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 <linux-sctp@vger.kernel.org>
*
* 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>
*/
#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 size);
/* 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 + 1))
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. */
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.
*/
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;
pending_data = max_tsn - cum_tsn;
gap = max_tsn - base_tsn;
if (gap == 0 || gap >= map->len)
goto out;
pending_data -= bitmap_weight(map->tsn_map, gap + 1);
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 size)
{
unsigned long *new;
unsigned long inc;
u16 len;
if (size > SCTP_TSN_MAP_SIZE)
return 0;
inc = ALIGN((size - 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->cumulative_tsn_ack_point);
kfree(map->tsn_map);
map->tsn_map = new;
map->len = len;
return 1;
}
