net/rxrpc/call_event.c - linux - Git at Google

 // 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)
 {
 	ktime_t delay = ms_to_ktime(READ_ONCE(rxrpc_idle_ack_delay));
 	ktime_t now = ktime_get_real();
 	ktime_t ping_at = ktime_add(now, delay);

 	trace_rxrpc_propose_ack(call, why, RXRPC_ACK_PING, serial);
 	if (ktime_before(ping_at, call->ping_at)) {
 		call->ping_at = ping_at;
 		trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_ping);
 	}
 }

 /*
  * 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)
 {
 	ktime_t now = ktime_get_real(), delay;

 	trace_rxrpc_propose_ack(call, why, RXRPC_ACK_DELAY, serial);

 	if (call->peer->srtt_us)
 		delay = (call->peer->srtt_us >> 3) * NSEC_PER_USEC;
 	else
 		delay = ms_to_ktime(READ_ONCE(rxrpc_soft_ack_delay));
 	ktime_add_ms(delay, call->tx_backoff);

 	call->delay_ack_at = ktime_add(now, delay);
 	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);
 }

 /*
  * 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_skb_priv *sp;
 	struct rxrpc_txbuf *txb;
 	rxrpc_seq_t transmitted = call->tx_transmitted;
 	ktime_t next_resend = KTIME_MAX, rto = ns_to_ktime(call->peer->rto_us * NSEC_PER_USEC);
 	ktime_t resend_at = KTIME_MAX, now, delay;
 	bool unacked = false, did_send = false;
 	unsigned int i;

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

 	now = ktime_get_real();

 	if (list_empty(&call->tx_buffer))
 		goto no_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) {
 		sp = rxrpc_skb(ack_skb);
 		ack = (void *)ack_skb->data + sizeof(struct rxrpc_wire_header);

 		for (i = 0; i < sp->ack.nr_acks; i++) {
 			rxrpc_seq_t seq;

 			if (ack->acks[i] & 1)
 				continue;
 			seq = sp->ack.first_ack + 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:
 			resend_at = ktime_add(txb->last_sent, rto);
 			if (after(txb->serial, call->acks_highest_serial)) {
 				if (ktime_after(resend_at, now) &&
 				    ktime_before(resend_at, next_resend))
 					next_resend = resend_at;
 				continue; /* Ack point not yet reached */
 			}

 			rxrpc_see_txbuf(txb, rxrpc_txbuf_see_unacked);

 			trace_rxrpc_retransmit(call, txb->seq, txb->serial,
 					       ktime_sub(resend_at, now));

 			txb->flags |= RXRPC_TXBUF_RESENT;
 			rxrpc_transmit_one(call, txb);
 			did_send = true;
 			now = ktime_get_real();

 			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.
 	 */
 	if (after_eq(call->acks_prev_seq, call->tx_transmitted))
 		goto no_further_resend;

 	list_for_each_entry_from(txb, &call->tx_buffer, call_link) {
 		resend_at = ktime_add(txb->last_sent, rto);

 		if (before_eq(txb->seq, call->acks_prev_seq))
 			continue;
 		if (after(txb->seq, call->tx_transmitted))
 			break; /* Not transmitted yet */

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

 		if (ktime_after(resend_at, now)) {
 			if (ktime_before(resend_at, next_resend))
 				next_resend = resend_at;
 			continue;
 		}

 	do_resend:
 		unacked = true;

 		txb->flags |= RXRPC_TXBUF_RESENT;
 		rxrpc_transmit_one(call, txb);
 		did_send = true;
 		rxrpc_inc_stat(call->rxnet, stat_tx_data_retrans);
 		now = ktime_get_real();
 	}

 no_further_resend:
 no_resend:
 	if (resend_at < KTIME_MAX) {
 		delay = rxrpc_get_rto_backoff(call->peer, did_send);
 		resend_at = ktime_add(resend_at, delay);
 		trace_rxrpc_timer_set(call, resend_at - now, rxrpc_timer_trace_resend_reset);
 	}
 	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 (!did_send) {
 		ktime_t next_ping = ktime_add_us(call->acks_latest_ts,
 						 call->peer->srtt_us >> 3);

 		if (ktime_sub(next_ping, now) <= 0)
 			rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
 				       rxrpc_propose_ack_ping_for_0_retrans);
 	}

