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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* 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.
  * Copyright (c) 2001 La Monte H.P. Yarroll
  *
  * This file is part of the SCTP kernel implementation
  *
  * This module provides the abstraction for an SCTP association.
  *
  * 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@us.ibm.com>
  *    Xingang Guo           <xingang.guo@intel.com>
  *    Hui Huang             <hui.huang@nokia.com>
  *    Sridhar Samudrala     <sri@us.ibm.com>
  *    Daisy Chang       <daisyc@us.ibm.com>
  *    Ryan Layer        <rmlayer@us.ibm.com>
  *    Kevin Gao             <kevin.gao@intel.com>
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/types.h>
 #include <linux/fcntl.h>
 #include <linux/poll.h>
 #include <linux/init.h>
 
 #include <linux/slab.h>
 #include <linux/in.h>
 #include <net/ipv6.h>
 #include <net/sctp/sctp.h>
 #include <net/sctp/sm.h>
 
 /* Forward declarations for internal functions. */
 static void sctp_select_active_and_retran_path(struct sctp_association *asoc);
 static void sctp_assoc_bh_rcv(struct work_struct *work);
 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc);
 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc);
 
 /* 1st Level Abstractions. */
 
 /* Initialize a new association from provided memory. */
 static struct sctp_association *sctp_association_init(
                     struct sctp_association *asoc,
                     const struct sctp_endpoint *ep,
                     const struct sock *sk,
                     enum sctp_scope scope, gfp_t gfp)
 {
     struct sctp_sock *sp;
     struct sctp_paramhdr *p;
     int i;
 
     /* Retrieve the SCTP per socket area.  */
     sp = sctp_sk((struct sock *)sk);
 
     /* Discarding const is appropriate here.  */
     asoc->ep = (struct sctp_endpoint *)ep;
     asoc->base.sk = (struct sock *)sk;
     asoc->base.net = sock_net(sk);
 
     sctp_endpoint_hold(asoc->ep);
     sock_hold(asoc->base.sk);
 
     /* Initialize the common base substructure.  */
     asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;
 
     /* Initialize the object handling fields.  */
     refcount_set(&asoc->base.refcnt, 1);
 
     /* Initialize the bind addr area.  */
     sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);
 
     asoc->state = SCTP_STATE_CLOSED;
     asoc->cookie_life = ms_to_ktime(sp->assocparams.sasoc_cookie_life);
     asoc->user_frag = sp->user_frag;
 
     /* Set the association max_retrans and RTO values from the
      * socket values.
      */
     asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
     asoc->pf_retrans  = sp->pf_retrans;
     asoc->ps_retrans  = sp->ps_retrans;
     asoc->pf_expose   = sp->pf_expose;
 
     asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
     asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
     asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
 
     /* Initialize the association's heartbeat interval based on the
      * sock configured value.
      */
     asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);
     asoc->probe_interval = msecs_to_jiffies(sp->probe_interval);
 
     asoc->encap_port = sp->encap_port;
 
     /* Initialize path max retrans value. */
     asoc->pathmaxrxt = sp->pathmaxrxt;
 
     asoc->flowlabel = sp->flowlabel;
     asoc->dscp = sp->dscp;
 
     /* Set association default SACK delay */
     asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);
     asoc->sackfreq = sp->sackfreq;
 
     /* Set the association default flags controlling
      * Heartbeat, SACK delay, and Path MTU Discovery.
      */
     asoc->param_flags = sp->param_flags;
 
     /* Initialize the maximum number of new data packets that can be sent
      * in a burst.
      */
     asoc->max_burst = sp->max_burst;
 
     asoc->subscribe = sp->subscribe;
 
     /* initialize association timers */
     asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
     asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
     asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;
 
     /* sctpimpguide Section 2.12.2
      * If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
      * recommended value of 5 times 'RTO.Max'.
      */
     asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]
         = 5 * asoc->rto_max;
 
     asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;
     asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] = sp->autoclose * HZ;
 
     /* Initializes the timers */
     for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i)
         timer_setup(&asoc->timers[i], sctp_timer_events[i], 0);
 
