[mirror_ubuntu-bionic-kernel.git] / net / sctp / tsnmap.c

/* SCTP kernel implementation
 * (C) Copyright IBM Corp. 2001, 2004
 * Copyright (c) 1999-2000 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 * Copyright (c) 2001 Intel Corp.
 *
 * This file is part of the SCTP kernel implementation
 *
 * These functions manipulate sctp tsn mapping array.
 *
 * 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>
 *    Jon Grimm             <jgrimm@us.ibm.com>
 *    Karl Knutson          <karl@athena.chicago.il.us>
 *    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/slab.h>
#include <linux/types.h>
#include <linux/bitmap.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>

static void sctp_tsnmap_update(struct sctp_tsnmap *map);
static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
				     __u16 len, __u16 *start, __u16 *end);
static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap);

/* Initialize a block of memory as a tsnmap.  */
struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len,
				     __u32 initial_tsn, gfp_t gfp)
{
	if (!map->tsn_map) {
		map->tsn_map = kzalloc(len>>3, gfp);
		if (map->tsn_map == NULL)
			return NULL;

		map->len = len;
	} else {
		bitmap_zero(map->tsn_map, map->len);
	}

	/* Keep track of TSNs represented by tsn_map.  */
	map->base_tsn = initial_tsn;
	map->cumulative_tsn_ack_point = initial_tsn - 1;
	map->max_tsn_seen = map->cumulative_tsn_ack_point;
	map->num_dup_tsns = 0;

	return map;
}

void sctp_tsnmap_free(struct sctp_tsnmap *map)
{
	map->len = 0;
	kfree(map->tsn_map);
}

/* Test the tracking state of this TSN.
 * Returns:
 *   0 if the TSN has not yet been seen
 *  >0 if the TSN has been seen (duplicate)
 *  <0 if the TSN is invalid (too large to track)
 */
int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn)
{
	u32 gap;

	/* Check to see if this is an old TSN */
	if (TSN_lte(tsn, map->cumulative_tsn_ack_point))
		return 1;

	/* Verify that we can hold this TSN and that it will not
	 * overlfow our map
	 */
	if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE))
		return -1;

	/* Calculate the index into the mapping arrays.  */
	gap = tsn - map->base_tsn;

	/* Check to see if TSN has already been recorded.  */
	if (gap < map->len && test_bit(gap, map->tsn_map))
		return 1;
	else
		return 0;
}


/* Mark this TSN as seen.  */
int sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn,
		     struct sctp_transport *trans)
{
	u16 gap;

	if (TSN_lt(tsn, map->base_tsn))
		return 0;

	gap = tsn - map->base_tsn;

	if (gap >= map->len && !sctp_tsnmap_grow(map, gap))
		return -ENOMEM;

	if (!sctp_tsnmap_has_gap(map) && gap == 0) {
		/* In this case the map has no gaps and the tsn we are
		 * recording is the next expected tsn.  We don't touch
		 * the map but simply bump the values.
		 */
		map->max_tsn_seen++;
		map->cumulative_tsn_ack_point++;
		if (trans)
			trans->sack_generation =
				trans->asoc->peer.sack_generation;
		map->base_tsn++;
	} else {
		/* Either we already have a gap, or about to record a gap, so
		 * have work to do.
		 *
		 * Bump the max.
		 */
		if (TSN_lt(map->max_tsn_seen, tsn))
			map->max_tsn_seen = tsn;

		/* Mark the TSN as received.  */
		set_bit(gap, map->tsn_map);

		/* Go fixup any internal TSN mapping variables including
		 * cumulative_tsn_ack_point.
		 */
		sctp_tsnmap_update(map);
	}

	return 0;
}


/* Initialize a Gap Ack Block iterator from memory being provided.  */
SCTP_STATIC void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map,
				       struct sctp_tsnmap_iter *iter)
{
	/* Only start looking one past the Cumulative TSN Ack Point.  */
	iter->start = map->cumulative_tsn_ack_point + 1;
}

/* Get the next Gap Ack Blocks. Returns 0 if there was not another block
 * to get.
 */
SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map,
					 struct sctp_tsnmap_iter *iter,
					 __u16 *start, __u16 *end)
{
	int ended = 0;
	__u16 start_ = 0, end_ = 0, offset;

