ar-ack.c 32.5 KB
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/* 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>
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#include <linux/slab.h>
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#include <linux/udp.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"

static unsigned rxrpc_ack_defer = 1;

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static const char *const rxrpc_acks[] = {
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	"---", "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
 */
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void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
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			 __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))
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		rxrpc_queue_call(call);
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	read_unlock_bh(&call->state_lock);
}

/*
 * propose an ACK be sent, locking the call structure
 */
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void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
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		       __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, &call->events);
		clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
	}
	read_unlock_bh(&call->state_lock);
}

/*
 * resend packets
 */
static void rxrpc_resend(struct rxrpc_call *call)
{
	struct rxrpc_skb_priv *sp;
	struct rxrpc_header *hdr;
	struct sk_buff *txb;
	unsigned long *p_txb, resend_at;
	int loop, stop;
	u8 resend;

	_enter("{%d,%d,%d,%d},",
	       call->acks_hard, call->acks_unacked,
	       atomic_read(&call->sequence),
	       CIRC_CNT(call->acks_head, call->acks_tail, call->acks_winsz));

	stop = 0;
	resend = 0;
	resend_at = 0;

	for (loop = call->acks_tail;
	     loop != call->acks_head || stop;
	     loop = (loop + 1) &  (call->acks_winsz - 1)
	     ) {
		p_txb = call->acks_window + loop;
		smp_read_barrier_depends();
		if (*p_txb & 1)
			continue;

		txb = (struct sk_buff *) *p_txb;
		sp = rxrpc_skb(txb);

		if (sp->need_resend) {
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			sp->need_resend = false;
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			/* each Tx packet has a new serial number */
			sp->hdr.serial =
				htonl(atomic_inc_return(&call->conn->serial));

			hdr = (struct rxrpc_header *) txb->head;
			hdr->serial = sp->hdr.serial;

			_proto("Tx DATA %%%u { #%d }",
			       ntohl(sp->hdr.serial), ntohl(sp->hdr.seq));
			if (rxrpc_send_packet(call->conn->trans, txb) < 0) {
				stop = 0;
				sp->resend_at = jiffies + 3;
			} else {
				sp->resend_at =
					jiffies + rxrpc_resend_timeout * HZ;
			}
		}

		if (time_after_eq(jiffies + 1, sp->resend_at)) {
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			sp->need_resend = true;
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			resend |= 1;
		} else if (resend & 2) {
			if (time_before(sp->resend_at, resend_at))
				resend_at = sp->resend_at;
		} else {
			resend_at = sp->resend_at;
			resend |= 2;
		}
	}

	rxrpc_set_resend(call, resend, resend_at);
	_leave("");
}

/*
 * handle resend timer expiry
 */
static void rxrpc_resend_timer(struct rxrpc_call *call)
{
	struct rxrpc_skb_priv *sp;
	struct sk_buff *txb;
	unsigned long *p_txb, resend_at;
	int loop;
	u8 resend;

	_enter("%d,%d,%d",
	       call->acks_tail, call->acks_unacked, call->acks_head);

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	if (call->state >= RXRPC_CALL_COMPLETE)
		return;

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	resend = 0;
	resend_at = 0;

	for (loop = call->acks_unacked;
	     loop != call->acks_head;
	     loop = (loop + 1) &  (call->acks_winsz - 1)
	     ) {
		p_txb = call->acks_window + loop;
		smp_read_barrier_depends();
		txb = (struct sk_buff *) (*p_txb & ~1);
		sp = rxrpc_skb(txb);

		ASSERT(!(*p_txb & 1));

		if (sp->need_resend) {
			;
		} else if (time_after_eq(jiffies + 1, sp->resend_at)) {
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			sp->need_resend = true;
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			resend |= 1;
		} else if (resend & 2) {
			if (time_before(sp->resend_at, resend_at))
				resend_at = sp->resend_at;
		} else {
			resend_at = sp->resend_at;
			resend |= 2;
		}
	}

	rxrpc_set_resend(call, resend, resend_at);
	_leave("");
}

/*
 * process soft ACKs of our transmitted packets
 * - these indicate packets the peer has or has not received, but hasn't yet
 *   given to the consumer, and so can still be discarded and re-requested
 */
static int rxrpc_process_soft_ACKs(struct rxrpc_call *call,
				   struct rxrpc_ackpacket *ack,
				   struct sk_buff *skb)
{
	struct rxrpc_skb_priv *sp;
	struct sk_buff *txb;
	unsigned long *p_txb, resend_at;
	int loop;
	u8 sacks[RXRPC_MAXACKS], resend;

