patch-2.4.23 linux-2.4.23/net/sctp/ulpqueue.c

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diff -urN linux-2.4.22/net/sctp/ulpqueue.c linux-2.4.23/net/sctp/ulpqueue.c
@@ -0,0 +1,820 @@
+/* SCTP kernel reference Implementation
+ * Copyright (c) 1999-2000 Cisco, Inc.
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ * Copyright (c) 2001-2003 International Business Machines, Corp.
+ * Copyright (c) 2001 Intel Corp.
+ * Copyright (c) 2001 Nokia, Inc.
+ * Copyright (c) 2001 La Monte H.P. Yarroll
+ *
+ * This abstraction carries sctp events to the ULP (sockets).
+ *
+ * The SCTP reference 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.
+ *
+ * The SCTP reference 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:
+ *    Jon Grimm             <jgrimm@us.ibm.com>
+ *    La Monte H.P. Yarroll <piggy@acm.org>
+ *    Sridhar Samudrala     <sri@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.
+ */
+
+#include <linux/types.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/sctp/structs.h>
+#include <net/sctp/sctp.h>
+#include <net/sctp/sm.h>
+
+/* Forward declarations for internal helpers.  */
+static inline struct sctp_ulpevent * sctp_ulpq_reasm(struct sctp_ulpq *ulpq,
+						     struct sctp_ulpevent *);
+static inline struct sctp_ulpevent *sctp_ulpq_order(struct sctp_ulpq *,
+						    struct sctp_ulpevent *);
+
+/* 1st Level Abstractions */
+
+/* Create a new ULP queue.  */
+struct sctp_ulpq *sctp_ulpq_new(struct sctp_association *asoc, int gfp)
+{
+	struct sctp_ulpq *ulpq;
+
+	ulpq = kmalloc(sizeof(struct sctp_ulpq), gfp);
+	if (!ulpq)
+		goto fail;
+	if (!sctp_ulpq_init(ulpq, asoc))
+		goto fail_init;
+	ulpq->malloced = 1;
+	return ulpq;
+
+fail_init:
+	kfree(ulpq);
+fail:
+	return NULL;
+}
+
+/* Initialize a ULP queue from a block of memory.  */
+struct sctp_ulpq *sctp_ulpq_init(struct sctp_ulpq *ulpq,
+				 struct sctp_association *asoc)
+{
+	memset(ulpq, sizeof(struct sctp_ulpq), 0x00);
+
+	ulpq->asoc = asoc;
+	skb_queue_head_init(&ulpq->reasm);
+	skb_queue_head_init(&ulpq->lobby);
+	ulpq->pd_mode  = 0;
+	ulpq->malloced = 0;
+
+	return ulpq;
+}
+
+
+/* Flush the reassembly and ordering queues.  */
+void sctp_ulpq_flush(struct sctp_ulpq *ulpq)
+{
+	struct sk_buff *skb;
+	struct sctp_ulpevent *event;
+
+	while ((skb = __skb_dequeue(&ulpq->lobby))) {
+		event = sctp_skb2event(skb);
+		sctp_ulpevent_free(event);
+	}
+
+	while ((skb = __skb_dequeue(&ulpq->reasm))) {
+		event = sctp_skb2event(skb);
+		sctp_ulpevent_free(event);
+	}
+
+}
+
+/* Dispose of a ulpqueue.  */
+void sctp_ulpq_free(struct sctp_ulpq *ulpq)
+{
+	sctp_ulpq_flush(ulpq);
+	if (ulpq->malloced)
+		kfree(ulpq);
+}
+
+/* Process an incoming DATA chunk.  */
+int sctp_ulpq_tail_data(struct sctp_ulpq *ulpq, sctp_chunk_t *chunk,
+			int gfp)
+{
+	struct sk_buff_head temp;
+	sctp_data_chunk_t *hdr;
+	struct sctp_ulpevent *event;
+
+	hdr = (sctp_data_chunk_t *) chunk->chunk_hdr;
+
+	/* Create an event from the incoming chunk. */
+	event = sctp_ulpevent_make_rcvmsg(chunk->asoc, chunk, gfp);
+	if (!event)
+		return -ENOMEM;
+
+	/* Do reassembly if needed.  */
+	event = sctp_ulpq_reasm(ulpq, event);
+
+	/* Do ordering if needed.  */
+	if ((event) && (event->msg_flags & MSG_EOR)){
+		/* Create a temporary list to collect chunks on.  */
+		skb_queue_head_init(&temp);
+		__skb_queue_tail(&temp, sctp_event2skb(event));
+
+		event = sctp_ulpq_order(ulpq, event);
+	}
+
+	/* Send event to the ULP.  */
+	if (event)
+		sctp_ulpq_tail_event(ulpq, event);
+
+	return 0;
+}
+
+/* Add a new event for propagation to the ULP.  */
+/* Clear the partial delivery mode for this socket.   Note: This
+ * assumes that no association is currently in partial delivery mode.