     /* Pull default initialization values from the sock options.
      * Note: This assumes that the values have already been
      * validated in the sock.
      */
     asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
     asoc->c.sinit_num_ostreams  = sp->initmsg.sinit_num_ostreams;
     asoc->max_init_attempts = sp->initmsg.sinit_max_attempts;
 
     asoc->max_init_timeo =
          msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);
 
     /* Set the local window size for receive.
      * This is also the rcvbuf space per association.
      * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
      * 1500 bytes in one SCTP packet.
      */
     if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)
         asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
     else
         asoc->rwnd = sk->sk_rcvbuf/2;
 
     asoc->a_rwnd = asoc->rwnd;
 
     /* Use my own max window until I learn something better.  */
     asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
 
     /* Initialize the receive memory counter */
     atomic_set(&asoc->rmem_alloc, 0);
 
     init_waitqueue_head(&asoc->wait);
 
     asoc->c.my_vtag = sctp_generate_tag(ep);
     asoc->c.my_port = ep->base.bind_addr.port;
 
     asoc->c.initial_tsn = sctp_generate_tsn(ep);
 
     asoc->next_tsn = asoc->c.initial_tsn;
 
     asoc->ctsn_ack_point = asoc->next_tsn - 1;
     asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
     asoc->highest_sacked = asoc->ctsn_ack_point;
     asoc->last_cwr_tsn = asoc->ctsn_ack_point;
 
     /* ADDIP Section 4.1 Asconf Chunk Procedures
      *
      * When an endpoint has an ASCONF signaled change to be sent to the
      * remote endpoint it should do the following:
      * ...
      * A2) a serial number should be assigned to the chunk. The serial
      * number SHOULD be a monotonically increasing number. The serial
      * numbers SHOULD be initialized at the start of the
      * association to the same value as the initial TSN.
      */
     asoc->addip_serial = asoc->c.initial_tsn;
     asoc->strreset_outseq = asoc->c.initial_tsn;
 
     INIT_LIST_HEAD(&asoc->addip_chunk_list);
     INIT_LIST_HEAD(&asoc->asconf_ack_list);
 
     /* Make an empty list of remote transport addresses.  */
     INIT_LIST_HEAD(&asoc->peer.transport_addr_list);
 
     /* RFC 2960 5.1 Normal Establishment of an Association
      *
      * After the reception of the first data chunk in an
      * association the endpoint must immediately respond with a
      * sack to acknowledge the data chunk.  Subsequent
      * acknowledgements should be done as described in Section
      * 6.2.
      *
      * [We implement this by telling a new association that it
      * already received one packet.]
      */
     asoc->peer.sack_needed = 1;
     asoc->peer.sack_generation = 1;
 
     /* Create an input queue.  */
     sctp_inq_init(&asoc->base.inqueue);
     sctp_inq_set_th_handler(&asoc->base.inqueue, sctp_assoc_bh_rcv);
 
     /* Create an output queue.  */
     sctp_outq_init(asoc, &asoc->outqueue);
 
     if (!sctp_ulpq_init(&asoc->ulpq, asoc))
         goto fail_init;
 
     if (sctp_stream_init(&asoc->stream, asoc->c.sinit_num_ostreams, 0, gfp))
         goto stream_free;
 
     /* Initialize default path MTU. */
     asoc->pathmtu = sp->pathmtu;
     sctp_assoc_update_frag_point(asoc);
 
     /* Assume that peer would support both address types unless we are
      * told otherwise.
      */
     asoc->peer.ipv4_address = 1;
     if (asoc->base.sk->sk_family == PF_INET6)
         asoc->peer.ipv6_address = 1;
     INIT_LIST_HEAD(&asoc->asocs);
 
     asoc->default_stream = sp->default_stream;
     asoc->default_ppid = sp->default_ppid;
     asoc->default_flags = sp->default_flags;
     asoc->default_context = sp->default_context;
     asoc->default_timetolive = sp->default_timetolive;
     asoc->default_rcv_context = sp->default_rcv_context;
 
