net/rxrpc/call_event.c - third_party/kernel - 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.
  */
 static void rxrpc_propose_ping(struct rxrpc_call *call,
 			       bool immediate, bool background)
 {
 	if (immediate) {
 		if (background &&
 		    !test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
 			rxrpc_queue_call(call);
 	} else {
 		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);
 		}
 	}
 }

 /*
  * propose an ACK be sent
  */
 static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
 				u32 serial, bool immediate, bool background,
 				enum rxrpc_propose_ack_trace why)
 {
 	enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
 	unsigned long expiry = rxrpc_soft_ack_delay;
 	s8 prior = rxrpc_ack_priority[ack_reason];

 	/* Pings are handled specially because we don't want to accidentally
 	 * lose a ping response by subsuming it into a ping.
 	 */
 	if (ack_reason == RXRPC_ACK_PING) {
 		rxrpc_propose_ping(call, immediate, background);
 		goto trace;
 	}

 	/* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
 	 * numbers, but we don't alter the timeout.
 	 */
 	_debug("prior %u %u vs %u %u",
 	       ack_reason, prior,
 	       call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]);
 	if (ack_reason == call->ackr_reason) {
 		if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) {
 			outcome = rxrpc_propose_ack_update;
 			call->ackr_serial = serial;
 		}
 		if (!immediate)
 			goto trace;
 	} else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
 		call->ackr_reason = ack_reason;
 		call->ackr_serial = serial;
 	} else {
 		outcome = rxrpc_propose_ack_subsume;
 	}

 	switch (ack_reason) {
 	case RXRPC_ACK_REQUESTED:
 		if (rxrpc_requested_ack_delay < expiry)
 			expiry = rxrpc_requested_ack_delay;
 		if (serial == 1)
 			immediate = false;
 		break;

 	case RXRPC_ACK_DELAY:
 		if (rxrpc_soft_ack_delay < expiry)
 			expiry = rxrpc_soft_ack_delay;
 		break;

 	case RXRPC_ACK_IDLE:
 		if (rxrpc_idle_ack_delay < expiry)
 			expiry = rxrpc_idle_ack_delay;
 		break;

 	default:
 		immediate = true;
 		break;
 	}

 	if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) {
 		_debug("already scheduled");
 	} else if (immediate || expiry == 0) {
 		_debug("immediate ACK %lx", call->events);
 		if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) &&
 		    background)
 			rxrpc_queue_call(call);
 	} else {
 		unsigned long now = jiffies, ack_at;

 		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->ack_at)) {
 			WRITE_ONCE(call->ack_at, ack_at);
 			rxrpc_reduce_call_timer(call, ack_at, now,
 						rxrpc_timer_set_for_ack);
 		}
 	}

 trace:
 	trace_rxrpc_propose_ack(call, why, ack_reason, serial, immediate,
 				background, outcome);
 }

 /*
  * propose an ACK be sent, locking the call structure
  */
 void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
 		       u32 serial, bool immediate, bool background,
 		       enum rxrpc_propose_ack_trace why)
 {
 	spin_lock_bh(&call->lock);
 	__rxrpc_propose_ACK(call, ack_reason, serial,
 			    immediate, background, why);
 	spin_unlock_bh(&call->lock);
 }

 /*
  * 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, unsigned long now_j)
 {
 	struct sk_buff *skb;
 	unsigned long resend_at;
 	rxrpc_seq_t cursor, seq, top;
 	ktime_t now, max_age, oldest, ack_ts;
 	int ix;
 	u8 annotation, anno_type, retrans = 0, unacked = 0;

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

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

 	spin_lock_bh(&call->lock);

 	cursor = call->tx_hard_ack;
 	top = call->tx_top;
 	ASSERT(before_eq(cursor, top));
 	if (cursor == top)
 		goto out_unlock;

