[linux-block.git] / net / rxrpc / call_event.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/circ_buf.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/udp.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"

/*
 * Propose a PING ACK be sent.
 */
void rxrpc_propose_ping(struct rxrpc_call *call, u32 serial,
			enum rxrpc_propose_ack_trace why)
{
	unsigned long now = jiffies;
	unsigned long ping_at = now + rxrpc_idle_ack_delay;

	if (time_before(ping_at, call->ping_at)) {
		WRITE_ONCE(call->ping_at, ping_at);
		rxrpc_reduce_call_timer(call, ping_at, now,
					rxrpc_timer_set_for_ping);
		trace_rxrpc_propose_ack(call, why, RXRPC_ACK_PING, serial);
	}
}

/*
 * Propose a DELAY ACK be sent in the future.
 */
void rxrpc_propose_delay_ACK(struct rxrpc_call *call, rxrpc_serial_t serial,
			     enum rxrpc_propose_ack_trace why)
{
	unsigned long expiry = rxrpc_soft_ack_delay;
	unsigned long now = jiffies, ack_at;

	call->ackr_serial = serial;

	if (rxrpc_soft_ack_delay < expiry)
		expiry = rxrpc_soft_ack_delay;
	if (call->peer->srtt_us != 0)
		ack_at = usecs_to_jiffies(call->peer->srtt_us >> 3);
	else
		ack_at = expiry;

	ack_at += READ_ONCE(call->tx_backoff);
	ack_at += now;
	if (time_before(ack_at, call->delay_ack_at)) {
		WRITE_ONCE(call->delay_ack_at, ack_at);
		rxrpc_reduce_call_timer(call, ack_at, now,
					rxrpc_timer_set_for_ack);
	}

	trace_rxrpc_propose_ack(call, why, RXRPC_ACK_DELAY, serial);
}

/*
 * Queue an ACK for immediate transmission.
 */
void rxrpc_send_ACK(struct rxrpc_call *call, u8 ack_reason,
		    rxrpc_serial_t serial, enum rxrpc_propose_ack_trace why)
{
	struct rxrpc_local *local = call->conn->local;
	struct rxrpc_txbuf *txb;

	if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
		return;

	rxrpc_inc_stat(call->rxnet, stat_tx_acks[ack_reason]);

	txb = rxrpc_alloc_txbuf(call, RXRPC_PACKET_TYPE_ACK,
				rcu_read_lock_held() ? GFP_ATOMIC | __GFP_NOWARN : GFP_NOFS);
	if (!txb) {
		kleave(" = -ENOMEM");
		return;
	}

	txb->ack_why		= why;
	txb->wire.seq		= 0;
	txb->wire.type		= RXRPC_PACKET_TYPE_ACK;
	txb->wire.flags		|= RXRPC_SLOW_START_OK;
	txb->ack.bufferSpace	= 0;
	txb->ack.maxSkew	= 0;
	txb->ack.firstPacket	= 0;
	txb->ack.previousPacket	= 0;
	txb->ack.serial		= htonl(serial);
	txb->ack.reason		= ack_reason;
	txb->ack.nAcks		= 0;

	if (!rxrpc_try_get_call(call, rxrpc_call_get_send_ack)) {
		rxrpc_put_txbuf(txb, rxrpc_txbuf_put_nomem);
		return;
	}

	spin_lock(&local->ack_tx_lock);
	list_add_tail(&txb->tx_link, &local->ack_tx_queue);
	spin_unlock(&local->ack_tx_lock);
	trace_rxrpc_send_ack(call, why, ack_reason, serial);

	rxrpc_wake_up_io_thread(local);
}

/*
 * 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.
 */
void rxrpc_resend(struct rxrpc_call *call, struct sk_buff *ack_skb)
{
	struct rxrpc_ackpacket *ack = NULL;
	struct rxrpc_txbuf *txb;
	unsigned long resend_at;
	rxrpc_seq_t transmitted = READ_ONCE(call->tx_transmitted);
	ktime_t now, max_age, oldest, ack_ts;
	bool unacked = false;
	unsigned int i;
	LIST_HEAD(retrans_queue);

	_enter("{%d,%d}", call->acks_hard_ack, call->tx_top);

	now = ktime_get_real();
	max_age = ktime_sub_us(now, jiffies_to_usecs(call->peer->rto_j));
	oldest = now;

	if (list_empty(&call->tx_buffer))
		goto no_resend;

	if (list_empty(&call->tx_buffer))
		goto no_further_resend;

	trace_rxrpc_resend(call, ack_skb);
	txb = list_first_entry(&call->tx_buffer, struct rxrpc_txbuf, call_link);