     /* AUTH related initializations */
     INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
     if (sctp_auth_asoc_copy_shkeys(ep, asoc, gfp))
         goto stream_free;
 
     asoc->active_key_id = ep->active_key_id;
     asoc->strreset_enable = ep->strreset_enable;
 
     /* Save the hmacs and chunks list into this association */
     if (ep->auth_hmacs_list)
         memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
             ntohs(ep->auth_hmacs_list->param_hdr.length));
     if (ep->auth_chunk_list)
         memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
             ntohs(ep->auth_chunk_list->param_hdr.length));
 
     /* Get the AUTH random number for this association */
     p = (struct sctp_paramhdr *)asoc->c.auth_random;
     p->type = SCTP_PARAM_RANDOM;
     p->length = htons(sizeof(*p) + SCTP_AUTH_RANDOM_LENGTH);
     get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);
 
     return asoc;
 
 stream_free:
     sctp_stream_free(&asoc->stream);
 fail_init:
     sock_put(asoc->base.sk);
     sctp_endpoint_put(asoc->ep);
     return NULL;
 }
 
 /* Allocate and initialize a new association */
 struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
                           const struct sock *sk,
                           enum sctp_scope scope, gfp_t gfp)
 {
     struct sctp_association *asoc;
 
     asoc = kzalloc(sizeof(*asoc), gfp);
     if (!asoc)
         goto fail;
 
     if (!sctp_association_init(asoc, ep, sk, scope, gfp))
         goto fail_init;
 
     SCTP_DBG_OBJCNT_INC(assoc);
 
     pr_debug("Created asoc %p\n", asoc);
 
     return asoc;
 
 fail_init:
     kfree(asoc);
 fail:
     return NULL;
 }
 
 /* Free this association if possible.  There may still be users, so
  * the actual deallocation may be delayed.
  */
 void sctp_association_free(struct sctp_association *asoc)
 {
     struct sock *sk = asoc->base.sk;
     struct sctp_transport *transport;
     struct list_head *pos, *temp;
     int i;
 
     /* Only real associations count against the endpoint, so
      * don't bother for if this is a temporary association.
      */
     if (!list_empty(&asoc->asocs)) {
         list_del(&asoc->asocs);
 
         /* Decrement the backlog value for a TCP-style listening
          * socket.
          */
         if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
             sk_acceptq_removed(sk);
     }
 
     /* Mark as dead, so other users can know this structure is
      * going away.
      */
     asoc->base.dead = true;
 
     /* Dispose of any data lying around in the outqueue. */
     sctp_outq_free(&asoc->outqueue);
 
     /* Dispose of any pending messages for the upper layer. */
     sctp_ulpq_free(&asoc->ulpq);
 
     /* Dispose of any pending chunks on the inqueue. */
     sctp_inq_free(&asoc->base.inqueue);
 
     sctp_tsnmap_free(&asoc->peer.tsn_map);
 
     /* Free stream information. */
     sctp_stream_free(&asoc->stream);
 
     if (asoc->strreset_chunk)
         sctp_chunk_free(asoc->strreset_chunk);
 
     /* Clean up the bound address list. */
     sctp_bind_addr_free(&asoc->base.bind_addr);
 
     /* Do we need to go through all of our timers and
      * delete them?   To be safe we will try to delete all, but we
      * should be able to go through and make a guess based
      * on our state.
      */
     for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
         if (del_timer(&asoc->timers[i]))
             sctp_association_put(asoc);
     }
 
     /* Free peer's cached cookie. */
     kfree(asoc->peer.cookie);
     kfree(asoc->peer.peer_random);
     kfree(asoc->peer.peer_chunks);
     kfree(asoc->peer.peer_hmacs);
 
     /* Release the transport structures. */
     list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
         transport = list_entry(pos, struct sctp_transport, transports);
         list_del_rcu(pos);
         sctp_unhash_transport(transport);
         sctp_transport_free(transport);
     }
 
     asoc->peer.transport_count = 0;
 
     sctp_asconf_queue_teardown(asoc);
 
     /* Free pending address space being deleted */
     kfree(asoc->asconf_addr_del_pending);
 
     /* AUTH - Free the endpoint shared keys */
     sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
 