 	/* Scan the packet list without dropping the lock and decide which of
 	 * the packets in the Tx buffer we're going to resend and what the new
 	 * resend timeout will be.
 	 */
 	trace_rxrpc_resend(call, (cursor + 1) & RXRPC_RXTX_BUFF_MASK);
 	oldest = now;
 	for (seq = cursor + 1; before_eq(seq, top); seq++) {
 		ix = seq & RXRPC_RXTX_BUFF_MASK;
 		annotation = call->rxtx_annotations[ix];
 		anno_type = annotation & RXRPC_TX_ANNO_MASK;
 		annotation &= ~RXRPC_TX_ANNO_MASK;
 		if (anno_type == RXRPC_TX_ANNO_ACK)
 			continue;

 		skb = call->rxtx_buffer[ix];
 		rxrpc_see_skb(skb, rxrpc_skb_seen);

 		if (anno_type == RXRPC_TX_ANNO_UNACK) {
 			if (ktime_after(skb->tstamp, max_age)) {
 				if (ktime_before(skb->tstamp, oldest))
 					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)));
 	}

 	resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
 	resend_at += jiffies + rxrpc_get_rto_backoff(call->peer, retrans);
 	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 (!retrans) {
 		rxrpc_reduce_call_timer(call, resend_at, now_j,
 					rxrpc_timer_set_for_resend);
 		spin_unlock_bh(&call->lock);
 		ack_ts = ktime_sub(now, call->acks_latest_ts);
 		if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3))
 			goto out;
 		rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
 				  rxrpc_propose_ack_ping_for_lost_ack);
 		rxrpc_send_ack_packet(call, true, NULL);
 		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
 	 * packets that it soft-ACKs.
 	 */
 	for (seq = cursor + 1; before_eq(seq, top); seq++) {
 		ix = seq & RXRPC_RXTX_BUFF_MASK;
 		annotation = call->rxtx_annotations[ix];
 		anno_type = annotation & RXRPC_TX_ANNO_MASK;
 		if (anno_type != RXRPC_TX_ANNO_RETRANS)
 			continue;

 		/* We need to reset the retransmission state, but we need to do
 		 * so before we drop the lock as a new ACK/NAK may come in and
 		 * confuse things
 		 */
 		annotation &= ~RXRPC_TX_ANNO_MASK;
 		annotation |= RXRPC_TX_ANNO_UNACK | RXRPC_TX_ANNO_RESENT;
 		call->rxtx_annotations[ix] = annotation;

 		skb = call->rxtx_buffer[ix];
 		if (!skb)
 			continue;

 		rxrpc_get_skb(skb, rxrpc_skb_got);
 		spin_unlock_bh(&call->lock);

 		if (rxrpc_send_data_packet(call, skb, true) < 0) {
 			rxrpc_free_skb(skb, rxrpc_skb_freed);
 			return;
 		}

 		if (rxrpc_is_client_call(call))
 			rxrpc_expose_client_call(call);

 		rxrpc_free_skb(skb, rxrpc_skb_freed);
 		spin_lock_bh(&call->lock);
 		if (after(call->tx_hard_ack, seq))
 			seq = call->tx_hard_ack;
 	}

 out_unlock:
 	spin_unlock_bh(&call->lock);
 out:
 	_leave("");
 }

 /*
  * Handle retransmission and deferred ACK/abort generation.
  */
 void rxrpc_process_call(struct work_struct *work)
 {
 	struct rxrpc_call *call =
 		container_of(work, struct rxrpc_call, processor);
 	rxrpc_serial_t *send_ack;
 	unsigned long now, next, t;
 	unsigned int iterations = 0;

 	rxrpc_see_call(call);

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

 recheck_state:
 	/* Limit the number of times we do this before returning to the manager */
 	iterations++;
 	if (iterations > 5)
 		goto requeue;

 	if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
 		rxrpc_send_abort_packet(call);
 		goto recheck_state;
 	}

 	if (call->state == RXRPC_CALL_COMPLETE) {
 		rxrpc_delete_call_timer(call);
 		goto out_put;
 	}

 	/* Work out if any timeouts tripped */
 	now = jiffies;
 	t = READ_ONCE(call->expect_rx_by);
 	if (time_after_eq(now, t)) {
 		trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
 		set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
 	}