	/* If there are no more gap acks possible, get out fast.  */
	if (TSN_lte(map->max_tsn_seen, iter->start))
		return 0;

	offset = iter->start - map->base_tsn;
	sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len,
				 &start_, &end_);

	/* The Gap Ack Block happens to end at the end of the map. */
	if (start_ && !end_)
		end_ = map->len - 1;

	/* If we found a Gap Ack Block, return the start and end and
	 * bump the iterator forward.
	 */
	if (end_) {
		/* Fix up the start and end based on the
		 * Cumulative TSN Ack which is always 1 behind base.
		 */
		*start = start_ + 1;
		*end = end_ + 1;

		/* Move the iterator forward.  */
		iter->start = map->cumulative_tsn_ack_point + *end + 1;
		ended = 1;
	}

	return ended;
}

/* Mark this and any lower TSN as seen.  */
void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn)
{
	u32 gap;

	if (TSN_lt(tsn, map->base_tsn))
		return;
	if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE))
		return;

	/* Bump the max.  */
	if (TSN_lt(map->max_tsn_seen, tsn))
		map->max_tsn_seen = tsn;

	gap = tsn - map->base_tsn + 1;

	map->base_tsn += gap;
	map->cumulative_tsn_ack_point += gap;
	if (gap >= map->len) {
		/* If our gap is larger then the map size, just
		 * zero out the map.
		 */
		bitmap_zero(map->tsn_map, map->len);
	} else {
		/* If the gap is smaller than the map size,
		 * shift the map by 'gap' bits and update further.
		 */
		bitmap_shift_right(map->tsn_map, map->tsn_map, gap, map->len);
		sctp_tsnmap_update(map);
	}
}

/********************************************************************
 * 2nd Level Abstractions
 ********************************************************************/

/* This private helper function updates the tsnmap buffers and
 * the Cumulative TSN Ack Point.
 */
static void sctp_tsnmap_update(struct sctp_tsnmap *map)
{
	u16 len;
	unsigned long zero_bit;


	len = map->max_tsn_seen - map->cumulative_tsn_ack_point;
	zero_bit = find_first_zero_bit(map->tsn_map, len);
	if (!zero_bit)
		return;		/* The first 0-bit is bit 0.  nothing to do */

	map->base_tsn += zero_bit;
	map->cumulative_tsn_ack_point += zero_bit;

	bitmap_shift_right(map->tsn_map, map->tsn_map, zero_bit, map->len);
}

/* How many data chunks  are we missing from our peer?
 */
__u16 sctp_tsnmap_pending(struct sctp_tsnmap *map)
{
	__u32 cum_tsn = map->cumulative_tsn_ack_point;
	__u32 max_tsn = map->max_tsn_seen;
	__u32 base_tsn = map->base_tsn;
	__u16 pending_data;
	u32 gap, i;

	pending_data = max_tsn - cum_tsn;
	gap = max_tsn - base_tsn;

	if (gap == 0 || gap >= map->len)
		goto out;

	for (i = 0; i < gap+1; i++) {
		if (test_bit(i, map->tsn_map))
			pending_data--;
	}

out:
	return pending_data;
}

/* This is a private helper for finding Gap Ack Blocks.  It searches a
 * single array for the start and end of a Gap Ack Block.
 *
 * The flags "started" and "ended" tell is if we found the beginning
 * or (respectively) the end of a Gap Ack Block.
 */
static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
				     __u16 len, __u16 *start, __u16 *end)
{
	int i = off;

	/* Look through the entire array, but break out
	 * early if we have found the end of the Gap Ack Block.
	 */

	/* Also, stop looking past the maximum TSN seen. */

	/* Look for the start. */
	i = find_next_bit(map, len, off);
	if (i < len)
		*start = i;

	/* Look for the end.  */
	if (*start) {
		/* We have found the start, let's find the
		 * end.  If we find the end, break out.
		 */
		i = find_next_zero_bit(map, len, i);
		if (i < len)
			*end = i - 1;
	}
}

/* Renege that we have seen a TSN.  */
void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn)
{
	u32 gap;

	if (TSN_lt(tsn, map->base_tsn))
		return;
	/* Assert: TSN is in range.  */
	if (!TSN_lt(tsn, map->base_tsn + map->len))
		return;

	gap = tsn - map->base_tsn;