	/* Scan the soft ACK table without dropping the lock and resend any
	 * explicitly NAK'd packets.
	 */
	if (ack_skb) {
		ack = (void *)ack_skb->data + sizeof(struct rxrpc_wire_header);

		for (i = 0; i < ack->nAcks; i++) {
			rxrpc_seq_t seq;

			if (ack->acks[i] & 1)
				continue;
			seq = ntohl(ack->firstPacket) + i;
			if (after(txb->seq, transmitted))
				break;
			if (after(txb->seq, seq))
				continue; /* A new hard ACK probably came in */
			list_for_each_entry_from(txb, &call->tx_buffer, call_link) {
				if (txb->seq == seq)
					goto found_txb;
			}
			goto no_further_resend;

		found_txb:
			if (after(ntohl(txb->wire.serial), call->acks_highest_serial))
				continue; /* Ack point not yet reached */

			rxrpc_see_txbuf(txb, rxrpc_txbuf_see_unacked);

			if (list_empty(&txb->tx_link)) {
				list_add_tail(&txb->tx_link, &retrans_queue);
				set_bit(RXRPC_TXBUF_RESENT, &txb->flags);
			}

			trace_rxrpc_retransmit(call, txb->seq,
					       ktime_to_ns(ktime_sub(txb->last_sent,
								     max_age)));

			if (list_is_last(&txb->call_link, &call->tx_buffer))
				goto no_further_resend;
			txb = list_next_entry(txb, call_link);
		}
	}

	/* Fast-forward through the Tx queue to the point the peer says it has
	 * seen.  Anything between the soft-ACK table and that point will get
	 * ACK'd or NACK'd in due course, so don't worry about it here; here we
	 * need to consider retransmitting anything beyond that point.
	 *
	 * Note that ACK for a packet can beat the update of tx_transmitted.
	 */
	if (after_eq(READ_ONCE(call->acks_prev_seq), READ_ONCE(call->tx_transmitted)))
		goto no_further_resend;

	list_for_each_entry_from(txb, &call->tx_buffer, call_link) {
		if (before_eq(txb->seq, READ_ONCE(call->acks_prev_seq)))
			continue;
		if (after(txb->seq, READ_ONCE(call->tx_transmitted)))
			break; /* Not transmitted yet */

		if (ack && ack->reason == RXRPC_ACK_PING_RESPONSE &&
		    before(ntohl(txb->wire.serial), ntohl(ack->serial)))
			goto do_resend; /* Wasn't accounted for by a more recent ping. */

		if (ktime_after(txb->last_sent, max_age)) {
			if (ktime_before(txb->last_sent, oldest))
				oldest = txb->last_sent;
			continue;
		}

	do_resend:
		unacked = true;
		if (list_empty(&txb->tx_link)) {
			list_add_tail(&txb->tx_link, &retrans_queue);
			set_bit(RXRPC_TXBUF_RESENT, &txb->flags);
			rxrpc_inc_stat(call->rxnet, stat_tx_data_retrans);
		}
	}

no_further_resend:
no_resend:
	resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
	resend_at += jiffies + rxrpc_get_rto_backoff(call->peer,
						     !list_empty(&retrans_queue));
	WRITE_ONCE(call->resend_at, resend_at);

	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 (list_empty(&retrans_queue)) {
		rxrpc_reduce_call_timer(call, resend_at, jiffies,
					rxrpc_timer_set_for_resend);
		ack_ts = ktime_sub(now, call->acks_latest_ts);
		if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3))
			goto out;
		rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
			       rxrpc_propose_ack_ping_for_lost_ack);
		goto out;
	}

	/* Retransmit the queue */
	while ((txb = list_first_entry_or_null(&retrans_queue,
					       struct rxrpc_txbuf, tx_link))) {
		list_del_init(&txb->tx_link);
		rxrpc_transmit_one(call, txb);
	}

out:
	_leave("");
}

static bool rxrpc_tx_window_has_space(struct rxrpc_call *call)
{
	unsigned int winsize = min_t(unsigned int, call->tx_winsize,
				     call->cong_cwnd + call->cong_extra);
	rxrpc_seq_t window = call->acks_hard_ack, wtop = window + winsize;
	rxrpc_seq_t tx_top = call->tx_top;
	int space;

	space = wtop - tx_top;
	return space > 0;
}

/*
 * Decant some if the sendmsg prepared queue into the transmission buffer.
 */
static void rxrpc_decant_prepared_tx(struct rxrpc_call *call)
{
	struct rxrpc_txbuf *txb;

	if (rxrpc_is_client_call(call) &&
	    !test_bit(RXRPC_CALL_EXPOSED, &call->flags))
		rxrpc_expose_client_call(call);

	while ((txb = list_first_entry_or_null(&call->tx_sendmsg,
					       struct rxrpc_txbuf, call_link))) {
		spin_lock(&call->tx_lock);
		list_del(&txb->call_link);
		spin_unlock(&call->tx_lock);

		call->tx_top = txb->seq;
		list_add_tail(&txb->call_link, &call->tx_buffer);

		rxrpc_transmit_one(call, txb);