 	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);
 		set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
 	}

 	t = READ_ONCE(call->expect_term_by);
 	if (time_after_eq(now, t)) {
 		trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
 		set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
 	}

 	t = READ_ONCE(call->ack_at);
 	if (time_after_eq(now, t)) {
 		trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
 		cmpxchg(&call->ack_at, t, now + MAX_JIFFY_OFFSET);
 		set_bit(RXRPC_CALL_EV_ACK, &call->events);
 	}

 	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_propose_ACK(call, RXRPC_ACK_PING, 0, true, true,
 				  rxrpc_propose_ack_ping_for_keepalive);
 		set_bit(RXRPC_CALL_EV_PING, &call->events);
 	}

 	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);
 		set_bit(RXRPC_CALL_EV_PING, &call->events);
 	}

 	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);
 		set_bit(RXRPC_CALL_EV_RESEND, &call->events);
 	}

 	/* Process events */
 	if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED, &call->events)) {
 		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);
 		}
 		set_bit(RXRPC_CALL_EV_ABORT, &call->events);
 		goto recheck_state;
 	}

 	send_ack = NULL;
 	if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events)) {
 		call->acks_lost_top = call->tx_top;
 		rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
 				  rxrpc_propose_ack_ping_for_lost_ack);
 		send_ack = &call->acks_lost_ping;
 	}

 	if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) ||
 	    send_ack) {
 		if (call->ackr_reason) {
 			rxrpc_send_ack_packet(call, false, send_ack);
 			goto recheck_state;
 		}
 	}

 	if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {
 		rxrpc_send_ack_packet(call, true, NULL);
 		goto recheck_state;
 	}

 	if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events) &&
 	    call->state != RXRPC_CALL_CLIENT_RECV_REPLY) {
 		rxrpc_resend(call, now);
 		goto recheck_state;
 	}

 	/* Make sure the timer is restarted */
 	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->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))
 		goto recheck_state;

 	rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);

 	/* other events may have been raised since we started checking */
 	if (call->events && call->state < RXRPC_CALL_COMPLETE)
 		goto requeue;

 out_put:
 	rxrpc_put_call(call, rxrpc_call_put);
 out:
 	_leave("");
 	return;

 requeue:
 	__rxrpc_queue_call(call);
 	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.
	*/
	static void rxrpc_propose_ping(struct rxrpc_call *call,
	bool immediate, bool background)
	{
	if (immediate) {
	if (background &&
	!test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
	rxrpc_queue_call(call);
	} else {
	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);
	}
	}
	}

	/*
	* propose an ACK be sent
	*/
	static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
	u32 serial, bool immediate, bool background,
	enum rxrpc_propose_ack_trace why)
	{
	enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
	unsigned long expiry = rxrpc_soft_ack_delay;
	s8 prior = rxrpc_ack_priority[ack_reason];

	/* Pings are handled specially because we don't want to accidentally
	* lose a ping response by subsuming it into a ping.
	*/
	if (ack_reason == RXRPC_ACK_PING) {
	rxrpc_propose_ping(call, immediate, background);
	goto trace;
	}

	/* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
	* numbers, but we don't alter the timeout.
	*/
	_debug("prior %u %u vs %u %u",
	ack_reason, prior,
	call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]);
	if (ack_reason == call->ackr_reason) {
	if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) {
	outcome = rxrpc_propose_ack_update;
	call->ackr_serial = serial;
	}
	if (!immediate)
	goto trace;
	} else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
	call->ackr_reason = ack_reason;
	call->ackr_serial = serial;
	} else {
	outcome = rxrpc_propose_ack_subsume;
	}

	switch (ack_reason) {
	case RXRPC_ACK_REQUESTED:
	if (rxrpc_requested_ack_delay < expiry)
	expiry = rxrpc_requested_ack_delay;
	if (serial == 1)
	immediate = false;
	break;

	case RXRPC_ACK_DELAY:
	if (rxrpc_soft_ack_delay < expiry)
	expiry = rxrpc_soft_ack_delay;
	break;

	case RXRPC_ACK_IDLE:
	if (rxrpc_idle_ack_delay < expiry)
	expiry = rxrpc_idle_ack_delay;
	break;

	default:
	immediate = true;
	break;
	}

	if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) {
	_debug("already scheduled");
	} else if (immediate \|\| expiry == 0) {
	_debug("immediate ACK %lx", call->events);
	if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) &&
	background)
	rxrpc_queue_call(call);
	} else {
	unsigned long now = jiffies, ack_at;

