Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1824 insertions, 0 deletions

diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
new file mode 100644
index 0000000000..23d6633966
--- /dev/null
+++ b/net/sctp/sm_sideeffect.c
@@ -0,0 +1,1824 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* SCTP kernel implementation
+ * (C) Copyright IBM Corp. 2001, 2004
+ * Copyright (c) 1999 Cisco, Inc.
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ *
+ * This file is part of the SCTP kernel implementation
+ *
+ * These functions work with the state functions in sctp_sm_statefuns.c
+ * to implement that state operations.  These functions implement the
+ * steps which require modifying existing data structures.
+ *
+ * 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>
+ *    Karl Knutson          <karl@athena.chicago.il.us>
+ *    Jon Grimm             <jgrimm@austin.ibm.com>
+ *    Hui Huang		    <hui.huang@nokia.com>
+ *    Dajiang Zhang	    <dajiang.zhang@nokia.com>
+ *    Daisy Chang	    <daisyc@us.ibm.com>
+ *    Sridhar Samudrala	    <sri@us.ibm.com>
+ *    Ardelle Fan	    <ardelle.fan@intel.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/skbuff.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/ip.h>
+#include <linux/gfp.h>
+#include <net/sock.h>
+#include <net/sctp/sctp.h>
+#include <net/sctp/sm.h>
+#include <net/sctp/stream_sched.h>
+
+static int sctp_cmd_interpreter(enum sctp_event_type event_type,
+				union sctp_subtype subtype,
+				enum sctp_state state,
+				struct sctp_endpoint *ep,
+				struct sctp_association *asoc,
+				void *event_arg,
+				enum sctp_disposition status,
+				struct sctp_cmd_seq *commands,
+				gfp_t gfp);
+static int sctp_side_effects(enum sctp_event_type event_type,
+			     union sctp_subtype subtype,
+			     enum sctp_state state,
+			     struct sctp_endpoint *ep,
+			     struct sctp_association **asoc,
+			     void *event_arg,
+			     enum sctp_disposition status,
+			     struct sctp_cmd_seq *commands,
+			     gfp_t gfp);
+
+/********************************************************************
+ * Helper functions
+ ********************************************************************/
+
+/* A helper function for delayed processing of INET ECN CE bit. */
+static void sctp_do_ecn_ce_work(struct sctp_association *asoc,
+				__u32 lowest_tsn)
+{
+	/* Save the TSN away for comparison when we receive CWR */
+
+	asoc->last_ecne_tsn = lowest_tsn;
+	asoc->need_ecne = 1;
+}
+
+/* Helper function for delayed processing of SCTP ECNE chunk.  */
+/* RFC 2960 Appendix A
+ *
+ * RFC 2481 details a specific bit for a sender to send in
+ * the header of its next outbound TCP segment to indicate to
+ * its peer that it has reduced its congestion window.  This
+ * is termed the CWR bit.  For SCTP the same indication is made
+ * by including the CWR chunk.  This chunk contains one data
+ * element, i.e. the TSN number that was sent in the ECNE chunk.
+ * This element represents the lowest TSN number in the datagram
+ * that was originally marked with the CE bit.
+ */
+static struct sctp_chunk *sctp_do_ecn_ecne_work(struct sctp_association *asoc,
+						__u32 lowest_tsn,
+						struct sctp_chunk *chunk)
+{
+	struct sctp_chunk *repl;
+
+	/* Our previously transmitted packet ran into some congestion
+	 * so we should take action by reducing cwnd and ssthresh
+	 * and then ACK our peer that we we've done so by
+	 * sending a CWR.
+	 */
+
+	/* First, try to determine if we want to actually lower
+	 * our cwnd variables.  Only lower them if the ECNE looks more
+	 * recent than the last response.
+	 */
+	if (TSN_lt(asoc->last_cwr_tsn, lowest_tsn)) {
+		struct sctp_transport *transport;
+
+		/* Find which transport's congestion variables
+		 * need to be adjusted.
+		 */
+		transport = sctp_assoc_lookup_tsn(asoc, lowest_tsn);
+
+		/* Update the congestion variables. */
+		if (transport)
+			sctp_transport_lower_cwnd(transport,
+						  SCTP_LOWER_CWND_ECNE);
+		asoc->last_cwr_tsn = lowest_tsn;
+	}
+
+	/* Always try to quiet the other end.  In case of lost CWR,
+	 * resend last_cwr_tsn.
+	 */
+	repl = sctp_make_cwr(asoc, asoc->last_cwr_tsn, chunk);
+
+	/* If we run out of memory, it will look like a lost CWR.  We'll
+	 * get back in sync eventually.
+	 */
+	return repl;
+}
+
+/* Helper function to do delayed processing of ECN CWR chunk.  */
+static void sctp_do_ecn_cwr_work(struct sctp_association *asoc,
+				 __u32 lowest_tsn)
+{
+	/* Turn off ECNE getting auto-prepended to every outgoing
+	 * packet
+	 */
+	asoc->need_ecne = 0;
+}
+
+/* Generate SACK if necessary.  We call this at the end of a packet.  */
+static int sctp_gen_sack(struct sctp_association *asoc, int force,
+			 struct sctp_cmd_seq *commands)
+{
+	struct sctp_transport *trans = asoc->peer.last_data_from;
+	__u32 ctsn, max_tsn_seen;
+	struct sctp_chunk *sack;
+	int error = 0;
+
+	if (force ||
+	    (!trans && (asoc->param_flags & SPP_SACKDELAY_DISABLE)) ||
+	    (trans && (trans->param_flags & SPP_SACKDELAY_DISABLE)))
+		asoc->peer.sack_needed = 1;
+
+	ctsn = sctp_tsnmap_get_ctsn(&asoc->peer.tsn_map);
+	max_tsn_seen = sctp_tsnmap_get_max_tsn_seen(&asoc->peer.tsn_map);
+
+	/* From 12.2 Parameters necessary per association (i.e. the TCB):
+	 *
+	 * Ack State : This flag indicates if the next received packet
+	 * 	     : is to be responded to with a SACK. ...
+	 *	     : When DATA chunks are out of order, SACK's
+	 *           : are not delayed (see Section 6).
+	 *
+	 * [This is actually not mentioned in Section 6, but we
+	 * implement it here anyway. --piggy]
+	 */
+	if (max_tsn_seen != ctsn)
+		asoc->peer.sack_needed = 1;
+
+	/* From 6.2  Acknowledgement on Reception of DATA Chunks:
+	 *
+	 * Section 4.2 of [RFC2581] SHOULD be followed. Specifically,
+	 * an acknowledgement SHOULD be generated for at least every
+	 * second packet (not every second DATA chunk) received, and
+	 * SHOULD be generated within 200 ms of the arrival of any
+	 * unacknowledged DATA chunk. ...
+	 */
+	if (!asoc->peer.sack_needed) {
+		asoc->peer.sack_cnt++;
+
+		/* Set the SACK delay timeout based on the
+		 * SACK delay for the last transport
+		 * data was received from, or the default
+		 * for the association.
+		 */
+		if (trans) {
+			/* We will need a SACK for the next packet.  */
+			if (asoc->peer.sack_cnt >= trans->sackfreq - 1)
+				asoc->peer.sack_needed = 1;
+
+			asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] =
+				trans->sackdelay;
+		} else {
+			/* We will need a SACK for the next packet.  */
+			if (asoc->peer.sack_cnt >= asoc->sackfreq - 1)
+				asoc->peer.sack_needed = 1;
+
+			asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] =
+				asoc->sackdelay;
+		}
+
+		/* Restart the SACK timer. */
+		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
+				SCTP_TO(SCTP_EVENT_TIMEOUT_SACK));
+	} else {
+		__u32 old_a_rwnd = asoc->a_rwnd;
+
+		asoc->a_rwnd = asoc->rwnd;
+		sack = sctp_make_sack(asoc);
+		if (!sack) {
+			asoc->a_rwnd = old_a_rwnd;
+			goto nomem;
+		}
+
+		asoc->peer.sack_needed = 0;
+		asoc->peer.sack_cnt = 0;
+
+		sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(sack));
+
+		/* Stop the SACK timer.  */
+		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
+				SCTP_TO(SCTP_EVENT_TIMEOUT_SACK));
+	}
+
+	return error;
+nomem:
+	error = -ENOMEM;
+	return error;
+}
+
+/* When the T3-RTX timer expires, it calls this function to create the
+ * relevant state machine event.