		// TODO: Drain the transmission buffers.  Do this somewhere better
		if (after(call->acks_hard_ack, call->tx_bottom + 16))
			rxrpc_shrink_call_tx_buffer(call);

		if (!rxrpc_tx_window_has_space(call))
			break;
	}
}

static void rxrpc_transmit_some_data(struct rxrpc_call *call)
{
	switch (call->state) {
	case RXRPC_CALL_SERVER_ACK_REQUEST:
		if (list_empty(&call->tx_sendmsg))
			return;
		fallthrough;

	case RXRPC_CALL_SERVER_SEND_REPLY:
	case RXRPC_CALL_SERVER_AWAIT_ACK:
	case RXRPC_CALL_CLIENT_SEND_REQUEST:
	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
		if (!rxrpc_tx_window_has_space(call))
			return;
		if (list_empty(&call->tx_sendmsg)) {
			rxrpc_inc_stat(call->rxnet, stat_tx_data_underflow);
			return;
		}
		rxrpc_decant_prepared_tx(call);
		break;
	default:
		return;
	}
}

/*
 * Ping the other end to fill our RTT cache and to retrieve the rwind
 * and MTU parameters.
 */
static void rxrpc_send_initial_ping(struct rxrpc_call *call)
{
	if (call->peer->rtt_count < 3 ||
	    ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000),
			 ktime_get_real()))
		rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
			       rxrpc_propose_ack_ping_for_params);
}

/*
 * Handle retransmission and deferred ACK/abort generation.
 */
void rxrpc_input_call_event(struct rxrpc_call *call, struct sk_buff *skb)
{
	unsigned long now, next, t;
	rxrpc_serial_t ackr_serial;
	bool resend = false, expired = false;

	rxrpc_see_call(call, rxrpc_call_see_input);

	//printk("\n--------------------\n");
	_enter("{%d,%s,%lx}",
	       call->debug_id, rxrpc_call_states[call->state], call->events);

	if (call->state == RXRPC_CALL_COMPLETE)
		goto out;

	if (skb && skb->mark == RXRPC_SKB_MARK_ERROR)
		goto out;

	/* If we see our async-event poke, check for timeout trippage. */
	now = jiffies;
	t = READ_ONCE(call->expect_rx_by);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
		expired = true;
	}

	t = READ_ONCE(call->expect_req_by);
	if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST &&
	    time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
		expired = true;
	}

	t = READ_ONCE(call->expect_term_by);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
		expired = true;
	}

	t = READ_ONCE(call->delay_ack_at);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
		cmpxchg(&call->delay_ack_at, t, now + MAX_JIFFY_OFFSET);
		ackr_serial = xchg(&call->ackr_serial, 0);
		rxrpc_send_ACK(call, RXRPC_ACK_DELAY, ackr_serial,
			       rxrpc_propose_ack_ping_for_lost_ack);
	}

	t = READ_ONCE(call->ack_lost_at);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now);
		cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET);
		set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
	}

	t = READ_ONCE(call->keepalive_at);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now);
		cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET);
		rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
			       rxrpc_propose_ack_ping_for_keepalive);
	}

	t = READ_ONCE(call->ping_at);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
		cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
		rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
			       rxrpc_propose_ack_ping_for_keepalive);
	}

	t = READ_ONCE(call->resend_at);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
		cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
		resend = true;
	}

	if (skb)
		rxrpc_input_call_packet(call, skb);

	rxrpc_transmit_some_data(call);

	if (test_and_clear_bit(RXRPC_CALL_EV_INITIAL_PING, &call->events))
		rxrpc_send_initial_ping(call);

	/* Process events */
	if (expired) {
		if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) &&
		    (int)call->conn->hi_serial - (int)call->rx_serial > 0) {
			trace_rxrpc_call_reset(call);
			rxrpc_abort_call("EXP", call, 0, RX_CALL_DEAD, -ECONNRESET);
		} else {
			rxrpc_abort_call("EXP", call, 0, RX_CALL_TIMEOUT, -ETIME);
		}
		rxrpc_send_abort_packet(call);
		goto out;
	}

	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 && call->state != RXRPC_CALL_CLIENT_RECV_REPLY)
		rxrpc_resend(call, NULL);

	if (test_and_clear_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags))
		rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
			       rxrpc_propose_ack_rx_idle);

	if (atomic_read(&call->ackr_nr_unacked) > 2)
		rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
			       rxrpc_propose_ack_input_data);