	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->ack_at)) {
	WRITE_ONCE(call->ack_at, ack_at);
	rxrpc_reduce_call_timer(call, ack_at, now,
	rxrpc_timer_set_for_ack);
	}
	}

	trace:
	trace_rxrpc_propose_ack(call, why, ack_reason, serial, immediate,
	background, outcome);
	}

	/*
	* propose an ACK be sent, locking the call structure
	*/
	void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
	u32 serial, bool immediate, bool background,
	enum rxrpc_propose_ack_trace why)
	{
	spin_lock_bh(&call->lock);
	__rxrpc_propose_ACK(call, ack_reason, serial,
	immediate, background, why);
	spin_unlock_bh(&call->lock);
	}

	/*
	* 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, unsigned long now_j)
	{
	struct sk_buff *skb;
	unsigned long resend_at;
	rxrpc_seq_t cursor, seq, top;
	ktime_t now, max_age, oldest, ack_ts;
	int ix;
	u8 annotation, anno_type, retrans = 0, unacked = 0;

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

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

	spin_lock_bh(&call->lock);

	cursor = call->tx_hard_ack;
	top = call->tx_top;
	ASSERT(before_eq(cursor, top));
	if (cursor == top)
	goto out_unlock;

	/* Scan the packet list without dropping the lock and decide which of
	* the packets in the Tx buffer we're going to resend and what the new
	* resend timeout will be.
	*/
	trace_rxrpc_resend(call, (cursor + 1) & RXRPC_RXTX_BUFF_MASK);
	oldest = now;
	for (seq = cursor + 1; before_eq(seq, top); seq++) {
	ix = seq & RXRPC_RXTX_BUFF_MASK;
	annotation = call->rxtx_annotations[ix];
	anno_type = annotation & RXRPC_TX_ANNO_MASK;
	annotation &= ~RXRPC_TX_ANNO_MASK;
	if (anno_type == RXRPC_TX_ANNO_ACK)
	continue;

	skb = call->rxtx_buffer[ix];
	rxrpc_see_skb(skb, rxrpc_skb_seen);

	if (anno_type == RXRPC_TX_ANNO_UNACK) {
	if (ktime_after(skb->tstamp, max_age)) {
	if (ktime_before(skb->tstamp, oldest))
	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)));
	}

	resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
	resend_at += jiffies + rxrpc_get_rto_backoff(call->peer, retrans);
	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 (!retrans) {
	rxrpc_reduce_call_timer(call, resend_at, now_j,
	rxrpc_timer_set_for_resend);
	spin_unlock_bh(&call->lock);
	ack_ts = ktime_sub(now, call->acks_latest_ts);
	if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3))
	goto out;
	rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
	rxrpc_propose_ack_ping_for_lost_ack);
	rxrpc_send_ack_packet(call, true, NULL);
	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
	* packets that it soft-ACKs.
	*/
	for (seq = cursor + 1; before_eq(seq, top); seq++) {
	ix = seq & RXRPC_RXTX_BUFF_MASK;
	annotation = call->rxtx_annotations[ix];
	anno_type = annotation & RXRPC_TX_ANNO_MASK;
	if (anno_type != RXRPC_TX_ANNO_RETRANS)
	continue;

