sctp: Rework the tsn map to use generic bitmap.

The tsn map currently use is 4K large and is stuck inside
the sctp_association structure making memory references REALLY
expensive.  What we really need is at most 4K worth of bits
so the biggest map we would have is 512 bytes.   Also, the
map is only really usefull when we have gaps to store and
report.  As such, starting with minimal map of say 32 TSNs (bits)
should be enough for normal low-loss operations.  We can grow
the map by some multiple of 32 along with some extra room any
time we receive the TSN which would put us outside of the map
boundry.  As we close gaps, we can shift the map to rebase
it on the latest TSN we've seen.  This saves 4088 bytes per
association just in the map alone along savings from the now
unnecessary structure members.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 148 insertions, 183 deletions

diff --git a/net/sctp/tsnmap.c b/net/sctp/tsnmap.c
index f3e58b2..142ed7c 100644
--- a/net/sctp/tsnmap.c
+++ b/net/sctp/tsnmap.c
@@ -43,37 +43,44 @@
  */
 
 #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(__u8 *map, __u16 off,
-				     __u16 len, __u16 base,
-				     int *started, __u16 *start,
-				     int *ended, __u16 *end);
+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)
+				     __u32 initial_tsn, gfp_t gfp)
 {
-	map->tsn_map = map->raw_map;
-	map->overflow_map = map->tsn_map + len;
-	map->len = len;
-
-	/* Clear out a TSN ack status.  */
-	memset(map->tsn_map, 0x00, map->len + map->len);
+	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->overflow_tsn = initial_tsn + map->len;
 	map->cumulative_tsn_ack_point = initial_tsn - 1;
 	map->max_tsn_seen = map->cumulative_tsn_ack_point;
-	map->malloced = 0;
 	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
@@ -82,66 +89,69 @@ struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len,
  */
 int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn)
 {
-	__s32 gap;
-	int dup;
+	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;
 
-	/* Verify that we can hold this TSN.  */
-	if (gap >= (/* base */ map->len + /* overflow */ map->len)) {
-		dup = -1;
-		goto out;
-	}
-
-	/* Honk if we've already seen this TSN.
-	 * We have three cases:
-	 *	1. The TSN is ancient or belongs to a previous tsn_map.
-	 *	2. The TSN is already marked in the tsn_map.
-	 *	3. The TSN is already marked in the tsn_map_overflow.
-	 */
-	if (gap < 0 ||
-	    (gap < map->len && map->tsn_map[gap]) ||
-	    (gap >= map->len && map->overflow_map[gap - map->len]))
-		dup = 1;
+	/* Check to see if TSN has already been recorded.  */
+	if (gap < map->len && test_bit(gap, map->tsn_map))
+		return 1;
 	else
-		dup = 0;
-
-out:
-	return dup;
+		return 0;
 }
 
 
 /* Mark this TSN as seen.  */
-void sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn)
+int sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn)
 {
-	__s32 gap;
+	u16 gap;
 
-	/* Vacuously mark any TSN which precedes the map base or
-	 * exceeds the end of the map.
-	 */
 	if (TSN_lt(tsn, map->base_tsn))
-		return;
-	if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
-		return;
-
-	/* Bump the max.  */
-	if (TSN_lt(map->max_tsn_seen, tsn))
-		map->max_tsn_seen = tsn;
+		return 0;
 
-	/* Assert: TSN is in range.  */
 	gap = tsn - map->base_tsn;
 
-	/* Mark the TSN as received.  */
-	if (gap < map->len)
-		map->tsn_map[gap]++;
-	else
-		map->overflow_map[gap - map->len]++;
+	if (gap >= map->len && !sctp_tsnmap_grow(map, gap))
+		return -ENOMEM;
 
-	/* Go fixup any internal TSN mapping variables including
-	 * cumulative_tsn_ack_point.
-	 */
-	sctp_tsnmap_update(map);
+	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++;
+		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;
 }
 
 
@@ -160,66 +170,34 @@ SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map,
 					 struct sctp_tsnmap_iter *iter,
 					 __u16 *start, __u16 *end)
 {
-	int started, ended;
-	__u16 start_, end_, offset;
-
-	/* We haven't found a gap yet.  */
-	started = ended = 0;
+	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;
 
-	/* Search the first mapping array.  */
-	if (iter->start - map->base_tsn < map->len) {
-
-		offset = iter->start - map->base_tsn;
-		sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len, 0,
-					 &started, &start_, &ended, &end_);
-	}
-
-	/* Do we need to check the overflow map? */
-	if (!ended) {
-		/* Fix up where we'd like to start searching in the
-		 * overflow map.
-		 */
-		if (iter->start - map->base_tsn < map->len)
-			offset = 0;
-		else
-			offset = iter->start - map->base_tsn - map->len;
-
-		/* Search the overflow map.  */
-		sctp_tsnmap_find_gap_ack(map->overflow_map,
-					 offset,
-					 map->len,
-					 map->len,
-					 &started, &start_,
-					 &ended, &end_);
-	}
+	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
-	 * overflow map.
-	 */
-	if (started && !ended) {
-		ended++;
-		end_ = map->len + map->len - 1;
-	}
+	/* 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 (ended) {
+	if (end_) {
 		/* Fix up the start and end based on the
-		 * Cumulative TSN Ack offset into the map.
+		 * Cumulative TSN Ack which is always 1 behind base.
 		 */
-		int gap = map->cumulative_tsn_ack_point -
-			map->base_tsn;
-
-		*start = start_ - gap;
-		*end = end_ - gap;
+		*start = start_ + 1;
+		*end = end_ + 1;
 