+ */
+int sctp_clear_pd(struct sock *sk)
+{
+	struct sctp_opt *sp;
+	sp = sctp_sk(sk);
+
+	sp->pd_mode = 0;
+	if (!skb_queue_empty(&sp->pd_lobby)) {
+		struct list_head *list;
+		sctp_skb_list_tail(&sp->pd_lobby, &sk->receive_queue);
+		list = (struct list_head *)&sctp_sk(sk)->pd_lobby;
+		INIT_LIST_HEAD(list);
+		return 1;
+	}
+	return 0;
+}
+
+/* Clear the pd_mode and restart any pending messages waiting for delivery. */
+static int sctp_ulpq_clear_pd(struct sctp_ulpq *ulpq)
+{
+	ulpq->pd_mode = 0;
+	return sctp_clear_pd(ulpq->asoc->base.sk);
+}
+
+
+
+int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event)
+{
+	struct sock *sk = ulpq->asoc->base.sk;
+	struct sk_buff_head *queue;
+	int clear_pd = 0;
+
+	/* If the socket is just going to throw this away, do not
+	 * even try to deliver it.
+	 */
+	if ((sk->dead) || (sk->shutdown & RCV_SHUTDOWN))
+		goto out_free;
+
+	/* Check if the user wishes to receive this event.  */
+	if (!sctp_ulpevent_is_enabled(event, &sctp_sk(sk)->subscribe))
+		goto out_free;
+
+	/* If we are in partial delivery mode, post to the lobby until
+	 * partial delivery is cleared, unless, of course _this_ is
+	 * the association the cause of the partial delivery.
+	 */
+
+	if (!sctp_sk(sk)->pd_mode) {
+		queue = &sk->receive_queue;
+	} else if (ulpq->pd_mode) {
+		if (event->msg_flags & MSG_NOTIFICATION)
+		       	queue = &sctp_sk(sk)->pd_lobby;
+		else {
+			clear_pd = event->msg_flags & MSG_EOR;
+			queue = &sk->receive_queue;
+		}
+	} else
+		queue = &sctp_sk(sk)->pd_lobby;
+
+
+	/* If we are harvesting multiple skbs they will be
+	 * collected on a list.
+	 */
+	if (sctp_event2skb(event)->list)
+		sctp_skb_list_tail(sctp_event2skb(event)->list, queue);
+	else
+		__skb_queue_tail(queue, sctp_event2skb(event));
+
+	/* Did we just complete partial delivery and need to get
+	 * rolling again?  Move pending data to the receive
+	 * queue.
