path: root/net/rxrpc/ar-ack.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.
 */

#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"

static unsigned int rxrpc_ack_defer = 1;

static const char *const rxrpc_acks[] = {
	"---", "REQ", "DUP", "OOS", "WIN", "MEM", "PNG", "PNR", "DLY", "IDL",
	"-?-"
};

static const s8 rxrpc_ack_priority[] = {
	[0]				= 0,
	[RXRPC_ACK_DELAY]		= 1,
	[RXRPC_ACK_REQUESTED]		= 2,
	[RXRPC_ACK_IDLE]		= 3,
	[RXRPC_ACK_PING_RESPONSE]	= 4,
	[RXRPC_ACK_DUPLICATE]		= 5,
	[RXRPC_ACK_OUT_OF_SEQUENCE]	= 6,
	[RXRPC_ACK_EXCEEDS_WINDOW]	= 7,
	[RXRPC_ACK_NOSPACE]		= 8,
};

/*
 * propose an ACK be sent
 */
void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
			 __be32 serial, bool immediate)
{
	unsigned long expiry;
	s8 prior = rxrpc_ack_priority[ack_reason];

	ASSERTCMP(prior, >, 0);

	_enter("{%d},%s,%%%x,%u",
	       call->debug_id, rxrpc_acks[ack_reason], ntohl(serial),
	       immediate);

	if (prior < rxrpc_ack_priority[call->ackr_reason]) {
		if (immediate)
			goto cancel_timer;
		return;
	}

	/* update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
	 * numbers */
	if (prior == rxrpc_ack_priority[call->ackr_reason]) {
		if (prior <= 4)
			call->ackr_serial = serial;
		if (immediate)
			goto cancel_timer;
		return;
	}

	call->ackr_reason = ack_reason;
	call->ackr_serial = serial;

	switch (ack_reason) {
	case RXRPC_ACK_DELAY:
		_debug("run delay timer");
		call->ack_timer.expires = jiffies + rxrpc_ack_timeout * HZ;
		add_timer(&call->ack_timer);
		return;

	case RXRPC_ACK_IDLE:
		if (!immediate) {
			_debug("run defer timer");
			expiry = 1;
			goto run_timer;
		}
		goto cancel_timer;

	case RXRPC_ACK_REQUESTED:
		if (!rxrpc_ack_defer)
			goto cancel_timer;
		if (!immediate || serial == cpu_to_be32(1)) {
			_debug("run defer timer");
			expiry = rxrpc_ack_defer;
			goto run_timer;
		}

	default:
		_debug("immediate ACK");
		goto cancel_timer;
	}

run_timer:
	expiry += jiffies;
	if (!timer_pending(&call->ack_timer) ||
	    time_after(call->ack_timer.expires, expiry))
		mod_timer(&call->ack_timer, expiry);
	return;

cancel_timer:
	_debug("cancel timer %%%u", ntohl(serial));
	try_to_del_timer_sync(&call->ack_timer);
	read_lock_bh(&call->state_lock);
	if (call->state <= RXRPC_CALL_COMPLETE &&
	    !test_and_set_bit(RXRPC_CALL_ACK, &call->events))
		rxrpc_queue_call(call);
	read_unlock_bh(&call->state_lock);
}

/*
 * propose an ACK be sent, locking the call structure
 */
void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
		       __be32 serial, bool immediate)
{
	s8 prior = rxrpc_ack_priority[ack_reason];

	if (prior > rxrpc_ack_priority[call->ackr_reason]) {
		spin_lock_bh(&call->lock);
		__rxrpc_propose_ACK(call, ack_reason, serial, immediate);
		spin_unlock_bh(&call->lock);
	}
}

/*
 * set the resend timer
 */
static void rxrpc_set_resend(struct rxrpc_call *call, u8 resend,
			     unsigned long resend_at)
{
	read_lock_bh(&call->state_lock);
	if (call->state >= RXRPC_CALL_COMPLETE)
		resend = 0;

	if (resend & 1) {
		_debug("SET RESEND");
		set_bit(RXRPC_CALL_RESEND, &call->events);
	}

	if (resend & 2) {
		_debug("MODIFY RESEND TIMER");
		set_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
		mod_timer(&call->resend_timer, resend_at);
	} else {
		_debug("KILL RESEND TIMER");
		del_timer_sync(&call->resend_timer);
		clear_bit(RXRPC_CALL_RESEND_TIMER,