[mirror_ubuntu-bionic-kernel.git] / net / rxrpc / call_event.c

/* 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)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#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,
				u16 skew, 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;
			call->ackr_skew = skew;
		}
		if (!immediate)
			goto trace;
	} else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
		call->ackr_reason = ack_reason;
		call->ackr_serial = serial;
		call->ackr_skew = skew;
	} 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->rtt_usage > 0)
			ack_at = nsecs_to_jiffies(call->peer->rtt);
		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,
		       u16 skew, u32 serial, bool immediate, bool background,
		       enum rxrpc_propose_ack_trace why)
{
	spin_lock_bh(&call->lock);
	__rxrpc_propose_ACK(call, ack_reason, skew, 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 rxrpc_skb_priv *sp;
	struct sk_buff *skb;
	unsigned long resend_at;
	rxrpc_seq_t cursor, seq, top;
	ktime_t now, max_age, oldest, ack_ts, timeout, min_timeo;
	int ix;
	u8 annotation, anno_type, retrans = 0, unacked = 0;

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

	if (call->peer->rtt_usage > 1)
		timeout = ns_to_ktime(call->peer->rtt * 3 / 2);
	else
		timeout = ms_to_ktime(rxrpc_resend_timeout);
	min_timeo = ns_to_ktime((1000000000 / HZ) * 4);
	if (ktime_before(timeout, min_timeo))
		timeout = min_timeo;

	now = ktime_get_real();
	max_age = ktime_sub(now, timeout);

	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.
	 */
	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_tx_seen);
		sp = rxrpc_skb(skb);

		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_resend_timeout;
	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,
					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_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;

		skb = call->rxtx_buffer[ix];
		rxrpc_get_skb(skb, rxrpc_skb_tx_got);
		spin_unlock_bh(&call->lock);

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

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

		rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
		spin_lock_bh(&call->lock);

		/* We need to clear the retransmit state, but there are two
		 * things we need to be aware of: A new ACK/NAK might have been
		 * received and the packet might have been hard-ACK'd (in which
		 * case it will no longer be in the buffer).
		 */
		if (after(seq, call->tx_hard_ack)) {
			annotation = call->rxtx_annotations[ix];
			anno_type = annotation & RXRPC_TX_ANNO_MASK;
			if (anno_type == RXRPC_TX_ANNO_RETRANS ||
			    anno_type == RXRPC_TX_ANNO_NAK) {
				annotation &= ~RXRPC_TX_ANNO_MASK;
				annotation |= RXRPC_TX_ANNO_UNACK;
			}
			annotation |= RXRPC_TX_ANNO_RESENT;
			call->rxtx_annotations[ix] = annotation;
		}

