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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /net/sctp/transport.c
downloadkernel-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'net/sctp/transport.c')
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diff --git a/net/sctp/transport.c b/net/sctp/transport.c
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+/* SCTP kernel reference Implementation
+ * Copyright (c) 1999-2000 Cisco, Inc.
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ * Copyright (c) 2001-2003 International Business Machines Corp.
+ * Copyright (c) 2001 Intel Corp.
+ * Copyright (c) 2001 La Monte H.P. Yarroll
+ *
+ * This file is part of the SCTP kernel reference Implementation
+ *
+ * This module provides the abstraction for an SCTP tranport representing
+ * a remote transport address. For local transport addresses, we just use
+ * union sctp_addr.
+ *
+ * The SCTP reference 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.
+ *
+ * The SCTP reference 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>
+ * Karl Knutson <karl@athena.chicago.il.us>
+ * Jon Grimm <jgrimm@us.ibm.com>
+ * Xingang Guo <xingang.guo@intel.com>
+ * Hui Huang <hui.huang@nokia.com>
+ * Sridhar Samudrala <sri@us.ibm.com>
+ * Ardelle Fan <ardelle.fan@intel.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/types.h>
+#include <net/sctp/sctp.h>
+#include <net/sctp/sm.h>
+
+/* 1st Level Abstractions. */
+
+/* Initialize a new transport from provided memory. */
+static struct sctp_transport *sctp_transport_init(struct sctp_transport *peer,
+ const union sctp_addr *addr,
+ int gfp)
+{
+ /* Copy in the address. */
+ peer->ipaddr = *addr;
+ peer->af_specific = sctp_get_af_specific(addr->sa.sa_family);
+ peer->asoc = NULL;
+
+ peer->dst = NULL;
+ memset(&peer->saddr, 0, sizeof(union sctp_addr));
+
+ /* From 6.3.1 RTO Calculation:
+ *
+ * C1) Until an RTT measurement has been made for a packet sent to the
+ * given destination transport address, set RTO to the protocol
+ * parameter 'RTO.Initial'.
+ */
+ peer->rtt = 0;
+ peer->rto = sctp_rto_initial;
+ peer->rttvar = 0;
+ peer->srtt = 0;
+ peer->rto_pending = 0;
+
+ peer->last_time_heard = jiffies;
+ peer->last_time_used = jiffies;
+ peer->last_time_ecne_reduced = jiffies;
+
+ peer->active = SCTP_ACTIVE;
+ peer->hb_allowed = 0;
+
+ /* Initialize the default path max_retrans. */
+ peer->max_retrans = sctp_max_retrans_path;
+ peer->error_count = 0;
+
+ INIT_LIST_HEAD(&peer->transmitted);
+ INIT_LIST_HEAD(&peer->send_ready);
+ INIT_LIST_HEAD(&peer->transports);
+
+ /* Set up the retransmission timer. */
+ init_timer(&peer->T3_rtx_timer);
+ peer->T3_rtx_timer.function = sctp_generate_t3_rtx_event;
+ peer->T3_rtx_timer.data = (unsigned long)peer;
+
+ /* Set up the heartbeat timer. */
+ init_timer(&peer->hb_timer);
+ peer->hb_interval = SCTP_DEFAULT_TIMEOUT_HEARTBEAT;
+ peer->hb_timer.function = sctp_generate_heartbeat_event;
+ peer->hb_timer.data = (unsigned long)peer;
+
+ atomic_set(&peer->refcnt, 1);
+ peer->dead = 0;
+
+ peer->malloced = 0;
+
+ /* Initialize the state information for SFR-CACC */
+ peer->cacc.changeover_active = 0;
+ peer->cacc.cycling_changeover = 0;
+ peer->cacc.next_tsn_at_change = 0;
+ peer->cacc.cacc_saw_newack = 0;
+
+ return peer;
+}
+
+/* Allocate and initialize a new transport. */
+struct sctp_transport *sctp_transport_new(const union sctp_addr *addr, int gfp)
+{
+ struct sctp_transport *transport;
+
+ transport = t_new(struct sctp_transport, gfp);
+ if (!transport)
+ goto fail;
+
+ if (!sctp_transport_init(transport, addr, gfp))
+ goto fail_init;
+
+ transport->malloced = 1;
+ SCTP_DBG_OBJCNT_INC(transport);
+
+ return transport;
+
+fail_init:
+ kfree(transport);
+
+fail:
+ return NULL;
+}
+
+/* This transport is no longer needed. Free up if possible, or
+ * delay until it last reference count.