+	 */
+	if (clear_pd)
+		sctp_ulpq_clear_pd(ulpq);
+
+	if (queue == &sk->receive_queue)
+		sk->data_ready(sk, 0);
+	return 1;
+
+out_free:
+	if (sctp_event2skb(event)->list)
+		skb_queue_purge(sctp_event2skb(event)->list);
+	else
+		kfree_skb(sctp_event2skb(event));
+	return 0;
+}
+
+/* 2nd Level Abstractions */
+
+/* Helper function to store chunks that need to be reassembled.  */
+static inline void sctp_ulpq_store_reasm(struct sctp_ulpq *ulpq,
+					 struct sctp_ulpevent *event)
+{
+	struct sk_buff *pos;
+	struct sctp_ulpevent *cevent;
+	__u32 tsn, ctsn;
+
+	tsn = event->sndrcvinfo.sinfo_tsn;
+
+	/* See if it belongs at the end. */
+	pos = skb_peek_tail(&ulpq->reasm);
+	if (!pos) {
+		__skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));
+		return;
+	}
+
+	/* Short circuit just dropping it at the end. */
+	cevent = sctp_skb2event(pos);
+	ctsn = cevent->sndrcvinfo.sinfo_tsn;
+	if (TSN_lt(ctsn, tsn)) {
+		__skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));
+		return;
+	}
+
+	/* Find the right place in this list. We store them by TSN.  */
+	skb_queue_walk(&ulpq->reasm, pos) {
+		cevent = sctp_skb2event(pos);
+		ctsn = cevent->sndrcvinfo.sinfo_tsn;
+
+		if (TSN_lt(tsn, ctsn))
+			break;
+	}
+
+	/* Insert before pos. */
+	__skb_insert(sctp_event2skb(event), pos->prev, pos, &ulpq->reasm);
+
+}
+
+/* Helper function to return an event corresponding to the reassembled
+ * datagram.
+ * This routine creates a re-assembled skb given the first and last skb's
+ * as stored in the reassembly queue. The skb's may be non-linear if the sctp
+ * payload was fragmented on the way and ip had to reassemble them.
+ * We add the rest of skb's to the first skb's fraglist.
+ */
+static inline struct sctp_ulpevent *sctp_make_reassembled_event(struct sk_buff *f_frag, struct sk_buff *l_frag)
+{
+	struct sk_buff *pos;
+	struct sctp_ulpevent *event;
+	struct sk_buff *pnext, *last;
+	struct sk_buff *list = skb_shinfo(f_frag)->frag_list;
+
+	/* Store the pointer to the 2nd skb */
+	if (f_frag == l_frag)
+		pos = NULL;
+	else
+		pos = f_frag->next;
+
+	/* Get the last skb in the f_frag's frag_list if present. */
+	for (last = list; list; last = list, list = list->next);
+
+	/* Add the list of remaining fragments to the first fragments
+	 * frag_list.
+	 */
+	if (last)
+		last->next = pos;
+	else
+		skb_shinfo(f_frag)->frag_list = pos;
+
+	/* Remove the first fragment from the reassembly queue.  */
+	__skb_unlink(f_frag, f_frag->list);
+	while (pos) {
+
+		pnext = pos->next;
+
+		/* Update the len and data_len fields of the first fragment. */
+		f_frag->len += pos->len;
+		f_frag->data_len += pos->len;
+
+		/* Remove the fragment from the reassembly queue.  */
+		__skb_unlink(pos, pos->list);
+
+		/* Break if we have reached the last fragment.  */
+		if (pos == l_frag)
+			break;
+
+		pos->next = pnext;
+		pos = pnext;
+	};
+
+	event = sctp_skb2event(f_frag);
+	SCTP_INC_STATS(SctpReasmUsrMsgs);
+
+	return event;
+}
+
+
+/* Helper function to check if an incoming chunk has filled up the last
+ * missing fragment in a SCTP datagram and return the corresponding event.
+ */
+static inline struct sctp_ulpevent *sctp_ulpq_retrieve_reassembled(struct sctp_ulpq *ulpq)
+{
+	struct sk_buff *pos;
+	struct sctp_ulpevent *cevent;
+	struct sk_buff *first_frag = NULL;
+	__u32 ctsn, next_tsn;
+	struct sctp_ulpevent *retval = NULL;
+
+	/* Initialized to 0 just to avoid compiler warning message.  Will
+	 * never be used with this value. It is referenced only after it
+	 * is set when we find the first fragment of a message.