	_enter("{%d,%d},{%d},",
	       call->acks_hard,
	       CIRC_CNT(call->acks_head, call->acks_tail, call->acks_winsz),
	       ack->nAcks);

	if (skb_copy_bits(skb, 0, sacks, ack->nAcks) < 0)
		goto protocol_error;

	resend = 0;
	resend_at = 0;
	for (loop = 0; loop < ack->nAcks; loop++) {
		p_txb = call->acks_window;
		p_txb += (call->acks_tail + loop) & (call->acks_winsz - 1);
		smp_read_barrier_depends();
		txb = (struct sk_buff *) (*p_txb & ~1);
		sp = rxrpc_skb(txb);

		switch (sacks[loop]) {
		case RXRPC_ACK_TYPE_ACK:
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			sp->need_resend = false;
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			*p_txb |= 1;
			break;
		case RXRPC_ACK_TYPE_NACK:
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			sp->need_resend = true;
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			*p_txb &= ~1;
			resend = 1;
			break;
		default:
			_debug("Unsupported ACK type %d", sacks[loop]);
			goto protocol_error;
		}
	}

	smp_mb();
	call->acks_unacked = (call->acks_tail + loop) & (call->acks_winsz - 1);

	/* anything not explicitly ACK'd is implicitly NACK'd, but may just not
	 * have been received or processed yet by the far end */
	for (loop = call->acks_unacked;
	     loop != call->acks_head;
	     loop = (loop + 1) &  (call->acks_winsz - 1)
	     ) {
		p_txb = call->acks_window + loop;
		smp_read_barrier_depends();
		txb = (struct sk_buff *) (*p_txb & ~1);
		sp = rxrpc_skb(txb);

		if (*p_txb & 1) {
			/* packet must have been discarded */
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			sp->need_resend = true;
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			*p_txb &= ~1;
			resend |= 1;
		} else if (sp->need_resend) {
			;
		} else if (time_after_eq(jiffies + 1, sp->resend_at)) {
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			sp->need_resend = true;
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			resend |= 1;
		} else if (resend & 2) {
			if (time_before(sp->resend_at, resend_at))
				resend_at = sp->resend_at;
		} else {
			resend_at = sp->resend_at;
			resend |= 2;
		}
	}

	rxrpc_set_resend(call, resend, resend_at);
	_leave(" = 0");
	return 0;

protocol_error:
	_leave(" = -EPROTO");
	return -EPROTO;
}

/*
 * discard hard-ACK'd packets from the Tx window
 */
static void rxrpc_rotate_tx_window(struct rxrpc_call *call, u32 hard)
{
	unsigned long _skb;
	int tail = call->acks_tail, old_tail;
	int win = CIRC_CNT(call->acks_head, tail, call->acks_winsz);

	_enter("{%u,%u},%u", call->acks_hard, win, hard);

	ASSERTCMP(hard - call->acks_hard, <=, win);

	while (call->acks_hard < hard) {
		smp_read_barrier_depends();
		_skb = call->acks_window[tail] & ~1;
		rxrpc_free_skb((struct sk_buff *) _skb);
		old_tail = tail;
		tail = (tail + 1) & (call->acks_winsz - 1);
		call->acks_tail = tail;
		if (call->acks_unacked == old_tail)
			call->acks_unacked = tail;
		call->acks_hard++;
	}

	wake_up(&call->tx_waitq);
}

/*
 * clear the Tx window in the event of a failure
 */
static void rxrpc_clear_tx_window(struct rxrpc_call *call)
{
	rxrpc_rotate_tx_window(call, atomic_read(&call->sequence));
}

/*
 * drain the out of sequence received packet queue into the packet Rx queue
 */
static int rxrpc_drain_rx_oos_queue(struct rxrpc_call *call)
{
	struct rxrpc_skb_priv *sp;
	struct sk_buff *skb;
	bool terminal;
	int ret;

	_enter("{%d,%d}", call->rx_data_post, call->rx_first_oos);

	spin_lock_bh(&call->lock);

	ret = -ECONNRESET;
	if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
		goto socket_unavailable;

	skb = skb_dequeue(&call->rx_oos_queue);
	if (skb) {
		sp = rxrpc_skb(skb);

		_debug("drain OOS packet %d [%d]",
		       ntohl(sp->hdr.seq), call->rx_first_oos);

		if (ntohl(sp->hdr.seq) != call->rx_first_oos) {
			skb_queue_head(&call->rx_oos_queue, skb);
			call->rx_first_oos = ntohl(rxrpc_skb(skb)->hdr.seq);
			_debug("requeue %p {%u}", skb, call->rx_first_oos);
		} else {
			skb->mark = RXRPC_SKB_MARK_DATA;
			terminal = ((sp->hdr.flags & RXRPC_LAST_PACKET) &&
				!(sp->hdr.flags & RXRPC_CLIENT_INITIATED));
			ret = rxrpc_queue_rcv_skb(call, skb, true, terminal);
			BUG_ON(ret < 0);
			_debug("drain #%u", call->rx_data_post);
			call->rx_data_post++;

			/* find out what the next packet is */
			skb = skb_peek(&call->rx_oos_queue);
			if (skb)
				call->rx_first_oos =
					ntohl(rxrpc_skb(skb)->hdr.seq);
			else
				call->rx_first_oos = 0;
			_debug("peek %p {%u}", skb, call->rx_first_oos);
		}
	}

	ret = 0;
socket_unavailable:
	spin_unlock_bh(&call->lock);
	_leave(" = %d", ret);
	return ret;
}