	/* Pretend we never saw the TSN.  */
	clear_bit(gap, map->tsn_map);
}

/* How many gap ack blocks do we have recorded? */
__u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map,
			   struct sctp_gap_ack_block *gabs)
{
	struct sctp_tsnmap_iter iter;
	int ngaps = 0;

	/* Refresh the gap ack information. */
	if (sctp_tsnmap_has_gap(map)) {
		__u16 start = 0, end = 0;
		sctp_tsnmap_iter_init(map, &iter);
		while (sctp_tsnmap_next_gap_ack(map, &iter,
						&start,
						&end)) {

			gabs[ngaps].start = htons(start);
			gabs[ngaps].end = htons(end);
			ngaps++;
			if (ngaps >= SCTP_MAX_GABS)
				break;
		}
	}
	return ngaps;
}

static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap)
{
	unsigned long *new;
	unsigned long inc;
	u16  len;

	if (gap >= SCTP_TSN_MAP_SIZE)
		return 0;

	inc = ALIGN((gap - map->len),BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT;
	len = min_t(u16, map->len + inc, SCTP_TSN_MAP_SIZE);

	new = kzalloc(len>>3, GFP_ATOMIC);
	if (!new)
		return 0;

	bitmap_copy(new, map->tsn_map, map->max_tsn_seen - map->base_tsn);
	kfree(map->tsn_map);
	map->tsn_map = new;
	map->len = len;