 	_leave("");
 }

 /*
  * Start transmitting the reply to a service.  This cancels the need to ACK the
  * request if we haven't yet done so.
  */
 static void rxrpc_begin_service_reply(struct rxrpc_call *call)
 {
 	rxrpc_set_call_state(call, RXRPC_CALL_SERVER_SEND_REPLY);
 	if (call->ackr_reason == RXRPC_ACK_DELAY)
 		call->ackr_reason = 0;
 	call->delay_ack_at = KTIME_MAX;
 	trace_rxrpc_timer_can(call, rxrpc_timer_trace_delayed_ack);
 }

 /*
  * Close the transmission phase.  After this point there is no more data to be
  * transmitted in the call.
  */
 static void rxrpc_close_tx_phase(struct rxrpc_call *call)
 {
 	_debug("________awaiting reply/ACK__________");

 	switch (__rxrpc_call_state(call)) {
 	case RXRPC_CALL_CLIENT_SEND_REQUEST:
 		rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_AWAIT_REPLY);
 		break;
 	case RXRPC_CALL_SERVER_SEND_REPLY:
 		rxrpc_set_call_state(call, RXRPC_CALL_SERVER_AWAIT_ACK);
 		break;
 	default:
 		break;
 	}
 }

 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 (!test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 		if (list_empty(&call->tx_sendmsg))
 			return;
 		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);

 		if (txb->flags & RXRPC_LAST_PACKET)
 			rxrpc_close_tx_phase(call);

 		rxrpc_transmit_one(call, txb);

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

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

 	case RXRPC_CALL_SERVER_SEND_REPLY:
 	case RXRPC_CALL_CLIENT_SEND_REQUEST:
 		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.
  */
 bool rxrpc_input_call_event(struct rxrpc_call *call, struct sk_buff *skb)
 {
 	ktime_t now, t;
 	bool resend = false;
 	s32 abort_code;

 	rxrpc_see_call(call, rxrpc_call_see_input);

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

 	if (__rxrpc_call_is_complete(call))
 		goto out;

 	/* Handle abort request locklessly, vs rxrpc_propose_abort(). */
 	abort_code = smp_load_acquire(&call->send_abort);
 	if (abort_code) {
 		rxrpc_abort_call(call, 0, call->send_abort, call->send_abort_err,
 				 call->send_abort_why);
 		goto out;
 	}

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

 	if (skb)
 		rxrpc_input_call_packet(call, skb);

 	/* If we see our async-event poke, check for timeout trippage. */
 	now = ktime_get_real();
 	t = ktime_sub(call->expect_rx_by, now);
 	if (t <= 0) {
 		trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_expect_rx);
 		goto expired;
 	}

 	t = ktime_sub(call->expect_req_by, now);
 	if (t <= 0) {
 		call->expect_req_by = KTIME_MAX;
 		if (__rxrpc_call_state(call) == RXRPC_CALL_SERVER_RECV_REQUEST) {
 			trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_idle);
 			goto expired;
 		}
 	}

 	t = ktime_sub(READ_ONCE(call->expect_term_by), now);
 	if (t <= 0) {
 		trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_hard);
 		goto expired;
 	}

 	t = ktime_sub(call->delay_ack_at, now);
 	if (t <= 0) {
 		trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_delayed_ack);
 		call->delay_ack_at = KTIME_MAX;
 		rxrpc_send_ACK(call, RXRPC_ACK_DELAY, 0,
 			       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);
 		call->ping_at = KTIME_MAX;
 		rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
 			       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);

 	now = ktime_get_real();
 	t = ktime_sub(call->keepalive_at, now);
 	if (t <= 0) {
 		trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_keepalive);
 		call->keepalive_at = KTIME_MAX;
 		rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
 			       rxrpc_propose_ack_ping_for_keepalive);
 	}

 	if (skb) {
 		struct rxrpc_skb_priv *sp = rxrpc_skb(skb);

 		if (sp->hdr.type == RXRPC_PACKET_TYPE_ACK)
 			rxrpc_congestion_degrade(call);
 	}

