/* SCTP kernel implementation

   * (C) Copyright IBM Corp. 2001, 2004
   * Copyright (c) 1999-2000 Cisco, Inc.
   * Copyright (c) 1999-2001 Motorola, Inc.
   * Copyright (c) 2001-2003 Intel Corp.
   *

   * This file is part of the SCTP kernel implementation

   *
   * These functions implement the sctp_outq class.   The outqueue handles
   * bundling and queueing of outgoing SCTP chunks.
   *

   * This SCTP implementation 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, or (at your option)
   * any later version.
   *

   * This SCTP implementation is distributed in the hope that it

   * will be useful, but WITHOUT ANY WARRANTY; without even the implied
   *                 ************************
   * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   * See the GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with GNU CC; see the file COPYING.  If not, write to
   * the Free Software Foundation, 59 Temple Place - Suite 330,
   * Boston, MA 02111-1307, USA.
   *
   * Please send any bug reports or fixes you make to the
   * email address(es):
   *    lksctp developers <lksctp-developers@lists.sourceforge.net>
   *
   * Or submit a bug report through the following website:
   *    http://www.sf.net/projects/lksctp
   *
   * Written or modified by:
   *    La Monte H.P. Yarroll <piggy@acm.org>
   *    Karl Knutson          <karl@athena.chicago.il.us>
   *    Perry Melange         <pmelange@null.cc.uic.edu>
   *    Xingang Guo           <xingang.guo@intel.com>
   *    Hui Huang 	    <hui.huang@nokia.com>
   *    Sridhar Samudrala     <sri@us.ibm.com>
   *    Jon Grimm             <jgrimm@us.ibm.com>
   *
   * Any bugs reported given to us we will try to fix... any fixes shared will
   * be incorporated into the next SCTP release.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/types.h>
  #include <linux/list.h>   /* For struct list_head */
  #include <linux/socket.h>
  #include <linux/ip.h>

  #include <linux/slab.h>

  #include <net/sock.h>	  /* For skb_set_owner_w */
  
  #include <net/sctp/sctp.h>
  #include <net/sctp/sm.h>
  
  /* Declare internal functions here.  */
  static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
  static void sctp_check_transmitted(struct sctp_outq *q,
  				   struct list_head *transmitted_queue,
  				   struct sctp_transport *transport,
  				   struct sctp_sackhdr *sack,

  				   __u32 *highest_new_tsn);

  
  static void sctp_mark_missing(struct sctp_outq *q,
  			      struct list_head *transmitted_queue,
  			      struct sctp_transport *transport,
  			      __u32 highest_new_tsn,
  			      int count_of_newacks);
  
  static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 sack_ctsn);

  static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout);

  /* Add data to the front of the queue. */
  static inline void sctp_outq_head_data(struct sctp_outq *q,
  					struct sctp_chunk *ch)
  {

  	list_add(&ch->list, &q->out_chunk_list);

  	q->out_qlen += ch->skb->len;

  }
  
  /* Take data from the front of the queue. */
  static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
  {

  	struct sctp_chunk *ch = NULL;
  
  	if (!list_empty(&q->out_chunk_list)) {
  		struct list_head *entry = q->out_chunk_list.next;
  
  		ch = list_entry(entry, struct sctp_chunk, list);
  		list_del_init(entry);

  		q->out_qlen -= ch->skb->len;

  	}

  	return ch;
  }
  /* Add data chunk to the end of the queue. */
  static inline void sctp_outq_tail_data(struct sctp_outq *q,
  				       struct sctp_chunk *ch)
  {

  	list_add_tail(&ch->list, &q->out_chunk_list);

  	q->out_qlen += ch->skb->len;

  }
  
  /*
   * SFR-CACC algorithm:
   * D) If count_of_newacks is greater than or equal to 2
   * and t was not sent to the current primary then the
   * sender MUST NOT increment missing report count for t.
   */
  static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
  				       struct sctp_transport *transport,
  				       int count_of_newacks)
  {
  	if (count_of_newacks >=2 && transport != primary)
  		return 1;
  	return 0;
  }
  
  /*
   * SFR-CACC algorithm:
   * F) If count_of_newacks is less than 2, let d be the
   * destination to which t was sent. If cacc_saw_newack
   * is 0 for destination d, then the sender MUST NOT
   * increment missing report count for t.
   */
  static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
  				       int count_of_newacks)
  {

  	if (count_of_newacks < 2 &&
  			(transport && !transport->cacc.cacc_saw_newack))

  		return 1;
  	return 0;
  }
  
  /*
   * SFR-CACC algorithm:
   * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
   * execute steps C, D, F.
   *
   * C has been implemented in sctp_outq_sack
   */
  static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
  				     struct sctp_transport *transport,
  				     int count_of_newacks)
  {
  	if (!primary->cacc.cycling_changeover) {
  		if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
  			return 1;
  		if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
  			return 1;
  		return 0;
  	}
  	return 0;
  }
  
  /*
   * SFR-CACC algorithm:
   * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
   * than next_tsn_at_change of the current primary, then
   * the sender MUST NOT increment missing report count
   * for t.
   */
  static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
  {
  	if (primary->cacc.cycling_changeover &&
  	    TSN_lt(tsn, primary->cacc.next_tsn_at_change))
  		return 1;
  	return 0;
  }
  
  /*
   * SFR-CACC algorithm:
   * 3) If the missing report count for TSN t is to be
   * incremented according to [RFC2960] and
   * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,

   * then the sender MUST further execute steps 3.1 and

   * 3.2 to determine if the missing report count for
   * TSN t SHOULD NOT be incremented.
   *
   * 3.3) If 3.1 and 3.2 do not dictate that the missing
   * report count for t should not be incremented, then

   * the sender SHOULD increment missing report count for

   * t (according to [RFC2960] and [SCTP_STEWART_2002]).
   */
  static inline int sctp_cacc_skip(struct sctp_transport *primary,
  				 struct sctp_transport *transport,
  				 int count_of_newacks,
  				 __u32 tsn)
  {
  	if (primary->cacc.changeover_active &&

  	    (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
  	     sctp_cacc_skip_3_2(primary, tsn)))

  		return 1;
  	return 0;
  }
  
  /* Initialize an existing sctp_outq.  This does the boring stuff.
   * You still need to define handlers if you really want to DO
   * something with this structure...
   */
  void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
  {
  	q->asoc = asoc;

  	INIT_LIST_HEAD(&q->out_chunk_list);
  	INIT_LIST_HEAD(&q->control_chunk_list);

  	INIT_LIST_HEAD(&q->retransmit);
  	INIT_LIST_HEAD(&q->sacked);
  	INIT_LIST_HEAD(&q->abandoned);

  	q->fast_rtx = 0;

  	q->outstanding_bytes = 0;
  	q->empty = 1;
  	q->cork  = 0;
  
  	q->malloced = 0;
  	q->out_qlen = 0;
  }
  
  /* Free the outqueue structure and any related pending chunks.
   */
  void sctp_outq_teardown(struct sctp_outq *q)
  {
  	struct sctp_transport *transport;

  	struct list_head *lchunk, *temp;

  	struct sctp_chunk *chunk, *tmp;

  
  	/* Throw away unacknowledged chunks. */

  	list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
  			transports) {

  		while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
  			chunk = list_entry(lchunk, struct sctp_chunk,
  					   transmitted_list);
  			/* Mark as part of a failed message. */
  			sctp_chunk_fail(chunk, q->error);
  			sctp_chunk_free(chunk);
  		}
  	}
  
  	/* Throw away chunks that have been gap ACKed.  */
  	list_for_each_safe(lchunk, temp, &q->sacked) {
  		list_del_init(lchunk);
  		chunk = list_entry(lchunk, struct sctp_chunk,
  				   transmitted_list);
  		sctp_chunk_fail(chunk, q->error);
  		sctp_chunk_free(chunk);
  	}
  
  	/* Throw away any chunks in the retransmit queue. */
  	list_for_each_safe(lchunk, temp, &q->retransmit) {
  		list_del_init(lchunk);
  		chunk = list_entry(lchunk, struct sctp_chunk,
  				   transmitted_list);
  		sctp_chunk_fail(chunk, q->error);
  		sctp_chunk_free(chunk);
  	}
  