	/* Make sure the timer is restarted */
	if (call->state != RXRPC_CALL_COMPLETE) {
		next = call->expect_rx_by;

#define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }

		set(call->expect_req_by);
		set(call->expect_term_by);
		set(call->delay_ack_at);
		set(call->ack_lost_at);
		set(call->resend_at);
		set(call->keepalive_at);
		set(call->ping_at);

		now = jiffies;
		if (time_after_eq(now, next))
			rxrpc_poke_call(call, rxrpc_call_poke_timer_now);

		rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
	}

out:
	if (call->state == RXRPC_CALL_COMPLETE)
		del_timer_sync(&call->timer);
	if (call->acks_hard_ack != call->tx_bottom)
		rxrpc_shrink_call_tx_buffer(call);
	_leave("");
}
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
17926a79 DH	2	/* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
	3	*
	4	* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
	5	* Written by David Howells (dhowells@redhat.com)
17926a79 DH	6	*/
17926a79 DH	7
9b6d5398 JP	8	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9b6d5398 JP	9
17926a79 DH	10	#include <linux/module.h>
	11	#include <linux/circ_buf.h>
	12	#include <linux/net.h>
	13	#include <linux/skbuff.h>
5a0e3ad6	14	#include <linux/slab.h>
17926a79 DH	15	#include <linux/udp.h>
	16	#include <net/sock.h>
	17	#include <net/af_rxrpc.h>
	18	#include "ar-internal.h"
	19
a5af7e1f DH	20	/*
	21	* Propose a PING ACK be sent.
	22	*/
72f0c6fb DH	23	void rxrpc_propose_ping(struct rxrpc_call *call, u32 serial,
72f0c6fb DH	24	enum rxrpc_propose_ack_trace why)
a5af7e1f	25	{
72f0c6fb DH	26	unsigned long now = jiffies;
72f0c6fb DH	27	unsigned long ping_at = now + rxrpc_idle_ack_delay;
a5af7e1f	28
72f0c6fb	29	if (time_before(ping_at, call->ping_at)) {
72f0c6fb DH	30	WRITE_ONCE(call->ping_at, ping_at);
	31	rxrpc_reduce_call_timer(call, ping_at, now,
	32	rxrpc_timer_set_for_ping);
530403d9	33	trace_rxrpc_propose_ack(call, why, RXRPC_ACK_PING, serial);
a5af7e1f DH	34	}
	35	}
	36
17926a79	37	/*
530403d9	38	* Propose a DELAY ACK be sent in the future.
17926a79	39	*/
4e76bd40 DH	40	void rxrpc_propose_delay_ACK(struct rxrpc_call *call, rxrpc_serial_t serial,
4e76bd40 DH	41	enum rxrpc_propose_ack_trace why)
17926a79	42	{
beb8e5e4	43	unsigned long expiry = rxrpc_soft_ack_delay;
72f0c6fb	44	unsigned long now = jiffies, ack_at;
17926a79	45
530403d9	46	call->ackr_serial = serial;
72f0c6fb	47
530403d9 DH	48	if (rxrpc_soft_ack_delay < expiry)
530403d9 DH	49	expiry = rxrpc_soft_ack_delay;
72f0c6fb DH	50	if (call->peer->srtt_us != 0)
	51	ack_at = usecs_to_jiffies(call->peer->srtt_us >> 3);
	52	else
	53	ack_at = expiry;
	54
	55	ack_at += READ_ONCE(call->tx_backoff);
	56	ack_at += now;
530403d9 DH	57	if (time_before(ack_at, call->delay_ack_at)) {
530403d9 DH	58	WRITE_ONCE(call->delay_ack_at, ack_at);
72f0c6fb DH	59	rxrpc_reduce_call_timer(call, ack_at, now,
72f0c6fb DH	60	rxrpc_timer_set_for_ack);
17926a79	61	}
9c7ad434	62
530403d9	63	trace_rxrpc_propose_ack(call, why, RXRPC_ACK_DELAY, serial);
17926a79 DH	64	}
17926a79 DH	65
72f0c6fb DH	66	/*
	67	* Queue an ACK for immediate transmission.
	68	*/
	69	void rxrpc_send_ACK(struct rxrpc_call *call, u8 ack_reason,
	70	rxrpc_serial_t serial, enum rxrpc_propose_ack_trace why)
	71	{
2cc80086	72	struct rxrpc_local *local = call->conn->local;
72f0c6fb DH	73	struct rxrpc_txbuf *txb;
	74
	75	if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
	76	return;
	77
	78	rxrpc_inc_stat(call->rxnet, stat_tx_acks[ack_reason]);
	79
	80	txb = rxrpc_alloc_txbuf(call, RXRPC_PACKET_TYPE_ACK,
446b3e14	81	rcu_read_lock_held() ? GFP_ATOMIC \| __GFP_NOWARN : GFP_NOFS);
72f0c6fb DH	82	if (!txb) {
	83	kleave(" = -ENOMEM");
