/rxrpc/call_event.c
+++ b/net/rxrpc/call_event.c
@@ -147,6 +147,14 @@
}
/*
+ * 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);
+}
+
+/*
* Perform retransmission of NAK'd and unack'd packets.
*/
static void rxrpc_resend(struct rxrpc_call *call)
@@ -154,9 +162,9 @@
struct rxrpc_skb_priv *sp;
struct sk_buff *skb;
rxrpc_seq_t cursor, seq, top;
- ktime_t now = ktime_get_real(), max_age, oldest, resend_at;
+ ktime_t now = ktime_get_real(), max_age, oldest, resend_at, ack_ts;
int ix;
- u8 annotation, anno_type;
+ u8 annotation, anno_type, retrans = 0, unacked = 0;
_enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
@@ -193,10 +201,13 @@
oldest = skb->tstamp;
continue;
}
+ if (!(annotation & RXRPC_TX_ANNO_RESENT))
+ unacked++;
}
/* Okay, we need to retransmit a packet. */
call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation;
+ retrans++;
trace_rxrpc_retransmit(call, seq, annotation | anno_type,
ktime_to_ns(ktime_sub(skb->tstamp, max_age)));
}
@@ -210,6 +221,25 @@
* reached the nsec timeout yet.
*/
+ if (unacked)
+ rxrpc_congestion_timeout(call);
+
+ /* 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 (!retrans) {
+ rxrpc_set_timer(call, rxrpc_timer_set_for_resend);
+ spin_unlock_bh(&call->lock);
+ ack_ts = ktime_sub(now, call->acks_latest_ts);
+ if (ktime_to_ns(ack_ts) < call->peer->rtt)
+ goto out;
+ rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false,
+ rxrpc_propose_ack_ping_for_lost_ack);
+ rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ACK);
+ goto out;
+ }
+
/* Now go through the Tx window and perform the retransmissions. We
* have to drop the lock for each send. If an ACK comes in whilst the
* lock is dropped, it may clear some of the retransmission markers for
@@ -260,6 +290,7 @@
out_unlock:
spin_unlock_bh(&call->lock);
+out:
_leave("");
}
@@ -293,6 +324,7 @@
if (time_after_eq(now, call->expire_at)) {
rxrpc_abort_call("EXP", call, 0, RX_CALL_TIMEOUT, ETIME);
set_bit(RXRPC_CALL_EV_ABORT, &call->events);
+ goto recheck_state;
}
if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) ||
diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c
index a53f4c2..d4b3293 100644
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -160,6 +160,14 @@
call->rx_winsize = rxrpc_rx_window_size;
call->tx_winsize = 16;
call->rx_expect_next = 1;
+
+ if (RXRPC_TX_SMSS > 2190)
+ call->cong_cwnd = 2;
+ else if (RXRPC_TX_SMSS > 1095)
+ call->cong_cwnd = 3;
+ else
+ call->cong_cwnd = 4;
+ call->cong_ssthresh = RXRPC_RXTX_BUFF_SIZE - 1;
return call;
nomem_2:
@@ -176,6 +184,7 @@
gfp_t gfp)
{
struct rxrpc_call *call;
+ ktime_t now;
_enter("");
@@ -185,6 +194,9 @@
call->state = RXRPC_CALL_CLIENT_AWAIT_CONN;
call->service_id = srx->srx_service;
call->tx_phase = true;
+ now = ktime_get_real();
+ call->acks_latest_ts = now;
+ call->cong_tstamp = now;
_leave(" = %p", call);
return call;
@@ -325,6 +337,7 @@
call->state = RXRPC_CALL_SERVER_ACCEPTING;
if (sp->hdr.securityIndex > 0)
call->state = RXRPC_CALL_SERVER_SECURING;
+ call->cong_tstamp = skb->tstamp;
/* Set the channel for this call. We don't get channel_lock as we're
* only defending against the data_ready handler (which we're called
diff --git a/net/rxrpc/conn_event.c b/net/rxrpc/conn_event.c
index a1cf1ec..37609ce 100644
--- a/net/rxrpc/conn_event.c
+++ b/net/rxrpc/conn_event.c
@@ -97,6 +97,7 @@
pkt.info.maxMTU = htonl(mtu);
pkt.info.rwind = htonl(rxrpc_rx_window_size);
pkt.info.jumbo_max = htonl(rxrpc_rx_jumbo_max);
+ pkt.whdr.flags |= RXRPC_SLOW_START_OK;
len += sizeof(pkt.ack) + sizeof(pkt.info);
break;
}
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 0344f44..094720d 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -37,6 +37,166 @@
}
/*
+ * Do TCP-style congestion management [RFC 5681].