		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) {
		del_timer_sync(&call->timer);
		rxrpc_notify_socket(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, 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)) {
		rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -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, 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)) {
		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;
}
Commit	Line	Data
	1	/* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
	2	*
	3	* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11
	12	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	13
	14	#include <linux/module.h>
	15	#include <linux/circ_buf.h>
	16	#include <linux/net.h>
	17	#include <linux/skbuff.h>
	18	#include <linux/slab.h>
	19	#include <linux/udp.h>
	20	#include <net/sock.h>
	21	#include <net/af_rxrpc.h>
	22	#include "ar-internal.h"
	23
	24	/*
	25	* Propose a PING ACK be sent.
	26	*/
	27	static void rxrpc_propose_ping(struct rxrpc_call *call,
	28	bool immediate, bool background)
	29	{
	30	if (immediate) {
	31	if (background &&
	32	!test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
	33	rxrpc_queue_call(call);
	34	} else {
	35	unsigned long now = jiffies;
	36	unsigned long ping_at = now + rxrpc_idle_ack_delay;
	37
	38	if (time_before(ping_at, call->ping_at)) {
	39	WRITE_ONCE(call->ping_at, ping_at);
	40	rxrpc_reduce_call_timer(call, ping_at, now,
	41	rxrpc_timer_set_for_ping);
	42	}
	43	}
	44	}
	45
	46	/*
	47	* propose an ACK be sent
	48	*/
	49	static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
	50	u16 skew, u32 serial, bool immediate,
	51	bool background,
	52	enum rxrpc_propose_ack_trace why)
	53	{
	54	enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
	55	unsigned long expiry = rxrpc_soft_ack_delay;
	56	s8 prior = rxrpc_ack_priority[ack_reason];
	57
	58	/* Pings are handled specially because we don't want to accidentally
	59	* lose a ping response by subsuming it into a ping.
	60	*/
	61	if (ack_reason == RXRPC_ACK_PING) {
	62	rxrpc_propose_ping(call, immediate, background);
	63	goto trace;
	64	}
	65
	66	/* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
	67	* numbers, but we don't alter the timeout.
	68	*/
	69	_debug("prior %u %u vs %u %u",
	70	ack_reason, prior,
	71	call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]);
	72	if (ack_reason == call->ackr_reason) {
	73	if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) {
	74	outcome = rxrpc_propose_ack_update;
	75	call->ackr_serial = serial;
	76	call->ackr_skew = skew;
	77	}
	78	if (!immediate)
	79	goto trace;
	80	} else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
	81	call->ackr_reason = ack_reason;
	82	call->ackr_serial = serial;
	83	call->ackr_skew = skew;
	84	} else {
	85	outcome = rxrpc_propose_ack_subsume;
	86	}
	87
	88	switch (ack_reason) {
	89	case RXRPC_ACK_REQUESTED:
	90	if (rxrpc_requested_ack_delay < expiry)
	91	expiry = rxrpc_requested_ack_delay;
	92	if (serial == 1)
	93	immediate = false;
	94	break;
	95
	96	case RXRPC_ACK_DELAY:
	97	if (rxrpc_soft_ack_delay < expiry)
	98	expiry = rxrpc_soft_ack_delay;
	99	break;
	100
	101	case RXRPC_ACK_IDLE:
	102	if (rxrpc_idle_ack_delay < expiry)
	103	expiry = rxrpc_idle_ack_delay;
	104	break;
	105
	106	default:
	107	immediate = true;
	108	break;
	109	}
	110
	111	if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) {
	112	_debug("already scheduled");
	113	} else if (immediate \|\| expiry == 0) {
	114	_debug("immediate ACK %lx", call->events);
	115	if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) &&
	116	background)
	117	rxrpc_queue_call(call);
	118	} else {
	119	unsigned long now = jiffies, ack_at;
	120
	121	if (call->peer->rtt_usage > 0)
	122	ack_at = nsecs_to_jiffies(call->peer->rtt);
	123	else
	124	ack_at = expiry;
	125
	126	ack_at += READ_ONCE(call->tx_backoff);
	127	ack_at += now;
	128	if (time_before(ack_at, call->ack_at)) {
	129	WRITE_ONCE(call->ack_at, ack_at);
	130	rxrpc_reduce_call_timer(call, ack_at, now,
	131	rxrpc_timer_set_for_ack);
	132	}
	133	}
	134
	135	trace:
	136	trace_rxrpc_propose_ack(call, why, ack_reason, serial, immediate,
	137	background, outcome);
	138	}
	139
	140	/*
	141	* propose an ACK be sent, locking the call structure
	142	*/
	143	void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
	144	u16 skew, u32 serial, bool immediate, bool background,
	145	enum rxrpc_propose_ack_trace why)
	146	{
	147	spin_lock_bh(&call->lock);
	148	__rxrpc_propose_ACK(call, ack_reason, skew, serial,
	149	immediate, background, why);
	150	spin_unlock_bh(&call->lock);
	151	}
	152
	153	/*
	154	* Handle congestion being detected by the retransmit timeout.
	155	*/
	156	static void rxrpc_congestion_timeout(struct rxrpc_call *call)
	157	{
	158	set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
	159	}
	160
	161	/*