+ */
+void sctp_generate_t3_rtx_event(struct timer_list *t)
+{
+	struct sctp_transport *transport =
+		from_timer(transport, t, T3_rtx_timer);
+	struct sctp_association *asoc = transport->asoc;
+	struct sock *sk = asoc->base.sk;
+	struct net *net = sock_net(sk);
+	int error;
+
+	/* Check whether a task is in the sock.  */
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk)) {
+		pr_debug("%s: sock is busy\n", __func__);
+
+		/* Try again later.  */
+		if (!mod_timer(&transport->T3_rtx_timer, jiffies + (HZ/20)))
+			sctp_transport_hold(transport);
+		goto out_unlock;
+	}
+
+	/* Run through the state machine.  */
+	error = sctp_do_sm(net, SCTP_EVENT_T_TIMEOUT,
+			   SCTP_ST_TIMEOUT(SCTP_EVENT_TIMEOUT_T3_RTX),
+			   asoc->state,
+			   asoc->ep, asoc,
+			   transport, GFP_ATOMIC);
+
+	if (error)
+		sk->sk_err = -error;
+
+out_unlock:
+	bh_unlock_sock(sk);
+	sctp_transport_put(transport);
+}
+
+/* This is a sa interface for producing timeout events.  It works
+ * for timeouts which use the association as their parameter.
+ */
+static void sctp_generate_timeout_event(struct sctp_association *asoc,
+					enum sctp_event_timeout timeout_type)
+{
+	struct sock *sk = asoc->base.sk;
+	struct net *net = sock_net(sk);
+	int error = 0;
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk)) {
+		pr_debug("%s: sock is busy: timer %d\n", __func__,
+			 timeout_type);
+
+		/* Try again later.  */
+		if (!mod_timer(&asoc->timers[timeout_type], jiffies + (HZ/20)))
+			sctp_association_hold(asoc);
+		goto out_unlock;
+	}
+
+	/* Is this association really dead and just waiting around for
+	 * the timer to let go of the reference?
+	 */
+	if (asoc->base.dead)
+		goto out_unlock;
+
+	/* Run through the state machine.  */
+	error = sctp_do_sm(net, SCTP_EVENT_T_TIMEOUT,
+			   SCTP_ST_TIMEOUT(timeout_type),
+			   asoc->state, asoc->ep, asoc,
+			   (void *)timeout_type, GFP_ATOMIC);
+
+	if (error)
+		sk->sk_err = -error;
+
+out_unlock:
+	bh_unlock_sock(sk);
+	sctp_association_put(asoc);
+}
+
+static void sctp_generate_t1_cookie_event(struct timer_list *t)
+{
+	struct sctp_association *asoc =
+		from_timer(asoc, t, timers[SCTP_EVENT_TIMEOUT_T1_COOKIE]);
+
+	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_T1_COOKIE);
+}
+
+static void sctp_generate_t1_init_event(struct timer_list *t)
+{
+	struct sctp_association *asoc =
+		from_timer(asoc, t, timers[SCTP_EVENT_TIMEOUT_T1_INIT]);
+
+	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_T1_INIT);
+}
+
+static void sctp_generate_t2_shutdown_event(struct timer_list *t)
+{
+	struct sctp_association *asoc =
+		from_timer(asoc, t, timers[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN]);
+
+	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_T2_SHUTDOWN);
+}
+
+static void sctp_generate_t4_rto_event(struct timer_list *t)
+{
+	struct sctp_association *asoc =
+		from_timer(asoc, t, timers[SCTP_EVENT_TIMEOUT_T4_RTO]);
+
+	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_T4_RTO);
+}
+
+static void sctp_generate_t5_shutdown_guard_event(struct timer_list *t)
+{
+	struct sctp_association *asoc =
+		from_timer(asoc, t,
+			   timers[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]);
+
+	sctp_generate_timeout_event(asoc,
+				    SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD);
+
+} /* sctp_generate_t5_shutdown_guard_event() */
+
+static void sctp_generate_autoclose_event(struct timer_list *t)
+{
+	struct sctp_association *asoc =
+		from_timer(asoc, t, timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE]);
+
+	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_AUTOCLOSE);
+}
+
+/* Generate a heart beat event.  If the sock is busy, reschedule.   Make
+ * sure that the transport is still valid.
+ */
+void sctp_generate_heartbeat_event(struct timer_list *t)
+{
+	struct sctp_transport *transport = from_timer(transport, t, hb_timer);
+	struct sctp_association *asoc = transport->asoc;
+	struct sock *sk = asoc->base.sk;
+	struct net *net = sock_net(sk);
+	u32 elapsed, timeout;
+	int error = 0;
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk)) {
+		pr_debug("%s: sock is busy\n", __func__);
+
+		/* Try again later.  */
+		if (!mod_timer(&transport->hb_timer, jiffies + (HZ/20)))
+			sctp_transport_hold(transport);
+		goto out_unlock;
+	}
+
+	/* Check if we should still send the heartbeat or reschedule */
+	elapsed = jiffies - transport->last_time_sent;
+	timeout = sctp_transport_timeout(transport);
+	if (elapsed < timeout) {
+		elapsed = timeout - elapsed;
+		if (!mod_timer(&transport->hb_timer, jiffies + elapsed))
+			sctp_transport_hold(transport);
+		goto out_unlock;
+	}
+
+	error = sctp_do_sm(net, SCTP_EVENT_T_TIMEOUT,
+			   SCTP_ST_TIMEOUT(SCTP_EVENT_TIMEOUT_HEARTBEAT),
+			   asoc->state, asoc->ep, asoc,
+			   transport, GFP_ATOMIC);
+
+	if (error)
+		sk->sk_err = -error;
+
+out_unlock:
+	bh_unlock_sock(sk);
+	sctp_transport_put(transport);
+}
+
+/* Handle the timeout of the ICMP protocol unreachable timer.  Trigger
+ * the correct state machine transition that will close the association.
+ */
+void sctp_generate_proto_unreach_event(struct timer_list *t)
+{
+	struct sctp_transport *transport =
+		from_timer(transport, t, proto_unreach_timer);
+	struct sctp_association *asoc = transport->asoc;
+	struct sock *sk = asoc->base.sk;
+	struct net *net = sock_net(sk);
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk)) {
+		pr_debug("%s: sock is busy\n", __func__);
+
+		/* Try again later.  */
+		if (!mod_timer(&transport->proto_unreach_timer,
+				jiffies + (HZ/20)))
+			sctp_transport_hold(transport);
+		goto out_unlock;
+	}
+
+	/* Is this structure just waiting around for us to actually
+	 * get destroyed?