+ */
+void sctp_transport_free(struct sctp_transport *transport)
+{
+ transport->dead = 1;
+
+ /* Try to delete the heartbeat timer. */
+ if (del_timer(&transport->hb_timer))
+ sctp_transport_put(transport);
+
+ /* Delete the T3_rtx timer if it's active.
+ * There is no point in not doing this now and letting
+ * structure hang around in memory since we know
+ * the tranport is going away.
+ */
+ if (timer_pending(&transport->T3_rtx_timer) &&
+ del_timer(&transport->T3_rtx_timer))
+ sctp_transport_put(transport);
+
+
+ sctp_transport_put(transport);
+}
+
+/* Destroy the transport data structure.
+ * Assumes there are no more users of this structure.
+ */
+static void sctp_transport_destroy(struct sctp_transport *transport)
+{
+ SCTP_ASSERT(transport->dead, "Transport is not dead", return);
+
+ if (transport->asoc)
+ sctp_association_put(transport->asoc);
+
+ sctp_packet_free(&transport->packet);
+
+ dst_release(transport->dst);
+ kfree(transport);
+ SCTP_DBG_OBJCNT_DEC(transport);
+}
+
+/* Start T3_rtx timer if it is not already running and update the heartbeat
+ * timer. This routine is called every time a DATA chunk is sent.
+ */
+void sctp_transport_reset_timers(struct sctp_transport *transport)
+{
+ /* RFC 2960 6.3.2 Retransmission Timer Rules
+ *
+ * R1) Every time a DATA chunk is sent to any address(including a
+ * retransmission), if the T3-rtx timer of that address is not running
+ * start it running so that it will expire after the RTO of that
+ * address.
+ */
+
+ if (!timer_pending(&transport->T3_rtx_timer))
+ if (!mod_timer(&transport->T3_rtx_timer,
+ jiffies + transport->rto))
+ sctp_transport_hold(transport);
+
+ /* When a data chunk is sent, reset the heartbeat interval. */
+ if (!mod_timer(&transport->hb_timer,
+ sctp_transport_timeout(transport)))
+ sctp_transport_hold(transport);
+}
+
+/* This transport has been assigned to an association.
+ * Initialize fields from the association or from the sock itself.
+ * Register the reference count in the association.
+ */
+void sctp_transport_set_owner(struct sctp_transport *transport,
+ struct sctp_association *asoc)
+{
+ transport->asoc = asoc;
+ sctp_association_hold(asoc);
+}
+
+/* Initialize the pmtu of a transport. */
+void sctp_transport_pmtu(struct sctp_transport *transport)
+{
+ struct dst_entry *dst;
+
+ dst = transport->af_specific->get_dst(NULL, &transport->ipaddr, NULL);
+
+ if (dst) {
+ transport->pmtu = dst_mtu(dst);
+ dst_release(dst);
+ } else
+ transport->pmtu = SCTP_DEFAULT_MAXSEGMENT;
+}
+
+/* Caches the dst entry and source address for a transport's destination
+ * address.