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

 	/* 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 &&
 	    __rxrpc_call_state(call) != RXRPC_CALL_CLIENT_RECV_REPLY &&
 	    !test_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags))
 		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 (call->ackr_nr_unacked > 2) {
 		if (call->peer->rtt_count < 3)
 			rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
 				       rxrpc_propose_ack_ping_for_rtt);
 		else if (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_old_rtt);
 		else
 			rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
 				       rxrpc_propose_ack_input_data);
 	}

 	/* Make sure the timer is restarted */
 	if (!__rxrpc_call_is_complete(call)) {
 		ktime_t next = READ_ONCE(call->expect_term_by), delay;

 #define set(T) { ktime_t _t = (T); if (ktime_before(_t, next)) next = _t; }

 		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->keepalive_at);
 		set(call->ping_at);

 		now = ktime_get_real();
 		delay = ktime_sub(next, now);
 		if (delay <= 0) {
 			rxrpc_poke_call(call, rxrpc_call_poke_timer_now);
 		} else {
 			unsigned long nowj = jiffies, delayj, nextj;

 			delayj = max(nsecs_to_jiffies(delay), 1);
 			nextj = nowj + delayj;
 			if (time_before(nextj, call->timer.expires) ||
 			    !timer_pending(&call->timer)) {
 				trace_rxrpc_timer_restart(call, delay, delayj);
 				timer_reduce(&call->timer, nextj);
 			}
 		}
 	}

 out:
 	if (__rxrpc_call_is_complete(call)) {
 		del_timer_sync(&call->timer);
 		if (!test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
 			rxrpc_disconnect_call(call);
 		if (call->security)
 			call->security->free_call_crypto(call);
 	}
 	if (call->acks_hard_ack != call->tx_bottom)
 		rxrpc_shrink_call_tx_buffer(call);
 	_leave("");
 	return true;

 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(call, 0, RX_CALL_DEAD, -ECONNRESET,
 				 rxrpc_abort_call_reset);
 	} else {
 		rxrpc_abort_call(call, 0, RX_CALL_TIMEOUT, -ETIME,
 				 rxrpc_abort_call_timeout);
 	}
 	goto out;
 }
	// 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)
	{
	ktime_t delay = ms_to_ktime(READ_ONCE(rxrpc_idle_ack_delay));
	ktime_t now = ktime_get_real();
	ktime_t ping_at = ktime_add(now, delay);

	trace_rxrpc_propose_ack(call, why, RXRPC_ACK_PING, serial);
	if (ktime_before(ping_at, call->ping_at)) {
	call->ping_at = ping_at;
	trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_ping);
	}
	}

	/*
	* 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)
	{
	ktime_t now = ktime_get_real(), delay;

	trace_rxrpc_propose_ack(call, why, RXRPC_ACK_DELAY, serial);

	if (call->peer->srtt_us)
	delay = (call->peer->srtt_us >> 3) * NSEC_PER_USEC;
	else
	delay = ms_to_ktime(READ_ONCE(rxrpc_soft_ack_delay));
	ktime_add_ms(delay, call->tx_backoff);

	call->delay_ack_at = ktime_add(now, delay);
	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);
	}

	/*
	* 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_skb_priv *sp;
	struct rxrpc_txbuf *txb;
	rxrpc_seq_t transmitted = call->tx_transmitted;
	ktime_t next_resend = KTIME_MAX, rto = ns_to_ktime(call->peer->rto_us * NSEC_PER_USEC);
	ktime_t resend_at = KTIME_MAX, now, delay;
	bool unacked = false, did_send = false;
	unsigned int i;

