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-rw-r--r--net/sctp/tsnmap.c379
1 files changed, 379 insertions, 0 deletions
diff --git a/net/sctp/tsnmap.c b/net/sctp/tsnmap.c
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+++ b/net/sctp/tsnmap.c
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+/* 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, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * 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;
+}
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