/*
 * insert an out of sequence packet into the buffer
 */
static void rxrpc_insert_oos_packet(struct rxrpc_call *call,
				    struct sk_buff *skb)
{
	struct rxrpc_skb_priv *sp, *psp;
	struct sk_buff *p;
	u32 seq;

	sp = rxrpc_skb(skb);
	seq = ntohl(sp->hdr.seq);
	_enter(",,{%u}", seq);

	skb->destructor = rxrpc_packet_destructor;
	ASSERTCMP(sp->call, ==, NULL);
	sp->call = call;
	rxrpc_get_call(call);

	/* insert into the buffer in sequence order */
	spin_lock_bh(&call->lock);

	skb_queue_walk(&call->rx_oos_queue, p) {
		psp = rxrpc_skb(p);
		if (ntohl(psp->hdr.seq) > seq) {
			_debug("insert oos #%u before #%u",
			       seq, ntohl(psp->hdr.seq));
			skb_insert(p, skb, &call->rx_oos_queue);
			goto inserted;
		}
	}

	_debug("append oos #%u", seq);
	skb_queue_tail(&call->rx_oos_queue, skb);
inserted:

	/* we might now have a new front to the queue */
	if (call->rx_first_oos == 0 || seq < call->rx_first_oos)
		call->rx_first_oos = seq;

	read_lock(&call->state_lock);
	if (call->state < RXRPC_CALL_COMPLETE &&
	    call->rx_data_post == call->rx_first_oos) {
		_debug("drain rx oos now");
		set_bit(RXRPC_CALL_DRAIN_RX_OOS, &call->events);
	}
	read_unlock(&call->state_lock);

	spin_unlock_bh(&call->lock);
	_leave(" [stored #%u]", call->rx_first_oos);
}

/*
 * clear the Tx window on final ACK reception
 */
static void rxrpc_zap_tx_window(struct rxrpc_call *call)
{
	struct rxrpc_skb_priv *sp;
	struct sk_buff *skb;
	unsigned long _skb, *acks_window;
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	u8 winsz = call->acks_winsz;
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	int tail;

	acks_window = call->acks_window;
	call->acks_window = NULL;

	while (CIRC_CNT(call->acks_head, call->acks_tail, winsz) > 0) {
		tail = call->acks_tail;
		smp_read_barrier_depends();
		_skb = acks_window[tail] & ~1;
		smp_mb();
		call->acks_tail = (call->acks_tail + 1) & (winsz - 1);

		skb = (struct sk_buff *) _skb;
		sp = rxrpc_skb(skb);
		_debug("+++ clear Tx %u", ntohl(sp->hdr.seq));
		rxrpc_free_skb(skb);
	}

	kfree(acks_window);
}

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/*
 * process the extra information that may be appended to an ACK packet
 */
static void rxrpc_extract_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
				  unsigned latest, int nAcks)
{
	struct rxrpc_ackinfo ackinfo;
	struct rxrpc_peer *peer;
	unsigned mtu;

	if (skb_copy_bits(skb, nAcks + 3, &ackinfo, sizeof(ackinfo)) < 0) {
		_leave(" [no ackinfo]");
		return;
	}

	_proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
	       latest,
	       ntohl(ackinfo.rxMTU), ntohl(ackinfo.maxMTU),
	       ntohl(ackinfo.rwind), ntohl(ackinfo.jumbo_max));

	mtu = min(ntohl(ackinfo.rxMTU), ntohl(ackinfo.maxMTU));

	peer = call->conn->trans->peer;
	if (mtu < peer->maxdata) {
		spin_lock_bh(&peer->lock);
		peer->maxdata = mtu;
		peer->mtu = mtu + peer->hdrsize;
		spin_unlock_bh(&peer->lock);
		_net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
	}
}

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/*
 * process packets in the reception queue
 */
static int rxrpc_process_rx_queue(struct rxrpc_call *call,
				  u32 *_abort_code)
{
	struct rxrpc_ackpacket ack;
	struct rxrpc_skb_priv *sp;
	struct sk_buff *skb;
	bool post_ACK;
	int latest;
	u32 hard, tx;

	_enter("");

process_further:
	skb = skb_dequeue(&call->rx_queue);
	if (!skb)
		return -EAGAIN;

	_net("deferred skb %p", skb);

	sp = rxrpc_skb(skb);

	_debug("process %s [st %d]", rxrpc_pkts[sp->hdr.type], call->state);

	post_ACK = false;

	switch (sp->hdr.type) {
		/* data packets that wind up here have been received out of
		 * order, need security processing or are jumbo packets */
	case RXRPC_PACKET_TYPE_DATA:
		_proto("OOSQ DATA %%%u { #%u }",
		       ntohl(sp->hdr.serial), ntohl(sp->hdr.seq));

		/* secured packets must be verified and possibly decrypted */
		if (rxrpc_verify_packet(call, skb, _abort_code) < 0)
			goto protocol_error;

		rxrpc_insert_oos_packet(call, skb);
		goto process_further;