	84	return;
	85	}
	86
	87	txb->ack_why = why;
	88	txb->wire.seq = 0;
	89	txb->wire.type = RXRPC_PACKET_TYPE_ACK;
	90	txb->wire.flags \|= RXRPC_SLOW_START_OK;
	91	txb->ack.bufferSpace = 0;
	92	txb->ack.maxSkew = 0;
	93	txb->ack.firstPacket = 0;
	94	txb->ack.previousPacket = 0;
	95	txb->ack.serial = htonl(serial);
	96	txb->ack.reason = ack_reason;
	97	txb->ack.nAcks = 0;
	98
cb0fc0c9	99	if (!rxrpc_try_get_call(call, rxrpc_call_get_send_ack)) {
72f0c6fb DH	100	rxrpc_put_txbuf(txb, rxrpc_txbuf_put_nomem);
	101	return;
	102	}
	103
3dd9c8b5	104	spin_lock(&local->ack_tx_lock);
72f0c6fb	105	list_add_tail(&txb->tx_link, &local->ack_tx_queue);
3dd9c8b5	106	spin_unlock(&local->ack_tx_lock);
72f0c6fb DH	107	trace_rxrpc_send_ack(call, why, ack_reason, serial);
72f0c6fb DH	108
5e6ef4f1	109	rxrpc_wake_up_io_thread(local);
72f0c6fb DH	110	}
72f0c6fb DH	111
57494343 DH	112	/*
	113	* Handle congestion being detected by the retransmit timeout.
	114	*/
	115	static void rxrpc_congestion_timeout(struct rxrpc_call *call)
	116	{
	117	set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
	118	}
	119
17926a79	120	/*
248f219c	121	* Perform retransmission of NAK'd and unack'd packets.
17926a79	122	*/
5e6ef4f1	123	void rxrpc_resend(struct rxrpc_call call, struct sk_buff ack_skb)
17926a79	124	{
d57a3a15	125	struct rxrpc_ackpacket *ack = NULL;
a4ea4c47	126	struct rxrpc_txbuf *txb;
2c13c05c	127	unsigned long resend_at;
a4ea4c47	128	rxrpc_seq_t transmitted = READ_ONCE(call->tx_transmitted);
c410bf01	129	ktime_t now, max_age, oldest, ack_ts;
a4ea4c47	130	bool unacked = false;
d57a3a15	131	unsigned int i;
a4ea4c47	132	LIST_HEAD(retrans_queue);
17926a79	133
a4ea4c47	134	_enter("{%d,%d}", call->acks_hard_ack, call->tx_top);
17926a79	135
a158bdd3	136	now = ktime_get_real();
214a9dc7	137	max_age = ktime_sub_us(now, jiffies_to_usecs(call->peer->rto_j));
d57a3a15 DH	138	oldest = now;
d57a3a15 DH	139
d57a3a15 DH	140	if (list_empty(&call->tx_buffer))
d57a3a15 DH	141	goto no_resend;
50235c4b	142
d57a3a15 DH	143	if (list_empty(&call->tx_buffer))
	144	goto no_further_resend;
	145
5e6ef4f1	146	trace_rxrpc_resend(call, ack_skb);
d57a3a15	147	txb = list_first_entry(&call->tx_buffer, struct rxrpc_txbuf, call_link);
17926a79	148
d57a3a15 DH	149	/* Scan the soft ACK table without dropping the lock and resend any
	150	* explicitly NAK'd packets.
	151	*/
5e6ef4f1 DH	152	if (ack_skb) {
	153	ack = (void *)ack_skb->data + sizeof(struct rxrpc_wire_header);
	154
d57a3a15 DH	155	for (i = 0; i < ack->nAcks; i++) {
d57a3a15 DH	156	rxrpc_seq_t seq;
17926a79	157
d57a3a15	158	if (ack->acks[i] & 1)
248f219c	159	continue;
d57a3a15 DH	160	seq = ntohl(ack->firstPacket) + i;
	161	if (after(txb->seq, transmitted))
	162	break;
	163	if (after(txb->seq, seq))
	164	continue; /* A new hard ACK probably came in */
	165	list_for_each_entry_from(txb, &call->tx_buffer, call_link) {
	166	if (txb->seq == seq)
	167	goto found_txb;
	168	}
	169	goto no_further_resend;
	170
	171	found_txb:
	172	if (after(ntohl(txb->wire.serial), call->acks_highest_serial))
	173	continue; /* Ack point not yet reached */
	174
	175	rxrpc_see_txbuf(txb, rxrpc_txbuf_see_unacked);
	176
	177	if (list_empty(&txb->tx_link)) {
d57a3a15 DH	178	list_add_tail(&txb->tx_link, &retrans_queue);
d57a3a15 DH	179	set_bit(RXRPC_TXBUF_RESENT, &txb->flags);
33c40e24	180	}
d57a3a15 DH	181
	182	trace_rxrpc_retransmit(call, txb->seq,
	183	ktime_to_ns(ktime_sub(txb->last_sent,
	184	max_age)));
	185
	186	if (list_is_last(&txb->call_link, &call->tx_buffer))
	187	goto no_further_resend;
	188	txb = list_next_entry(txb, call_link);
17926a79	189	}
d57a3a15	190	}
17926a79	191