+	 */
+	if (asoc->base.dead)
+		goto out_unlock;
+
+	sctp_do_sm(net, SCTP_EVENT_T_OTHER,
+		   SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
+		   asoc->state, asoc->ep, asoc, transport, GFP_ATOMIC);
+
+out_unlock:
+	bh_unlock_sock(sk);
+	sctp_transport_put(transport);
+}
+
+ /* Handle the timeout of the RE-CONFIG timer. */
+void sctp_generate_reconf_event(struct timer_list *t)
+{
+	struct sctp_transport *transport =
+		from_timer(transport, t, reconf_timer);
+	struct sctp_association *asoc = transport->asoc;
+	struct sock *sk = asoc->base.sk;
+	struct net *net = sock_net(sk);
+	int error = 0;
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk)) {
+		pr_debug("%s: sock is busy\n", __func__);
+
+		/* Try again later.  */
+		if (!mod_timer(&transport->reconf_timer, jiffies + (HZ / 20)))
+			sctp_transport_hold(transport);
+		goto out_unlock;
+	}
+
+	/* This happens when the response arrives after the timer is triggered. */
+	if (!asoc->strreset_chunk)
+		goto out_unlock;
+
+	error = sctp_do_sm(net, SCTP_EVENT_T_TIMEOUT,
+			   SCTP_ST_TIMEOUT(SCTP_EVENT_TIMEOUT_RECONF),
+			   asoc->state, asoc->ep, asoc,
+			   transport, GFP_ATOMIC);
+
+	if (error)
+		sk->sk_err = -error;
+
+out_unlock:
+	bh_unlock_sock(sk);
+	sctp_transport_put(transport);
+}
+
+/* Handle the timeout of the probe timer. */
+void sctp_generate_probe_event(struct timer_list *t)
+{
+	struct sctp_transport *transport = from_timer(transport, t, probe_timer);
+	struct sctp_association *asoc = transport->asoc;
+	struct sock *sk = asoc->base.sk;
+	struct net *net = sock_net(sk);
+	int error = 0;
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk)) {
+		pr_debug("%s: sock is busy\n", __func__);
+
+		/* Try again later.  */
+		if (!mod_timer(&transport->probe_timer, jiffies + (HZ / 20)))
+			sctp_transport_hold(transport);
+		goto out_unlock;
+	}
+
+	error = sctp_do_sm(net, SCTP_EVENT_T_TIMEOUT,
+			   SCTP_ST_TIMEOUT(SCTP_EVENT_TIMEOUT_PROBE),
+			   asoc->state, asoc->ep, asoc,
+			   transport, GFP_ATOMIC);
+
+	if (error)
+		sk->sk_err = -error;
+
+out_unlock:
+	bh_unlock_sock(sk);
+	sctp_transport_put(transport);
+}
+
+/* Inject a SACK Timeout event into the state machine.  */
+static void sctp_generate_sack_event(struct timer_list *t)
+{
+	struct sctp_association *asoc =
+		from_timer(asoc, t, timers[SCTP_EVENT_TIMEOUT_SACK]);
+
+	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_SACK);
+}
+
+sctp_timer_event_t *sctp_timer_events[SCTP_NUM_TIMEOUT_TYPES] = {
+	[SCTP_EVENT_TIMEOUT_NONE] =		NULL,
+	[SCTP_EVENT_TIMEOUT_T1_COOKIE] =	sctp_generate_t1_cookie_event,
+	[SCTP_EVENT_TIMEOUT_T1_INIT] =		sctp_generate_t1_init_event,
+	[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] =	sctp_generate_t2_shutdown_event,
+	[SCTP_EVENT_TIMEOUT_T3_RTX] =		NULL,
+	[SCTP_EVENT_TIMEOUT_T4_RTO] =		sctp_generate_t4_rto_event,
+	[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD] =
+					sctp_generate_t5_shutdown_guard_event,
+	[SCTP_EVENT_TIMEOUT_HEARTBEAT] =	NULL,
+	[SCTP_EVENT_TIMEOUT_RECONF] =		NULL,
+	[SCTP_EVENT_TIMEOUT_SACK] =		sctp_generate_sack_event,
+	[SCTP_EVENT_TIMEOUT_AUTOCLOSE] =	sctp_generate_autoclose_event,
+};
+
+
+/* RFC 2960 8.2 Path Failure Detection
+ *
+ * When its peer endpoint is multi-homed, an endpoint should keep a
+ * error counter for each of the destination transport addresses of the
+ * peer endpoint.
+ *
+ * Each time the T3-rtx timer expires on any address, or when a
+ * HEARTBEAT sent to an idle address is not acknowledged within a RTO,
+ * the error counter of that destination address will be incremented.
+ * When the value in the error counter exceeds the protocol parameter
+ * 'Path.Max.Retrans' of that destination address, the endpoint should
+ * mark the destination transport address as inactive, and a
+ * notification SHOULD be sent to the upper layer.
+ *
+ */
+static void sctp_do_8_2_transport_strike(struct sctp_cmd_seq *commands,
+					 struct sctp_association *asoc,
+					 struct sctp_transport *transport,
+					 int is_hb)
+{
+	/* The check for association's overall error counter exceeding the
+	 * threshold is done in the state function.
+	 */
+	/* We are here due to a timer expiration.  If the timer was
+	 * not a HEARTBEAT, then normal error tracking is done.
+	 * If the timer was a heartbeat, we only increment error counts
+	 * when we already have an outstanding HEARTBEAT that has not
+	 * been acknowledged.
+	 * Additionally, some tranport states inhibit error increments.
+	 */
+	if (!is_hb) {
+		asoc->overall_error_count++;
+		if (transport->state != SCTP_INACTIVE)
+			transport->error_count++;
+	 } else if (transport->hb_sent) {
+		if (transport->state != SCTP_UNCONFIRMED)
+			asoc->overall_error_count++;
+		if (transport->state != SCTP_INACTIVE)
+			transport->error_count++;
+	}
+
+	/* If the transport error count is greater than the pf_retrans
+	 * threshold, and less than pathmaxrtx, and if the current state
+	 * is SCTP_ACTIVE, then mark this transport as Partially Failed,
+	 * see SCTP Quick Failover Draft, section 5.1
+	 */
+	if (asoc->base.net->sctp.pf_enable &&
+	    transport->state == SCTP_ACTIVE &&
+	    transport->error_count < transport->pathmaxrxt &&
+	    transport->error_count > transport->pf_retrans) {
+
+		sctp_assoc_control_transport(asoc, transport,
+					     SCTP_TRANSPORT_PF,
+					     0);
+
+		/* Update the hb timer to resend a heartbeat every rto */
+		sctp_transport_reset_hb_timer(transport);
+	}
+
+	if (transport->state != SCTP_INACTIVE &&
+	    (transport->error_count > transport->pathmaxrxt)) {
+		pr_debug("%s: association:%p transport addr:%pISpc failed\n",
+			 __func__, asoc, &transport->ipaddr.sa);
+
+		sctp_assoc_control_transport(asoc, transport,
+					     SCTP_TRANSPORT_DOWN,
+					     SCTP_FAILED_THRESHOLD);
+	}
+
+	if (transport->error_count > transport->ps_retrans &&
+	    asoc->peer.primary_path == transport &&
+	    asoc->peer.active_path != transport)
+		sctp_assoc_set_primary(asoc, asoc->peer.active_path);
+
+	/* E2) For the destination address for which the timer
+	 * expires, set RTO <- RTO * 2 ("back off the timer").  The
+	 * maximum value discussed in rule C7 above (RTO.max) may be
+	 * used to provide an upper bound to this doubling operation.
+	 *
+	 * Special Case:  the first HB doesn't trigger exponential backoff.
+	 * The first unacknowledged HB triggers it.  We do this with a flag
+	 * that indicates that we have an outstanding HB.
+	 */
+	if (!is_hb || transport->hb_sent) {
+		transport->rto = min((transport->rto * 2), transport->asoc->rto_max);
+		sctp_max_rto(asoc, transport);
+	}
+}
+
+/* Worker routine to handle INIT command failure.  */
+static void sctp_cmd_init_failed(struct sctp_cmd_seq *commands,
+				 struct sctp_association *asoc,
+				 unsigned int error)
+{
+	struct sctp_ulpevent *event;
+
+	event = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_CANT_STR_ASSOC,
+						(__u16)error, 0, 0, NULL,
+						GFP_ATOMIC);
+
+	if (event)
+		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
+				SCTP_ULPEVENT(event));
+
+	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
+			SCTP_STATE(SCTP_STATE_CLOSED));
+
+	/* SEND_FAILED sent later when cleaning up the association. */
+	asoc->outqueue.error = error;
+	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
+}
+
+/* Worker routine to handle SCTP_CMD_ASSOC_FAILED.  */
+static void sctp_cmd_assoc_failed(struct sctp_cmd_seq *commands,
+				  struct sctp_association *asoc,
+				  enum sctp_event_type event_type,
+				  union sctp_subtype subtype,
+				  struct sctp_chunk *chunk,
+				  unsigned int error)
+{
+	struct sctp_ulpevent *event;
+	struct sctp_chunk *abort;
+
+	/* Cancel any partial delivery in progress. */
+	asoc->stream.si->abort_pd(&asoc->ulpq, GFP_ATOMIC);
+
+	if (event_type == SCTP_EVENT_T_CHUNK && subtype.chunk == SCTP_CID_ABORT)
+		event = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_LOST,
+						(__u16)error, 0, 0, chunk,
+						GFP_ATOMIC);
+	else
+		event = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_LOST,
+						(__u16)error, 0, 0, NULL,
+						GFP_ATOMIC);
+	if (event)
+		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
+				SCTP_ULPEVENT(event));
+
+	if (asoc->overall_error_count >= asoc->max_retrans) {
+		abort = sctp_make_violation_max_retrans(asoc, chunk);
+		if (abort)
+			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
+					SCTP_CHUNK(abort));
+	}
+
+	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
+			SCTP_STATE(SCTP_STATE_CLOSED));
+
+	/* SEND_FAILED sent later when cleaning up the association. */
+	asoc->outqueue.error = error;
+	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
+}
+
+/* Process an init chunk (may be real INIT/INIT-ACK or an embedded INIT
+ * inside the cookie.  In reality, this is only used for INIT-ACK processing
+ * since all other cases use "temporary" associations and can do all
+ * their work in statefuns directly.