 		/* Move the iterator forward.  */
 		iter->start = map->cumulative_tsn_ack_point + *end + 1;
+		ended = 1;
 	}
 
 	return ended;
@@ -228,35 +206,33 @@ SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map,
 /* Mark this and any lower TSN as seen.  */
 void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn)
 {
-	__s32 gap;
+	u32 gap;
 
-	/* Vacuously mark any TSN which precedes the map base or
-	 * exceeds the end of the map.
-	 */
 	if (TSN_lt(tsn, map->base_tsn))
 		return;
-	if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
+	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;
 
-	/* Assert: TSN is in range.  */
 	gap = tsn - map->base_tsn + 1;
 
-	/* Mark the TSNs as received.  */
-	if (gap <= map->len)
-		memset(map->tsn_map, 0x01, gap);
-	else {
-		memset(map->tsn_map, 0x01, map->len);
-		memset(map->overflow_map, 0x01, (gap - map->len));
+	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 then 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);
 	}
-
-	/* Go fixup any internal TSN mapping variables including
-	 * cumulative_tsn_ack_point.
-	 */
-	sctp_tsnmap_update(map);
 }
 
 /********************************************************************
@@ -268,27 +244,19 @@ void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn)
  */
 static void sctp_tsnmap_update(struct sctp_tsnmap *map)
 {
-	__u32 ctsn;
-
-	ctsn = map->cumulative_tsn_ack_point;
-	do {
-		ctsn++;
-		if (ctsn == map->overflow_tsn) {
-			/* Now tsn_map must have been all '1's,
-			 * so we swap the map and check the overflow table
-			 */
-			__u8 *tmp = map->tsn_map;
-			memset(tmp, 0, map->len);
-			map->tsn_map = map->overflow_map;
-			map->overflow_map = tmp;
-
-			/* Update the tsn_map boundaries.  */
-			map->base_tsn += map->len;
-			map->overflow_tsn += map->len;
-		}
-	} while (map->tsn_map[ctsn - map->base_tsn]);
+	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;
 
-	map->cumulative_tsn_ack_point = ctsn - 1; /* Back up one. */
+	bitmap_shift_right(map->tsn_map, map->tsn_map, zero_bit, map->len);
 }
 
 /* How many data chunks  are we missing from our peer?
@@ -299,31 +267,19 @@ __u16 sctp_tsnmap_pending(struct sctp_tsnmap *map)
 	__u32 max_tsn = map->max_tsn_seen;
 	__u32 base_tsn = map->base_tsn;
 	__u16 pending_data;
-	__s32 gap, start, end, i;
+	u32 gap, i;
 
 	pending_data = max_tsn - cum_tsn;
 	gap = max_tsn - base_tsn;
 
-	if (gap <= 0 || gap >= (map->len + map->len))
+	if (gap == 0 || gap >= map->len)
 		goto out;
 
-	start = ((cum_tsn >= base_tsn) ? (cum_tsn - base_tsn + 1) : 0);
-	end = ((gap > map->len ) ? map->len : gap + 1);
-
-	for (i = start; i < end; i++) {
-		if (map->tsn_map[i])
+	for (i = 0; i < gap+1; i++) {
+		if (test_bit(i, map->tsn_map))
 			pending_data--;
 	}
 
-	if (gap >= map->len) {
-		start = 0;
-		end = gap - map->len + 1;
-		for (i = start; i < end; i++) {
-			if (map->overflow_map[i])
-				pending_data--;
-		}
-	}
-
 out:
 	return pending_data;
 }
@@ -334,10 +290,8 @@ out:
  * 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(__u8 *map, __u16 off,
-				     __u16 len, __u16 base,
-				     int *started, __u16 *start,
-				     int *ended, __u16 *end)
+static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
+				     __u16 len, __u16 *start, __u16 *end)
 {
 	int i = off;
 
@@ -348,49 +302,36 @@ static void sctp_tsnmap_find_gap_ack(__u8 *map, __u16 off,
 	/* Also, stop looking past the maximum TSN seen. */
 
 	/* Look for the start. */
-	if (!(*started)) {
-		for (; i < len; i++) {
-			if (map[i]) {
-				(*started)++;
-				*start = base + i;
-				break;
-			}
-		}
-	}
+	i = find_next_bit(map, len, off);
+	if (i < len)
+		*start = i;
 
 	/* Look for the end.  */
-	if (*started) {
+	if (*start) {
 		/* We have found the start, let's find the
 		 * end.  If we find the end, break out.
 		 */
-		for (; i < len; i++) {
-			if (!map[i]) {
-				(*ended)++;
-				*end = base + i - 1;
-				break;
-			}
-		}
+		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)
 {
-	__s32 gap;
+	u32 gap;
 
 	if (TSN_lt(tsn, map->base_tsn))
 		return;
-	if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
+	/* Assert: TSN is in range.  */
+	if (!TSN_lt(tsn, map->base_tsn + map->len))
 		return;
 
-	/* Assert: TSN is in range.  */
 	gap = tsn - map->base_tsn;
 
 	/* Pretend we never saw the TSN.  */
-	if (gap < map->len)
-		map->tsn_map[gap] = 0;
-	else
-		map->overflow_map[gap - map->len] = 0;
+	clear_bit(gap, map->tsn_map);
 }
 
 /* How many gap ack blocks do we have recorded? */
@@ -416,3 +357,27 @@ __u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map)
 	}
 	return gabs;
 }
+
+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;
+}