		/* partial ACK to process */
	case RXRPC_PACKET_TYPE_ACK:
		if (skb_copy_bits(skb, 0, &ack, sizeof(ack)) < 0) {
			_debug("extraction failure");
			goto protocol_error;
		}
		if (!skb_pull(skb, sizeof(ack)))
			BUG();

		latest = ntohl(sp->hdr.serial);
		hard = ntohl(ack.firstPacket);
		tx = atomic_read(&call->sequence);

		_proto("Rx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
		       latest,
		       ntohs(ack.maxSkew),
		       hard,
		       ntohl(ack.previousPacket),
		       ntohl(ack.serial),
		       rxrpc_acks[ack.reason],
		       ack.nAcks);

643 644
		rxrpc_extract_ackinfo(call, skb, latest, ack.nAcks);

645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818
		if (ack.reason == RXRPC_ACK_PING) {
			_proto("Rx ACK %%%u PING Request", latest);
			rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
					  sp->hdr.serial, true);
		}

		/* discard any out-of-order or duplicate ACKs */
		if (latest - call->acks_latest <= 0) {
			_debug("discard ACK %d <= %d",
			       latest, call->acks_latest);
			goto discard;
		}
		call->acks_latest = latest;

		if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST &&
		    call->state != RXRPC_CALL_CLIENT_AWAIT_REPLY &&
		    call->state != RXRPC_CALL_SERVER_SEND_REPLY &&
		    call->state != RXRPC_CALL_SERVER_AWAIT_ACK)
			goto discard;

		_debug("Tx=%d H=%u S=%d", tx, call->acks_hard, call->state);

		if (hard > 0) {
			if (hard - 1 > tx) {
				_debug("hard-ACK'd packet %d not transmitted"
				       " (%d top)",
				       hard - 1, tx);
				goto protocol_error;
			}

			if ((call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY ||
			     call->state == RXRPC_CALL_SERVER_AWAIT_ACK) &&
			    hard > tx)
				goto all_acked;

			smp_rmb();
			rxrpc_rotate_tx_window(call, hard - 1);
		}

		if (ack.nAcks > 0) {
			if (hard - 1 + ack.nAcks > tx) {
				_debug("soft-ACK'd packet %d+%d not"
				       " transmitted (%d top)",
				       hard - 1, ack.nAcks, tx);
				goto protocol_error;
			}

			if (rxrpc_process_soft_ACKs(call, &ack, skb) < 0)
				goto protocol_error;
		}
		goto discard;

		/* complete ACK to process */
	case RXRPC_PACKET_TYPE_ACKALL:
		goto all_acked;

		/* abort and busy are handled elsewhere */
	case RXRPC_PACKET_TYPE_BUSY:
	case RXRPC_PACKET_TYPE_ABORT:
		BUG();

		/* connection level events - also handled elsewhere */
	case RXRPC_PACKET_TYPE_CHALLENGE:
	case RXRPC_PACKET_TYPE_RESPONSE:
	case RXRPC_PACKET_TYPE_DEBUG:
		BUG();
	}

	/* if we've had a hard ACK that covers all the packets we've sent, then
	 * that ends that phase of the operation */
all_acked:
	write_lock_bh(&call->state_lock);
	_debug("ack all %d", call->state);

	switch (call->state) {
	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
		call->state = RXRPC_CALL_CLIENT_RECV_REPLY;
		break;
	case RXRPC_CALL_SERVER_AWAIT_ACK:
		_debug("srv complete");
		call->state = RXRPC_CALL_COMPLETE;
		post_ACK = true;
		break;
	case RXRPC_CALL_CLIENT_SEND_REQUEST:
	case RXRPC_CALL_SERVER_RECV_REQUEST:
		goto protocol_error_unlock; /* can't occur yet */
	default:
		write_unlock_bh(&call->state_lock);
		goto discard; /* assume packet left over from earlier phase */
	}

	write_unlock_bh(&call->state_lock);

	/* if all the packets we sent are hard-ACK'd, then we can discard
	 * whatever we've got left */
	_debug("clear Tx %d",
	       CIRC_CNT(call->acks_head, call->acks_tail, call->acks_winsz));

	del_timer_sync(&call->resend_timer);
	clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
	clear_bit(RXRPC_CALL_RESEND_TIMER, &call->events);

	if (call->acks_window)
		rxrpc_zap_tx_window(call);

	if (post_ACK) {
		/* post the final ACK message for userspace to pick up */
		_debug("post ACK");
		skb->mark = RXRPC_SKB_MARK_FINAL_ACK;
		sp->call = call;
		rxrpc_get_call(call);
		spin_lock_bh(&call->lock);
		if (rxrpc_queue_rcv_skb(call, skb, true, true) < 0)
			BUG();
		spin_unlock_bh(&call->lock);
		goto process_further;
	}

discard:
	rxrpc_free_skb(skb);
	goto process_further;

protocol_error_unlock:
	write_unlock_bh(&call->state_lock);
protocol_error:
	rxrpc_free_skb(skb);
	_leave(" = -EPROTO");
	return -EPROTO;
}