  	/* Throw away any chunks that are in the abandoned queue. */
  	list_for_each_safe(lchunk, temp, &q->abandoned) {
  		list_del_init(lchunk);
  		chunk = list_entry(lchunk, struct sctp_chunk,
  				   transmitted_list);
  		sctp_chunk_fail(chunk, q->error);
  		sctp_chunk_free(chunk);
  	}
  
  	/* Throw away any leftover data chunks. */
  	while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
  
  		/* Mark as send failure. */
  		sctp_chunk_fail(chunk, q->error);
  		sctp_chunk_free(chunk);
  	}
  
  	q->error = 0;
  
  	/* Throw away any leftover control chunks. */

  	list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
  		list_del_init(&chunk->list);

  		sctp_chunk_free(chunk);

  	}

  }
  
  /* Free the outqueue structure and any related pending chunks.  */
  void sctp_outq_free(struct sctp_outq *q)
  {
  	/* Throw away leftover chunks. */
  	sctp_outq_teardown(q);
  
  	/* If we were kmalloc()'d, free the memory.  */
  	if (q->malloced)
  		kfree(q);
  }
  
  /* Put a new chunk in an sctp_outq.  */
  int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk)
  {
  	int error = 0;
  
  	SCTP_DEBUG_PRINTK("sctp_outq_tail(%p, %p[%s])
  ",
  			  q, chunk, chunk && chunk->chunk_hdr ?
  			  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
  			  : "Illegal Chunk");
  
  	/* If it is data, queue it up, otherwise, send it
  	 * immediately.
  	 */

  	if (sctp_chunk_is_data(chunk)) {

  		/* Is it OK to queue data chunks?  */
  		/* From 9. Termination of Association
  		 *
  		 * When either endpoint performs a shutdown, the
  		 * association on each peer will stop accepting new
  		 * data from its user and only deliver data in queue
  		 * at the time of sending or receiving the SHUTDOWN
  		 * chunk.
  		 */
  		switch (q->asoc->state) {

  		case SCTP_STATE_CLOSED:
  		case SCTP_STATE_SHUTDOWN_PENDING:
  		case SCTP_STATE_SHUTDOWN_SENT:
  		case SCTP_STATE_SHUTDOWN_RECEIVED:
  		case SCTP_STATE_SHUTDOWN_ACK_SENT:
  			/* Cannot send after transport endpoint shutdown */
  			error = -ESHUTDOWN;
  			break;
  
  		default:
  			SCTP_DEBUG_PRINTK("outqueueing (%p, %p[%s])
  ",
  			  q, chunk, chunk && chunk->chunk_hdr ?
  			  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
  			  : "Illegal Chunk");
  
  			sctp_outq_tail_data(q, chunk);
  			if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
  				SCTP_INC_STATS(SCTP_MIB_OUTUNORDERCHUNKS);
  			else
  				SCTP_INC_STATS(SCTP_MIB_OUTORDERCHUNKS);
  			q->empty = 0;
  			break;

  		}

  	} else {

  		list_add_tail(&chunk->list, &q->control_chunk_list);

  		SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
  	}
  
  	if (error < 0)
  		return error;
  
  	if (!q->cork)
  		error = sctp_outq_flush(q, 0);
  
  	return error;
  }
  
  /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
   * and the abandoned list are in ascending order.
   */
  static void sctp_insert_list(struct list_head *head, struct list_head *new)
  {
  	struct list_head *pos;
  	struct sctp_chunk *nchunk, *lchunk;
  	__u32 ntsn, ltsn;
  	int done = 0;
  
  	nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
  	ntsn = ntohl(nchunk->subh.data_hdr->tsn);
  
  	list_for_each(pos, head) {
  		lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
  		ltsn = ntohl(lchunk->subh.data_hdr->tsn);
  		if (TSN_lt(ntsn, ltsn)) {
  			list_add(new, pos->prev);
  			done = 1;
  			break;
  		}
  	}
  	if (!done)

  		list_add_tail(new, head);

  }
  
  /* Mark all the eligible packets on a transport for retransmission.  */
  void sctp_retransmit_mark(struct sctp_outq *q,
  			  struct sctp_transport *transport,

  			  __u8 reason)

  {
  	struct list_head *lchunk, *ltemp;
  	struct sctp_chunk *chunk;
  
  	/* Walk through the specified transmitted queue.  */
  	list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
  		chunk = list_entry(lchunk, struct sctp_chunk,
  				   transmitted_list);
  
  		/* If the chunk is abandoned, move it to abandoned list. */
  		if (sctp_chunk_abandoned(chunk)) {
  			list_del_init(lchunk);
  			sctp_insert_list(&q->abandoned, lchunk);

  
  			/* If this chunk has not been previousely acked,
  			 * stop considering it 'outstanding'.  Our peer
  			 * will most likely never see it since it will
  			 * not be retransmitted
  			 */
  			if (!chunk->tsn_gap_acked) {

  				if (chunk->transport)
  					chunk->transport->flight_size -=
  							sctp_data_size(chunk);

  				q->outstanding_bytes -= sctp_data_size(chunk);

  				q->asoc->peer.rwnd += sctp_data_size(chunk);

  			}

  			continue;
  		}

  		/* If we are doing  retransmission due to a timeout or pmtu
  		 * discovery, only the  chunks that are not yet acked should
  		 * be added to the retransmit queue.

  		 */

  		if ((reason == SCTP_RTXR_FAST_RTX  &&

  			    (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||

  		    (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {

  			/* RFC 2960 6.2.1 Processing a Received SACK
  			 *
  			 * C) Any time a DATA chunk is marked for
  			 * retransmission (via either T3-rtx timer expiration
  			 * (Section 6.3.3) or via fast retransmit
  			 * (Section 7.2.4)), add the data size of those
  			 * chunks to the rwnd.
  			 */

  			q->asoc->peer.rwnd += sctp_data_size(chunk);

  			q->outstanding_bytes -= sctp_data_size(chunk);

  			if (chunk->transport)
  				transport->flight_size -= sctp_data_size(chunk);

  
  			/* sctpimpguide-05 Section 2.8.2
  			 * M5) If a T3-rtx timer expires, the
  			 * 'TSN.Missing.Report' of all affected TSNs is set
  			 * to 0.
  			 */
  			chunk->tsn_missing_report = 0;
  
  			/* If a chunk that is being used for RTT measurement
  			 * has to be retransmitted, we cannot use this chunk
  			 * anymore for RTT measurements. Reset rto_pending so
  			 * that a new RTT measurement is started when a new
  			 * data chunk is sent.
  			 */
  			if (chunk->rtt_in_progress) {
  				chunk->rtt_in_progress = 0;
  				transport->rto_pending = 0;
  			}
  
  			/* Move the chunk to the retransmit queue. The chunks
  			 * on the retransmit queue are always kept in order.
  			 */
  			list_del_init(lchunk);
  			sctp_insert_list(&q->retransmit, lchunk);
  		}
  	}

  	SCTP_DEBUG_PRINTK("%s: transport: %p, reason: %d, "

  			  "cwnd: %d, ssthresh: %d, flight_size: %d, "

  			  "pba: %d
  ", __func__,

  			  transport, reason,

  			  transport->cwnd, transport->ssthresh,
  			  transport->flight_size,
  			  transport->partial_bytes_acked);
  
  }
  
  /* Mark all the eligible packets on a transport for retransmission and force
   * one packet out.
   */
  void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
  		     sctp_retransmit_reason_t reason)
  {
  	int error = 0;

  
  	switch(reason) {
  	case SCTP_RTXR_T3_RTX:

  		SCTP_INC_STATS(SCTP_MIB_T3_RETRANSMITS);

  		sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
  		/* Update the retran path if the T3-rtx timer has expired for
  		 * the current retran path.
  		 */
  		if (transport == transport->asoc->peer.retran_path)
  			sctp_assoc_update_retran_path(transport->asoc);

  		transport->asoc->rtx_data_chunks +=
  			transport->asoc->unack_data;

  		break;
  	case SCTP_RTXR_FAST_RTX:

