kernel-ark/net/sctp/tsnmap.c
Neil Horman 4244854d22 sctp: be more restrictive in transport selection on bundled sacks
It was noticed recently that when we send data on a transport, its possible that
we might bundle a sack that arrived on a different transport.  While this isn't
a major problem, it does go against the SHOULD requirement in section 6.4 of RFC
2960:

 An endpoint SHOULD transmit reply chunks (e.g., SACK, HEARTBEAT ACK,
   etc.) to the same destination transport address from which it
   received the DATA or control chunk to which it is replying.  This
   rule should also be followed if the endpoint is bundling DATA chunks
   together with the reply chunk.

This patch seeks to correct that.  It restricts the bundling of sack operations
to only those transports which have moved the ctsn of the association forward
since the last sack.  By doing this we guarantee that we only bundle outbound
saks on a transport that has received a chunk since the last sack.  This brings
us into stricter compliance with the RFC.

Vlad had initially suggested that we strictly allow only sack bundling on the
transport that last moved the ctsn forward.  While this makes sense, I was
concerned that doing so prevented us from bundling in the case where we had
received chunks that moved the ctsn on multiple transports.  In those cases, the
RFC allows us to select any of the transports having received chunks to bundle
the sack on.  so I've modified the approach to allow for that, by adding a state
variable to each transport that tracks weather it has moved the ctsn since the
last sack.  This I think keeps our behavior (and performance), close enough to
our current profile that I think we can do this without a sysctl knob to
enable/disable it.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Vlad Yaseivch <vyasevich@gmail.com>
CC: David S. Miller <davem@davemloft.net>
CC: linux-sctp@vger.kernel.org
Reported-by: Michele Baldessari <michele@redhat.com>
Reported-by: sorin serban <sserban@redhat.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-06-30 22:44:35 -07:00

390 lines
9.8 KiB
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;
}