     /* AUTH - Free the association shared key */
     sctp_auth_key_put(asoc->asoc_shared_key);
 
     sctp_association_put(asoc);
 }
 
 /* Cleanup and free up an association. */
 static void sctp_association_destroy(struct sctp_association *asoc)
 {
     if (unlikely(!asoc->base.dead)) {
         WARN(1, "Attempt to destroy undead association %p!\n", asoc);
         return;
     }
 
     sctp_endpoint_put(asoc->ep);
     sock_put(asoc->base.sk);
 
     if (asoc->assoc_id != 0) {
         spin_lock_bh(&sctp_assocs_id_lock);
         idr_remove(&sctp_assocs_id, asoc->assoc_id);
         spin_unlock_bh(&sctp_assocs_id_lock);
     }
 
     WARN_ON(atomic_read(&asoc->rmem_alloc));
 
     kfree_rcu(asoc, rcu);
     SCTP_DBG_OBJCNT_DEC(assoc);
 }
 
 /* Change the primary destination address for the peer. */
 void sctp_assoc_set_primary(struct sctp_association *asoc,
                 struct sctp_transport *transport)
 {
     int changeover = 0;
 
     /* it's a changeover only if we already have a primary path
      * that we are changing
      */
     if (asoc->peer.primary_path != NULL &&
         asoc->peer.primary_path != transport)
         changeover = 1 ;
 
     asoc->peer.primary_path = transport;
     sctp_ulpevent_notify_peer_addr_change(transport,
                           SCTP_ADDR_MADE_PRIM, 0);
 
     /* Set a default msg_name for events. */
     memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
            sizeof(union sctp_addr));
 
     /* If the primary path is changing, assume that the
      * user wants to use this new path.
      */
     if ((transport->state == SCTP_ACTIVE) ||
         (transport->state == SCTP_UNKNOWN))
         asoc->peer.active_path = transport;
 
     /*
      * SFR-CACC algorithm:
      * Upon the receipt of a request to change the primary
      * destination address, on the data structure for the new
      * primary destination, the sender MUST do the following:
      *
      * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
      * to this destination address earlier. The sender MUST set
      * CYCLING_CHANGEOVER to indicate that this switch is a
      * double switch to the same destination address.
      *
      * Really, only bother is we have data queued or outstanding on
      * the association.
      */
     if (!asoc->outqueue.outstanding_bytes && !asoc->outqueue.out_qlen)
         return;
 
     if (transport->cacc.changeover_active)
         transport->cacc.cycling_changeover = changeover;
 
     /* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
      * a changeover has occurred.
      */
     transport->cacc.changeover_active = changeover;
 
     /* 3) The sender MUST store the next TSN to be sent in
      * next_tsn_at_change.
      */
     transport->cacc.next_tsn_at_change = asoc->next_tsn;
 }
 
 /* Remove a transport from an association.  */
 void sctp_assoc_rm_peer(struct sctp_association *asoc,
             struct sctp_transport *peer)
 {
     struct sctp_transport *transport;
     struct list_head *pos;
     struct sctp_chunk *ch;
 
     pr_debug("%s: association:%p addr:%pISpc\n",
          __func__, asoc, &peer->ipaddr.sa);
 
     /* If we are to remove the current retran_path, update it
      * to the next peer before removing this peer from the list.
      */
     if (asoc->peer.retran_path == peer)
         sctp_assoc_update_retran_path(asoc);
 
     /* Remove this peer from the list. */
     list_del_rcu(&peer->transports);
     /* Remove this peer from the transport hashtable */
     sctp_unhash_transport(peer);
 
     /* Get the first transport of asoc. */
     pos = asoc->peer.transport_addr_list.next;
     transport = list_entry(pos, struct sctp_transport, transports);
 
     /* Update any entries that match the peer to be deleted. */
     if (asoc->peer.primary_path == peer)
         sctp_assoc_set_primary(asoc, transport);
     if (asoc->peer.active_path == peer)
         asoc->peer.active_path = transport;
     if (asoc->peer.retran_path == peer)
         asoc->peer.retran_path = transport;
     if (asoc->peer.last_data_from == peer)
         asoc->peer.last_data_from = transport;
 
     if (asoc->strreset_chunk &&
         asoc->strreset_chunk->transport == peer) {
         asoc->strreset_chunk->transport = transport;
         sctp_transport_reset_reconf_timer(transport);
     }
 