  		SCTP_INC_STATS(SCTP_MIB_FAST_RETRANSMITS);

  		sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);

  		q->fast_rtx = 1;

  		break;
  	case SCTP_RTXR_PMTUD:

  		SCTP_INC_STATS(SCTP_MIB_PMTUD_RETRANSMITS);

  		break;

  	case SCTP_RTXR_T1_RTX:
  		SCTP_INC_STATS(SCTP_MIB_T1_RETRANSMITS);

  		transport->asoc->init_retries++;

  		break;

  	default:
  		BUG();

  	}

  	sctp_retransmit_mark(q, transport, reason);

  
  	/* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
  	 * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
  	 * following the procedures outlined in C1 - C5.
  	 */

  	if (reason == SCTP_RTXR_T3_RTX)
  		sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);

  	/* Flush the queues only on timeout, since fast_rtx is only
  	 * triggered during sack processing and the queue
  	 * will be flushed at the end.
  	 */
  	if (reason != SCTP_RTXR_FAST_RTX)
  		error = sctp_outq_flush(q, /* rtx_timeout */ 1);

  
  	if (error)
  		q->asoc->base.sk->sk_err = -error;
  }
  
  /*
   * Transmit DATA chunks on the retransmit queue.  Upon return from
   * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
   * need to be transmitted by the caller.
   * We assume that pkt->transport has already been set.
   *
   * The return value is a normal kernel error return value.
   */
  static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
  			       int rtx_timeout, int *start_timer)
  {
  	struct list_head *lqueue;

  	struct sctp_transport *transport = pkt->transport;
  	sctp_xmit_t status;
  	struct sctp_chunk *chunk, *chunk1;

  	int fast_rtx;

  	int error = 0;

  	int timer = 0;

  	int done = 0;

  	lqueue = &q->retransmit;

  	fast_rtx = q->fast_rtx;

  	/* This loop handles time-out retransmissions, fast retransmissions,
  	 * and retransmissions due to opening of whindow.
  	 *
  	 * RFC 2960 6.3.3 Handle T3-rtx Expiration

  	 *
  	 * E3) Determine how many of the earliest (i.e., lowest TSN)
  	 * outstanding DATA chunks for the address for which the
  	 * T3-rtx has expired will fit into a single packet, subject
  	 * to the MTU constraint for the path corresponding to the
  	 * destination transport address to which the retransmission
  	 * is being sent (this may be different from the address for
  	 * which the timer expires [see Section 6.4]). Call this value
  	 * K. Bundle and retransmit those K DATA chunks in a single
  	 * packet to the destination endpoint.
  	 *
  	 * [Just to be painfully clear, if we are retransmitting
  	 * because a timeout just happened, we should send only ONE
  	 * packet of retransmitted data.]

  	 *
  	 * For fast retransmissions we also send only ONE packet.  However,
  	 * if we are just flushing the queue due to open window, we'll
  	 * try to send as much as possible.

  	 */

  	list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {

  		/* If the chunk is abandoned, move it to abandoned list. */
  		if (sctp_chunk_abandoned(chunk)) {
  			list_del_init(&chunk->transmitted_list);
  			sctp_insert_list(&q->abandoned,
  					 &chunk->transmitted_list);
  			continue;
  		}

  
  		/* Make sure that Gap Acked TSNs are not retransmitted.  A
  		 * simple approach is just to move such TSNs out of the
  		 * way and into a 'transmitted' queue and skip to the
  		 * next chunk.
  		 */
  		if (chunk->tsn_gap_acked) {

  			list_del(&chunk->transmitted_list);
  			list_add_tail(&chunk->transmitted_list,
  					&transport->transmitted);

  			continue;
  		}

  		/* If we are doing fast retransmit, ignore non-fast_rtransmit
  		 * chunks
  		 */
  		if (fast_rtx && !chunk->fast_retransmit)
  			continue;

  redo:

  		/* Attempt to append this chunk to the packet. */
  		status = sctp_packet_append_chunk(pkt, chunk);
  
  		switch (status) {
  		case SCTP_XMIT_PMTU_FULL:

  			if (!pkt->has_data && !pkt->has_cookie_echo) {
  				/* If this packet did not contain DATA then
  				 * retransmission did not happen, so do it
  				 * again.  We'll ignore the error here since
  				 * control chunks are already freed so there
  				 * is nothing we can do.
  				 */
  				sctp_packet_transmit(pkt);
  				goto redo;
  			}

  			/* Send this packet.  */

  			error = sctp_packet_transmit(pkt);

  
  			/* If we are retransmitting, we should only
  			 * send a single packet.

  			 * Otherwise, try appending this chunk again.

  			 */

  			if (rtx_timeout || fast_rtx)
  				done = 1;

  			else
  				goto redo;

  			/* Bundle next chunk in the next round.  */

  			break;
  
  		case SCTP_XMIT_RWND_FULL:

  			/* Send this packet. */

  			error = sctp_packet_transmit(pkt);

  
  			/* Stop sending DATA as there is no more room
  			 * at the receiver.
  			 */

  			done = 1;

  			break;
  
  		case SCTP_XMIT_NAGLE_DELAY:

  			/* Send this packet. */

  			error = sctp_packet_transmit(pkt);

  
  			/* Stop sending DATA because of nagle delay. */

  			done = 1;

  			break;
  
  		default:
  			/* The append was successful, so add this chunk to
  			 * the transmitted list.
  			 */

  			list_del(&chunk->transmitted_list);
  			list_add_tail(&chunk->transmitted_list,
  					&transport->transmitted);

  			/* Mark the chunk as ineligible for fast retransmit

  			 * after it is retransmitted.
  			 */

  			if (chunk->fast_retransmit == SCTP_NEED_FRTX)
  				chunk->fast_retransmit = SCTP_DONT_FRTX;

  			q->empty = 0;

  			break;

  		}

  		/* Set the timer if there were no errors */
  		if (!error && !timer)
  			timer = 1;

  		if (done)
  			break;
  	}
  
  	/* If we are here due to a retransmit timeout or a fast
  	 * retransmit and if there are any chunks left in the retransmit
  	 * queue that could not fit in the PMTU sized packet, they need
  	 * to be marked as ineligible for a subsequent fast retransmit.
  	 */
  	if (rtx_timeout || fast_rtx) {
  		list_for_each_entry(chunk1, lqueue, transmitted_list) {

  			if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
  				chunk1->fast_retransmit = SCTP_DONT_FRTX;

  		}
  	}

  	*start_timer = timer;
  
  	/* Clear fast retransmit hint */
  	if (fast_rtx)
  		q->fast_rtx = 0;

  	return error;
  }
  
  /* Cork the outqueue so queued chunks are really queued. */
  int sctp_outq_uncork(struct sctp_outq *q)
  {
  	int error = 0;

  	if (q->cork)

  		q->cork = 0;

  	error = sctp_outq_flush(q, 0);

  	return error;
  }

  /*
   * Try to flush an outqueue.
   *
   * Description: Send everything in q which we legally can, subject to
   * congestion limitations.
   * * Note: This function can be called from multiple contexts so appropriate
   * locking concerns must be made.  Today we use the sock lock to protect
   * this function.
   */

  static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)

  {
  	struct sctp_packet *packet;
  	struct sctp_packet singleton;
  	struct sctp_association *asoc = q->asoc;
  	__u16 sport = asoc->base.bind_addr.port;
  	__u16 dport = asoc->peer.port;
  	__u32 vtag = asoc->peer.i.init_tag;

  	struct sctp_transport *transport = NULL;
  	struct sctp_transport *new_transport;

  	struct sctp_chunk *chunk, *tmp;

  	sctp_xmit_t status;
  	int error = 0;
  	int start_timer = 0;

  	int one_packet = 0;

  
  	/* These transports have chunks to send. */
  	struct list_head transport_list;
  	struct list_head *ltransport;
  
  	INIT_LIST_HEAD(&transport_list);
  	packet = NULL;
  