+ */
+static int sctp_cmd_process_init(struct sctp_cmd_seq *commands,
+				 struct sctp_association *asoc,
+				 struct sctp_chunk *chunk,
+				 struct sctp_init_chunk *peer_init,
+				 gfp_t gfp)
+{
+	int error;
+
+	/* We only process the init as a sideeffect in a single
+	 * case.   This is when we process the INIT-ACK.   If we
+	 * fail during INIT processing (due to malloc problems),
+	 * just return the error and stop processing the stack.
+	 */
+	if (!sctp_process_init(asoc, chunk, sctp_source(chunk), peer_init, gfp))
+		error = -ENOMEM;
+	else
+		error = 0;
+
+	return error;
+}
+
+/* Helper function to break out starting up of heartbeat timers.  */
+static void sctp_cmd_hb_timers_start(struct sctp_cmd_seq *cmds,
+				     struct sctp_association *asoc)
+{
+	struct sctp_transport *t;
+
+	/* Start a heartbeat timer for each transport on the association.
+	 * hold a reference on the transport to make sure none of
+	 * the needed data structures go away.
+	 */
+	list_for_each_entry(t, &asoc->peer.transport_addr_list, transports)
+		sctp_transport_reset_hb_timer(t);
+}
+
+static void sctp_cmd_hb_timers_stop(struct sctp_cmd_seq *cmds,
+				    struct sctp_association *asoc)
+{
+	struct sctp_transport *t;
+
+	/* Stop all heartbeat timers. */
+
+	list_for_each_entry(t, &asoc->peer.transport_addr_list,
+			transports) {
+		if (del_timer(&t->hb_timer))
+			sctp_transport_put(t);
+	}
+}
+
+/* Helper function to stop any pending T3-RTX timers */
+static void sctp_cmd_t3_rtx_timers_stop(struct sctp_cmd_seq *cmds,
+					struct sctp_association *asoc)
+{
+	struct sctp_transport *t;
+
+	list_for_each_entry(t, &asoc->peer.transport_addr_list,
+			transports) {
+		if (del_timer(&t->T3_rtx_timer))
+			sctp_transport_put(t);
+	}
+}
+
+
+/* Helper function to handle the reception of an HEARTBEAT ACK.  */
+static void sctp_cmd_transport_on(struct sctp_cmd_seq *cmds,
+				  struct sctp_association *asoc,
+				  struct sctp_transport *t,
+				  struct sctp_chunk *chunk)
+{
+	struct sctp_sender_hb_info *hbinfo;
+	int was_unconfirmed = 0;
+
+	/* 8.3 Upon the receipt of the HEARTBEAT ACK, the sender of the
+	 * HEARTBEAT should clear the error counter of the destination
+	 * transport address to which the HEARTBEAT was sent.
+	 */
+	t->error_count = 0;
+
+	/*
+	 * Although RFC4960 specifies that the overall error count must
+	 * be cleared when a HEARTBEAT ACK is received, we make an
+	 * exception while in SHUTDOWN PENDING. If the peer keeps its
+	 * window shut forever, we may never be able to transmit our
+	 * outstanding data and rely on the retransmission limit be reached
+	 * to shutdown the association.
+	 */
+	if (t->asoc->state < SCTP_STATE_SHUTDOWN_PENDING)
+		t->asoc->overall_error_count = 0;
+
+	/* Clear the hb_sent flag to signal that we had a good
+	 * acknowledgement.
+	 */
+	t->hb_sent = 0;
+
+	/* Mark the destination transport address as active if it is not so
+	 * marked.
+	 */
+	if ((t->state == SCTP_INACTIVE) || (t->state == SCTP_UNCONFIRMED)) {
+		was_unconfirmed = 1;
+		sctp_assoc_control_transport(asoc, t, SCTP_TRANSPORT_UP,
+					     SCTP_HEARTBEAT_SUCCESS);
+	}
+
+	if (t->state == SCTP_PF)
+		sctp_assoc_control_transport(asoc, t, SCTP_TRANSPORT_UP,
+					     SCTP_HEARTBEAT_SUCCESS);
+
+	/* HB-ACK was received for a the proper HB.  Consider this
+	 * forward progress.
+	 */
+	if (t->dst)
+		sctp_transport_dst_confirm(t);
+
+	/* The receiver of the HEARTBEAT ACK should also perform an
+	 * RTT measurement for that destination transport address
+	 * using the time value carried in the HEARTBEAT ACK chunk.
+	 * If the transport's rto_pending variable has been cleared,
+	 * it was most likely due to a retransmit.  However, we want
+	 * to re-enable it to properly update the rto.
+	 */
+	if (t->rto_pending == 0)
+		t->rto_pending = 1;
+
+	hbinfo = (struct sctp_sender_hb_info *)chunk->skb->data;
+	sctp_transport_update_rto(t, (jiffies - hbinfo->sent_at));
+
+	/* Update the heartbeat timer.  */
+	sctp_transport_reset_hb_timer(t);
+
+	if (was_unconfirmed && asoc->peer.transport_count == 1)
+		sctp_transport_immediate_rtx(t);
+}
+
+
+/* Helper function to process the process SACK command.  */
+static int sctp_cmd_process_sack(struct sctp_cmd_seq *cmds,
+				 struct sctp_association *asoc,
+				 struct sctp_chunk *chunk)
+{
+	int err = 0;
+
+	if (sctp_outq_sack(&asoc->outqueue, chunk)) {
+		/* There are no more TSNs awaiting SACK.  */
+		err = sctp_do_sm(asoc->base.net, SCTP_EVENT_T_OTHER,
+				 SCTP_ST_OTHER(SCTP_EVENT_NO_PENDING_TSN),
+				 asoc->state, asoc->ep, asoc, NULL,
+				 GFP_ATOMIC);
+	}
+
+	return err;
+}
+
+/* Helper function to set the timeout value for T2-SHUTDOWN timer and to set
+ * the transport for a shutdown chunk.
+ */
+static void sctp_cmd_setup_t2(struct sctp_cmd_seq *cmds,
+			      struct sctp_association *asoc,
+			      struct sctp_chunk *chunk)
+{
+	struct sctp_transport *t;
+
+	if (chunk->transport)
+		t = chunk->transport;
+	else {
+		t = sctp_assoc_choose_alter_transport(asoc,
+					      asoc->shutdown_last_sent_to);
+		chunk->transport = t;
+	}
+	asoc->shutdown_last_sent_to = t;
+	asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = t->rto;
+}
+
+/* Helper function to change the state of an association. */
+static void sctp_cmd_new_state(struct sctp_cmd_seq *cmds,
+			       struct sctp_association *asoc,
+			       enum sctp_state state)
+{
+	struct sock *sk = asoc->base.sk;
+
+	asoc->state = state;
+
+	pr_debug("%s: asoc:%p[%s]\n", __func__, asoc, sctp_state_tbl[state]);
+
+	if (sctp_style(sk, TCP)) {
+		/* Change the sk->sk_state of a TCP-style socket that has
+		 * successfully completed a connect() call.
+		 */
+		if (sctp_state(asoc, ESTABLISHED) && sctp_sstate(sk, CLOSED))
+			inet_sk_set_state(sk, SCTP_SS_ESTABLISHED);
+
+		/* Set the RCV_SHUTDOWN flag when a SHUTDOWN is received. */
+		if (sctp_state(asoc, SHUTDOWN_RECEIVED) &&
+		    sctp_sstate(sk, ESTABLISHED)) {
+			inet_sk_set_state(sk, SCTP_SS_CLOSING);
+			sk->sk_shutdown |= RCV_SHUTDOWN;
+		}
+	}
+
+	if (sctp_state(asoc, COOKIE_WAIT)) {
+		/* Reset init timeouts since they may have been
+		 * increased due to timer expirations.
+		 */
+		asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] =
+						asoc->rto_initial;
+		asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] =
+						asoc->rto_initial;
+	}
+
+	if (sctp_state(asoc, ESTABLISHED)) {
+		kfree(asoc->peer.cookie);
+		asoc->peer.cookie = NULL;
+	}
+
+	if (sctp_state(asoc, ESTABLISHED) ||
+	    sctp_state(asoc, CLOSED) ||
+	    sctp_state(asoc, SHUTDOWN_RECEIVED)) {
+		/* Wake up any processes waiting in the asoc's wait queue in
+		 * sctp_wait_for_connect() or sctp_wait_for_sndbuf().