/*
 * post a message to the socket Rx queue for recvmsg() to pick up
 */
static int rxrpc_post_message(struct rxrpc_call *call, u32 mark, u32 error,
			      bool fatal)
{
	struct rxrpc_skb_priv *sp;
	struct sk_buff *skb;
	int ret;

	_enter("{%d,%lx},%u,%u,%d",
	       call->debug_id, call->flags, mark, error, fatal);

	/* remove timers and things for fatal messages */
	if (fatal) {
		del_timer_sync(&call->resend_timer);
		del_timer_sync(&call->ack_timer);
		clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
	}

	if (mark != RXRPC_SKB_MARK_NEW_CALL &&
	    !test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
		_leave("[no userid]");
		return 0;
	}

	if (!test_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags)) {
		skb = alloc_skb(0, GFP_NOFS);
		if (!skb)
			return -ENOMEM;

		rxrpc_new_skb(skb);

		skb->mark = mark;

		sp = rxrpc_skb(skb);
		memset(sp, 0, sizeof(*sp));
		sp->error = error;
		sp->call = call;
		rxrpc_get_call(call);

		spin_lock_bh(&call->lock);
		ret = rxrpc_queue_rcv_skb(call, skb, true, fatal);
		spin_unlock_bh(&call->lock);
J
Julia Lawall 已提交
819
		BUG_ON(ret < 0);
820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838
	}

	return 0;
}

/*
 * handle background processing of incoming call packets and ACK / abort
 * generation
 */
void rxrpc_process_call(struct work_struct *work)
{
	struct rxrpc_call *call =
		container_of(work, struct rxrpc_call, processor);
	struct rxrpc_ackpacket ack;
	struct rxrpc_ackinfo ackinfo;
	struct rxrpc_header hdr;
	struct msghdr msg;
	struct kvec iov[5];
	unsigned long bits;
839
	__be32 data, pad;
840
	size_t len;
841
	int genbit, loop, nbit, ioc, ret, mtu;
842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937
	u32 abort_code = RX_PROTOCOL_ERROR;
	u8 *acks = NULL;

	//printk("\n--------------------\n");
	_enter("{%d,%s,%lx} [%lu]",
	       call->debug_id, rxrpc_call_states[call->state], call->events,
	       (jiffies - call->creation_jif) / (HZ / 10));

	if (test_and_set_bit(RXRPC_CALL_PROC_BUSY, &call->flags)) {
		_debug("XXXXXXXXXXXXX RUNNING ON MULTIPLE CPUS XXXXXXXXXXXXX");
		return;
	}

	/* there's a good chance we're going to have to send a message, so set
	 * one up in advance */
	msg.msg_name	= &call->conn->trans->peer->srx.transport.sin;
	msg.msg_namelen	= sizeof(call->conn->trans->peer->srx.transport.sin);
	msg.msg_control	= NULL;
	msg.msg_controllen = 0;
	msg.msg_flags	= 0;

	hdr.epoch	= call->conn->epoch;
	hdr.cid		= call->cid;
	hdr.callNumber	= call->call_id;
	hdr.seq		= 0;
	hdr.type	= RXRPC_PACKET_TYPE_ACK;
	hdr.flags	= call->conn->out_clientflag;
	hdr.userStatus	= 0;
	hdr.securityIndex = call->conn->security_ix;
	hdr._rsvd	= 0;
	hdr.serviceId	= call->conn->service_id;

	memset(iov, 0, sizeof(iov));
	iov[0].iov_base	= &hdr;
	iov[0].iov_len	= sizeof(hdr);

	/* deal with events of a final nature */
	if (test_bit(RXRPC_CALL_RELEASE, &call->events)) {
		rxrpc_release_call(call);
		clear_bit(RXRPC_CALL_RELEASE, &call->events);
	}

	if (test_bit(RXRPC_CALL_RCVD_ERROR, &call->events)) {
		int error;

		clear_bit(RXRPC_CALL_CONN_ABORT, &call->events);
		clear_bit(RXRPC_CALL_REJECT_BUSY, &call->events);
		clear_bit(RXRPC_CALL_ABORT, &call->events);

		error = call->conn->trans->peer->net_error;
		_debug("post net error %d", error);

		if (rxrpc_post_message(call, RXRPC_SKB_MARK_NET_ERROR,
				       error, true) < 0)
			goto no_mem;
		clear_bit(RXRPC_CALL_RCVD_ERROR, &call->events);
		goto kill_ACKs;
	}

	if (test_bit(RXRPC_CALL_CONN_ABORT, &call->events)) {
		ASSERTCMP(call->state, >, RXRPC_CALL_COMPLETE);

		clear_bit(RXRPC_CALL_REJECT_BUSY, &call->events);
		clear_bit(RXRPC_CALL_ABORT, &call->events);