  	/*
  	 * 6.10 Bundling
  	 *   ...
  	 *   When bundling control chunks with DATA chunks, an
  	 *   endpoint MUST place control chunks first in the outbound
  	 *   SCTP packet.  The transmitter MUST transmit DATA chunks
  	 *   within a SCTP packet in increasing order of TSN.
  	 *   ...
  	 */

  	list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {

  		/* RFC 5061, 5.3
  		 * F1) This means that until such time as the ASCONF
  		 * containing the add is acknowledged, the sender MUST
  		 * NOT use the new IP address as a source for ANY SCTP
  		 * packet except on carrying an ASCONF Chunk.
  		 */
  		if (asoc->src_out_of_asoc_ok &&
  		    chunk->chunk_hdr->type != SCTP_CID_ASCONF)
  			continue;

  		list_del_init(&chunk->list);

  		/* Pick the right transport to use. */
  		new_transport = chunk->transport;
  
  		if (!new_transport) {

  			/*
  			 * If we have a prior transport pointer, see if
  			 * the destination address of the chunk
  			 * matches the destination address of the
  			 * current transport.  If not a match, then
  			 * try to look up the transport with a given
  			 * destination address.  We do this because
  			 * after processing ASCONFs, we may have new
  			 * transports created.
  			 */
  			if (transport &&
  			    sctp_cmp_addr_exact(&chunk->dest,
  						&transport->ipaddr))
  					new_transport = transport;
  			else
  				new_transport = sctp_assoc_lookup_paddr(asoc,
  								&chunk->dest);
  
  			/* if we still don't have a new transport, then
  			 * use the current active path.
  			 */
  			if (!new_transport)
  				new_transport = asoc->peer.active_path;

  		} else if ((new_transport->state == SCTP_INACTIVE) ||
  			   (new_transport->state == SCTP_UNCONFIRMED)) {

  			/* If the chunk is Heartbeat or Heartbeat Ack,
  			 * send it to chunk->transport, even if it's

  			 * inactive.
  			 *
  			 * 3.3.6 Heartbeat Acknowledgement:

  			 * ...

  			 * A HEARTBEAT ACK is always sent to the source IP
  			 * address of the IP datagram containing the
  			 * HEARTBEAT chunk to which this ack is responding.

  			 * ...

  			 *
  			 * ASCONF_ACKs also must be sent to the source.

  			 */
  			if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&

  			    chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK &&
  			    chunk->chunk_hdr->type != SCTP_CID_ASCONF_ACK)

  				new_transport = asoc->peer.active_path;
  		}
  
  		/* Are we switching transports?
  		 * Take care of transport locks.
  		 */
  		if (new_transport != transport) {
  			transport = new_transport;
  			if (list_empty(&transport->send_ready)) {
  				list_add_tail(&transport->send_ready,
  					      &transport_list);
  			}
  			packet = &transport->packet;
  			sctp_packet_config(packet, vtag,
  					   asoc->peer.ecn_capable);
  		}
  
  		switch (chunk->chunk_hdr->type) {
  		/*
  		 * 6.10 Bundling
  		 *   ...
  		 *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
  		 *   COMPLETE with any other chunks.  [Send them immediately.]
  		 */
  		case SCTP_CID_INIT:
  		case SCTP_CID_INIT_ACK:
  		case SCTP_CID_SHUTDOWN_COMPLETE:
  			sctp_packet_init(&singleton, transport, sport, dport);
  			sctp_packet_config(&singleton, vtag, 0);
  			sctp_packet_append_chunk(&singleton, chunk);
  			error = sctp_packet_transmit(&singleton);
  			if (error < 0)
  				return error;
  			break;
  
  		case SCTP_CID_ABORT:

  			if (sctp_test_T_bit(chunk)) {
  				packet->vtag = asoc->c.my_vtag;
  			}

  		/* The following chunks are "response" chunks, i.e.
  		 * they are generated in response to something we
  		 * received.  If we are sending these, then we can
  		 * send only 1 packet containing these chunks.
  		 */

  		case SCTP_CID_HEARTBEAT_ACK:

  		case SCTP_CID_SHUTDOWN_ACK:

  		case SCTP_CID_COOKIE_ACK:

  		case SCTP_CID_COOKIE_ECHO:
  		case SCTP_CID_ERROR:

  		case SCTP_CID_ECN_CWR:

  		case SCTP_CID_ASCONF_ACK:

  			one_packet = 1;

  			/* Fall through */

  
  		case SCTP_CID_SACK:
  		case SCTP_CID_HEARTBEAT:
  		case SCTP_CID_SHUTDOWN:
  		case SCTP_CID_ECN_ECNE:
  		case SCTP_CID_ASCONF:

  		case SCTP_CID_FWD_TSN:

  			status = sctp_packet_transmit_chunk(packet, chunk,
  							    one_packet);
  			if (status  != SCTP_XMIT_OK) {
  				/* put the chunk back */
  				list_add(&chunk->list, &q->control_chunk_list);

  			} else if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN) {
  				/* PR-SCTP C5) If a FORWARD TSN is sent, the
  				 * sender MUST assure that at least one T3-rtx
  				 * timer is running.
  				 */

  				sctp_transport_reset_timers(transport);

  			}

  			break;
  
  		default:
  			/* We built a chunk with an illegal type! */
  			BUG();

  		}

  	}

  	if (q->asoc->src_out_of_asoc_ok)
  		goto sctp_flush_out;

  	/* Is it OK to send data chunks?  */
  	switch (asoc->state) {
  	case SCTP_STATE_COOKIE_ECHOED:
  		/* Only allow bundling when this packet has a COOKIE-ECHO
  		 * chunk.
  		 */
  		if (!packet || !packet->has_cookie_echo)
  			break;
  
  		/* fallthru */
  	case SCTP_STATE_ESTABLISHED:
  	case SCTP_STATE_SHUTDOWN_PENDING:
  	case SCTP_STATE_SHUTDOWN_RECEIVED:
  		/*
  		 * RFC 2960 6.1  Transmission of DATA Chunks
  		 *
  		 * C) When the time comes for the sender to transmit,
  		 * before sending new DATA chunks, the sender MUST
  		 * first transmit any outstanding DATA chunks which
  		 * are marked for retransmission (limited by the
  		 * current cwnd).
  		 */
  		if (!list_empty(&q->retransmit)) {

  			if (asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
  				goto sctp_flush_out;

  			if (transport == asoc->peer.retran_path)
  				goto retran;
  
  			/* Switch transports & prepare the packet.  */
  
  			transport = asoc->peer.retran_path;
  
  			if (list_empty(&transport->send_ready)) {
  				list_add_tail(&transport->send_ready,
  					      &transport_list);
  			}
  
  			packet = &transport->packet;
  			sctp_packet_config(packet, vtag,
  					   asoc->peer.ecn_capable);
  		retran:
  			error = sctp_outq_flush_rtx(q, packet,
  						    rtx_timeout, &start_timer);
  
  			if (start_timer)

  				sctp_transport_reset_timers(transport);

  
  			/* This can happen on COOKIE-ECHO resend.  Only
  			 * one chunk can get bundled with a COOKIE-ECHO.
  			 */
  			if (packet->has_cookie_echo)
  				goto sctp_flush_out;
  
  			/* Don't send new data if there is still data
  			 * waiting to retransmit.
  			 */
  			if (!list_empty(&q->retransmit))
  				goto sctp_flush_out;
  		}

  		/* Apply Max.Burst limitation to the current transport in
  		 * case it will be used for new data.  We are going to
  		 * rest it before we return, but we want to apply the limit
  		 * to the currently queued data.
  		 */
  		if (transport)
  			sctp_transport_burst_limited(transport);

  		/* Finally, transmit new packets.  */

  		while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
  			/* RFC 2960 6.5 Every DATA chunk MUST carry a valid
  			 * stream identifier.
  			 */
  			if (chunk->sinfo.sinfo_stream >=
  			    asoc->c.sinit_num_ostreams) {
  
  				/* Mark as failed send. */
  				sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
  				sctp_chunk_free(chunk);
  				continue;
  			}
  
  			/* Has this chunk expired? */
  			if (sctp_chunk_abandoned(chunk)) {
  				sctp_chunk_fail(chunk, 0);
  				sctp_chunk_free(chunk);
  				continue;
  			}
  