+	 */
+	next_tsn = 0;
+
+	/* The chunks are held in the reasm queue sorted by TSN.
+	 * Walk through the queue sequentially and look for a sequence of
+	 * fragmented chunks that complete a datagram.
+	 * 'first_frag' and next_tsn are reset when we find a chunk which
+	 * is the first fragment of a datagram. Once these 2 fields are set
+	 * we expect to find the remaining middle fragments and the last
+	 * fragment in order. If not, first_frag is reset to NULL and we
+	 * start the next pass when we find another first fragment.
+	 */
+	skb_queue_walk(&ulpq->reasm, pos) {
+		cevent = sctp_skb2event(pos);
+		ctsn = cevent->sndrcvinfo.sinfo_tsn;
+
+		switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
+		case SCTP_DATA_FIRST_FRAG:
+			first_frag = pos;
+			next_tsn = ctsn + 1;
+			break;
+
+		case SCTP_DATA_MIDDLE_FRAG:
+			if ((first_frag) && (ctsn == next_tsn))
+				next_tsn++;
+			else
+				first_frag = NULL;
+			break;
+
+		case SCTP_DATA_LAST_FRAG:
+			if (first_frag && (ctsn == next_tsn))
+				goto found;
+			else
+				first_frag = NULL;
+			break;
+		};
+
+	}
+done:
+	return retval;
+found:
+	retval = sctp_make_reassembled_event(first_frag, pos);
+	if (retval)
+		retval->msg_flags |= MSG_EOR;
+	goto done;
+}
+
+/* Retrieve the next set of fragments of a partial message. */
+static inline struct sctp_ulpevent *sctp_ulpq_retrieve_partial(struct sctp_ulpq *ulpq)
+{
+	struct sk_buff *pos, *last_frag, *first_frag;
+	struct sctp_ulpevent *cevent;
+	__u32 ctsn, next_tsn;
+	int is_last;
+	struct sctp_ulpevent *retval;
+
+	/* The chunks are held in the reasm queue sorted by TSN.
+	 * Walk through the queue sequentially and look for the first
+	 * sequence of fragmented chunks.
+	 */
+
+	if (skb_queue_empty(&ulpq->reasm))
+		return NULL;
+
+	last_frag = first_frag = NULL;
+	retval = NULL;
+	next_tsn = 0;
+	is_last = 0;
+
+	skb_queue_walk(&ulpq->reasm, pos) {
+		cevent = sctp_skb2event(pos);
+		ctsn = cevent->sndrcvinfo.sinfo_tsn;
+
+		switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
+		case SCTP_DATA_MIDDLE_FRAG:
+			if (!first_frag) {
+				first_frag = pos;
+				next_tsn = ctsn + 1;
+				last_frag = pos;
+			} else if (next_tsn == ctsn)
+				next_tsn++;
+			else
+				goto done;
+			break;
+		case SCTP_DATA_LAST_FRAG:
+			if (!first_frag)
+				first_frag = pos;
+			else if (ctsn != next_tsn)
+				goto done;
+			last_frag = pos;
+			is_last = 1;
+			goto done;
+		default:
+			return NULL;
+		};
+	}
+
+	/* We have the reassembled event. There is no need to look
+	 * further.
+	 */
+done:
+	retval = sctp_make_reassembled_event(first_frag, last_frag);
+	if (retval && is_last)
+		retval->msg_flags |= MSG_EOR;
+
+	return retval;
+}
+
+
+/* Helper function to reassemble chunks.  Hold chunks on the reasm queue that
+ * need reassembling.
+ */
+static inline struct sctp_ulpevent *sctp_ulpq_reasm(struct sctp_ulpq *ulpq,
+						   struct sctp_ulpevent *event)
+{
+	struct sctp_ulpevent *retval = NULL;
+
+	/* Check if this is part of a fragmented message.  */
+	if (SCTP_DATA_NOT_FRAG == (event->msg_flags & SCTP_DATA_FRAG_MASK)) {
+		event->msg_flags |= MSG_EOR;
+		return event;
+	}
+
+	sctp_ulpq_store_reasm(ulpq, event);
+	if (!ulpq->pd_mode)
+		retval = sctp_ulpq_retrieve_reassembled(ulpq);
+	else {
+		__u32 ctsn, ctsnap;
+
+		/* Do not even bother unless this is the next tsn to
+		 * be delivered.