+		 */
+		if (waitqueue_active(&asoc->wait))
+			wake_up_interruptible(&asoc->wait);
+
+		/* Wake up any processes waiting in the sk's sleep queue of
+		 * a TCP-style or UDP-style peeled-off socket in
+		 * sctp_wait_for_accept() or sctp_wait_for_packet().
+		 * For a UDP-style socket, the waiters are woken up by the
+		 * notifications.
+		 */
+		if (!sctp_style(sk, UDP))
+			sk->sk_state_change(sk);
+	}
+
+	if (sctp_state(asoc, SHUTDOWN_PENDING) &&
+	    !sctp_outq_is_empty(&asoc->outqueue))
+		sctp_outq_uncork(&asoc->outqueue, GFP_ATOMIC);
+}
+
+/* Helper function to delete an association. */
+static void sctp_cmd_delete_tcb(struct sctp_cmd_seq *cmds,
+				struct sctp_association *asoc)
+{
+	struct sock *sk = asoc->base.sk;
+
+	/* If it is a non-temporary association belonging to a TCP-style
+	 * listening socket that is not closed, do not free it so that accept()
+	 * can pick it up later.
+	 */
+	if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING) &&
+	    (!asoc->temp) && (sk->sk_shutdown != SHUTDOWN_MASK))
+		return;
+
+	sctp_association_free(asoc);
+}
+
+/*
+ * ADDIP Section 4.1 ASCONF Chunk Procedures
+ * A4) Start a T-4 RTO timer, using the RTO value of the selected
+ * destination address (we use active path instead of primary path just
+ * because primary path may be inactive.
+ */
+static void sctp_cmd_setup_t4(struct sctp_cmd_seq *cmds,
+			      struct sctp_association *asoc,
+			      struct sctp_chunk *chunk)
+{
+	struct sctp_transport *t;
+
+	t = sctp_assoc_choose_alter_transport(asoc, chunk->transport);
+	asoc->timeouts[SCTP_EVENT_TIMEOUT_T4_RTO] = t->rto;
+	chunk->transport = t;
+}
+
+/* Process an incoming Operation Error Chunk. */
+static void sctp_cmd_process_operr(struct sctp_cmd_seq *cmds,
+				   struct sctp_association *asoc,
+				   struct sctp_chunk *chunk)
+{
+	struct sctp_errhdr *err_hdr;
+	struct sctp_ulpevent *ev;
+
+	while (chunk->chunk_end > chunk->skb->data) {
+		err_hdr = (struct sctp_errhdr *)(chunk->skb->data);
+
+		ev = sctp_ulpevent_make_remote_error(asoc, chunk, 0,
+						     GFP_ATOMIC);
+		if (!ev)
+			return;
+
+		asoc->stream.si->enqueue_event(&asoc->ulpq, ev);
+
+		switch (err_hdr->cause) {
+		case SCTP_ERROR_UNKNOWN_CHUNK:
+		{
+			struct sctp_chunkhdr *unk_chunk_hdr;
+
+			unk_chunk_hdr = (struct sctp_chunkhdr *)(err_hdr + 1);
+			switch (unk_chunk_hdr->type) {
+			/* ADDIP 4.1 A9) If the peer responds to an ASCONF with
+			 * an ERROR chunk reporting that it did not recognized
+			 * the ASCONF chunk type, the sender of the ASCONF MUST
+			 * NOT send any further ASCONF chunks and MUST stop its
+			 * T-4 timer.
+			 */
+			case SCTP_CID_ASCONF:
+				if (asoc->peer.asconf_capable == 0)
+					break;
+
+				asoc->peer.asconf_capable = 0;
+				sctp_add_cmd_sf(cmds, SCTP_CMD_TIMER_STOP,
+					SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
+				break;
+			default:
+				break;
+			}
+			break;
+		}
+		default:
+			break;
+		}
+	}
+}
+
+/* Helper function to remove the association non-primary peer
+ * transports.
+ */
+static void sctp_cmd_del_non_primary(struct sctp_association *asoc)
+{
+	struct sctp_transport *t;
+	struct list_head *temp;
+	struct list_head *pos;
+
+	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
+		t = list_entry(pos, struct sctp_transport, transports);
+		if (!sctp_cmp_addr_exact(&t->ipaddr,
+					 &asoc->peer.primary_addr)) {
+			sctp_assoc_rm_peer(asoc, t);
+		}
+	}
+}
+
+/* Helper function to set sk_err on a 1-1 style socket. */
+static void sctp_cmd_set_sk_err(struct sctp_association *asoc, int error)
+{
+	struct sock *sk = asoc->base.sk;
+
+	if (!sctp_style(sk, UDP))
+		sk->sk_err = error;
+}
+
+/* Helper function to generate an association change event */
+static void sctp_cmd_assoc_change(struct sctp_cmd_seq *commands,
+				  struct sctp_association *asoc,
+				  u8 state)
+{
+	struct sctp_ulpevent *ev;
+
+	ev = sctp_ulpevent_make_assoc_change(asoc, 0, state, 0,
+					    asoc->c.sinit_num_ostreams,
+					    asoc->c.sinit_max_instreams,
+					    NULL, GFP_ATOMIC);
+	if (ev)
+		asoc->stream.si->enqueue_event(&asoc->ulpq, ev);
+}
+
+static void sctp_cmd_peer_no_auth(struct sctp_cmd_seq *commands,
+				  struct sctp_association *asoc)
+{
+	struct sctp_ulpevent *ev;
+
+	ev = sctp_ulpevent_make_authkey(asoc, 0, SCTP_AUTH_NO_AUTH, GFP_ATOMIC);
+	if (ev)
+		asoc->stream.si->enqueue_event(&asoc->ulpq, ev);
+}
+
+/* Helper function to generate an adaptation indication event */
+static void sctp_cmd_adaptation_ind(struct sctp_cmd_seq *commands,
+				    struct sctp_association *asoc)
+{
+	struct sctp_ulpevent *ev;
+
+	ev = sctp_ulpevent_make_adaptation_indication(asoc, GFP_ATOMIC);
+
+	if (ev)
+		asoc->stream.si->enqueue_event(&asoc->ulpq, ev);
+}
+
+
+static void sctp_cmd_t1_timer_update(struct sctp_association *asoc,
+				     enum sctp_event_timeout timer,
+				     char *name)
+{
+	struct sctp_transport *t;
+
+	t = asoc->init_last_sent_to;
+	asoc->init_err_counter++;
+
+	if (t->init_sent_count > (asoc->init_cycle + 1)) {
+		asoc->timeouts[timer] *= 2;
+		if (asoc->timeouts[timer] > asoc->max_init_timeo) {
+			asoc->timeouts[timer] = asoc->max_init_timeo;
+		}
+		asoc->init_cycle++;
+
+		pr_debug("%s: T1[%s] timeout adjustment init_err_counter:%d"
+			 " cycle:%d timeout:%ld\n", __func__, name,
+			 asoc->init_err_counter, asoc->init_cycle,
+			 asoc->timeouts[timer]);
+	}
+
+}
+
+/* Send the whole message, chunk by chunk, to the outqueue.
+ * This way the whole message is queued up and bundling if
+ * encouraged for small fragments.
+ */
+static void sctp_cmd_send_msg(struct sctp_association *asoc,
+			      struct sctp_datamsg *msg, gfp_t gfp)
+{
+	struct sctp_chunk *chunk;
+
+	list_for_each_entry(chunk, &msg->chunks, frag_list)
+		sctp_outq_tail(&asoc->outqueue, chunk, gfp);
+
+	asoc->outqueue.sched->enqueue(&asoc->outqueue, msg);
+}
+
+
+/* These three macros allow us to pull the debugging code out of the
+ * main flow of sctp_do_sm() to keep attention focused on the real
+ * functionality there.
+ */
+#define debug_pre_sfn() \
+	pr_debug("%s[pre-fn]: ep:%p, %s, %s, asoc:%p[%s], %s\n", __func__, \
+		 ep, sctp_evttype_tbl[event_type], (*debug_fn)(subtype),   \
+		 asoc, sctp_state_tbl[state], state_fn->name)
+
+#define debug_post_sfn() \
+	pr_debug("%s[post-fn]: asoc:%p, status:%s\n", __func__, asoc, \
+		 sctp_status_tbl[status])
+
+#define debug_post_sfx() \
+	pr_debug("%s[post-sfx]: error:%d, asoc:%p[%s]\n", __func__, error, \
+		 asoc, sctp_state_tbl[(asoc && sctp_id2assoc(ep->base.sk, \
+		 sctp_assoc2id(asoc))) ? asoc->state : SCTP_STATE_CLOSED])
+
+/*
+ * This is the master state machine processing function.