  			/* If there is a specified transport, use it.
  			 * Otherwise, we want to use the active path.
  			 */
  			new_transport = chunk->transport;

  			if (!new_transport ||

  			    ((new_transport->state == SCTP_INACTIVE) ||
  			     (new_transport->state == SCTP_UNCONFIRMED)))

  				new_transport = asoc->peer.active_path;

  			if (new_transport->state == SCTP_UNCONFIRMED)
  				continue;

  
  			/* Change packets if necessary.  */
  			if (new_transport != transport) {
  				transport = new_transport;
  
  				/* Schedule to have this transport's
  				 * packet flushed.
  				 */
  				if (list_empty(&transport->send_ready)) {
  					list_add_tail(&transport->send_ready,
  						      &transport_list);
  				}
  
  				packet = &transport->packet;
  				sctp_packet_config(packet, vtag,
  						   asoc->peer.ecn_capable);

  				/* We've switched transports, so apply the
  				 * Burst limit to the new transport.
  				 */
  				sctp_transport_burst_limited(transport);

  			}
  
  			SCTP_DEBUG_PRINTK("sctp_outq_flush(%p, %p[%s]), ",
  					  q, chunk,
  					  chunk && chunk->chunk_hdr ?
  					  sctp_cname(SCTP_ST_CHUNK(
  						  chunk->chunk_hdr->type))
  					  : "Illegal Chunk");
  
  			SCTP_DEBUG_PRINTK("TX TSN 0x%x skb->head "
  					"%p skb->users %d.
  ",
  					ntohl(chunk->subh.data_hdr->tsn),
  					chunk->skb ?chunk->skb->head : NULL,
  					chunk->skb ?
  					atomic_read(&chunk->skb->users) : -1);
  
  			/* Add the chunk to the packet.  */

  			status = sctp_packet_transmit_chunk(packet, chunk, 0);

  
  			switch (status) {
  			case SCTP_XMIT_PMTU_FULL:
  			case SCTP_XMIT_RWND_FULL:
  			case SCTP_XMIT_NAGLE_DELAY:
  				/* We could not append this chunk, so put
  				 * the chunk back on the output queue.
  				 */
  				SCTP_DEBUG_PRINTK("sctp_outq_flush: could "
  					"not transmit TSN: 0x%x, status: %d
  ",
  					ntohl(chunk->subh.data_hdr->tsn),
  					status);
  				sctp_outq_head_data(q, chunk);
  				goto sctp_flush_out;
  				break;
  
  			case SCTP_XMIT_OK:

  				/* The sender is in the SHUTDOWN-PENDING state,
  				 * The sender MAY set the I-bit in the DATA
  				 * chunk header.
  				 */
  				if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
  					chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;

  				break;
  
  			default:
  				BUG();
  			}

  			/* BUG: We assume that the sctp_packet_transmit()

  			 * call below will succeed all the time and add the
  			 * chunk to the transmitted list and restart the
  			 * timers.
  			 * It is possible that the call can fail under OOM
  			 * conditions.
  			 *
  			 * Is this really a problem?  Won't this behave
  			 * like a lost TSN?
  			 */
  			list_add_tail(&chunk->transmitted_list,
  				      &transport->transmitted);

  			sctp_transport_reset_timers(transport);

  
  			q->empty = 0;
  
  			/* Only let one DATA chunk get bundled with a
  			 * COOKIE-ECHO chunk.
  			 */
  			if (packet->has_cookie_echo)
  				goto sctp_flush_out;
  		}
  		break;
  
  	default:
  		/* Do nothing.  */
  		break;
  	}
  
  sctp_flush_out:
  
  	/* Before returning, examine all the transports touched in
  	 * this call.  Right now, we bluntly force clear all the
  	 * transports.  Things might change after we implement Nagle.
  	 * But such an examination is still required.
  	 *
  	 * --xguo
  	 */
  	while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL ) {
  		struct sctp_transport *t = list_entry(ltransport,
  						      struct sctp_transport,
  						      send_ready);
  		packet = &t->packet;
  		if (!sctp_packet_empty(packet))
  			error = sctp_packet_transmit(packet);

  
  		/* Clear the burst limited state, if any */
  		sctp_transport_burst_reset(t);

  	}
  
  	return error;
  }
  
  /* Update unack_data based on the incoming SACK chunk */
  static void sctp_sack_update_unack_data(struct sctp_association *assoc,
  					struct sctp_sackhdr *sack)
  {
  	sctp_sack_variable_t *frags;
  	__u16 unack_data;
  	int i;
  
  	unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
  
  	frags = sack->variable;
  	for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
  		unack_data -= ((ntohs(frags[i].gab.end) -
  				ntohs(frags[i].gab.start) + 1));
  	}
  
  	assoc->unack_data = unack_data;
  }

  /* This is where we REALLY process a SACK.
   *
   * Process the SACK against the outqueue.  Mostly, this just frees
   * things off the transmitted queue.
   */
  int sctp_outq_sack(struct sctp_outq *q, struct sctp_sackhdr *sack)
  {
  	struct sctp_association *asoc = q->asoc;
  	struct sctp_transport *transport;
  	struct sctp_chunk *tchunk = NULL;

  	struct list_head *lchunk, *transport_list, *temp;

  	sctp_sack_variable_t *frags = sack->variable;
  	__u32 sack_ctsn, ctsn, tsn;
  	__u32 highest_tsn, highest_new_tsn;
  	__u32 sack_a_rwnd;
  	unsigned outstanding;
  	struct sctp_transport *primary = asoc->peer.primary_path;
  	int count_of_newacks = 0;

  	int gap_ack_blocks;

  	u8 accum_moved = 0;

  
  	/* Grab the association's destination address list. */
  	transport_list = &asoc->peer.transport_addr_list;
  
  	sack_ctsn = ntohl(sack->cum_tsn_ack);

  	gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);

  	/*
  	 * SFR-CACC algorithm:
  	 * On receipt of a SACK the sender SHOULD execute the
  	 * following statements.
  	 *
  	 * 1) If the cumulative ack in the SACK passes next tsn_at_change
  	 * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
  	 * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
  	 * all destinations.

  	 * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
  	 * is set the receiver of the SACK MUST take the following actions:
  	 *
  	 * A) Initialize the cacc_saw_newack to 0 for all destination
  	 * addresses.

  	 *
  	 * Only bother if changeover_active is set. Otherwise, this is
  	 * totally suboptimal to do on every SACK.

  	 */

  	if (primary->cacc.changeover_active) {
  		u8 clear_cycling = 0;
  
  		if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
  			primary->cacc.changeover_active = 0;
  			clear_cycling = 1;
  		}
  
  		if (clear_cycling || gap_ack_blocks) {
  			list_for_each_entry(transport, transport_list,
  					transports) {
  				if (clear_cycling)
  					transport->cacc.cycling_changeover = 0;
  				if (gap_ack_blocks)
  					transport->cacc.cacc_saw_newack = 0;
  			}

  		}
  	}
  
  	/* Get the highest TSN in the sack. */
  	highest_tsn = sack_ctsn;

  	if (gap_ack_blocks)
  		highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);

  	if (TSN_lt(asoc->highest_sacked, highest_tsn))

  		asoc->highest_sacked = highest_tsn;

  	highest_new_tsn = sack_ctsn;

  	/* Run through the retransmit queue.  Credit bytes received
  	 * and free those chunks that we can.
  	 */

  	sctp_check_transmitted(q, &q->retransmit, NULL, sack, &highest_new_tsn);

  
  	/* Run through the transmitted queue.
  	 * Credit bytes received and free those chunks which we can.
  	 *
  	 * This is a MASSIVE candidate for optimization.
  	 */

  	list_for_each_entry(transport, transport_list, transports) {

  		sctp_check_transmitted(q, &transport->transmitted,

  				       transport, sack, &highest_new_tsn);

  		/*
  		 * SFR-CACC algorithm:
  		 * C) Let count_of_newacks be the number of
  		 * destinations for which cacc_saw_newack is set.
  		 */
  		if (transport->cacc.cacc_saw_newack)
  			count_of_newacks ++;
  	}