     /* If we remove the transport an INIT was last sent to, set it to
      * NULL. Combined with the update of the retran path above, this
      * will cause the next INIT to be sent to the next available
      * transport, maintaining the cycle.
      */
     if (asoc->init_last_sent_to == peer)
         asoc->init_last_sent_to = NULL;
 
     /* If we remove the transport an SHUTDOWN was last sent to, set it
      * to NULL. Combined with the update of the retran path above, this
      * will cause the next SHUTDOWN to be sent to the next available
      * transport, maintaining the cycle.
      */
     if (asoc->shutdown_last_sent_to == peer)
         asoc->shutdown_last_sent_to = NULL;
 
     /* If we remove the transport an ASCONF was last sent to, set it to
      * NULL.
      */
     if (asoc->addip_last_asconf &&
         asoc->addip_last_asconf->transport == peer)
         asoc->addip_last_asconf->transport = NULL;
 
     /* If we have something on the transmitted list, we have to
      * save it off.  The best place is the active path.
      */
     if (!list_empty(&peer->transmitted)) {
         struct sctp_transport *active = asoc->peer.active_path;
 
         /* Reset the transport of each chunk on this list */
         list_for_each_entry(ch, &peer->transmitted,
                     transmitted_list) {
             ch->transport = NULL;
             ch->rtt_in_progress = 0;
         }
 
         list_splice_tail_init(&peer->transmitted,
                     &active->transmitted);
 
         /* Start a T3 timer here in case it wasn't running so
          * that these migrated packets have a chance to get
          * retransmitted.
          */
         if (!timer_pending(&active->T3_rtx_timer))
             if (!mod_timer(&active->T3_rtx_timer,
                     jiffies + active->rto))
                 sctp_transport_hold(active);
     }
 
     list_for_each_entry(ch, &asoc->outqueue.out_chunk_list, list)
         if (ch->transport == peer)
             ch->transport = NULL;
 
     asoc->peer.transport_count--;
 
     sctp_ulpevent_notify_peer_addr_change(peer, SCTP_ADDR_REMOVED, 0);
     sctp_transport_free(peer);
 }
 
 /* Add a transport address to an association.  */
 struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
                        const union sctp_addr *addr,
                        const gfp_t gfp,
                        const int peer_state)
 {
     struct sctp_transport *peer;
     struct sctp_sock *sp;
     unsigned short port;
 
     sp = sctp_sk(asoc->base.sk);
 
     /* AF_INET and AF_INET6 share common port field. */
     port = ntohs(addr->v4.sin_port);
 
     pr_debug("%s: association:%p addr:%pISpc state:%d\n", __func__,
          asoc, &addr->sa, peer_state);
 
     /* Set the port if it has not been set yet.  */
     if (0 == asoc->peer.port)
         asoc->peer.port = port;
 
     /* Check to see if this is a duplicate. */
     peer = sctp_assoc_lookup_paddr(asoc, addr);
     if (peer) {
         /* An UNKNOWN state is only set on transports added by
          * user in sctp_connectx() call.  Such transports should be
          * considered CONFIRMED per RFC 4960, Section 5.4.
          */
         if (peer->state == SCTP_UNKNOWN) {
             peer->state = SCTP_ACTIVE;
         }
         return peer;
     }
 
     peer = sctp_transport_new(asoc->base.net, addr, gfp);
     if (!peer)
         return NULL;
 
     sctp_transport_set_owner(peer, asoc);
 
     /* Initialize the peer's heartbeat interval based on the
      * association configured value.
      */
     peer->hbinterval = asoc->hbinterval;
     peer->probe_interval = asoc->probe_interval;
 
     peer->encap_port = asoc->encap_port;
 
     /* Set the path max_retrans.  */
     peer->pathmaxrxt = asoc->pathmaxrxt;
 