+ */
+void sctp_transport_route(struct sctp_transport *transport,
+ union sctp_addr *saddr, struct sctp_sock *opt)
+{
+ struct sctp_association *asoc = transport->asoc;
+ struct sctp_af *af = transport->af_specific;
+ union sctp_addr *daddr = &transport->ipaddr;
+ struct dst_entry *dst;
+
+ dst = af->get_dst(asoc, daddr, saddr);
+
+ if (saddr)
+ memcpy(&transport->saddr, saddr, sizeof(union sctp_addr));
+ else
+ af->get_saddr(asoc, dst, daddr, &transport->saddr);
+
+ transport->dst = dst;
+ if (dst) {
+ transport->pmtu = dst_mtu(dst);
+
+ /* Initialize sk->sk_rcv_saddr, if the transport is the
+ * association's active path for getsockname().
+ */
+ if (asoc && (transport == asoc->peer.active_path))
+ af->to_sk_saddr(&transport->saddr, asoc->base.sk);
+ } else
+ transport->pmtu = SCTP_DEFAULT_MAXSEGMENT;
+}
+
+/* Hold a reference to a transport. */
+void sctp_transport_hold(struct sctp_transport *transport)
+{
+ atomic_inc(&transport->refcnt);
+}
+
+/* Release a reference to a transport and clean up
+ * if there are no more references.
+ */
+void sctp_transport_put(struct sctp_transport *transport)
+{
+ if (atomic_dec_and_test(&transport->refcnt))
+ sctp_transport_destroy(transport);
+}
+
+/* Update transport's RTO based on the newly calculated RTT. */
+void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt)
+{
+ /* Check for valid transport. */
+ SCTP_ASSERT(tp, "NULL transport", return);
+
+ /* We should not be doing any RTO updates unless rto_pending is set. */
+ SCTP_ASSERT(tp->rto_pending, "rto_pending not set", return);
+
+ if (tp->rttvar || tp->srtt) {
+ /* 6.3.1 C3) When a new RTT measurement R' is made, set
+ * RTTVAR <- (1 - RTO.Beta) * RTTVAR + RTO.Beta * |SRTT - R'|
+ * SRTT <- (1 - RTO.Alpha) * SRTT + RTO.Alpha * R'
+ */
+
+ /* Note: The above algorithm has been rewritten to
+ * express rto_beta and rto_alpha as inverse powers
+ * of two.
+ * For example, assuming the default value of RTO.Alpha of
+ * 1/8, rto_alpha would be expressed as 3.
+ */
+ tp->rttvar = tp->rttvar - (tp->rttvar >> sctp_rto_beta)
+ + ((abs(tp->srtt - rtt)) >> sctp_rto_beta);
+ tp->srtt = tp->srtt - (tp->srtt >> sctp_rto_alpha)
+ + (rtt >> sctp_rto_alpha);
+ } else {
+ /* 6.3.1 C2) When the first RTT measurement R is made, set
+ * SRTT <- R, RTTVAR <- R/2.
+ */
+ tp->srtt = rtt;
+ tp->rttvar = rtt >> 1;
+ }
+
+ /* 6.3.1 G1) Whenever RTTVAR is computed, if RTTVAR = 0, then
+ * adjust RTTVAR <- G, where G is the CLOCK GRANULARITY.
+ */
+ if (tp->rttvar == 0)
+ tp->rttvar = SCTP_CLOCK_GRANULARITY;
+
+ /* 6.3.1 C3) After the computation, update RTO <- SRTT + 4 * RTTVAR. */
+ tp->rto = tp->srtt + (tp->rttvar << 2);
+
+ /* 6.3.1 C6) Whenever RTO is computed, if it is less than RTO.Min
+ * seconds then it is rounded up to RTO.Min seconds.
+ */
+ if (tp->rto < tp->asoc->rto_min)
+ tp->rto = tp->asoc->rto_min;
+
+ /* 6.3.1 C7) A maximum value may be placed on RTO provided it is
+ * at least RTO.max seconds.
+ */
+ if (tp->rto > tp->asoc->rto_max)
+ tp->rto = tp->asoc->rto_max;
+
+ tp->rtt = rtt;
+
+ /* Reset rto_pending so that a new RTT measurement is started when a
+ * new data chunk is sent.