  	/* Move the Cumulative TSN Ack Point if appropriate.  */
  	if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
  		asoc->ctsn_ack_point = sack_ctsn;
  		accum_moved = 1;
  	}

  	if (gap_ack_blocks) {

  
  		if (asoc->fast_recovery && accum_moved)
  			highest_new_tsn = highest_tsn;

  		list_for_each_entry(transport, transport_list, transports)
  			sctp_mark_missing(q, &transport->transmitted, transport,
  					  highest_new_tsn, count_of_newacks);

  	}

  	/* Update unack_data field in the assoc. */
  	sctp_sack_update_unack_data(asoc, sack);
  
  	ctsn = asoc->ctsn_ack_point;
  
  	/* Throw away stuff rotting on the sack queue.  */
  	list_for_each_safe(lchunk, temp, &q->sacked) {
  		tchunk = list_entry(lchunk, struct sctp_chunk,
  				    transmitted_list);
  		tsn = ntohl(tchunk->subh.data_hdr->tsn);

  		if (TSN_lte(tsn, ctsn)) {
  			list_del_init(&tchunk->transmitted_list);

  			sctp_chunk_free(tchunk);

  		}

  	}
  
  	/* ii) Set rwnd equal to the newly received a_rwnd minus the
  	 *     number of bytes still outstanding after processing the
  	 *     Cumulative TSN Ack and the Gap Ack Blocks.
  	 */
  
  	sack_a_rwnd = ntohl(sack->a_rwnd);
  	outstanding = q->outstanding_bytes;
  
  	if (outstanding < sack_a_rwnd)
  		sack_a_rwnd -= outstanding;
  	else
  		sack_a_rwnd = 0;
  
  	asoc->peer.rwnd = sack_a_rwnd;
  
  	sctp_generate_fwdtsn(q, sack_ctsn);
  
  	SCTP_DEBUG_PRINTK("%s: sack Cumulative TSN Ack is 0x%x.
  ",

  			  __func__, sack_ctsn);

  	SCTP_DEBUG_PRINTK("%s: Cumulative TSN Ack of association, "
  			  "%p is 0x%x. Adv peer ack point: 0x%x
  ",

  			  __func__, asoc, ctsn, asoc->adv_peer_ack_point);

  
  	/* See if all chunks are acked.
  	 * Make sure the empty queue handler will get run later.
  	 */

  	q->empty = (list_empty(&q->out_chunk_list) &&

  		    list_empty(&q->retransmit));

  	if (!q->empty)
  		goto finish;

  	list_for_each_entry(transport, transport_list, transports) {

  		q->empty = q->empty && list_empty(&transport->transmitted);
  		if (!q->empty)
  			goto finish;
  	}
  
  	SCTP_DEBUG_PRINTK("sack queue is empty.
  ");
  finish:
  	return q->empty;
  }
  
  /* Is the outqueue empty?  */
  int sctp_outq_is_empty(const struct sctp_outq *q)
  {
  	return q->empty;
  }
  
  /********************************************************************
   * 2nd Level Abstractions
   ********************************************************************/
  
  /* Go through a transport's transmitted list or the association's retransmit
   * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
   * The retransmit list will not have an associated transport.
   *
   * I added coherent debug information output.	--xguo
   *
   * Instead of printing 'sacked' or 'kept' for each TSN on the
   * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
   * KEPT TSN6-TSN7, etc.
   */
  static void sctp_check_transmitted(struct sctp_outq *q,
  				   struct list_head *transmitted_queue,
  				   struct sctp_transport *transport,
  				   struct sctp_sackhdr *sack,

  				   __u32 *highest_new_tsn_in_sack)

  {
  	struct list_head *lchunk;
  	struct sctp_chunk *tchunk;
  	struct list_head tlist;
  	__u32 tsn;
  	__u32 sack_ctsn;
  	__u32 rtt;
  	__u8 restart_timer = 0;
  	int bytes_acked = 0;

  	int migrate_bytes = 0;

  
  	/* These state variables are for coherent debug output. --xguo */
  
  #if SCTP_DEBUG
  	__u32 dbg_ack_tsn = 0;	/* An ACKed TSN range starts here... */
  	__u32 dbg_last_ack_tsn = 0;  /* ...and finishes here.	     */
  	__u32 dbg_kept_tsn = 0;	/* An un-ACKed range starts here...  */
  	__u32 dbg_last_kept_tsn = 0; /* ...and finishes here.	     */
  
  	/* 0 : The last TSN was ACKed.
  	 * 1 : The last TSN was NOT ACKed (i.e. KEPT).
  	 * -1: We need to initialize.
  	 */
  	int dbg_prt_state = -1;
  #endif /* SCTP_DEBUG */
  
  	sack_ctsn = ntohl(sack->cum_tsn_ack);
  
  	INIT_LIST_HEAD(&tlist);
  
  	/* The while loop will skip empty transmitted queues. */
  	while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
  		tchunk = list_entry(lchunk, struct sctp_chunk,
  				    transmitted_list);
  
  		if (sctp_chunk_abandoned(tchunk)) {
  			/* Move the chunk to abandoned list. */
  			sctp_insert_list(&q->abandoned, lchunk);

  
  			/* If this chunk has not been acked, stop
  			 * considering it as 'outstanding'.
  			 */
  			if (!tchunk->tsn_gap_acked) {

  				if (tchunk->transport)
  					tchunk->transport->flight_size -=
  							sctp_data_size(tchunk);

  				q->outstanding_bytes -= sctp_data_size(tchunk);
  			}

  			continue;
  		}
  
  		tsn = ntohl(tchunk->subh.data_hdr->tsn);
  		if (sctp_acked(sack, tsn)) {
  			/* If this queue is the retransmit queue, the
  			 * retransmit timer has already reclaimed
  			 * the outstanding bytes for this chunk, so only
  			 * count bytes associated with a transport.
  			 */
  			if (transport) {
  				/* If this chunk is being used for RTT
  				 * measurement, calculate the RTT and update
  				 * the RTO using this value.
  				 *
  				 * 6.3.1 C5) Karn's algorithm: RTT measurements
  				 * MUST NOT be made using packets that were
  				 * retransmitted (and thus for which it is
  				 * ambiguous whether the reply was for the
  				 * first instance of the packet or a later
  				 * instance).
  				 */

  				if (!tchunk->tsn_gap_acked &&

  				    tchunk->rtt_in_progress) {

  					tchunk->rtt_in_progress = 0;

  					rtt = jiffies - tchunk->sent_at;
  					sctp_transport_update_rto(transport,
  								  rtt);
  				}
  			}

  
  			/* If the chunk hasn't been marked as ACKED,
  			 * mark it and account bytes_acked if the
  			 * chunk had a valid transport (it will not
  			 * have a transport if ASCONF had deleted it
  			 * while DATA was outstanding).
  			 */
  			if (!tchunk->tsn_gap_acked) {
  				tchunk->tsn_gap_acked = 1;

  				*highest_new_tsn_in_sack = tsn;

  				bytes_acked += sctp_data_size(tchunk);
  				if (!tchunk->transport)
  					migrate_bytes += sctp_data_size(tchunk);
  			}

  			if (TSN_lte(tsn, sack_ctsn)) {

  				/* RFC 2960  6.3.2 Retransmission Timer Rules
  				 *
  				 * R3) Whenever a SACK is received
  				 * that acknowledges the DATA chunk
  				 * with the earliest outstanding TSN
  				 * for that address, restart T3-rtx
  				 * timer for that address with its
  				 * current RTO.
  				 */
  				restart_timer = 1;
  
  				if (!tchunk->tsn_gap_acked) {

  					/*
  					 * SFR-CACC algorithm:
  					 * 2) If the SACK contains gap acks
  					 * and the flag CHANGEOVER_ACTIVE is
  					 * set the receiver of the SACK MUST
  					 * take the following action:
  					 *
  					 * B) For each TSN t being acked that
  					 * has not been acked in any SACK so
  					 * far, set cacc_saw_newack to 1 for
  					 * the destination that the TSN was
  					 * sent to.
  					 */
  					if (transport &&
  					    sack->num_gap_ack_blocks &&
  					    q->asoc->peer.primary_path->cacc.
  					    changeover_active)
  						transport->cacc.cacc_saw_newack
  							= 1;
  				}
  
  				list_add_tail(&tchunk->transmitted_list,
  					      &q->sacked);
  			} else {
  				/* RFC2960 7.2.4, sctpimpguide-05 2.8.2
  				 * M2) Each time a SACK arrives reporting
  				 * 'Stray DATA chunk(s)' record the highest TSN
  				 * reported as newly acknowledged, call this
  				 * value 'HighestTSNinSack'. A newly
  				 * acknowledged DATA chunk is one not
  				 * previously acknowledged in a SACK.
  				 *
  				 * When the SCTP sender of data receives a SACK
  				 * chunk that acknowledges, for the first time,
  				 * the receipt of a DATA chunk, all the still
  				 * unacknowledged DATA chunks whose TSN is
  				 * older than that newly acknowledged DATA
  				 * chunk, are qualified as 'Stray DATA chunks'.
  				 */

  				list_add_tail(lchunk, &tlist);
  			}
  
  #if SCTP_DEBUG
  			switch (dbg_prt_state) {
  			case 0:	/* last TSN was ACKed */
  				if (dbg_last_ack_tsn + 1 == tsn) {
  					/* This TSN belongs to the
  					 * current ACK range.
  					 */
  					break;
  				}
  
  				if (dbg_last_ack_tsn != dbg_ack_tsn) {
  					/* Display the end of the
  					 * current range.
  					 */