     /* And the partial failure retrans threshold */
     peer->pf_retrans = asoc->pf_retrans;
     /* And the primary path switchover retrans threshold */
     peer->ps_retrans = asoc->ps_retrans;
 
     /* Initialize the peer's SACK delay timeout based on the
      * association configured value.
      */
     peer->sackdelay = asoc->sackdelay;
     peer->sackfreq = asoc->sackfreq;
 
     if (addr->sa.sa_family == AF_INET6) {
         __be32 info = addr->v6.sin6_flowinfo;
 
         if (info) {
             peer->flowlabel = ntohl(info & IPV6_FLOWLABEL_MASK);
             peer->flowlabel |= SCTP_FLOWLABEL_SET_MASK;
         } else {
             peer->flowlabel = asoc->flowlabel;
         }
     }
     peer->dscp = asoc->dscp;
 
     /* Enable/disable heartbeat, SACK delay, and path MTU discovery
      * based on association setting.
      */
     peer->param_flags = asoc->param_flags;
 
     /* Initialize the pmtu of the transport. */
     sctp_transport_route(peer, NULL, sp);
 
     /* If this is the first transport addr on this association,
      * initialize the association PMTU to the peer's PMTU.
      * If not and the current association PMTU is higher than the new
      * peer's PMTU, reset the association PMTU to the new peer's PMTU.
      */
     sctp_assoc_set_pmtu(asoc, asoc->pathmtu ?
                   min_t(int, peer->pathmtu, asoc->pathmtu) :
                   peer->pathmtu);
 
     peer->pmtu_pending = 0;
 
     /* The asoc->peer.port might not be meaningful yet, but
      * initialize the packet structure anyway.
      */
     sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
              asoc->peer.port);
 
     /* 7.2.1 Slow-Start
      *
      * o The initial cwnd before DATA transmission or after a sufficiently
      *   long idle period MUST be set to
      *      min(4*MTU, max(2*MTU, 4380 bytes))
      *
      * o The initial value of ssthresh MAY be arbitrarily high
      *   (for example, implementations MAY use the size of the
      *   receiver advertised window).
      */
     peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
 
     /* At this point, we may not have the receiver's advertised window,
      * so initialize ssthresh to the default value and it will be set
      * later when we process the INIT.
      */
     peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
 
     peer->partial_bytes_acked = 0;
     peer->flight_size = 0;
     peer->burst_limited = 0;
 
     /* Set the transport's RTO.initial value */
     peer->rto = asoc->rto_initial;
     sctp_max_rto(asoc, peer);
 
     /* Set the peer's active state. */
     peer->state = peer_state;
 
     /* Add this peer into the transport hashtable */
     if (sctp_hash_transport(peer)) {
         sctp_transport_free(peer);
         return NULL;
     }
 
     sctp_transport_pl_reset(peer);
 
     /* Attach the remote transport to our asoc.  */
     list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list);
     asoc->peer.transport_count++;
 
     sctp_ulpevent_notify_peer_addr_change(peer, SCTP_ADDR_ADDED, 0);
 
     /* If we do not yet have a primary path, set one.  */
     if (!asoc->peer.primary_path) {
         sctp_assoc_set_primary(asoc, peer);
         asoc->peer.retran_path = peer;
     }
 
     if (asoc->peer.active_path == asoc->peer.retran_path &&
         peer->state != SCTP_UNCONFIRMED) {
         asoc->peer.retran_path = peer;
     }
 
     return peer;
 }
 
 /* Delete a transport address from an association.  */
 void sctp_assoc_del_peer(struct sctp_association *asoc,
              const union sctp_addr *addr)
 {
     struct list_head    *pos;
     struct list_head    *temp;
     struct sctp_transport   *transport;
 
     list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
         transport = list_entry(pos, struct sctp_transport, transports);
         if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
             /* Do book keeping for removing the peer and free it. */
             sctp_assoc_rm_peer(asoc, transport);
             break;
         }
     }
 }
 
 /* Lookup a transport by address. */
 struct sctp_transport *sctp_assoc_lookup_paddr(
                     const struct sctp_association *asoc,
                     const union sctp_addr *address)
 {
     struct sctp_transport *t;
 