+ */
+ tp->rto_pending = 0;
+
+ SCTP_DEBUG_PRINTK("%s: transport: %p, rtt: %d, srtt: %d "
+ "rttvar: %d, rto: %d\n", __FUNCTION__,
+ tp, rtt, tp->srtt, tp->rttvar, tp->rto);
+}
+
+/* This routine updates the transport's cwnd and partial_bytes_acked
+ * parameters based on the bytes acked in the received SACK.
+ */
+void sctp_transport_raise_cwnd(struct sctp_transport *transport,
+ __u32 sack_ctsn, __u32 bytes_acked)
+{
+ __u32 cwnd, ssthresh, flight_size, pba, pmtu;
+
+ cwnd = transport->cwnd;
+ flight_size = transport->flight_size;
+
+ /* The appropriate cwnd increase algorithm is performed if, and only
+ * if the cumulative TSN has advanced and the congestion window is
+ * being fully utilized.
+ */
+ if ((transport->asoc->ctsn_ack_point >= sack_ctsn) ||
+ (flight_size < cwnd))
+ return;
+
+ ssthresh = transport->ssthresh;
+ pba = transport->partial_bytes_acked;
+ pmtu = transport->asoc->pmtu;
+
+ if (cwnd <= ssthresh) {
+ /* RFC 2960 7.2.1, sctpimpguide-05 2.14.2 When cwnd is less
+ * than or equal to ssthresh an SCTP endpoint MUST use the
+ * slow start algorithm to increase cwnd only if the current
+ * congestion window is being fully utilized and an incoming
+ * SACK advances the Cumulative TSN Ack Point. Only when these
+ * two conditions are met can the cwnd be increased otherwise
+ * the cwnd MUST not be increased. If these conditions are met
+ * then cwnd MUST be increased by at most the lesser of
+ * 1) the total size of the previously outstanding DATA
+ * chunk(s) acknowledged, and 2) the destination's path MTU.
+ */
+ if (bytes_acked > pmtu)
+ cwnd += pmtu;
+ else
+ cwnd += bytes_acked;
+ SCTP_DEBUG_PRINTK("%s: SLOW START: transport: %p, "
+ "bytes_acked: %d, cwnd: %d, ssthresh: %d, "
+ "flight_size: %d, pba: %d\n",
+ __FUNCTION__,
+ transport, bytes_acked, cwnd,
+ ssthresh, flight_size, pba);
+ } else {
+ /* RFC 2960 7.2.2 Whenever cwnd is greater than ssthresh,
+ * upon each SACK arrival that advances the Cumulative TSN Ack
+ * Point, increase partial_bytes_acked by the total number of
+ * bytes of all new chunks acknowledged in that SACK including
+ * chunks acknowledged by the new Cumulative TSN Ack and by
+ * Gap Ack Blocks.
+ *
+ * When partial_bytes_acked is equal to or greater than cwnd
+ * and before the arrival of the SACK the sender had cwnd or
+ * more bytes of data outstanding (i.e., before arrival of the
+ * SACK, flightsize was greater than or equal to cwnd),
+ * increase cwnd by MTU, and reset partial_bytes_acked to
+ * (partial_bytes_acked - cwnd).
+ */
+ pba += bytes_acked;
+ if (pba >= cwnd) {
+ cwnd += pmtu;
+ pba = ((cwnd < pba) ? (pba - cwnd) : 0);
+ }
+ SCTP_DEBUG_PRINTK("%s: CONGESTION AVOIDANCE: "
+ "transport: %p, bytes_acked: %d, cwnd: %d, "
+ "ssthresh: %d, flight_size: %d, pba: %d\n",
+ __FUNCTION__,
+ transport, bytes_acked, cwnd,
+ ssthresh, flight_size, pba);
+ }
+
+ transport->cwnd = cwnd;
+ transport->partial_bytes_acked = pba;
+}
+
+/* This routine is used to lower the transport's cwnd when congestion is
+ * detected.