  					SCTP_DEBUG_PRINTK_CONT("-%08x",
  							       dbg_last_ack_tsn);

  				}
  
  				/* Start a new range.  */

  				SCTP_DEBUG_PRINTK_CONT(",%08x", tsn);

  				dbg_ack_tsn = tsn;
  				break;
  
  			case 1:	/* The last TSN was NOT ACKed. */
  				if (dbg_last_kept_tsn != dbg_kept_tsn) {
  					/* Display the end of current range. */

  					SCTP_DEBUG_PRINTK_CONT("-%08x",
  							       dbg_last_kept_tsn);

  				}

  				SCTP_DEBUG_PRINTK_CONT("
  ");

  
  				/* FALL THROUGH... */
  			default:
  				/* This is the first-ever TSN we examined.  */
  				/* Start a new range of ACK-ed TSNs.  */
  				SCTP_DEBUG_PRINTK("ACKed: %08x", tsn);
  				dbg_prt_state = 0;
  				dbg_ack_tsn = tsn;

  			}

  
  			dbg_last_ack_tsn = tsn;
  #endif /* SCTP_DEBUG */
  
  		} else {
  			if (tchunk->tsn_gap_acked) {
  				SCTP_DEBUG_PRINTK("%s: Receiver reneged on "
  						  "data TSN: 0x%x
  ",

  						  __func__,

  						  tsn);
  				tchunk->tsn_gap_acked = 0;

  				if (tchunk->transport)
  					bytes_acked -= sctp_data_size(tchunk);

  
  				/* RFC 2960 6.3.2 Retransmission Timer Rules
  				 *
  				 * R4) Whenever a SACK is received missing a
  				 * TSN that was previously acknowledged via a
  				 * Gap Ack Block, start T3-rtx for the
  				 * destination address to which the DATA
  				 * chunk was originally
  				 * transmitted if it is not already running.
  				 */
  				restart_timer = 1;
  			}
  
  			list_add_tail(lchunk, &tlist);
  
  #if SCTP_DEBUG
  			/* See the above comments on ACK-ed TSNs. */
  			switch (dbg_prt_state) {
  			case 1:
  				if (dbg_last_kept_tsn + 1 == tsn)
  					break;
  
  				if (dbg_last_kept_tsn != dbg_kept_tsn)

  					SCTP_DEBUG_PRINTK_CONT("-%08x",
  							       dbg_last_kept_tsn);

  				SCTP_DEBUG_PRINTK_CONT(",%08x", tsn);

  				dbg_kept_tsn = tsn;
  				break;
  
  			case 0:
  				if (dbg_last_ack_tsn != dbg_ack_tsn)

  					SCTP_DEBUG_PRINTK_CONT("-%08x",
  							       dbg_last_ack_tsn);
  				SCTP_DEBUG_PRINTK_CONT("
  ");

  
  				/* FALL THROUGH... */
  			default:
  				SCTP_DEBUG_PRINTK("KEPT: %08x",tsn);
  				dbg_prt_state = 1;
  				dbg_kept_tsn = tsn;

  			}

  
  			dbg_last_kept_tsn = tsn;
  #endif /* SCTP_DEBUG */
  		}
  	}
  
  #if SCTP_DEBUG
  	/* Finish off the last range, displaying its ending TSN.  */
  	switch (dbg_prt_state) {
  	case 0:
  		if (dbg_last_ack_tsn != dbg_ack_tsn) {

  			SCTP_DEBUG_PRINTK_CONT("-%08x
  ", dbg_last_ack_tsn);

  		} else {

  			SCTP_DEBUG_PRINTK_CONT("
  ");

  		}
  	break;
  
  	case 1:
  		if (dbg_last_kept_tsn != dbg_kept_tsn) {

  			SCTP_DEBUG_PRINTK_CONT("-%08x
  ", dbg_last_kept_tsn);

  		} else {

  			SCTP_DEBUG_PRINTK_CONT("
  ");

  		}

  	}

  #endif /* SCTP_DEBUG */
  	if (transport) {
  		if (bytes_acked) {

  			struct sctp_association *asoc = transport->asoc;

  			/* We may have counted DATA that was migrated
  			 * to this transport due to DEL-IP operation.
  			 * Subtract those bytes, since the were never
  			 * send on this transport and shouldn't be
  			 * credited to this transport.
  			 */
  			bytes_acked -= migrate_bytes;

  			/* 8.2. When an outstanding TSN is acknowledged,
  			 * the endpoint shall clear the error counter of
  			 * the destination transport address to which the
  			 * DATA chunk was last sent.
  			 * The association's overall error counter is
  			 * also cleared.
  			 */
  			transport->error_count = 0;
  			transport->asoc->overall_error_count = 0;

  			/*
  			 * While in SHUTDOWN PENDING, we may have started
  			 * the T5 shutdown guard timer after reaching the
  			 * retransmission limit. Stop that timer as soon
  			 * as the receiver acknowledged any data.
  			 */
  			if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
  			    del_timer(&asoc->timers
  				[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
  					sctp_association_put(asoc);

  			/* Mark the destination transport address as
  			 * active if it is not so marked.
  			 */

  			if ((transport->state == SCTP_INACTIVE) ||
  			    (transport->state == SCTP_UNCONFIRMED)) {

  				sctp_assoc_control_transport(
  					transport->asoc,
  					transport,
  					SCTP_TRANSPORT_UP,
  					SCTP_RECEIVED_SACK);
  			}
  
  			sctp_transport_raise_cwnd(transport, sack_ctsn,
  						  bytes_acked);
  
  			transport->flight_size -= bytes_acked;

  			if (transport->flight_size == 0)
  				transport->partial_bytes_acked = 0;

  			q->outstanding_bytes -= bytes_acked + migrate_bytes;

  		} else {
  			/* RFC 2960 6.1, sctpimpguide-06 2.15.2
  			 * When a sender is doing zero window probing, it
  			 * should not timeout the association if it continues
  			 * to receive new packets from the receiver. The
  			 * reason is that the receiver MAY keep its window
  			 * closed for an indefinite time.
  			 * A sender is doing zero window probing when the
  			 * receiver's advertised window is zero, and there is
  			 * only one data chunk in flight to the receiver.

  			 *
  			 * Allow the association to timeout while in SHUTDOWN
  			 * PENDING or SHUTDOWN RECEIVED in case the receiver
  			 * stays in zero window mode forever.