+ */
+static void rxrpc_congestion_management(struct rxrpc_call *call,
+ struct sk_buff *skb,
+ struct rxrpc_ack_summary *summary)
+{
+ enum rxrpc_congest_change change = rxrpc_cong_no_change;
+ struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+ unsigned int cumulative_acks = call->cong_cumul_acks;
+ unsigned int cwnd = call->cong_cwnd;
+ bool resend = false;
+
+ summary->flight_size =
+ (call->tx_top - call->tx_hard_ack) - summary->nr_acks;
+
+ if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
+ summary->retrans_timeo = true;
+ call->cong_ssthresh = max_t(unsigned int,
+ summary->flight_size / 2, 2);
+ cwnd = 1;
+ if (cwnd > call->cong_ssthresh &&
+ call->cong_mode == RXRPC_CALL_SLOW_START) {
+ call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
+ call->cong_tstamp = skb->tstamp;
+ cumulative_acks = 0;
+ }
+ }
+
+ cumulative_acks += summary->nr_new_acks;
+ cumulative_acks += summary->nr_rot_new_acks;
+ if (cumulative_acks > 255)
+ cumulative_acks = 255;
+
+ summary->mode = call->cong_mode;
+ summary->cwnd = call->cong_cwnd;
+ summary->ssthresh = call->cong_ssthresh;
+ summary->cumulative_acks = cumulative_acks;
+ summary->dup_acks = call->cong_dup_acks;
+
+ switch (call->cong_mode) {
+ case RXRPC_CALL_SLOW_START:
+ if (summary->nr_nacks > 0)
+ goto packet_loss_detected;
+ if (summary->cumulative_acks > 0)
+ cwnd += 1;
+ if (cwnd > call->cong_ssthresh) {
+ call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
+ call->cong_tstamp = skb->tstamp;
+ }
+ goto out;
+
+ case RXRPC_CALL_CONGEST_AVOIDANCE:
+ if (summary->nr_nacks > 0)
+ goto packet_loss_detected;
+
+ /* We analyse the number of packets that get ACK'd per RTT
+ * period and increase the window if we managed to fill it.
+ */
+ if (call->peer->rtt_usage == 0)
+ goto out;
+ if (ktime_before(skb->tstamp,
+ ktime_add_ns(call->cong_tstamp,
+ call->peer->rtt)))
+ goto out_no_clear_ca;
+ change = rxrpc_cong_rtt_window_end;
+ call->cong_tstamp = skb->tstamp;
+ if (cumulative_acks >= cwnd)
+ cwnd++;
+ goto out;
+
+ case RXRPC_CALL_PACKET_LOSS:
+ if (summary->nr_nacks == 0)
+ goto resume_normality;
+
+ if (summary->new_low_nack) {
+ change = rxrpc_cong_new_low_nack;
+ call->cong_dup_acks = 1;
+ if (call->cong_extra > 1)
+ call->cong_extra = 1;
+ goto send_extra_data;
+ }
+
+ call->cong_dup_acks++;
+ if (call->cong_dup_acks < 3)
+ goto send_extra_data;
+
+ change = rxrpc_cong_begin_retransmission;
+ call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT;
+ call->cong_ssthresh = max_t(unsigned int,
+ summary->flight_size / 2, 2);
+ cwnd = call->cong_ssthresh + 3;
+ call->cong_extra = 0;
+ call->cong_dup_acks = 0;
+ resend = true;
+ goto out;
+
+ case RXRPC_CALL_FAST_RETRANSMIT:
+ if (!summary->new_low_nack) {
+ if (summary->nr_new_acks == 0)
+ cwnd += 1;
+ call->cong_dup_acks++;
+ if (call->cong_dup_acks == 2) {
+ change = rxrpc_cong_retransmit_again;
+ call->cong_dup_acks = 0;
+ resend = true;
+ }
+ } else {
+ change = rxrpc_cong_progress;
+ cwnd = call->cong_ssthresh;
+ if (summary->nr_nacks == 0)
+ goto resume_normality;
+ }
+ goto out;
+
+ default:
+ BUG();
+ goto out;
+ }
+
+resume_normality:
+ change = rxrpc_cong_cleared_nacks;
+ call->cong_dup_acks = 0;
+ call->cong_extra = 0;
+ call->cong_tstamp = skb->tstamp;
+ if (cwnd <= call->cong_ssthresh)
+ call->cong_mode = RXRPC_CALL_SLOW_START;
+ else
+ call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
+out:
+ cumulative_acks = 0;
+out_no_clear_ca:
+ if (cwnd >= RXRPC_RXTX_BUFF_SIZE - 1)
+ cwnd = RXRPC_RXTX_BUFF_SIZE - 1;
+ call->cong_cwnd = cwnd;
+ call->cong_cumul_acks = cumulative_acks;
+ trace_rxrpc_congest(call, summary, sp->hdr.serial, change);
+ if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
+ rxrpc_queue_call(call);
+ return;
+
+packet_loss_detected:
+ change = rxrpc_cong_saw_nack;
+ call->cong_mode = RXRPC_CALL_PACKET_LOSS;
+ call->cong_dup_acks = 0;
+ goto send_extra_data;
+
+send_extra_data:
+ /* Send some previously unsent DATA if we have some to advance the ACK
+ * state.
+ */
+ if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
+ RXRPC_TX_ANNO_LAST ||
+ summary->nr_acks != call->tx_top - call->tx_hard_ack) {
+ call->cong_extra++;
+ wake_up(&call->waitq);
+ }
+ goto out_no_clear_ca;
+}
+
+/*
* Ping the other end to fill our RTT cache and to retrieve the rwind
* and MTU parameters.