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

	now = ktime_get_real();

	if (list_empty(&call->tx_buffer))
	goto no_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) {
	sp = rxrpc_skb(ack_skb);
	ack = (void *)ack_skb->data + sizeof(struct rxrpc_wire_header);

	for (i = 0; i < sp->ack.nr_acks; i++) {
	rxrpc_seq_t seq;

	if (ack->acks[i] & 1)
	continue;
	seq = sp->ack.first_ack + 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:
	resend_at = ktime_add(txb->last_sent, rto);
	if (after(txb->serial, call->acks_highest_serial)) {
	if (ktime_after(resend_at, now) &&
	ktime_before(resend_at, next_resend))
	next_resend = resend_at;
	continue; /* Ack point not yet reached */
	}

	rxrpc_see_txbuf(txb, rxrpc_txbuf_see_unacked);

	trace_rxrpc_retransmit(call, txb->seq, txb->serial,
	ktime_sub(resend_at, now));

	txb->flags \|= RXRPC_TXBUF_RESENT;
	rxrpc_transmit_one(call, txb);
	did_send = true;
	now = ktime_get_real();

	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.
	*/
	if (after_eq(call->acks_prev_seq, call->tx_transmitted))
	goto no_further_resend;

	list_for_each_entry_from(txb, &call->tx_buffer, call_link) {
	resend_at = ktime_add(txb->last_sent, rto);

	if (before_eq(txb->seq, call->acks_prev_seq))
	continue;
	if (after(txb->seq, call->tx_transmitted))
	break; /* Not transmitted yet */

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

	if (ktime_after(resend_at, now)) {
	if (ktime_before(resend_at, next_resend))
	next_resend = resend_at;
	continue;
	}

	do_resend:
	unacked = true;

	txb->flags \|= RXRPC_TXBUF_RESENT;
	rxrpc_transmit_one(call, txb);
	did_send = true;
	rxrpc_inc_stat(call->rxnet, stat_tx_data_retrans);
	now = ktime_get_real();
	}

	no_further_resend:
	no_resend:
	if (resend_at < KTIME_MAX) {
	delay = rxrpc_get_rto_backoff(call->peer, did_send);
	resend_at = ktime_add(resend_at, delay);
	trace_rxrpc_timer_set(call, resend_at - now, rxrpc_timer_trace_resend_reset);
	}
	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 (!did_send) {
	ktime_t next_ping = ktime_add_us(call->acks_latest_ts,
	call->peer->srtt_us >> 3);

	if (ktime_sub(next_ping, now) <= 0)
	rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
	rxrpc_propose_ack_ping_for_0_retrans);
	}

	_leave("");
	}

	/*
	* Start transmitting the reply to a service. This cancels the need to ACK the
	* request if we haven't yet done so.
	*/
	static void rxrpc_begin_service_reply(struct rxrpc_call *call)
	{
	rxrpc_set_call_state(call, RXRPC_CALL_SERVER_SEND_REPLY);
	if (call->ackr_reason == RXRPC_ACK_DELAY)
	call->ackr_reason = 0;
	call->delay_ack_at = KTIME_MAX;
	trace_rxrpc_timer_can(call, rxrpc_timer_trace_delayed_ack);
	}

	/*
	* Close the transmission phase. After this point there is no more data to be
	* transmitted in the call.
	*/
	static void rxrpc_close_tx_phase(struct rxrpc_call *call)
	{
	_debug("________awaiting reply/ACK__________");

	switch (__rxrpc_call_state(call)) {
	case RXRPC_CALL_CLIENT_SEND_REQUEST:
	rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_AWAIT_REPLY);
	break;
	case RXRPC_CALL_SERVER_SEND_REPLY:
	rxrpc_set_call_state(call, RXRPC_CALL_SERVER_AWAIT_ACK);
	break;
	default:
	break;
	}
	}

	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 (!test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
	if (list_empty(&call->tx_sendmsg))
	return;
	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);

	if (txb->flags & RXRPC_LAST_PACKET)
	rxrpc_close_tx_phase(call);

	rxrpc_transmit_one(call, txb);

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

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

	case RXRPC_CALL_SERVER_SEND_REPLY:
	case RXRPC_CALL_CLIENT_SEND_REQUEST:
	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.
	*/
	bool rxrpc_input_call_event(struct rxrpc_call call, struct sk_buff skb)
	{
	ktime_t now, t;
	bool resend = false;
	s32 abort_code;

	rxrpc_see_call(call, rxrpc_call_see_input);