	return 1;
}
Commit	Line	Data
60c778b2	1	/* SCTP kernel implementation
1da177e4 LT	2	* (C) Copyright IBM Corp. 2001, 2004
	3	* Copyright (c) 1999-2000 Cisco, Inc.
	4	* Copyright (c) 1999-2001 Motorola, Inc.
	5	* Copyright (c) 2001 Intel Corp.
	6	*
60c778b2	7	* This file is part of the SCTP kernel implementation
1da177e4 LT	8	*
	9	* These functions manipulate sctp tsn mapping array.
	10	*
60c778b2	11	* This SCTP implementation is free software;
1da177e4 LT	12	* you can redistribute it and/or modify it under the terms of
	13	* the GNU General Public License as published by
	14	* the Free Software Foundation; either version 2, or (at your option)
	15	* any later version.
	16	*
60c778b2	17	* This SCTP implementation is distributed in the hope that it
1da177e4 LT	18	* will be useful, but WITHOUT ANY WARRANTY; without even the implied
	19	* ************************
	20	* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
	21	* See the GNU General Public License for more details.
	22	*
	23	* You should have received a copy of the GNU General Public License
	24	* along with GNU CC; see the file COPYING. If not, write to
	25	* the Free Software Foundation, 59 Temple Place - Suite 330,
	26	* Boston, MA 02111-1307, USA.
	27	*
	28	* Please send any bug reports or fixes you make to the
	29	* email address(es):
	30	* lksctp developers <lksctp-developers@lists.sourceforge.net>
	31	*
	32	* Or submit a bug report through the following website:
	33	* http://www.sf.net/projects/lksctp
	34	*
	35	* Written or modified by:
	36	* La Monte H.P. Yarroll <piggy@acm.org>
	37	* Jon Grimm <jgrimm@us.ibm.com>
	38	* Karl Knutson <karl@athena.chicago.il.us>
	39	* Sridhar Samudrala <sri@us.ibm.com>
	40	*
	41	* Any bugs reported given to us we will try to fix... any fixes shared will
	42	* be incorporated into the next SCTP release.
	43	*/
	44
5a0e3ad6	45	#include <linux/slab.h>
1da177e4	46	#include <linux/types.h>
8e1ee18c	47	#include <linux/bitmap.h>
1da177e4 LT	48	#include <net/sctp/sctp.h>
	49	#include <net/sctp/sm.h>
	50
	51	static void sctp_tsnmap_update(struct sctp_tsnmap *map);
8e1ee18c VY	52	static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
	53	__u16 len, __u16 start, __u16 end);
	54	static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap);
1da177e4 LT	55
	56	/* Initialize a block of memory as a tsnmap. */
	57	struct sctp_tsnmap sctp_tsnmap_init(struct sctp_tsnmap map, __u16 len,
8e1ee18c	58	__u32 initial_tsn, gfp_t gfp)
1da177e4	59	{
8e1ee18c VY	60	if (!map->tsn_map) {
	61	map->tsn_map = kzalloc(len>>3, gfp);
	62	if (map->tsn_map == NULL)
	63	return NULL;
	64
	65	map->len = len;
	66	} else {
	67	bitmap_zero(map->tsn_map, map->len);
	68	}
1da177e4 LT	69
	70	/* Keep track of TSNs represented by tsn_map. */
	71	map->base_tsn = initial_tsn;
1da177e4 LT	72	map->cumulative_tsn_ack_point = initial_tsn - 1;
1da177e4 LT	73	map->max_tsn_seen = map->cumulative_tsn_ack_point;
1da177e4 LT	74	map->num_dup_tsns = 0;
	75
	76	return map;
	77	}
	78
8e1ee18c VY	79	void sctp_tsnmap_free(struct sctp_tsnmap *map)
	80	{
	81	map->len = 0;
	82	kfree(map->tsn_map);
	83	}
	84
1da177e4 LT	85	/* Test the tracking state of this TSN.
	86	* Returns:
	87	* 0 if the TSN has not yet been seen
	88	* >0 if the TSN has been seen (duplicate)
	89	* <0 if the TSN is invalid (too large to track)
	90	*/
	91	int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn)
	92	{
8e1ee18c VY	93	u32 gap;
	94
	95	/* Check to see if this is an old TSN */
	96	if (TSN_lte(tsn, map->cumulative_tsn_ack_point))
	97	return 1;
	98
	99	/* Verify that we can hold this TSN and that it will not
	100	* overlfow our map
	101	*/
	102	if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE))
	103	return -1;
1da177e4 LT	104
	105	/* Calculate the index into the mapping arrays. */
	106	gap = tsn - map->base_tsn;
	107
8e1ee18c VY	108	/* Check to see if TSN has already been recorded. */
	109	if (gap < map->len && test_bit(gap, map->tsn_map))
	110	return 1;
1da177e4	111	else
8e1ee18c	112	return 0;
1da177e4 LT	113	}
	114
	115
	116	/* Mark this TSN as seen. */
4244854d NH	117	int sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn,
4244854d NH	118	struct sctp_transport *trans)