  			 */
  			if (!q->asoc->peer.rwnd &&
  			    !list_empty(&tlist) &&

  			    (sack_ctsn+2 == q->asoc->next_tsn) &&
  			    q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {

  				SCTP_DEBUG_PRINTK("%s: SACK received for zero "
  						  "window probe: %u
  ",

  						  __func__, sack_ctsn);

  				q->asoc->overall_error_count = 0;
  				transport->error_count = 0;
  			}
  		}
  
  		/* RFC 2960 6.3.2 Retransmission Timer Rules
  		 *
  		 * R2) Whenever all outstanding data sent to an address have
  		 * been acknowledged, turn off the T3-rtx timer of that
  		 * address.
  		 */
  		if (!transport->flight_size) {
  			if (timer_pending(&transport->T3_rtx_timer) &&
  			    del_timer(&transport->T3_rtx_timer)) {
  				sctp_transport_put(transport);
  			}
  		} else if (restart_timer) {
  			if (!mod_timer(&transport->T3_rtx_timer,
  				       jiffies + transport->rto))
  				sctp_transport_hold(transport);
  		}
  	}
  
  	list_splice(&tlist, transmitted_queue);
  }
  
  /* Mark chunks as missing and consequently may get retransmitted. */
  static void sctp_mark_missing(struct sctp_outq *q,
  			      struct list_head *transmitted_queue,
  			      struct sctp_transport *transport,
  			      __u32 highest_new_tsn_in_sack,
  			      int count_of_newacks)
  {
  	struct sctp_chunk *chunk;

  	__u32 tsn;
  	char do_fast_retransmit = 0;

  	struct sctp_association *asoc = q->asoc;
  	struct sctp_transport *primary = asoc->peer.primary_path;

  	list_for_each_entry(chunk, transmitted_queue, transmitted_list) {

  		tsn = ntohl(chunk->subh.data_hdr->tsn);
  
  		/* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
  		 * 'Unacknowledged TSN's', if the TSN number of an
  		 * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
  		 * value, increment the 'TSN.Missing.Report' count on that
  		 * chunk if it has NOT been fast retransmitted or marked for
  		 * fast retransmit already.
  		 */

  		if (chunk->fast_retransmit == SCTP_CAN_FRTX &&

  		    !chunk->tsn_gap_acked &&
  		    TSN_lt(tsn, highest_new_tsn_in_sack)) {
  
  			/* SFR-CACC may require us to skip marking
  			 * this chunk as missing.
  			 */

  			if (!transport || !sctp_cacc_skip(primary,
  						chunk->transport,
  						count_of_newacks, tsn)) {

  				chunk->tsn_missing_report++;
  
  				SCTP_DEBUG_PRINTK(
  					"%s: TSN 0x%x missing counter: %d
  ",

  					__func__, tsn,

  					chunk->tsn_missing_report);
  			}
  		}
  		/*
  		 * M4) If any DATA chunk is found to have a
  		 * 'TSN.Missing.Report'

  		 * value larger than or equal to 3, mark that chunk for

  		 * retransmission and start the fast retransmit procedure.
  		 */

  		if (chunk->tsn_missing_report >= 3) {

  			chunk->fast_retransmit = SCTP_NEED_FRTX;

  			do_fast_retransmit = 1;
  		}
  	}
  
  	if (transport) {
  		if (do_fast_retransmit)
  			sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
  
  		SCTP_DEBUG_PRINTK("%s: transport: %p, cwnd: %d, "
  				  "ssthresh: %d, flight_size: %d, pba: %d
  ",

  				  __func__, transport, transport->cwnd,

  				  transport->ssthresh, transport->flight_size,

  				  transport->partial_bytes_acked);
  	}
  }
  
  /* Is the given TSN acked by this packet?  */
  static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
  {
  	int i;
  	sctp_sack_variable_t *frags;
  	__u16 gap;
  	__u32 ctsn = ntohl(sack->cum_tsn_ack);

  	if (TSN_lte(tsn, ctsn))

  		goto pass;
  
  	/* 3.3.4 Selective Acknowledgement (SACK) (3):
  	 *
  	 * Gap Ack Blocks:
  	 *  These fields contain the Gap Ack Blocks. They are repeated
  	 *  for each Gap Ack Block up to the number of Gap Ack Blocks
  	 *  defined in the Number of Gap Ack Blocks field. All DATA
  	 *  chunks with TSNs greater than or equal to (Cumulative TSN
  	 *  Ack + Gap Ack Block Start) and less than or equal to
  	 *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
  	 *  Block are assumed to have been received correctly.
  	 */
  
  	frags = sack->variable;
  	gap = tsn - ctsn;
  	for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
  		if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
  		    TSN_lte(gap, ntohs(frags[i].gab.end)))
  			goto pass;
  	}
  
  	return 0;
  pass:
  	return 1;
  }
  
  static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,

  				    int nskips, __be16 stream)

  {
  	int i;
  
  	for (i = 0; i < nskips; i++) {
  		if (skiplist[i].stream == stream)
  			return i;
  	}
  	return i;
  }
  
  /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
  static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
  {
  	struct sctp_association *asoc = q->asoc;
  	struct sctp_chunk *ftsn_chunk = NULL;
  	struct sctp_fwdtsn_skip ftsn_skip_arr[10];
  	int nskips = 0;
  	int skip_pos = 0;
  	__u32 tsn;
  	struct sctp_chunk *chunk;
  	struct list_head *lchunk, *temp;

  	if (!asoc->peer.prsctp_capable)
  		return;

  	/* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
  	 * received SACK.

  	 *

  	 * If (Advanced.Peer.Ack.Point < SackCumAck), then update
  	 * Advanced.Peer.Ack.Point to be equal to SackCumAck.
  	 */
  	if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
  		asoc->adv_peer_ack_point = ctsn;
  
  	/* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
  	 * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
  	 * the chunk next in the out-queue space is marked as "abandoned" as
  	 * shown in the following example:
  	 *
  	 * Assuming that a SACK arrived with the Cumulative TSN ACK 102
  	 * and the Advanced.Peer.Ack.Point is updated to this value:

  	 *

  	 *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
  	 *   normal SACK processing           local advancement
  	 *                ...                           ...
  	 *   Adv.Ack.Pt-> 102 acked                     102 acked
  	 *                103 abandoned                 103 abandoned
  	 *                104 abandoned     Adv.Ack.P-> 104 abandoned
  	 *                105                           105
  	 *                106 acked                     106 acked
  	 *                ...                           ...
  	 *
  	 * In this example, the data sender successfully advanced the
  	 * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
  	 */
  	list_for_each_safe(lchunk, temp, &q->abandoned) {
  		chunk = list_entry(lchunk, struct sctp_chunk,
  					transmitted_list);
  		tsn = ntohl(chunk->subh.data_hdr->tsn);
  
  		/* Remove any chunks in the abandoned queue that are acked by
  		 * the ctsn.

  		 */

  		if (TSN_lte(tsn, ctsn)) {
  			list_del_init(lchunk);

  			sctp_chunk_free(chunk);
  		} else {
  			if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
  				asoc->adv_peer_ack_point = tsn;
  				if (chunk->chunk_hdr->flags &
  					 SCTP_DATA_UNORDERED)
  					continue;
  				skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
  						nskips,
  						chunk->subh.data_hdr->stream);
  				ftsn_skip_arr[skip_pos].stream =
  					chunk->subh.data_hdr->stream;
  				ftsn_skip_arr[skip_pos].ssn =
  					 chunk->subh.data_hdr->ssn;
  				if (skip_pos == nskips)
  					nskips++;
  				if (nskips == 10)
  					break;
  			} else
  				break;
  		}
  	}
  
  	/* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
  	 * is greater than the Cumulative TSN ACK carried in the received
  	 * SACK, the data sender MUST send the data receiver a FORWARD TSN
  	 * chunk containing the latest value of the
  	 * "Advanced.Peer.Ack.Point".
  	 *
  	 * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
  	 * list each stream and sequence number in the forwarded TSN. This
  	 * information will enable the receiver to easily find any
  	 * stranded TSN's waiting on stream reorder queues. Each stream
  	 * SHOULD only be reported once; this means that if multiple
  	 * abandoned messages occur in the same stream then only the
  	 * highest abandoned stream sequence number is reported. If the
  	 * total size of the FORWARD TSN does NOT fit in a single MTU then
  	 * the sender of the FORWARD TSN SHOULD lower the
  	 * Advanced.Peer.Ack.Point to the last TSN that will fit in a
  	 * single MTU.
  	 */
  	if (asoc->adv_peer_ack_point > ctsn)
  		ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,

  					      nskips, &ftsn_skip_arr[0]);

  
  	if (ftsn_chunk) {

  		list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);

  		SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
  	}
  }