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

	if (__rxrpc_call_is_complete(call))
	goto out;

	/* Handle abort request locklessly, vs rxrpc_propose_abort(). */
	abort_code = smp_load_acquire(&call->send_abort);
	if (abort_code) {
	rxrpc_abort_call(call, 0, call->send_abort, call->send_abort_err,
	call->send_abort_why);
	goto out;
	}

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

	if (skb)
	rxrpc_input_call_packet(call, skb);

	/* If we see our async-event poke, check for timeout trippage. */
	now = ktime_get_real();
	t = ktime_sub(call->expect_rx_by, now);
	if (t <= 0) {
	trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_expect_rx);
	goto expired;
	}

	t = ktime_sub(call->expect_req_by, now);
	if (t <= 0) {
	call->expect_req_by = KTIME_MAX;
	if (__rxrpc_call_state(call) == RXRPC_CALL_SERVER_RECV_REQUEST) {
	trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_idle);
	goto expired;
	}
	}

	t = ktime_sub(READ_ONCE(call->expect_term_by), now);
	if (t <= 0) {
	trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_hard);
	goto expired;
	}

	t = ktime_sub(call->delay_ack_at, now);
	if (t <= 0) {
	trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_delayed_ack);
	call->delay_ack_at = KTIME_MAX;
	rxrpc_send_ACK(call, RXRPC_ACK_DELAY, 0,
	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);
	call->ping_at = KTIME_MAX;
	rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
	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);

	now = ktime_get_real();
	t = ktime_sub(call->keepalive_at, now);
	if (t <= 0) {
	trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_keepalive);
	call->keepalive_at = KTIME_MAX;
	rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
	rxrpc_propose_ack_ping_for_keepalive);
	}

	if (skb) {
	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);

	if (sp->hdr.type == RXRPC_PACKET_TYPE_ACK)
	rxrpc_congestion_degrade(call);
	}

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

	/* 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 &&
	__rxrpc_call_state(call) != RXRPC_CALL_CLIENT_RECV_REPLY &&
	!test_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags))
	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 (call->ackr_nr_unacked > 2) {
	if (call->peer->rtt_count < 3)
	rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
	rxrpc_propose_ack_ping_for_rtt);
	else if (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_old_rtt);
	else
	rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
	rxrpc_propose_ack_input_data);
	}

	/* Make sure the timer is restarted */
	if (!__rxrpc_call_is_complete(call)) {
	ktime_t next = READ_ONCE(call->expect_term_by), delay;

	#define set(T) { ktime_t _t = (T); if (ktime_before(_t, next)) next = _t; }

	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->keepalive_at);
	set(call->ping_at);

	now = ktime_get_real();
	delay = ktime_sub(next, now);
	if (delay <= 0) {
	rxrpc_poke_call(call, rxrpc_call_poke_timer_now);
	} else {
	unsigned long nowj = jiffies, delayj, nextj;

	delayj = max(nsecs_to_jiffies(delay), 1);
	nextj = nowj + delayj;
	if (time_before(nextj, call->timer.expires) \|\|
	!timer_pending(&call->timer)) {
	trace_rxrpc_timer_restart(call, delay, delayj);
	timer_reduce(&call->timer, nextj);
	}
	}
	}

	out:
	if (__rxrpc_call_is_complete(call)) {
	del_timer_sync(&call->timer);
	if (!test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
	rxrpc_disconnect_call(call);
	if (call->security)
	call->security->free_call_crypto(call);
	}
	if (call->acks_hard_ack != call->tx_bottom)
	rxrpc_shrink_call_tx_buffer(call);
	_leave("");
	return true;

	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(call, 0, RX_CALL_DEAD, -ECONNRESET,
	rxrpc_abort_call_reset);
	} else {
	rxrpc_abort_call(call, 0, RX_CALL_TIMEOUT, -ETIME,
	rxrpc_abort_call_timeout);
	}
	goto out;
	}