		_debug("post conn abort");

		if (rxrpc_post_message(call, RXRPC_SKB_MARK_LOCAL_ERROR,
				       call->conn->error, true) < 0)
			goto no_mem;
		clear_bit(RXRPC_CALL_CONN_ABORT, &call->events);
		goto kill_ACKs;
	}

	if (test_bit(RXRPC_CALL_REJECT_BUSY, &call->events)) {
		hdr.type = RXRPC_PACKET_TYPE_BUSY;
		genbit = RXRPC_CALL_REJECT_BUSY;
		goto send_message;
	}

	if (test_bit(RXRPC_CALL_ABORT, &call->events)) {
		ASSERTCMP(call->state, >, RXRPC_CALL_COMPLETE);

		if (rxrpc_post_message(call, RXRPC_SKB_MARK_LOCAL_ERROR,
				       ECONNABORTED, true) < 0)
			goto no_mem;
		hdr.type = RXRPC_PACKET_TYPE_ABORT;
		data = htonl(call->abort_code);
		iov[1].iov_base = &data;
		iov[1].iov_len = sizeof(data);
		genbit = RXRPC_CALL_ABORT;
		goto send_message;
	}

	if (test_bit(RXRPC_CALL_ACK_FINAL, &call->events)) {
		genbit = RXRPC_CALL_ACK_FINAL;
938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960

		ack.bufferSpace	= htons(8);
		ack.maxSkew	= 0;
		ack.serial	= 0;
		ack.reason	= RXRPC_ACK_IDLE;
		ack.nAcks	= 0;
		call->ackr_reason = 0;

		spin_lock_bh(&call->lock);
		ack.serial = call->ackr_serial;
		ack.previousPacket = call->ackr_prev_seq;
		ack.firstPacket = htonl(call->rx_data_eaten + 1);
		spin_unlock_bh(&call->lock);

		pad = 0;

		iov[1].iov_base = &ack;
		iov[1].iov_len	= sizeof(ack);
		iov[2].iov_base = &pad;
		iov[2].iov_len	= 3;
		iov[3].iov_base = &ackinfo;
		iov[3].iov_len	= sizeof(ackinfo);
		goto send_ACK;
961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166
	}

	if (call->events & ((1 << RXRPC_CALL_RCVD_BUSY) |
			    (1 << RXRPC_CALL_RCVD_ABORT))
	    ) {
		u32 mark;

		if (test_bit(RXRPC_CALL_RCVD_ABORT, &call->events))
			mark = RXRPC_SKB_MARK_REMOTE_ABORT;
		else
			mark = RXRPC_SKB_MARK_BUSY;

		_debug("post abort/busy");
		rxrpc_clear_tx_window(call);
		if (rxrpc_post_message(call, mark, ECONNABORTED, true) < 0)
			goto no_mem;

		clear_bit(RXRPC_CALL_RCVD_BUSY, &call->events);
		clear_bit(RXRPC_CALL_RCVD_ABORT, &call->events);
		goto kill_ACKs;
	}

	if (test_and_clear_bit(RXRPC_CALL_RCVD_ACKALL, &call->events)) {
		_debug("do implicit ackall");
		rxrpc_clear_tx_window(call);
	}

	if (test_bit(RXRPC_CALL_LIFE_TIMER, &call->events)) {
		write_lock_bh(&call->state_lock);
		if (call->state <= RXRPC_CALL_COMPLETE) {
			call->state = RXRPC_CALL_LOCALLY_ABORTED;
			call->abort_code = RX_CALL_TIMEOUT;
			set_bit(RXRPC_CALL_ABORT, &call->events);
		}
		write_unlock_bh(&call->state_lock);

		_debug("post timeout");
		if (rxrpc_post_message(call, RXRPC_SKB_MARK_LOCAL_ERROR,
				       ETIME, true) < 0)
			goto no_mem;

		clear_bit(RXRPC_CALL_LIFE_TIMER, &call->events);
		goto kill_ACKs;
	}

	/* deal with assorted inbound messages */
	if (!skb_queue_empty(&call->rx_queue)) {
		switch (rxrpc_process_rx_queue(call, &abort_code)) {
		case 0:
		case -EAGAIN:
			break;
		case -ENOMEM:
			goto no_mem;
		case -EKEYEXPIRED:
		case -EKEYREJECTED:
		case -EPROTO:
			rxrpc_abort_call(call, abort_code);
			goto kill_ACKs;
		}
	}

	/* handle resending */
	if (test_and_clear_bit(RXRPC_CALL_RESEND_TIMER, &call->events))
		rxrpc_resend_timer(call);
	if (test_and_clear_bit(RXRPC_CALL_RESEND, &call->events))
		rxrpc_resend(call);

	/* consider sending an ordinary ACK */
	if (test_bit(RXRPC_CALL_ACK, &call->events)) {
		_debug("send ACK: window: %d - %d { %lx }",
		       call->rx_data_eaten, call->ackr_win_top,
		       call->ackr_window[0]);

		if (call->state > RXRPC_CALL_SERVER_ACK_REQUEST &&
		    call->ackr_reason != RXRPC_ACK_PING_RESPONSE) {
			/* ACK by sending reply DATA packet in this state */
			clear_bit(RXRPC_CALL_ACK, &call->events);
			goto maybe_reschedule;
		}

		genbit = RXRPC_CALL_ACK;

		acks = kzalloc(call->ackr_win_top - call->rx_data_eaten,
			       GFP_NOFS);
		if (!acks)
			goto no_mem;