d57a3a15 DH	192	/* Fast-forward through the Tx queue to the point the peer says it has
	193	* seen. Anything between the soft-ACK table and that point will get
	194	* ACK'd or NACK'd in due course, so don't worry about it here; here we
	195	* need to consider retransmitting anything beyond that point.
	196	*
	197	* Note that ACK for a packet can beat the update of tx_transmitted.
	198	*/
	199	if (after_eq(READ_ONCE(call->acks_prev_seq), READ_ONCE(call->tx_transmitted)))
	200	goto no_further_resend;
	201
	202	list_for_each_entry_from(txb, &call->tx_buffer, call_link) {
	203	if (before_eq(txb->seq, READ_ONCE(call->acks_prev_seq)))
	204	continue;
	205	if (after(txb->seq, READ_ONCE(call->tx_transmitted)))
	206	break; /* Not transmitted yet */
	207
	208	if (ack && ack->reason == RXRPC_ACK_PING_RESPONSE &&
	209	before(ntohl(txb->wire.serial), ntohl(ack->serial)))
	210	goto do_resend; /* Wasn't accounted for by a more recent ping. */
	211
	212	if (ktime_after(txb->last_sent, max_age)) {
	213	if (ktime_before(txb->last_sent, oldest))
	214	oldest = txb->last_sent;
	215	continue;
	216	}
	217
	218	do_resend:
	219	unacked = true;
	220	if (list_empty(&txb->tx_link)) {
d57a3a15 DH	221	list_add_tail(&txb->tx_link, &retrans_queue);
	222	set_bit(RXRPC_TXBUF_RESENT, &txb->flags);
	223	rxrpc_inc_stat(call->rxnet, stat_tx_data_retrans);
	224	}
dfa7d920	225	}
248f219c	226
d57a3a15	227	no_further_resend:
d57a3a15	228	no_resend:
59299aa1	229	resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
a4ea4c47 DH	230	resend_at += jiffies + rxrpc_get_rto_backoff(call->peer,
a4ea4c47 DH	231	!list_empty(&retrans_queue));
a158bdd3	232	WRITE_ONCE(call->resend_at, resend_at);
248f219c	233
57494343 DH	234	if (unacked)
	235	rxrpc_congestion_timeout(call);
	236
	237	/* If there was nothing that needed retransmission then it's likely
	238	* that an ACK got lost somewhere. Send a ping to find out instead of
	239	* retransmitting data.
	240	*/
a4ea4c47	241	if (list_empty(&retrans_queue)) {
5e6ef4f1	242	rxrpc_reduce_call_timer(call, resend_at, jiffies,
a158bdd3	243	rxrpc_timer_set_for_resend);
57494343	244	ack_ts = ktime_sub(now, call->acks_latest_ts);
c410bf01	245	if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3))
57494343	246	goto out;
72f0c6fb DH	247	rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
72f0c6fb DH	248	rxrpc_propose_ack_ping_for_lost_ack);
57494343 DH	249	goto out;
	250	}
	251
5e6ef4f1	252	/* Retransmit the queue */
a4ea4c47 DH	253	while ((txb = list_first_entry_or_null(&retrans_queue,
	254	struct rxrpc_txbuf, tx_link))) {
	255	list_del_init(&txb->tx_link);
5e6ef4f1	256	rxrpc_transmit_one(call, txb);
dfa7d920	257	}
248f219c	258
57494343	259	out:
248f219c	260	_leave("");
17926a79 DH	261	}
17926a79 DH	262
cf37b598 DH	263	static bool rxrpc_tx_window_has_space(struct rxrpc_call *call)
	264	{
	265	unsigned int winsize = min_t(unsigned int, call->tx_winsize,
	266	call->cong_cwnd + call->cong_extra);
	267	rxrpc_seq_t window = call->acks_hard_ack, wtop = window + winsize;
	268	rxrpc_seq_t tx_top = call->tx_top;
	269	int space;
	270
	271	space = wtop - tx_top;
	272	return space > 0;
	273	}
	274
	275	/*
	276	* Decant some if the sendmsg prepared queue into the transmission buffer.
	277	*/
	278	static void rxrpc_decant_prepared_tx(struct rxrpc_call *call)
	279	{
	280	struct rxrpc_txbuf *txb;
	281
	282	if (rxrpc_is_client_call(call) &&
	283	!test_bit(RXRPC_CALL_EXPOSED, &call->flags))
	284	rxrpc_expose_client_call(call);
	285
	286	while ((txb = list_first_entry_or_null(&call->tx_sendmsg,
	287	struct rxrpc_txbuf, call_link))) {
	288	spin_lock(&call->tx_lock);