	/* We need to reset the retransmission state, but we need to do
	* so before we drop the lock as a new ACK/NAK may come in and
	* confuse things
	*/
	annotation &= ~RXRPC_TX_ANNO_MASK;
	annotation \|= RXRPC_TX_ANNO_UNACK \| RXRPC_TX_ANNO_RESENT;
	call->rxtx_annotations[ix] = annotation;

	skb = call->rxtx_buffer[ix];
	if (!skb)
	continue;

	rxrpc_get_skb(skb, rxrpc_skb_got);
	spin_unlock_bh(&call->lock);

	if (rxrpc_send_data_packet(call, skb, true) < 0) {
	rxrpc_free_skb(skb, rxrpc_skb_freed);
	return;
	}

	if (rxrpc_is_client_call(call))
	rxrpc_expose_client_call(call);

	rxrpc_free_skb(skb, rxrpc_skb_freed);
	spin_lock_bh(&call->lock);
	if (after(call->tx_hard_ack, seq))
	seq = call->tx_hard_ack;
	}

	out_unlock:
	spin_unlock_bh(&call->lock);
	out:
	_leave("");
	}

	/*
	* Handle retransmission and deferred ACK/abort generation.
	*/
	void rxrpc_process_call(struct work_struct *work)
	{
	struct rxrpc_call *call =
	container_of(work, struct rxrpc_call, processor);
	rxrpc_serial_t *send_ack;
	unsigned long now, next, t;
	unsigned int iterations = 0;

	rxrpc_see_call(call);

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

	recheck_state:
	/* Limit the number of times we do this before returning to the manager */
	iterations++;
	if (iterations > 5)
	goto requeue;

	if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
	rxrpc_send_abort_packet(call);
	goto recheck_state;
	}

	if (call->state == RXRPC_CALL_COMPLETE) {
	rxrpc_delete_call_timer(call);
	goto out_put;
	}

	/* Work out if any timeouts tripped */
	now = jiffies;
	t = READ_ONCE(call->expect_rx_by);
	if (time_after_eq(now, t)) {
	trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
	set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
	}

	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);
	set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
	}

	t = READ_ONCE(call->expect_term_by);
	if (time_after_eq(now, t)) {
	trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
	set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
	}

	t = READ_ONCE(call->ack_at);
	if (time_after_eq(now, t)) {
	trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
	cmpxchg(&call->ack_at, t, now + MAX_JIFFY_OFFSET);
	set_bit(RXRPC_CALL_EV_ACK, &call->events);
	}

	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_propose_ACK(call, RXRPC_ACK_PING, 0, true, true,
	rxrpc_propose_ack_ping_for_keepalive);
	set_bit(RXRPC_CALL_EV_PING, &call->events);
	}

	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);
	set_bit(RXRPC_CALL_EV_PING, &call->events);
	}

	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);
	set_bit(RXRPC_CALL_EV_RESEND, &call->events);
	}

	/* Process events */
	if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED, &call->events)) {
	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);
	}
	set_bit(RXRPC_CALL_EV_ABORT, &call->events);
	goto recheck_state;
	}

	send_ack = NULL;
	if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events)) {
	call->acks_lost_top = call->tx_top;
	rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
	rxrpc_propose_ack_ping_for_lost_ack);
	send_ack = &call->acks_lost_ping;
	}

	if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) \|\|
	send_ack) {
	if (call->ackr_reason) {
	rxrpc_send_ack_packet(call, false, send_ack);
	goto recheck_state;
	}
	}

	if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {
	rxrpc_send_ack_packet(call, true, NULL);
	goto recheck_state;
	}

	if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events) &&
	call->state != RXRPC_CALL_CLIENT_RECV_REPLY) {
	rxrpc_resend(call, now);
	goto recheck_state;
	}

	/* Make sure the timer is restarted */
	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->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))
	goto recheck_state;

	rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);

	/* other events may have been raised since we started checking */
	if (call->events && call->state < RXRPC_CALL_COMPLETE)
	goto requeue;

	out_put:
	rxrpc_put_call(call, rxrpc_call_put);
	out:
	_leave("");
	return;

	requeue:
	__rxrpc_queue_call(call);
	goto out;
	}