+		 */
+		ctsn = event->sndrcvinfo.sinfo_tsn;
+		ctsnap = sctp_tsnmap_get_ctsn(&ulpq->asoc->peer.tsn_map);
+		if (TSN_lte(ctsn, ctsnap))
+			retval = sctp_ulpq_retrieve_partial(ulpq);
+	}
+
+	return retval;
+}
+
+/* Retrieve the first part (sequential fragments) for partial delivery.  */
+static inline struct sctp_ulpevent *sctp_ulpq_retrieve_first(struct sctp_ulpq *ulpq)
+{
+	struct sk_buff *pos, *last_frag, *first_frag;
+	struct sctp_ulpevent *cevent;
+	__u32 ctsn, next_tsn;
+	struct sctp_ulpevent *retval;
+
+	/* The chunks are held in the reasm queue sorted by TSN.
+	 * Walk through the queue sequentially and look for a sequence of
+	 * fragmented chunks that start a datagram.
+	 */
+
+	if (skb_queue_empty(&ulpq->reasm))
+		return NULL;
+
+	last_frag = first_frag = NULL;
+	retval = NULL;
+	next_tsn = 0;
+
+	skb_queue_walk(&ulpq->reasm, pos) {
+		cevent = sctp_skb2event(pos);
+		ctsn = cevent->sndrcvinfo.sinfo_tsn;
+
+		switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
+		case SCTP_DATA_FIRST_FRAG:
+			if (!first_frag) {
+				first_frag = pos;
+				next_tsn = ctsn + 1;
+				last_frag = pos;
+			} else
+				goto done;
+			break;
+
+		case SCTP_DATA_MIDDLE_FRAG:
+			if (!first_frag)
+				return NULL;
+			if (ctsn == next_tsn) {
+				next_tsn++;
+				last_frag = pos;
+			} else
+				goto done;
+			break;
+		default:
+			return NULL;
+		};
+	}
+
+	/* We have the reassembled event. There is no need to look
+	 * further.
+	 */
+done:
+	retval = sctp_make_reassembled_event(first_frag, last_frag);
+	return retval;
+}
+
+/* Helper function to gather skbs that have possibly become
+ * ordered by an an incoming chunk.
+ */
+static inline void sctp_ulpq_retrieve_ordered(struct sctp_ulpq *ulpq,
+					      struct sctp_ulpevent *event)
+{
+	struct sk_buff *pos, *tmp;
+	struct sctp_ulpevent *cevent;
+	struct sctp_stream *in;
+	__u16 sid, csid;
+	__u16 ssn, cssn;
+
+	sid = event->sndrcvinfo.sinfo_stream;
+	ssn = event->sndrcvinfo.sinfo_ssn;
+	in  = &ulpq->asoc->ssnmap->in;
+
+	/* We are holding the chunks by stream, by SSN.  */
+	sctp_skb_for_each(pos, &ulpq->lobby, tmp) {
+		cevent = sctp_skb2event(pos);
+		csid = cevent->sndrcvinfo.sinfo_stream;
+		cssn = cevent->sndrcvinfo.sinfo_ssn;
+
+		/* Have we gone too far?  */
+		if (csid > sid)
+			break;
+
+		/* Have we not gone far enough?  */
+		if (csid < sid)
+			continue;
+
+		if (cssn != sctp_ssn_peek(in, sid))
+			break;
+
+		/* Found it, so mark in the ssnmap. */
+		sctp_ssn_next(in, sid);
+
+		__skb_unlink(pos, pos->list);
+
+		/* Attach all gathered skbs to the event.  */
+		__skb_queue_tail(sctp_event2skb(event)->list, pos);
+	}
+}
+
+/* Helper function to store chunks needing ordering.  */
+static inline void sctp_ulpq_store_ordered(struct sctp_ulpq *ulpq,
+					   struct sctp_ulpevent *event)
+{
+	struct sk_buff *pos;
+	struct sctp_ulpevent *cevent;
+	__u16 sid, csid;
+	__u16 ssn, cssn;
+
+	pos = skb_peek_tail(&ulpq->lobby);
+	if (!pos) {
+		__skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
+		return;
+	}
+
+	sid = event->sndrcvinfo.sinfo_stream;
+	ssn = event->sndrcvinfo.sinfo_ssn;
+	
+	cevent = sctp_skb2event(pos);
+	csid = cevent->sndrcvinfo.sinfo_stream;
+	cssn = cevent->sndrcvinfo.sinfo_ssn;
+	if (sid > csid) {
+		__skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
+		return;
+	}
+
+	if ((sid == csid) && SSN_lt(cssn, ssn)) {
+		__skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
+		return;
+	}
+
+	/* Find the right place in this list.  We store them by
+	 * stream ID and then by SSN.