		//hdr.flags	= RXRPC_SLOW_START_OK;
		ack.bufferSpace	= htons(8);
		ack.maxSkew	= 0;
		ack.serial	= 0;
		ack.reason	= 0;

		spin_lock_bh(&call->lock);
		ack.reason = call->ackr_reason;
		ack.serial = call->ackr_serial;
		ack.previousPacket = call->ackr_prev_seq;
		ack.firstPacket = htonl(call->rx_data_eaten + 1);

		ack.nAcks = 0;
		for (loop = 0; loop < RXRPC_ACKR_WINDOW_ASZ; loop++) {
			nbit = loop * BITS_PER_LONG;
			for (bits = call->ackr_window[loop]; bits; bits >>= 1
			     ) {
				_debug("- l=%d n=%d b=%lx", loop, nbit, bits);
				if (bits & 1) {
					acks[nbit] = RXRPC_ACK_TYPE_ACK;
					ack.nAcks = nbit + 1;
				}
				nbit++;
			}
		}
		call->ackr_reason = 0;
		spin_unlock_bh(&call->lock);

		pad = 0;

		iov[1].iov_base = &ack;
		iov[1].iov_len	= sizeof(ack);
		iov[2].iov_base = acks;
		iov[2].iov_len	= ack.nAcks;
		iov[3].iov_base = &pad;
		iov[3].iov_len	= 3;
		iov[4].iov_base = &ackinfo;
		iov[4].iov_len	= sizeof(ackinfo);

		switch (ack.reason) {
		case RXRPC_ACK_REQUESTED:
		case RXRPC_ACK_DUPLICATE:
		case RXRPC_ACK_OUT_OF_SEQUENCE:
		case RXRPC_ACK_EXCEEDS_WINDOW:
		case RXRPC_ACK_NOSPACE:
		case RXRPC_ACK_PING:
		case RXRPC_ACK_PING_RESPONSE:
			goto send_ACK_with_skew;
		case RXRPC_ACK_DELAY:
		case RXRPC_ACK_IDLE:
			goto send_ACK;
		}
	}

	/* handle completion of security negotiations on an incoming
	 * connection */
	if (test_and_clear_bit(RXRPC_CALL_SECURED, &call->events)) {
		_debug("secured");
		spin_lock_bh(&call->lock);

		if (call->state == RXRPC_CALL_SERVER_SECURING) {
			_debug("securing");
			write_lock(&call->conn->lock);
			if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
			    !test_bit(RXRPC_CALL_RELEASE, &call->events)) {
				_debug("not released");
				call->state = RXRPC_CALL_SERVER_ACCEPTING;
				list_move_tail(&call->accept_link,
					       &call->socket->acceptq);
			}
			write_unlock(&call->conn->lock);
			read_lock(&call->state_lock);
			if (call->state < RXRPC_CALL_COMPLETE)
				set_bit(RXRPC_CALL_POST_ACCEPT, &call->events);
			read_unlock(&call->state_lock);
		}

		spin_unlock_bh(&call->lock);
		if (!test_bit(RXRPC_CALL_POST_ACCEPT, &call->events))
			goto maybe_reschedule;
	}

	/* post a notification of an acceptable connection to the app */
	if (test_bit(RXRPC_CALL_POST_ACCEPT, &call->events)) {
		_debug("post accept");
		if (rxrpc_post_message(call, RXRPC_SKB_MARK_NEW_CALL,
				       0, false) < 0)
			goto no_mem;
		clear_bit(RXRPC_CALL_POST_ACCEPT, &call->events);
		goto maybe_reschedule;
	}

	/* handle incoming call acceptance */
	if (test_and_clear_bit(RXRPC_CALL_ACCEPTED, &call->events)) {
		_debug("accepted");
		ASSERTCMP(call->rx_data_post, ==, 0);
		call->rx_data_post = 1;
		read_lock_bh(&call->state_lock);
		if (call->state < RXRPC_CALL_COMPLETE)
			set_bit(RXRPC_CALL_DRAIN_RX_OOS, &call->events);
		read_unlock_bh(&call->state_lock);
	}

	/* drain the out of sequence received packet queue into the packet Rx
	 * queue */
	if (test_and_clear_bit(RXRPC_CALL_DRAIN_RX_OOS, &call->events)) {
		while (call->rx_data_post == call->rx_first_oos)
			if (rxrpc_drain_rx_oos_queue(call) < 0)
				break;
		goto maybe_reschedule;
	}

	/* other events may have been raised since we started checking */
	goto maybe_reschedule;

send_ACK_with_skew:
	ack.maxSkew = htons(atomic_read(&call->conn->hi_serial) -
			    ntohl(ack.serial));
send_ACK:
1167 1168 1169 1170 1171 1172 1173 1174 1175
	mtu = call->conn->trans->peer->if_mtu;
	mtu -= call->conn->trans->peer->hdrsize;
	ackinfo.maxMTU	= htonl(mtu);
	ackinfo.rwind	= htonl(32);