	289	list_del(&txb->call_link);
	290	spin_unlock(&call->tx_lock);
	291
	292	call->tx_top = txb->seq;
	293	list_add_tail(&txb->call_link, &call->tx_buffer);
	294
	295	rxrpc_transmit_one(call, txb);
	296
	297	// TODO: Drain the transmission buffers. Do this somewhere better
	298	if (after(call->acks_hard_ack, call->tx_bottom + 16))
	299	rxrpc_shrink_call_tx_buffer(call);
	300
	301	if (!rxrpc_tx_window_has_space(call))
	302	break;
	303	}
	304	}
	305
	306	static void rxrpc_transmit_some_data(struct rxrpc_call *call)
	307	{
	308	switch (call->state) {
	309	case RXRPC_CALL_SERVER_ACK_REQUEST:
	310	if (list_empty(&call->tx_sendmsg))
	311	return;
	312	fallthrough;
	313
	314	case RXRPC_CALL_SERVER_SEND_REPLY:
	315	case RXRPC_CALL_SERVER_AWAIT_ACK:
	316	case RXRPC_CALL_CLIENT_SEND_REQUEST:
	317	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
	318	if (!rxrpc_tx_window_has_space(call))
	319	return;
32cf8edb DH	320	if (list_empty(&call->tx_sendmsg)) {
32cf8edb DH	321	rxrpc_inc_stat(call->rxnet, stat_tx_data_underflow);
cf37b598	322	return;
32cf8edb	323	}
cf37b598 DH	324	rxrpc_decant_prepared_tx(call);
	325	break;
	326	default:
	327	return;
	328	}
	329	}
	330
5e6ef4f1 DH	331	/*
	332	* Ping the other end to fill our RTT cache and to retrieve the rwind
	333	* and MTU parameters.
	334	*/
	335	static void rxrpc_send_initial_ping(struct rxrpc_call *call)
	336	{
	337	if (call->peer->rtt_count < 3 \|\|
	338	ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000),
	339	ktime_get_real()))
	340	rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
	341	rxrpc_propose_ack_ping_for_params);
	342	}
	343
17926a79	344	/*
248f219c	345	* Handle retransmission and deferred ACK/abort generation.
17926a79	346	*/
5e6ef4f1	347	void rxrpc_input_call_event(struct rxrpc_call call, struct sk_buff skb)
17926a79	348	{
a158bdd3	349	unsigned long now, next, t;
72f0c6fb	350	rxrpc_serial_t ackr_serial;
5e6ef4f1	351	bool resend = false, expired = false;
17926a79	352
cb0fc0c9	353	rxrpc_see_call(call, rxrpc_call_see_input);
e34d4234	354
17926a79	355	//printk("\n--------------------\n");
248f219c DH	356	_enter("{%d,%s,%lx}",
248f219c DH	357	call->debug_id, rxrpc_call_states[call->state], call->events);
17926a79	358
5e6ef4f1 DH	359	if (call->state == RXRPC_CALL_COMPLETE)
5e6ef4f1 DH	360	goto out;
17926a79	361
5e6ef4f1	362	if (skb && skb->mark == RXRPC_SKB_MARK_ERROR)
3feda9d6	363	goto out;
17926a79	364
5e6ef4f1	365	/* If we see our async-event poke, check for timeout trippage. */
a158bdd3 DH	366	now = jiffies;
	367	t = READ_ONCE(call->expect_rx_by);
	368	if (time_after_eq(now, t)) {
	369	trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
5e6ef4f1	370	expired = true;
a158bdd3 DH	371	}
	372
	373	t = READ_ONCE(call->expect_req_by);
	374	if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST &&
	375	time_after_eq(now, t)) {
	376	trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
5e6ef4f1	377	expired = true;
a158bdd3 DH	378	}
	379
	380	t = READ_ONCE(call->expect_term_by);
	381	if (time_after_eq(now, t)) {
	382	trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
5e6ef4f1	383	expired = true;
a158bdd3 DH	384	}
a158bdd3 DH	385
530403d9	386	t = READ_ONCE(call->delay_ack_at);
a158bdd3 DH	387	if (time_after_eq(now, t)) {
a158bdd3 DH	388	trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
530403d9 DH	389	cmpxchg(&call->delay_ack_at, t, now + MAX_JIFFY_OFFSET);
	390	ackr_serial = xchg(&call->ackr_serial, 0);
	391	rxrpc_send_ACK(call, RXRPC_ACK_DELAY, ackr_serial,
	392	rxrpc_propose_ack_ping_for_lost_ack);
a158bdd3 DH	393	}
a158bdd3 DH	394
bd1fdf8c DH	395	t = READ_ONCE(call->ack_lost_at);