+ */
+void sctp_transport_lower_cwnd(struct sctp_transport *transport,
+ sctp_lower_cwnd_t reason)
+{
+ switch (reason) {
+ case SCTP_LOWER_CWND_T3_RTX:
+ /* RFC 2960 Section 7.2.3, sctpimpguide
+ * When the T3-rtx timer expires on an address, SCTP should
+ * perform slow start by:
+ * ssthresh = max(cwnd/2, 4*MTU)
+ * cwnd = 1*MTU
+ * partial_bytes_acked = 0
+ */
+ transport->ssthresh = max(transport->cwnd/2,
+ 4*transport->asoc->pmtu);
+ transport->cwnd = transport->asoc->pmtu;
+ break;
+
+ case SCTP_LOWER_CWND_FAST_RTX:
+ /* RFC 2960 7.2.4 Adjust the ssthresh and cwnd of the
+ * destination address(es) to which the missing DATA chunks
+ * were last sent, according to the formula described in
+ * Section 7.2.3.
+ *
+ * RFC 2960 7.2.3, sctpimpguide Upon detection of packet
+ * losses from SACK (see Section 7.2.4), An endpoint
+ * should do the following:
+ * ssthresh = max(cwnd/2, 4*MTU)
+ * cwnd = ssthresh
+ * partial_bytes_acked = 0
+ */
+ transport->ssthresh = max(transport->cwnd/2,
+ 4*transport->asoc->pmtu);
+ transport->cwnd = transport->ssthresh;
+ break;
+
+ case SCTP_LOWER_CWND_ECNE:
+ /* RFC 2481 Section 6.1.2.
+ * If the sender receives an ECN-Echo ACK packet
+ * then the sender knows that congestion was encountered in the
+ * network on the path from the sender to the receiver. The
+ * indication of congestion should be treated just as a
+ * congestion loss in non-ECN Capable TCP. That is, the TCP
+ * source halves the congestion window "cwnd" and reduces the
+ * slow start threshold "ssthresh".
+ * A critical condition is that TCP does not react to
+ * congestion indications more than once every window of
+ * data (or more loosely more than once every round-trip time).
+ */
+ if ((jiffies - transport->last_time_ecne_reduced) >
+ transport->rtt) {
+ transport->ssthresh = max(transport->cwnd/2,
+ 4*transport->asoc->pmtu);
+ transport->cwnd = transport->ssthresh;
+ transport->last_time_ecne_reduced = jiffies;
+ }
+ break;
+
+ case SCTP_LOWER_CWND_INACTIVE:
+ /* RFC 2960 Section 7.2.1, sctpimpguide
+ * When the endpoint does not transmit data on a given
+ * transport address, the cwnd of the transport address
+ * should be adjusted to max(cwnd/2, 4*MTU) per RTO.
+ * NOTE: Although the draft recommends that this check needs
+ * to be done every RTO interval, we do it every hearbeat
+ * interval.
+ */
+ if ((jiffies - transport->last_time_used) > transport->rto)
+ transport->cwnd = max(transport->cwnd/2,
+ 4*transport->asoc->pmtu);
+ break;
+ };
+
+ transport->partial_bytes_acked = 0;
+ SCTP_DEBUG_PRINTK("%s: transport: %p reason: %d cwnd: "
+ "%d ssthresh: %d\n", __FUNCTION__,
+ transport, reason,
+ transport->cwnd, transport->ssthresh);
+}
+
+/* What is the next timeout value for this transport? */
+unsigned long sctp_transport_timeout(struct sctp_transport *t)
+{
+ unsigned long timeout;
+ timeout = t->hb_interval + t->rto + sctp_jitter(t->rto);
+ timeout += jiffies;
+ return timeout;
+}