	/* permit the peer to send us jumbo packets if it wants to */
	ackinfo.rxMTU	= htonl(5692);
	ackinfo.jumbo_max = htonl(4);

1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225
	hdr.serial = htonl(atomic_inc_return(&call->conn->serial));
	_proto("Tx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
	       ntohl(hdr.serial),
	       ntohs(ack.maxSkew),
	       ntohl(ack.firstPacket),
	       ntohl(ack.previousPacket),
	       ntohl(ack.serial),
	       rxrpc_acks[ack.reason],
	       ack.nAcks);

	del_timer_sync(&call->ack_timer);
	if (ack.nAcks > 0)
		set_bit(RXRPC_CALL_TX_SOFT_ACK, &call->flags);
	goto send_message_2;

send_message:
	_debug("send message");

	hdr.serial = htonl(atomic_inc_return(&call->conn->serial));
	_proto("Tx %s %%%u", rxrpc_pkts[hdr.type], ntohl(hdr.serial));
send_message_2:

	len = iov[0].iov_len;
	ioc = 1;
	if (iov[4].iov_len) {
		ioc = 5;
		len += iov[4].iov_len;
		len += iov[3].iov_len;
		len += iov[2].iov_len;
		len += iov[1].iov_len;
	} else if (iov[3].iov_len) {
		ioc = 4;
		len += iov[3].iov_len;
		len += iov[2].iov_len;
		len += iov[1].iov_len;
	} else if (iov[2].iov_len) {
		ioc = 3;
		len += iov[2].iov_len;
		len += iov[1].iov_len;
	} else if (iov[1].iov_len) {
		ioc = 2;
		len += iov[1].iov_len;
	}

	ret = kernel_sendmsg(call->conn->trans->local->socket,
			     &msg, iov, ioc, len);
	if (ret < 0) {
		_debug("sendmsg failed: %d", ret);
		read_lock_bh(&call->state_lock);
		if (call->state < RXRPC_CALL_DEAD)
1226
			rxrpc_queue_call(call);
1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269
		read_unlock_bh(&call->state_lock);
		goto error;
	}

	switch (genbit) {
	case RXRPC_CALL_ABORT:
		clear_bit(genbit, &call->events);
		clear_bit(RXRPC_CALL_RCVD_ABORT, &call->events);
		goto kill_ACKs;

	case RXRPC_CALL_ACK_FINAL:
		write_lock_bh(&call->state_lock);
		if (call->state == RXRPC_CALL_CLIENT_FINAL_ACK)
			call->state = RXRPC_CALL_COMPLETE;
		write_unlock_bh(&call->state_lock);
		goto kill_ACKs;

	default:
		clear_bit(genbit, &call->events);
		switch (call->state) {
		case RXRPC_CALL_CLIENT_AWAIT_REPLY:
		case RXRPC_CALL_CLIENT_RECV_REPLY:
		case RXRPC_CALL_SERVER_RECV_REQUEST:
		case RXRPC_CALL_SERVER_ACK_REQUEST:
			_debug("start ACK timer");
			rxrpc_propose_ACK(call, RXRPC_ACK_DELAY,
					  call->ackr_serial, false);
		default:
			break;
		}
		goto maybe_reschedule;
	}

kill_ACKs:
	del_timer_sync(&call->ack_timer);
	if (test_and_clear_bit(RXRPC_CALL_ACK_FINAL, &call->events))
		rxrpc_put_call(call);
	clear_bit(RXRPC_CALL_ACK, &call->events);

maybe_reschedule:
	if (call->events || !skb_queue_empty(&call->rx_queue)) {
		read_lock_bh(&call->state_lock);
		if (call->state < RXRPC_CALL_DEAD)
1270
			rxrpc_queue_call(call);
1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283
		read_unlock_bh(&call->state_lock);
	}

	/* don't leave aborted connections on the accept queue */
	if (call->state >= RXRPC_CALL_COMPLETE &&
	    !list_empty(&call->accept_link)) {
		_debug("X unlinking once-pending call %p { e=%lx f=%lx c=%x }",
		       call, call->events, call->flags,
		       ntohl(call->conn->cid));

		read_lock_bh(&call->state_lock);
		if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
		    !test_and_set_bit(RXRPC_CALL_RELEASE, &call->events))
1284
			rxrpc_queue_call(call);
1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297
		read_unlock_bh(&call->state_lock);
	}

error:
	clear_bit(RXRPC_CALL_PROC_BUSY, &call->flags);
	kfree(acks);

	/* because we don't want two CPUs both processing the work item for one
	 * call at the same time, we use a flag to note when it's busy; however
	 * this means there's a race between clearing the flag and setting the
	 * work pending bit and the work item being processed again */
	if (call->events && !work_pending(&call->processor)) {
		_debug("jumpstart %x", ntohl(call->conn->cid));
1298
		rxrpc_queue_call(call);
1299 1300 1301 1302 1303 1304 1305 1306 1307
	}

	_leave("");
	return;

no_mem:
	_debug("out of memory");
	goto maybe_reschedule;
}