	162	* Perform retransmission of NAK'd and unack'd packets.
	163	*/
	164	static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
	165	{
	166	struct rxrpc_skb_priv *sp;
	167	struct sk_buff *skb;
	168	unsigned long resend_at;
	169	rxrpc_seq_t cursor, seq, top;
	170	ktime_t now, max_age, oldest, ack_ts, timeout, min_timeo;
	171	int ix;
	172	u8 annotation, anno_type, retrans = 0, unacked = 0;
	173
	174	_enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
	175
	176	if (call->peer->rtt_usage > 1)
	177	timeout = ns_to_ktime(call->peer->rtt * 3 / 2);
	178	else
	179	timeout = ms_to_ktime(rxrpc_resend_timeout);
	180	min_timeo = ns_to_ktime((1000000000 / HZ) * 4);
	181	if (ktime_before(timeout, min_timeo))
	182	timeout = min_timeo;
	183
	184	now = ktime_get_real();
	185	max_age = ktime_sub(now, timeout);
	186
	187	spin_lock_bh(&call->lock);
	188
	189	cursor = call->tx_hard_ack;
	190	top = call->tx_top;
	191	ASSERT(before_eq(cursor, top));
	192	if (cursor == top)
	193	goto out_unlock;
	194
	195	/* Scan the packet list without dropping the lock and decide which of
	196	* the packets in the Tx buffer we're going to resend and what the new
	197	* resend timeout will be.
	198	*/
	199	oldest = now;
	200	for (seq = cursor + 1; before_eq(seq, top); seq++) {
	201	ix = seq & RXRPC_RXTX_BUFF_MASK;
	202	annotation = call->rxtx_annotations[ix];
	203	anno_type = annotation & RXRPC_TX_ANNO_MASK;
	204	annotation &= ~RXRPC_TX_ANNO_MASK;
	205	if (anno_type == RXRPC_TX_ANNO_ACK)
	206	continue;
	207
	208	skb = call->rxtx_buffer[ix];
	209	rxrpc_see_skb(skb, rxrpc_skb_tx_seen);
	210	sp = rxrpc_skb(skb);
	211
	212	if (anno_type == RXRPC_TX_ANNO_UNACK) {
	213	if (ktime_after(skb->tstamp, max_age)) {
	214	if (ktime_before(skb->tstamp, oldest))
	215	oldest = skb->tstamp;
	216	continue;
	217	}
	218	if (!(annotation & RXRPC_TX_ANNO_RESENT))
	219	unacked++;
	220	}
	221
	222	/* Okay, we need to retransmit a packet. */
	223	call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS \| annotation;
	224	retrans++;
	225	trace_rxrpc_retransmit(call, seq, annotation \| anno_type,
	226	ktime_to_ns(ktime_sub(skb->tstamp, max_age)));
	227	}
	228
	229	resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
	230	resend_at += jiffies + rxrpc_resend_timeout;
	231	WRITE_ONCE(call->resend_at, resend_at);
	232
	233	if (unacked)
	234	rxrpc_congestion_timeout(call);
	235
	236	/* If there was nothing that needed retransmission then it's likely
	237	* that an ACK got lost somewhere. Send a ping to find out instead of
	238	* retransmitting data.
	239	*/
	240	if (!retrans) {
	241	rxrpc_reduce_call_timer(call, resend_at, now,
	242	rxrpc_timer_set_for_resend);
	243	spin_unlock_bh(&call->lock);
	244	ack_ts = ktime_sub(now, call->acks_latest_ts);
	245	if (ktime_to_ns(ack_ts) < call->peer->rtt)
	246	goto out;
	247	rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false,
	248	rxrpc_propose_ack_ping_for_lost_ack);
	249	rxrpc_send_ack_packet(call, true, NULL);
	250	goto out;
	251	}
	252
	253	/* Now go through the Tx window and perform the retransmissions. We
	254	* have to drop the lock for each send. If an ACK comes in whilst the
	255	* lock is dropped, it may clear some of the retransmission markers for
	256	* packets that it soft-ACKs.
	257	*/
	258	for (seq = cursor + 1; before_eq(seq, top); seq++) {
	259	ix = seq & RXRPC_RXTX_BUFF_MASK;
	260	annotation = call->rxtx_annotations[ix];
	261	anno_type = annotation & RXRPC_TX_ANNO_MASK;
	262	if (anno_type != RXRPC_TX_ANNO_RETRANS)
	263	continue;
	264
	265	skb = call->rxtx_buffer[ix];
	266	rxrpc_get_skb(skb, rxrpc_skb_tx_got);
	267	spin_unlock_bh(&call->lock);
	268
	269	if (rxrpc_send_data_packet(call, skb, true) < 0) {
	270	rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
	271	return;
	272	}
	273
	274	if (rxrpc_is_client_call(call))
	275	rxrpc_expose_client_call(call);
	276
	277	rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
	278	spin_lock_bh(&call->lock);
	279
	280	/* We need to clear the retransmit state, but there are two
	281	* things we need to be aware of: A new ACK/NAK might have been
	282	* received and the packet might have been hard-ACK'd (in which
	283	* case it will no longer be in the buffer).
	284	*/
	285	if (after(seq, call->tx_hard_ack)) {
	286	annotation = call->rxtx_annotations[ix];
	287	anno_type = annotation & RXRPC_TX_ANNO_MASK;
	288	if (anno_type == RXRPC_TX_ANNO_RETRANS \|\|
	289	anno_type == RXRPC_TX_ANNO_NAK) {
	290	annotation &= ~RXRPC_TX_ANNO_MASK;
	291	annotation \|= RXRPC_TX_ANNO_UNACK;
	292	}
	293	annotation \|= RXRPC_TX_ANNO_RESENT;
	294	call->rxtx_annotations[ix] = annotation;
	295	}
	296
	297	if (after(call->tx_hard_ack, seq))
	298	seq = call->tx_hard_ack;
	299	}
	300
	301	out_unlock:
	302	spin_unlock_bh(&call->lock);
	303	out:
	304	_leave("");
	305	}
	306
	307	/*
	308	* Handle retransmission and deferred ACK/abort generation.
	309	*/
	310	void rxrpc_process_call(struct work_struct *work)