+ *
+ * If you want to understand all of lksctp, this is a
+ * good place to start.
+ */
+int sctp_do_sm(struct net *net, enum sctp_event_type event_type,
+	       union sctp_subtype subtype, enum sctp_state state,
+	       struct sctp_endpoint *ep, struct sctp_association *asoc,
+	       void *event_arg, gfp_t gfp)
+{
+	typedef const char *(printfn_t)(union sctp_subtype);
+	static printfn_t *table[] = {
+		NULL, sctp_cname, sctp_tname, sctp_oname, sctp_pname,
+	};
+	printfn_t *debug_fn  __attribute__ ((unused)) = table[event_type];
+	const struct sctp_sm_table_entry *state_fn;
+	struct sctp_cmd_seq commands;
+	enum sctp_disposition status;
+	int error = 0;
+
+	/* Look up the state function, run it, and then process the
+	 * side effects.  These three steps are the heart of lksctp.
+	 */
+	state_fn = sctp_sm_lookup_event(net, event_type, state, subtype);
+
+	sctp_init_cmd_seq(&commands);
+
+	debug_pre_sfn();
+	status = state_fn->fn(net, ep, asoc, subtype, event_arg, &commands);
+	debug_post_sfn();
+
+	error = sctp_side_effects(event_type, subtype, state,
+				  ep, &asoc, event_arg, status,
+				  &commands, gfp);
+	debug_post_sfx();
+
+	return error;
+}
+
+/*****************************************************************
+ * This the master state function side effect processing function.
+ *****************************************************************/
+static int sctp_side_effects(enum sctp_event_type event_type,
+			     union sctp_subtype subtype,
+			     enum sctp_state state,
+			     struct sctp_endpoint *ep,
+			     struct sctp_association **asoc,
+			     void *event_arg,
+			     enum sctp_disposition status,
+			     struct sctp_cmd_seq *commands,
+			     gfp_t gfp)
+{
+	int error;
+
+	/* FIXME - Most of the dispositions left today would be categorized
+	 * as "exceptional" dispositions.  For those dispositions, it
+	 * may not be proper to run through any of the commands at all.
+	 * For example, the command interpreter might be run only with
+	 * disposition SCTP_DISPOSITION_CONSUME.
+	 */
+	if (0 != (error = sctp_cmd_interpreter(event_type, subtype, state,
+					       ep, *asoc,
+					       event_arg, status,
+					       commands, gfp)))
+		goto bail;
+
+	switch (status) {
+	case SCTP_DISPOSITION_DISCARD:
+		pr_debug("%s: ignored sctp protocol event - state:%d, "
+			 "event_type:%d, event_id:%d\n", __func__, state,
+			 event_type, subtype.chunk);
+		break;
+
+	case SCTP_DISPOSITION_NOMEM:
+		/* We ran out of memory, so we need to discard this
+		 * packet.
+		 */
+		/* BUG--we should now recover some memory, probably by
+		 * reneging...
+		 */
+		error = -ENOMEM;
+		break;
+
+	case SCTP_DISPOSITION_DELETE_TCB:
+	case SCTP_DISPOSITION_ABORT:
+		/* This should now be a command. */
+		*asoc = NULL;
+		break;
+
+	case SCTP_DISPOSITION_CONSUME:
+		/*
+		 * We should no longer have much work to do here as the
+		 * real work has been done as explicit commands above.
+		 */
+		break;
+
+	case SCTP_DISPOSITION_VIOLATION:
+		net_err_ratelimited("protocol violation state %d chunkid %d\n",
+				    state, subtype.chunk);
+		break;
+
+	case SCTP_DISPOSITION_NOT_IMPL:
+		pr_warn("unimplemented feature in state %d, event_type %d, event_id %d\n",
+			state, event_type, subtype.chunk);
+		break;
+
+	case SCTP_DISPOSITION_BUG:
+		pr_err("bug in state %d, event_type %d, event_id %d\n",
+		       state, event_type, subtype.chunk);
+		BUG();
+		break;
+
+	default:
+		pr_err("impossible disposition %d in state %d, event_type %d, event_id %d\n",
+		       status, state, event_type, subtype.chunk);
+		error = status;
+		if (error >= 0)
+			error = -EINVAL;
+		WARN_ON_ONCE(1);
+		break;
+	}
+
+bail:
+	return error;
+}
+
+/********************************************************************
+ * 2nd Level Abstractions
+ ********************************************************************/
+
+/* This is the side-effect interpreter.  */
+static int sctp_cmd_interpreter(enum sctp_event_type event_type,
+				union sctp_subtype subtype,
+				enum sctp_state state,
+				struct sctp_endpoint *ep,
+				struct sctp_association *asoc,
+				void *event_arg,
+				enum sctp_disposition status,
+				struct sctp_cmd_seq *commands,
+				gfp_t gfp)
+{
+	struct sctp_sock *sp = sctp_sk(ep->base.sk);
+	struct sctp_chunk *chunk = NULL, *new_obj;
+	struct sctp_packet *packet;
+	struct sctp_sackhdr sackh;
+	struct timer_list *timer;
+	struct sctp_transport *t;
+	unsigned long timeout;
+	struct sctp_cmd *cmd;
+	int local_cork = 0;
+	int error = 0;
+	int force;
+
+	if (SCTP_EVENT_T_TIMEOUT != event_type)
+		chunk = event_arg;
+
+	/* Note:  This whole file is a huge candidate for rework.
+	 * For example, each command could either have its own handler, so
+	 * the loop would look like:
+	 *     while (cmds)
+	 *         cmd->handle(x, y, z)
+	 * --jgrimm
+	 */
+	while (NULL != (cmd = sctp_next_cmd(commands))) {
+		switch (cmd->verb) {
+		case SCTP_CMD_NOP:
+			/* Do nothing. */
+			break;
+
+		case SCTP_CMD_NEW_ASOC:
+			/* Register a new association.  */
+			if (local_cork) {
+				sctp_outq_uncork(&asoc->outqueue, gfp);
+				local_cork = 0;
+			}
+
+			/* Register with the endpoint.  */
+			asoc = cmd->obj.asoc;
+			BUG_ON(asoc->peer.primary_path == NULL);
+			sctp_endpoint_add_asoc(ep, asoc);
+			break;
+
+		case SCTP_CMD_PURGE_OUTQUEUE:
+		       sctp_outq_teardown(&asoc->outqueue);
+		       break;
+
+		case SCTP_CMD_DELETE_TCB:
+			if (local_cork) {
+				sctp_outq_uncork(&asoc->outqueue, gfp);
+				local_cork = 0;
+			}
+			/* Delete the current association.  */
+			sctp_cmd_delete_tcb(commands, asoc);
+			asoc = NULL;
+			break;
+
+		case SCTP_CMD_NEW_STATE:
+			/* Enter a new state.  */
+			sctp_cmd_new_state(commands, asoc, cmd->obj.state);
+			break;
+
+		case SCTP_CMD_REPORT_TSN:
+			/* Record the arrival of a TSN.  */
+			error = sctp_tsnmap_mark(&asoc->peer.tsn_map,
+						 cmd->obj.u32, NULL);
+			break;
+
+		case SCTP_CMD_REPORT_FWDTSN:
+			asoc->stream.si->report_ftsn(&asoc->ulpq, cmd->obj.u32);
+			break;
+
+		case SCTP_CMD_PROCESS_FWDTSN:
+			asoc->stream.si->handle_ftsn(&asoc->ulpq,
+						     cmd->obj.chunk);
+			break;
+
+		case SCTP_CMD_GEN_SACK:
+			/* Generate a Selective ACK.
+			 * The argument tells us whether to just count
+			 * the packet and MAYBE generate a SACK, or
+			 * force a SACK out.