+	 */
+	skb_queue_walk(&ulpq->lobby, pos) {
+		cevent = sctp_skb2event(pos);
+		csid = cevent->sndrcvinfo.sinfo_stream;
+		cssn = cevent->sndrcvinfo.sinfo_ssn;
+
+		if (csid > sid)
+			break;
+		if (csid == sid && SSN_lt(ssn, cssn))
+			break;
+	}
+
+
+	/* Insert before pos. */
+	__skb_insert(sctp_event2skb(event), pos->prev, pos, &ulpq->lobby);
+
+}
+
+static inline struct sctp_ulpevent *sctp_ulpq_order(struct sctp_ulpq *ulpq,
+					struct sctp_ulpevent *event)
+{
+	__u16 sid, ssn;
+	struct sctp_stream *in;
+
+	/* Check if this message needs ordering.  */
+	if (SCTP_DATA_UNORDERED & event->msg_flags)
+		return event;
+
+	/* Note: The stream ID must be verified before this routine.  */
+	sid = event->sndrcvinfo.sinfo_stream;
+	ssn = event->sndrcvinfo.sinfo_ssn;
+	in  = &ulpq->asoc->ssnmap->in;
+
+	/* Is this the expected SSN for this stream ID?  */
+	if (ssn != sctp_ssn_peek(in, sid)) {
+		/* We've received something out of order, so find where it
+		 * needs to be placed.  We order by stream and then by SSN.
+		 */
+		sctp_ulpq_store_ordered(ulpq, event);
+		return NULL;
+	}
+
+	/* Mark that the next chunk has been found.  */
+	sctp_ssn_next(in, sid);
+
+	/* Go find any other chunks that were waiting for
+	 * ordering.