	311	{
	312	struct rxrpc_call *call =
	313	container_of(work, struct rxrpc_call, processor);
	314	rxrpc_serial_t *send_ack;
	315	unsigned long now, next, t;
	316	unsigned int iterations = 0;
	317
	318	rxrpc_see_call(call);
	319
	320	//printk("\n--------------------\n");
	321	_enter("{%d,%s,%lx}",
	322	call->debug_id, rxrpc_call_states[call->state], call->events);
	323
	324	recheck_state:
	325	/* Limit the number of times we do this before returning to the manager */
	326	iterations++;
	327	if (iterations > 5)
	328	goto requeue;
	329
	330	if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
	331	rxrpc_send_abort_packet(call);
	332	goto recheck_state;
	333	}
	334
	335	if (call->state == RXRPC_CALL_COMPLETE) {
	336	del_timer_sync(&call->timer);
	337	rxrpc_notify_socket(call);
	338	goto out_put;
	339	}
	340
	341	/* Work out if any timeouts tripped */
	342	now = jiffies;
	343	t = READ_ONCE(call->expect_rx_by);
	344	if (time_after_eq(now, t)) {
	345	trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
	346	set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
	347	}
	348
	349	t = READ_ONCE(call->expect_req_by);
	350	if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST &&
	351	time_after_eq(now, t)) {
	352	trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
	353	set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
	354	}
	355
	356	t = READ_ONCE(call->expect_term_by);
	357	if (time_after_eq(now, t)) {
	358	trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
	359	set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
	360	}
	361
	362	t = READ_ONCE(call->ack_at);
	363	if (time_after_eq(now, t)) {
	364	trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
	365	cmpxchg(&call->ack_at, t, now + MAX_JIFFY_OFFSET);
	366	set_bit(RXRPC_CALL_EV_ACK, &call->events);
	367	}
	368
	369	t = READ_ONCE(call->ack_lost_at);
	370	if (time_after_eq(now, t)) {
	371	trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now);
	372	cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET);
	373	set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
	374	}
	375
	376	t = READ_ONCE(call->keepalive_at);
	377	if (time_after_eq(now, t)) {
	378	trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now);
	379	cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET);
	380	rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, true,
	381	rxrpc_propose_ack_ping_for_keepalive);
	382	set_bit(RXRPC_CALL_EV_PING, &call->events);
	383	}
	384
	385	t = READ_ONCE(call->ping_at);
	386	if (time_after_eq(now, t)) {
	387	trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
	388	cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
	389	set_bit(RXRPC_CALL_EV_PING, &call->events);
	390	}
	391
	392	t = READ_ONCE(call->resend_at);
	393	if (time_after_eq(now, t)) {
	394	trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
	395	cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
	396	set_bit(RXRPC_CALL_EV_RESEND, &call->events);
	397	}
	398
	399	/* Process events */
	400	if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED, &call->events)) {
	401	rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ETIME);
	402	set_bit(RXRPC_CALL_EV_ABORT, &call->events);
	403	goto recheck_state;
	404	}
	405
	406	send_ack = NULL;
	407	if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events)) {
	408	call->acks_lost_top = call->tx_top;
	409	rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false,
	410	rxrpc_propose_ack_ping_for_lost_ack);
	411	send_ack = &call->acks_lost_ping;
	412	}
	413
	414	if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) \|\|
	415	send_ack) {
	416	if (call->ackr_reason) {
	417	rxrpc_send_ack_packet(call, false, send_ack);
	418	goto recheck_state;
	419	}
	420	}
	421
	422	if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {
	423	rxrpc_send_ack_packet(call, true, NULL);
	424	goto recheck_state;
	425	}
	426
	427	if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) {
	428	rxrpc_resend(call, now);
	429	goto recheck_state;
	430	}
	431
	432	/* Make sure the timer is restarted */
	433	next = call->expect_rx_by;
	434
	435	#define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }
	436
	437	set(call->expect_req_by);
	438	set(call->expect_term_by);
	439	set(call->ack_at);
	440	set(call->ack_lost_at);
	441	set(call->resend_at);
	442	set(call->keepalive_at);
	443	set(call->ping_at);
	444
	445	now = jiffies;
	446	if (time_after_eq(now, next))
	447	goto recheck_state;
	448
	449	rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
	450
	451	/* other events may have been raised since we started checking */
	452	if (call->events && call->state < RXRPC_CALL_COMPLETE)
	453	goto requeue;
	454
	455	out_put:
	456	rxrpc_put_call(call, rxrpc_call_put);
	457	out:
	458	_leave("");
	459	return;
	460
	461	requeue:
	462	__rxrpc_queue_call(call);
	463	goto out;
	464	}