1da177e4	119	{
8e1ee18c	120	u16 gap;
1da177e4	121
1da177e4	122	if (TSN_lt(tsn, map->base_tsn))
8e1ee18c	123	return 0;
1da177e4	124
1da177e4 LT	125	gap = tsn - map->base_tsn;
1da177e4 LT	126
8e1ee18c VY	127	if (gap >= map->len && !sctp_tsnmap_grow(map, gap))
8e1ee18c VY	128	return -ENOMEM;
1da177e4	129
8e1ee18c VY	130	if (!sctp_tsnmap_has_gap(map) && gap == 0) {
	131	/* In this case the map has no gaps and the tsn we are
	132	* recording is the next expected tsn. We don't touch
	133	* the map but simply bump the values.
	134	*/
	135	map->max_tsn_seen++;
	136	map->cumulative_tsn_ack_point++;
4244854d NH	137	if (trans)
	138	trans->sack_generation =
	139	trans->asoc->peer.sack_generation;
8e1ee18c VY	140	map->base_tsn++;
	141	} else {
	142	/* Either we already have a gap, or about to record a gap, so
	143	* have work to do.
	144	*
	145	* Bump the max.
	146	*/
	147	if (TSN_lt(map->max_tsn_seen, tsn))
	148	map->max_tsn_seen = tsn;
	149
	150	/* Mark the TSN as received. */
	151	set_bit(gap, map->tsn_map);
	152
	153	/* Go fixup any internal TSN mapping variables including
	154	* cumulative_tsn_ack_point.
	155	*/
	156	sctp_tsnmap_update(map);
	157	}
	158
	159	return 0;
1da177e4 LT	160	}
	161
	162
	163	/* Initialize a Gap Ack Block iterator from memory being provided. */
	164	SCTP_STATIC void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map,
	165	struct sctp_tsnmap_iter *iter)
	166	{
	167	/* Only start looking one past the Cumulative TSN Ack Point. */
	168	iter->start = map->cumulative_tsn_ack_point + 1;
	169	}
	170
	171	/* Get the next Gap Ack Blocks. Returns 0 if there was not another block
	172	* to get.
	173	*/
	174	SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map,
	175	struct sctp_tsnmap_iter *iter,
	176	__u16 start, __u16 end)
	177	{
8e1ee18c VY	178	int ended = 0;
8e1ee18c VY	179	__u16 start_ = 0, end_ = 0, offset;
1da177e4 LT	180
	181	/* If there are no more gap acks possible, get out fast. */
	182	if (TSN_lte(map->max_tsn_seen, iter->start))
	183	return 0;
	184
8e1ee18c VY	185	offset = iter->start - map->base_tsn;
	186	sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len,
	187	&start_, &end_);
1da177e4	188
8e1ee18c VY	189	/* The Gap Ack Block happens to end at the end of the map. */
	190	if (start_ && !end_)
	191	end_ = map->len - 1;
1da177e4 LT	192
	193	/* If we found a Gap Ack Block, return the start and end and
	194	* bump the iterator forward.
	195	*/
8e1ee18c	196	if (end_) {
1da177e4	197	/* Fix up the start and end based on the
8e1ee18c	198	* Cumulative TSN Ack which is always 1 behind base.
1da177e4	199	*/
8e1ee18c VY	200	*start = start_ + 1;
8e1ee18c VY	201	*end = end_ + 1;
1da177e4 LT	202
	203	/* Move the iterator forward. */
	204	iter->start = map->cumulative_tsn_ack_point + *end + 1;
8e1ee18c	205	ended = 1;
1da177e4 LT	206	}
	207
	208	return ended;
	209	}
	210
	211	/* Mark this and any lower TSN as seen. */
	212	void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn)
	213	{
8e1ee18c	214	u32 gap;
1da177e4	215
1da177e4 LT	216	if (TSN_lt(tsn, map->base_tsn))
1da177e4 LT	217	return;
8e1ee18c	218	if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE))
1da177e4 LT	219	return;
	220
	221	/* Bump the max. */
	222	if (TSN_lt(map->max_tsn_seen, tsn))
	223	map->max_tsn_seen = tsn;
	224
1da177e4 LT	225	gap = tsn - map->base_tsn + 1;
1da177e4 LT	226
8e1ee18c VY	227	map->base_tsn += gap;
	228	map->cumulative_tsn_ack_point += gap;
	229	if (gap >= map->len) {
	230	/* If our gap is larger then the map size, just
	231	* zero out the map.
	232	*/
	233	bitmap_zero(map->tsn_map, map->len);
	234	} else {
025dfdaf	235	/* If the gap is smaller than the map size,
8e1ee18c VY	236	* shift the map by 'gap' bits and update further.
	237	*/
	238	bitmap_shift_right(map->tsn_map, map->tsn_map, gap, map->len);
	239	sctp_tsnmap_update(map);
1da177e4	240	}
1da177e4 LT	241	}
	242
	243	/********************************************************************
	244	* 2nd Level Abstractions
	245	********************************************************************/
	246
	247	/* This private helper function updates the tsnmap buffers and
	248	* the Cumulative TSN Ack Point.
	249	*/