+	 */
+	sctp_ulpq_retrieve_ordered(ulpq, event);
+
+	return event;
+}
+
+/* Renege 'needed' bytes from the ordering queue. */
+static __u16 sctp_ulpq_renege_order(struct sctp_ulpq *ulpq, __u16 needed)
+{
+	__u16 freed = 0;
+	__u32 tsn;
+	struct sk_buff *skb;
+	struct sctp_ulpevent *event;
+	struct sctp_tsnmap *tsnmap;
+
+	tsnmap = &ulpq->asoc->peer.tsn_map;
+
+	while ((skb = __skb_dequeue_tail(&ulpq->lobby))) {
+		freed += skb_headlen(skb);
+		event = sctp_skb2event(skb);
+		tsn = event->sndrcvinfo.sinfo_tsn;
+
+		sctp_ulpevent_free(event);
+		sctp_tsnmap_renege(tsnmap, tsn);
+		if (freed >= needed)
+			return freed;
+	}
+
+	return freed;
+}
+
+/* Renege 'needed' bytes from the reassembly queue. */
+static __u16 sctp_ulpq_renege_frags(struct sctp_ulpq *ulpq, __u16 needed)
+{
+	__u16 freed = 0;
+	__u32 tsn;
+	struct sk_buff *skb;
+	struct sctp_ulpevent *event;
+	struct sctp_tsnmap *tsnmap;
+
+	tsnmap = &ulpq->asoc->peer.tsn_map;
+
+	/* Walk backwards through the list, reneges the newest tsns. */
+	while ((skb = __skb_dequeue_tail(&ulpq->reasm))) {
+		freed += skb_headlen(skb);
+		event = sctp_skb2event(skb);
+		tsn = event->sndrcvinfo.sinfo_tsn;
+
+		sctp_ulpevent_free(event);
+		sctp_tsnmap_renege(tsnmap, tsn);
+		if (freed >= needed)
+			return freed;
+	}
+
+	return freed;
+}
+
+/* Partial deliver the first message as there is pressure on rwnd. */
+void sctp_ulpq_partial_delivery(struct sctp_ulpq *ulpq,
+				struct sctp_chunk *chunk, int gfp)
+{
+	struct sctp_ulpevent *event;
+	struct sctp_association *asoc;
+
+	asoc = ulpq->asoc;
+
+	/* Are we already in partial delivery mode?  */
+	if (!sctp_sk(asoc->base.sk)->pd_mode) {
+
+		/* Is partial delivery possible?  */
+		event = sctp_ulpq_retrieve_first(ulpq);
+		/* Send event to the ULP.   */
+		if (event) {
+			sctp_ulpq_tail_event(ulpq, event);
+			sctp_sk(asoc->base.sk)->pd_mode = 1;
+			ulpq->pd_mode = 1;
+			return;
+		}
+	}
+}
+
+/* Renege some packets to make room for an incoming chunk.  */
+void sctp_ulpq_renege(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
+		      int gfp)
+{
+	struct sctp_association *asoc;
+	__u16 needed, freed;
+
+	asoc = ulpq->asoc;
+
+	if (chunk) {
+		needed = ntohs(chunk->chunk_hdr->length);
+		needed -= sizeof(sctp_data_chunk_t);
+	} else 
+		needed = SCTP_DEFAULT_MAXWINDOW;
+
+	freed = 0;
+
+	if (skb_queue_empty(&asoc->base.sk->receive_queue)) {
+		freed = sctp_ulpq_renege_order(ulpq, needed);
+		if (freed < needed) {
+			freed += sctp_ulpq_renege_frags(ulpq, needed - freed);
+		}
+	}
+	/* If able to free enough room, accept this chunk. */
+	if (chunk && (freed >= needed)) {
+		__u32 tsn;
+		tsn = ntohl(chunk->subh.data_hdr->tsn);
+		sctp_tsnmap_mark(&asoc->peer.tsn_map, tsn);
+		sctp_ulpq_tail_data(ulpq, chunk, gfp);
+		
+		sctp_ulpq_partial_delivery(ulpq, chunk, gfp);
+	}
+
+	return;
+}
+
+
+
+/* Notify the application if an association is aborted and in
+ * partial delivery mode.  Send up any pending received messages.
+ */
+void sctp_ulpq_abort_pd(struct sctp_ulpq *ulpq, int gfp)
+{
+	struct sctp_ulpevent *ev = NULL;
+	struct sock *sk;
+
+	if (!ulpq->pd_mode)
+		return;
+
+	sk = ulpq->asoc->base.sk;
+	if (sctp_ulpevent_type_enabled(SCTP_PARTIAL_DELIVERY_EVENT,
+				       &sctp_sk(sk)->subscribe))
+		ev = sctp_ulpevent_make_pdapi(ulpq->asoc,
+					      SCTP_PARTIAL_DELIVERY_ABORTED,
+					      gfp);
+	if (ev)
+		__skb_queue_tail(&sk->receive_queue, sctp_event2skb(ev));
+
+	/* If there is data waiting, send it up the socket now. */
+	if (sctp_ulpq_clear_pd(ulpq) || ev)
+		sk->data_ready(sk, 0);
+}
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)