*/
@@ -524,7 +684,6 @@
rxrpc_seq_t seq, int nr_acks,
struct rxrpc_ack_summary *summary)
{
- bool resend = false;
int ix;
u8 annotation, anno_type;
@@ -556,16 +715,11 @@
continue;
call->rxtx_annotations[ix] =
RXRPC_TX_ANNO_NAK | annotation;
- resend = true;
break;
default:
return rxrpc_proto_abort("SFT", call, 0);
}
}
-
- if (resend &&
- !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
- rxrpc_queue_call(call);
}
/*
@@ -663,6 +817,7 @@
sp->hdr.serial, call->acks_latest);
return;
}
+ call->acks_latest_ts = skb->tstamp;
call->acks_latest = sp->hdr.serial;
if (before(hard_ack, call->tx_hard_ack) ||
@@ -692,6 +847,8 @@
rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
false, true,
rxrpc_propose_ack_ping_for_lost_reply);
+
+ return rxrpc_congestion_management(call, skb, &summary);
}
/*
diff --git a/net/rxrpc/misc.c b/net/rxrpc/misc.c
index a608769..aedb897 100644
--- a/net/rxrpc/misc.c
+++ b/net/rxrpc/misc.c
@@ -200,6 +200,7 @@
const char rxrpc_propose_ack_traces[rxrpc_propose_ack__nr_trace][8] = {
[rxrpc_propose_ack_client_tx_end] = "ClTxEnd",
[rxrpc_propose_ack_input_data] = "DataIn ",
+ [rxrpc_propose_ack_ping_for_lost_ack] = "LostAck",
[rxrpc_propose_ack_ping_for_lost_reply] = "LostRpl",
[rxrpc_propose_ack_ping_for_params] = "Params ",
[rxrpc_propose_ack_respond_to_ack] = "Rsp2Ack",
@@ -214,3 +215,21 @@
[rxrpc_propose_ack_update] = " Update",
[rxrpc_propose_ack_subsume] = " Subsume",
};
+
+const char rxrpc_congest_modes[NR__RXRPC_CONGEST_MODES][10] = {
+ [RXRPC_CALL_SLOW_START] = "SlowStart",
+ [RXRPC_CALL_CONGEST_AVOIDANCE] = "CongAvoid",
+ [RXRPC_CALL_PACKET_LOSS] = "PktLoss ",
+ [RXRPC_CALL_FAST_RETRANSMIT] = "FastReTx ",
+};
+
+const char rxrpc_congest_changes[rxrpc_congest__nr_change][9] = {
+ [rxrpc_cong_begin_retransmission] = " Retrans",
+ [rxrpc_cong_cleared_nacks] = " Cleared",
+ [rxrpc_cong_new_low_nack] = " NewLowN",
+ [rxrpc_cong_no_change] = "",
+ [rxrpc_cong_progress] = " Progres",
+ [rxrpc_cong_retransmit_again] = " ReTxAgn",
+ [rxrpc_cong_rtt_window_end] = " RttWinE",
+ [rxrpc_cong_saw_nack] = " SawNack",
+};
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index 3eb0144..cf43a71 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -157,6 +157,8 @@
spin_unlock_bh(&call->lock);
+ pkt->whdr.flags |= RXRPC_SLOW_START_OK;
+
iov[0].iov_len += sizeof(pkt->ack) + n;
iov[1].iov_base = &pkt->ackinfo;
iov[1].iov_len = sizeof(pkt->ackinfo);
@@ -276,8 +278,11 @@
msg.msg_controllen = 0;
msg.msg_flags = 0;
- /* If our RTT cache needs working on, request an ACK. */
- if ((call->peer->rtt_usage < 3 && sp->hdr.seq & 1) ||
+ /* If our RTT cache needs working on, request an ACK. Also request
+ * ACKs if a DATA packet appears to have been lost.
+ */
+ if (call->cong_mode == RXRPC_CALL_FAST_RETRANSMIT ||
+ (call->peer->rtt_usage < 3 && sp->hdr.seq & 1) ||
ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000),
ktime_get_real()))
whdr.flags |= RXRPC_REQUEST_ACK;
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index 9993937..1f8040d 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -45,7 +45,9 @@
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
ret = 0;
- if (call->tx_top - call->tx_hard_ack < call->tx_winsize)
+ if (call->tx_top - call->tx_hard_ack <
+ min_t(unsigned int, call->tx_winsize,
+ call->cong_cwnd + call->cong_extra))
break;
if (call->state >= RXRPC_CALL_COMPLETE) {
ret = -call->error;
@@ -203,7 +205,8 @@
_debug("alloc");
if (call->tx_top - call->tx_hard_ack >=
- call->tx_winsize) {
+ min_t(unsigned int, call->tx_winsize,
+ call->cong_cwnd + call->cong_extra)) {
ret = -EAGAIN;
if (msg->msg_flags & MSG_DONTWAIT)
goto maybe_error;