	396	if (time_after_eq(now, t)) {
	397	trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now);
	398	cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET);
	399	set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
	400	}
	401
415f44e4 DH	402	t = READ_ONCE(call->keepalive_at);
	403	if (time_after_eq(now, t)) {
	404	trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now);
	405	cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET);
72f0c6fb DH	406	rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
72f0c6fb DH	407	rxrpc_propose_ack_ping_for_keepalive);
415f44e4 DH	408	}
415f44e4 DH	409
a158bdd3 DH	410	t = READ_ONCE(call->ping_at);
	411	if (time_after_eq(now, t)) {
	412	trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
	413	cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
72f0c6fb DH	414	rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
72f0c6fb DH	415	rxrpc_propose_ack_ping_for_keepalive);
a158bdd3 DH	416	}
	417
	418	t = READ_ONCE(call->resend_at);
	419	if (time_after_eq(now, t)) {
	420	trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
	421	cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
5e6ef4f1	422	resend = true;
a158bdd3 DH	423	}
a158bdd3 DH	424
5e6ef4f1 DH	425	if (skb)
	426	rxrpc_input_call_packet(call, skb);
	427
cf37b598 DH	428	rxrpc_transmit_some_data(call);
cf37b598 DH	429
5e6ef4f1 DH	430	if (test_and_clear_bit(RXRPC_CALL_EV_INITIAL_PING, &call->events))
	431	rxrpc_send_initial_ping(call);
	432
a158bdd3	433	/* Process events */
5e6ef4f1	434	if (expired) {
1a025028 DH	435	if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) &&
	436	(int)call->conn->hi_serial - (int)call->rx_serial > 0) {
	437	trace_rxrpc_call_reset(call);
de696c47	438	rxrpc_abort_call("EXP", call, 0, RX_CALL_DEAD, -ECONNRESET);
1a025028	439	} else {
de696c47	440	rxrpc_abort_call("EXP", call, 0, RX_CALL_TIMEOUT, -ETIME);
1a025028	441	}
5e6ef4f1 DH	442	rxrpc_send_abort_packet(call);
5e6ef4f1 DH	443	goto out;
17926a79 DH	444	}
17926a79 DH	445
5e6ef4f1	446	if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events))
72f0c6fb DH	447	rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
72f0c6fb DH	448	rxrpc_propose_ack_ping_for_lost_ack);
a5af7e1f	449
5e6ef4f1 DH	450	if (resend && call->state != RXRPC_CALL_CLIENT_RECV_REPLY)
	451	rxrpc_resend(call, NULL);
	452
	453	if (test_and_clear_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags))
	454	rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
	455	rxrpc_propose_ack_rx_idle);
	456
	457	if (atomic_read(&call->ackr_nr_unacked) > 2)
	458	rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
	459	rxrpc_propose_ack_input_data);
17926a79	460
a158bdd3	461	/* Make sure the timer is restarted */
5e6ef4f1 DH	462	if (call->state != RXRPC_CALL_COMPLETE) {
5e6ef4f1 DH	463	next = call->expect_rx_by;
a158bdd3 DH	464
a158bdd3 DH	465	#define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }
3d7682af	466
5e6ef4f1 DH	467	set(call->expect_req_by);
	468	set(call->expect_term_by);
	469	set(call->delay_ack_at);
	470	set(call->ack_lost_at);
	471	set(call->resend_at);
	472	set(call->keepalive_at);
	473	set(call->ping_at);
a158bdd3	474
5e6ef4f1 DH	475	now = jiffies;
	476	if (time_after_eq(now, next))
	477	rxrpc_poke_call(call, rxrpc_call_poke_timer_now);
17926a79	478
5e6ef4f1 DH	479	rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
5e6ef4f1 DH	480	}
17926a79	481
248f219c	482	out:
5e6ef4f1 DH	483	if (call->state == RXRPC_CALL_COMPLETE)
	484	del_timer_sync(&call->timer);
	485	if (call->acks_hard_ack != call->tx_bottom)
	486	rxrpc_shrink_call_tx_buffer(call);
17926a79	487	_leave("");
17926a79	488	}