	250	static void sctp_tsnmap_update(struct sctp_tsnmap *map)
	251	{
8e1ee18c VY	252	u16 len;
	253	unsigned long zero_bit;
	254
	255
	256	len = map->max_tsn_seen - map->cumulative_tsn_ack_point;
	257	zero_bit = find_first_zero_bit(map->tsn_map, len);
	258	if (!zero_bit)
	259	return; /* The first 0-bit is bit 0. nothing to do */
	260
	261	map->base_tsn += zero_bit;
	262	map->cumulative_tsn_ack_point += zero_bit;
1da177e4	263
8e1ee18c	264	bitmap_shift_right(map->tsn_map, map->tsn_map, zero_bit, map->len);
1da177e4 LT	265	}
	266
	267	/* How many data chunks are we missing from our peer?
	268	*/
	269	__u16 sctp_tsnmap_pending(struct sctp_tsnmap *map)
	270	{
	271	__u32 cum_tsn = map->cumulative_tsn_ack_point;
	272	__u32 max_tsn = map->max_tsn_seen;
	273	__u32 base_tsn = map->base_tsn;
	274	__u16 pending_data;
8e1ee18c	275	u32 gap, i;
1da177e4 LT	276
	277	pending_data = max_tsn - cum_tsn;
	278	gap = max_tsn - base_tsn;
	279
8e1ee18c	280	if (gap == 0 \|\| gap >= map->len)
1da177e4 LT	281	goto out;
1da177e4 LT	282
8e1ee18c VY	283	for (i = 0; i < gap+1; i++) {
8e1ee18c VY	284	if (test_bit(i, map->tsn_map))
1da177e4 LT	285	pending_data--;
	286	}
	287
1da177e4 LT	288	out:
	289	return pending_data;
	290	}
	291
	292	/* This is a private helper for finding Gap Ack Blocks. It searches a
	293	* single array for the start and end of a Gap Ack Block.
	294	*
	295	* The flags "started" and "ended" tell is if we found the beginning
	296	* or (respectively) the end of a Gap Ack Block.
	297	*/
8e1ee18c VY	298	static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
8e1ee18c VY	299	__u16 len, __u16 start, __u16 end)
1da177e4 LT	300	{
	301	int i = off;
	302
	303	/* Look through the entire array, but break out
	304	* early if we have found the end of the Gap Ack Block.
	305	*/
	306
	307	/* Also, stop looking past the maximum TSN seen. */
	308
	309	/* Look for the start. */
8e1ee18c VY	310	i = find_next_bit(map, len, off);
	311	if (i < len)
	312	*start = i;
1da177e4 LT	313
1da177e4 LT	314	/* Look for the end. */
8e1ee18c	315	if (*start) {
1da177e4 LT	316	/* We have found the start, let's find the
	317	* end. If we find the end, break out.
	318	*/
8e1ee18c VY	319	i = find_next_zero_bit(map, len, i);
	320	if (i < len)
	321	*end = i - 1;
1da177e4 LT	322	}
	323	}
	324
	325	/* Renege that we have seen a TSN. */
	326	void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn)
	327	{
8e1ee18c	328	u32 gap;
1da177e4 LT	329
	330	if (TSN_lt(tsn, map->base_tsn))
	331	return;
8e1ee18c VY	332	/* Assert: TSN is in range. */
8e1ee18c VY	333	if (!TSN_lt(tsn, map->base_tsn + map->len))
1da177e4 LT	334	return;
1da177e4 LT	335
1da177e4 LT	336	gap = tsn - map->base_tsn;
	337
	338	/* Pretend we never saw the TSN. */
8e1ee18c	339	clear_bit(gap, map->tsn_map);
1da177e4 LT	340	}
	341
	342	/* How many gap ack blocks do we have recorded? */
02015180 VY	343	__u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map,
02015180 VY	344	struct sctp_gap_ack_block *gabs)
1da177e4 LT	345	{
1da177e4 LT	346	struct sctp_tsnmap_iter iter;
02015180	347	int ngaps = 0;
1da177e4 LT	348
	349	/* Refresh the gap ack information. */
	350	if (sctp_tsnmap_has_gap(map)) {
59ed5aba	351	__u16 start = 0, end = 0;
1da177e4 LT	352	sctp_tsnmap_iter_init(map, &iter);
1da177e4 LT	353	while (sctp_tsnmap_next_gap_ack(map, &iter,
9f81bcd9 AV	354	&start,
9f81bcd9 AV	355	&end)) {
1da177e4	356
02015180 VY	357	gabs[ngaps].start = htons(start);
	358	gabs[ngaps].end = htons(end);
	359	ngaps++;
	360	if (ngaps >= SCTP_MAX_GABS)
1da177e4 LT	361	break;
	362	}
	363	}
02015180	364	return ngaps;
1da177e4	365	}
8e1ee18c VY	366
	367	static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap)
	368	{
	369	unsigned long *new;
	370	unsigned long inc;
	371	u16 len;
	372
	373	if (gap >= SCTP_TSN_MAP_SIZE)
	374	return 0;
	375
	376	inc = ALIGN((gap - map->len),BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT;
	377	len = min_t(u16, map->len + inc, SCTP_TSN_MAP_SIZE);
	378
	379	new = kzalloc(len>>3, GFP_ATOMIC);
	380	if (!new)
	381	return 0;
	382
	383	bitmap_copy(new, map->tsn_map, map->max_tsn_seen - map->base_tsn);
	384	kfree(map->tsn_map);
	385	map->tsn_map = new;
	386	map->len = len;
	387
	388	return 1;
	389	}