+			 */
+			force = cmd->obj.i32;
+			error = sctp_gen_sack(asoc, force, commands);
+			break;
+
+		case SCTP_CMD_PROCESS_SACK:
+			/* Process an inbound SACK.  */
+			error = sctp_cmd_process_sack(commands, asoc,
+						      cmd->obj.chunk);
+			break;
+
+		case SCTP_CMD_GEN_INIT_ACK:
+			/* Generate an INIT ACK chunk.  */
+			new_obj = sctp_make_init_ack(asoc, chunk, GFP_ATOMIC,
+						     0);
+			if (!new_obj) {
+				error = -ENOMEM;
+				break;
+			}
+
+			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
+					SCTP_CHUNK(new_obj));
+			break;
+
+		case SCTP_CMD_PEER_INIT:
+			/* Process a unified INIT from the peer.
+			 * Note: Only used during INIT-ACK processing.  If
+			 * there is an error just return to the outter
+			 * layer which will bail.
+			 */
+			error = sctp_cmd_process_init(commands, asoc, chunk,
+						      cmd->obj.init, gfp);
+			break;
+
+		case SCTP_CMD_GEN_COOKIE_ECHO:
+			/* Generate a COOKIE ECHO chunk.  */
+			new_obj = sctp_make_cookie_echo(asoc, chunk);
+			if (!new_obj) {
+				if (cmd->obj.chunk)
+					sctp_chunk_free(cmd->obj.chunk);
+				error = -ENOMEM;
+				break;
+			}
+			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
+					SCTP_CHUNK(new_obj));
+
+			/* If there is an ERROR chunk to be sent along with
+			 * the COOKIE_ECHO, send it, too.
+			 */
+			if (cmd->obj.chunk)
+				sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
+						SCTP_CHUNK(cmd->obj.chunk));
+
+			if (new_obj->transport) {
+				new_obj->transport->init_sent_count++;
+				asoc->init_last_sent_to = new_obj->transport;
+			}
+
+			/* FIXME - Eventually come up with a cleaner way to
+			 * enabling COOKIE-ECHO + DATA bundling during
+			 * multihoming stale cookie scenarios, the following
+			 * command plays with asoc->peer.retran_path to
+			 * avoid the problem of sending the COOKIE-ECHO and
+			 * DATA in different paths, which could result
+			 * in the association being ABORTed if the DATA chunk
+			 * is processed first by the server.  Checking the
+			 * init error counter simply causes this command
+			 * to be executed only during failed attempts of
+			 * association establishment.
+			 */
+			if ((asoc->peer.retran_path !=
+			     asoc->peer.primary_path) &&
+			    (asoc->init_err_counter > 0)) {
+				sctp_add_cmd_sf(commands,
+						SCTP_CMD_FORCE_PRIM_RETRAN,
+						SCTP_NULL());
+			}
+
+			break;
+
+		case SCTP_CMD_GEN_SHUTDOWN:
+			/* Generate SHUTDOWN when in SHUTDOWN_SENT state.
+			 * Reset error counts.
+			 */
+			asoc->overall_error_count = 0;
+
+			/* Generate a SHUTDOWN chunk.  */
+			new_obj = sctp_make_shutdown(asoc, chunk);
+			if (!new_obj) {
+				error = -ENOMEM;
+				break;
+			}
+			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
+					SCTP_CHUNK(new_obj));
+			break;
+
+		case SCTP_CMD_CHUNK_ULP:
+			/* Send a chunk to the sockets layer.  */
+			pr_debug("%s: sm_sideff: chunk_up:%p, ulpq:%p\n",
+				 __func__, cmd->obj.chunk, &asoc->ulpq);
+
+			asoc->stream.si->ulpevent_data(&asoc->ulpq,
+						       cmd->obj.chunk,
+						       GFP_ATOMIC);
+			break;
+
+		case SCTP_CMD_EVENT_ULP:
+			/* Send a notification to the sockets layer.  */
+			pr_debug("%s: sm_sideff: event_up:%p, ulpq:%p\n",
+				 __func__, cmd->obj.ulpevent, &asoc->ulpq);
+
+			asoc->stream.si->enqueue_event(&asoc->ulpq,
+						       cmd->obj.ulpevent);
+			break;
+
+		case SCTP_CMD_REPLY:
+			/* If an caller has not already corked, do cork. */
+			if (!asoc->outqueue.cork) {
+				sctp_outq_cork(&asoc->outqueue);
+				local_cork = 1;
+			}
+			/* Send a chunk to our peer.  */
+			sctp_outq_tail(&asoc->outqueue, cmd->obj.chunk, gfp);
+			break;
+
+		case SCTP_CMD_SEND_PKT:
+			/* Send a full packet to our peer.  */
+			packet = cmd->obj.packet;
+			sctp_packet_transmit(packet, gfp);
+			sctp_ootb_pkt_free(packet);
+			break;
+
+		case SCTP_CMD_T1_RETRAN:
+			/* Mark a transport for retransmission.  */
+			sctp_retransmit(&asoc->outqueue, cmd->obj.transport,
+					SCTP_RTXR_T1_RTX);
+			break;
+
+		case SCTP_CMD_RETRAN:
+			/* Mark a transport for retransmission.  */
+			sctp_retransmit(&asoc->outqueue, cmd->obj.transport,
+					SCTP_RTXR_T3_RTX);
+			break;
+
+		case SCTP_CMD_ECN_CE:
+			/* Do delayed CE processing.   */
+			sctp_do_ecn_ce_work(asoc, cmd->obj.u32);
+			break;
+
+		case SCTP_CMD_ECN_ECNE:
+			/* Do delayed ECNE processing. */
+			new_obj = sctp_do_ecn_ecne_work(asoc, cmd->obj.u32,
+							chunk);
+			if (new_obj)
+				sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
+						SCTP_CHUNK(new_obj));
+			break;
+
+		case SCTP_CMD_ECN_CWR:
+			/* Do delayed CWR processing.  */
+			sctp_do_ecn_cwr_work(asoc, cmd->obj.u32);
+			break;
+
+		case SCTP_CMD_SETUP_T2:
+			sctp_cmd_setup_t2(commands, asoc, cmd->obj.chunk);
+			break;
+
+		case SCTP_CMD_TIMER_START_ONCE:
+			timer = &asoc->timers[cmd->obj.to];
+
+			if (timer_pending(timer))
+				break;
+			fallthrough;
+
+		case SCTP_CMD_TIMER_START:
+			timer = &asoc->timers[cmd->obj.to];
+			timeout = asoc->timeouts[cmd->obj.to];
+			BUG_ON(!timeout);
+
+			/*
+			 * SCTP has a hard time with timer starts.  Because we process
+			 * timer starts as side effects, it can be hard to tell if we
+			 * have already started a timer or not, which leads to BUG
+			 * halts when we call add_timer. So here, instead of just starting
+			 * a timer, if the timer is already started, and just mod
+			 * the timer with the shorter of the two expiration times
+			 */
+			if (!timer_pending(timer))
+				sctp_association_hold(asoc);
+			timer_reduce(timer, jiffies + timeout);
+			break;
+
+		case SCTP_CMD_TIMER_RESTART:
+			timer = &asoc->timers[cmd->obj.to];
+			timeout = asoc->timeouts[cmd->obj.to];
+			if (!mod_timer(timer, jiffies + timeout))
+				sctp_association_hold(asoc);
+			break;
+
+		case SCTP_CMD_TIMER_STOP:
+			timer = &asoc->timers[cmd->obj.to];
+			if (del_timer(timer))
+				sctp_association_put(asoc);
+			break;
+
+		case SCTP_CMD_INIT_CHOOSE_TRANSPORT:
+			chunk = cmd->obj.chunk;
+			t = sctp_assoc_choose_alter_transport(asoc,
+						asoc->init_last_sent_to);
+			asoc->init_last_sent_to = t;
+			chunk->transport = t;
+			t->init_sent_count++;
+			/* Set the new transport as primary */
+			sctp_assoc_set_primary(asoc, t);
+			break;
+
+		case SCTP_CMD_INIT_RESTART:
+			/* Do the needed accounting and updates
+			 * associated with restarting an initialization
+			 * timer. Only multiply the timeout by two if
+			 * all transports have been tried at the current
+			 * timeout.
+			 */
+			sctp_cmd_t1_timer_update(asoc,
+						SCTP_EVENT_TIMEOUT_T1_INIT,
+						"INIT");
+
+			sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
+					SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
+			break;
+
+		case SCTP_CMD_COOKIEECHO_RESTART:
+			/* Do the needed accounting and updates
+			 * associated with restarting an initialization
+			 * timer. Only multiply the timeout by two if
+			 * all transports have been tried at the current
+			 * timeout.
+			 */
+			sctp_cmd_t1_timer_update(asoc,
+						SCTP_EVENT_TIMEOUT_T1_COOKIE,
+						"COOKIE");
+
+			/* If we've sent any data bundled with
+			 * COOKIE-ECHO we need to resend.
+			 */
+			list_for_each_entry(t, &asoc->peer.transport_addr_list,
+					transports) {
+				sctp_retransmit_mark(&asoc->outqueue, t,
+					    SCTP_RTXR_T1_RTX);
+			}
+
+			sctp_add_cmd_sf(commands,
+					SCTP_CMD_TIMER_RESTART,
+					SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
+			break;
+
+		case SCTP_CMD_INIT_FAILED:
+			sctp_cmd_init_failed(commands, asoc, cmd->obj.u16);
+			break;
+
+		case SCTP_CMD_ASSOC_FAILED:
+			sctp_cmd_assoc_failed(commands, asoc, event_type,
+					      subtype, chunk, cmd->obj.u16);
+			break;
+
+		case SCTP_CMD_INIT_COUNTER_INC:
+			asoc->init_err_counter++;
+			break;
+
+		case SCTP_CMD_INIT_COUNTER_RESET:
+			asoc->init_err_counter = 0;
+			asoc->init_cycle = 0;
+			list_for_each_entry(t, &asoc->peer.transport_addr_list,
+					    transports) {
+				t->init_sent_count = 0;
+			}
+			break;
+
+		case SCTP_CMD_REPORT_DUP:
+			sctp_tsnmap_mark_dup(&asoc->peer.tsn_map,
+					     cmd->obj.u32);
+			break;
+
+		case SCTP_CMD_REPORT_BAD_TAG:
+			pr_debug("%s: vtag mismatch!\n", __func__);
+			break;
+
+		case SCTP_CMD_STRIKE:
+			/* Mark one strike against a transport.  */
+			sctp_do_8_2_transport_strike(commands, asoc,
+						    cmd->obj.transport, 0);
+			break;
+
+		case SCTP_CMD_TRANSPORT_IDLE:
+			t = cmd->obj.transport;
+			sctp_transport_lower_cwnd(t, SCTP_LOWER_CWND_INACTIVE);
+			break;
+
+		case SCTP_CMD_TRANSPORT_HB_SENT:
+			t = cmd->obj.transport;
+			sctp_do_8_2_transport_strike(commands, asoc,
+						     t, 1);
+			t->hb_sent = 1;
+			break;
+
+		case SCTP_CMD_TRANSPORT_ON:
+			t = cmd->obj.transport;
+			sctp_cmd_transport_on(commands, asoc, t, chunk);
+			break;
+
+		case SCTP_CMD_HB_TIMERS_START:
+			sctp_cmd_hb_timers_start(commands, asoc);
+			break;
+
+		case SCTP_CMD_HB_TIMER_UPDATE:
+			t = cmd->obj.transport;
+			sctp_transport_reset_hb_timer(t);
+			break;
+
+		case SCTP_CMD_HB_TIMERS_STOP:
+			sctp_cmd_hb_timers_stop(commands, asoc);
+			break;
+
+		case SCTP_CMD_PROBE_TIMER_UPDATE:
+			t = cmd->obj.transport;
+			sctp_transport_reset_probe_timer(t);
+			break;
+
+		case SCTP_CMD_REPORT_ERROR:
+			error = cmd->obj.error;
+			break;
+
+		case SCTP_CMD_PROCESS_CTSN:
+			/* Dummy up a SACK for processing. */
+			sackh.cum_tsn_ack = cmd->obj.be32;
+			sackh.a_rwnd = htonl(asoc->peer.rwnd +
+					     asoc->outqueue.outstanding_bytes);
+			sackh.num_gap_ack_blocks = 0;
+			sackh.num_dup_tsns = 0;
+			chunk->subh.sack_hdr = &sackh;
+			sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_SACK,
+					SCTP_CHUNK(chunk));
+			break;
+
+		case SCTP_CMD_DISCARD_PACKET:
+			/* We need to discard the whole packet.
+			 * Uncork the queue since there might be
+			 * responses pending
+			 */
+			chunk->pdiscard = 1;
+			if (asoc) {
+				sctp_outq_uncork(&asoc->outqueue, gfp);
+				local_cork = 0;
+			}
+			break;
+
+		case SCTP_CMD_RTO_PENDING:
+			t = cmd->obj.transport;
+			t->rto_pending = 1;
+			break;
+
+		case SCTP_CMD_PART_DELIVER:
+			asoc->stream.si->start_pd(&asoc->ulpq, GFP_ATOMIC);
+			break;
+
+		case SCTP_CMD_RENEGE:
+			asoc->stream.si->renege_events(&asoc->ulpq,
+						       cmd->obj.chunk,
+						       GFP_ATOMIC);
+			break;
+
+		case SCTP_CMD_SETUP_T4:
+			sctp_cmd_setup_t4(commands, asoc, cmd->obj.chunk);
+			break;
+
+		case SCTP_CMD_PROCESS_OPERR:
+			sctp_cmd_process_operr(commands, asoc, chunk);
+			break;
+		case SCTP_CMD_CLEAR_INIT_TAG:
+			asoc->peer.i.init_tag = 0;
+			break;
+		case SCTP_CMD_DEL_NON_PRIMARY:
+			sctp_cmd_del_non_primary(asoc);
+			break;
+		case SCTP_CMD_T3_RTX_TIMERS_STOP:
+			sctp_cmd_t3_rtx_timers_stop(commands, asoc);
+			break;
+		case SCTP_CMD_FORCE_PRIM_RETRAN:
+			t = asoc->peer.retran_path;
+			asoc->peer.retran_path = asoc->peer.primary_path;
+			sctp_outq_uncork(&asoc->outqueue, gfp);
+			local_cork = 0;
+			asoc->peer.retran_path = t;
+			break;
+		case SCTP_CMD_SET_SK_ERR:
+			sctp_cmd_set_sk_err(asoc, cmd->obj.error);
+			break;
+		case SCTP_CMD_ASSOC_CHANGE:
+			sctp_cmd_assoc_change(commands, asoc,
+					      cmd->obj.u8);
+			break;
+		case SCTP_CMD_ADAPTATION_IND:
+			sctp_cmd_adaptation_ind(commands, asoc);
+			break;
+		case SCTP_CMD_PEER_NO_AUTH:
+			sctp_cmd_peer_no_auth(commands, asoc);
+			break;
+
+		case SCTP_CMD_ASSOC_SHKEY:
+			error = sctp_auth_asoc_init_active_key(asoc,
+						GFP_ATOMIC);
+			break;
+		case SCTP_CMD_UPDATE_INITTAG:
+			asoc->peer.i.init_tag = cmd->obj.u32;
+			break;
+		case SCTP_CMD_SEND_MSG:
+			if (!asoc->outqueue.cork) {
+				sctp_outq_cork(&asoc->outqueue);
+				local_cork = 1;
+			}
+			sctp_cmd_send_msg(asoc, cmd->obj.msg, gfp);
+			break;
+		case SCTP_CMD_PURGE_ASCONF_QUEUE:
+			sctp_asconf_queue_teardown(asoc);
+			break;
+
+		case SCTP_CMD_SET_ASOC:
+			if (asoc && local_cork) {
+				sctp_outq_uncork(&asoc->outqueue, gfp);
+				local_cork = 0;
+			}
+			asoc = cmd->obj.asoc;
+			break;
+
+		default:
+			pr_warn("Impossible command: %u\n",
+				cmd->verb);
+			break;
+		}
+
+		if (error) {
+			cmd = sctp_next_cmd(commands);
+			while (cmd) {
+				if (cmd->verb == SCTP_CMD_REPLY)
+					sctp_chunk_free(cmd->obj.chunk);
+				cmd = sctp_next_cmd(commands);
+			}
+			break;
+		}
+	}
+
+	/* If this is in response to a received chunk, wait until
+	 * we are done with the packet to open the queue so that we don't
+	 * send multiple packets in response to a single request.
+	 */
+	if (asoc && SCTP_EVENT_T_CHUNK == event_type && chunk) {
+		if (chunk->end_of_packet || chunk->singleton)
+			sctp_outq_uncork(&asoc->outqueue, gfp);
+	} else if (local_cork)
+		sctp_outq_uncork(&asoc->outqueue, gfp);
+
+	if (sp->data_ready_signalled)
+		sp->data_ready_signalled = 0;
+
+	return error;
+}