     /* Cycle through all transports searching for a peer address. */
 
     list_for_each_entry(t, &asoc->peer.transport_addr_list,
             transports) {
         if (sctp_cmp_addr_exact(address, &t->ipaddr))
             return t;
     }
 
     return NULL;
 }
 
 /* Remove all transports except a give one */
 void sctp_assoc_del_nonprimary_peers(struct sctp_association *asoc,
                      struct sctp_transport *primary)
 {
     struct sctp_transport   *temp;
     struct sctp_transport   *t;
 
     list_for_each_entry_safe(t, temp, &asoc->peer.transport_addr_list,
                  transports) {
         /* if the current transport is not the primary one, delete it */
         if (t != primary)
             sctp_assoc_rm_peer(asoc, t);
     }
 }
 
 /* Engage in transport control operations.
  * Mark the transport up or down and send a notification to the user.
  * Select and update the new active and retran paths.
  */
 void sctp_assoc_control_transport(struct sctp_association *asoc,
                   struct sctp_transport *transport,
                   enum sctp_transport_cmd command,
                   sctp_sn_error_t error)
 {
     int spc_state = SCTP_ADDR_AVAILABLE;
     bool ulp_notify = true;
 
     /* Record the transition on the transport.  */
     switch (command) {
     case SCTP_TRANSPORT_UP:
         /* If we are moving from UNCONFIRMED state due
          * to heartbeat success, report the SCTP_ADDR_CONFIRMED
          * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
          */
         if (transport->state == SCTP_PF &&
             asoc->pf_expose != SCTP_PF_EXPOSE_ENABLE)
             ulp_notify = false;
         else if (transport->state == SCTP_UNCONFIRMED &&
              error == SCTP_HEARTBEAT_SUCCESS)
             spc_state = SCTP_ADDR_CONFIRMED;
 
         transport->state = SCTP_ACTIVE;
         sctp_transport_pl_reset(transport);
         break;
 
     case SCTP_TRANSPORT_DOWN:
         /* If the transport was never confirmed, do not transition it
          * to inactive state.  Also, release the cached route since
          * there may be a better route next time.
          */
         if (transport->state != SCTP_UNCONFIRMED) {
             transport->state = SCTP_INACTIVE;
             sctp_transport_pl_reset(transport);
             spc_state = SCTP_ADDR_UNREACHABLE;
         } else {
             sctp_transport_dst_release(transport);
             ulp_notify = false;
         }
         break;
 
     case SCTP_TRANSPORT_PF:
         transport->state = SCTP_PF;
         if (asoc->pf_expose != SCTP_PF_EXPOSE_ENABLE)
             ulp_notify = false;
         else
             spc_state = SCTP_ADDR_POTENTIALLY_FAILED;
         break;
 
     default:
         return;
     }
 
     /* Generate and send a SCTP_PEER_ADDR_CHANGE notification
      * to the user.
      */
     if (ulp_notify)
         sctp_ulpevent_notify_peer_addr_change(transport,
                               spc_state, error);
 
     /* Select new active and retran paths. */
     sctp_select_active_and_retran_path(asoc);
 }
 
 /* Hold a reference to an association. */
 void sctp_association_hold(struct sctp_association *asoc)
 {
     refcount_inc(&asoc->base.refcnt);
 }
 
 /* Release a reference to an association and cleanup
  * if there are no more references.
  */
 void sctp_association_put(struct sctp_association *asoc)
 {
     if (refcount_dec_and_test(&asoc->base.refcnt))
         sctp_association_destroy(asoc);
 }
 
 /* Allocate the next TSN, Transmission Sequence Number, for the given
  * association.
  */
 __u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
 {
     /* From Section 1.6 Serial Number Arithmetic:
      * Transmission Sequence Numbers wrap around when they reach
      * 2**32 - 1.  That is, the next TSN a DATA chunk MUST use
      * after transmitting TSN = 2*32 - 1 is TSN = 0.
      */
     __u32 retval = asoc->next_tsn;
     asoc->next_tsn++;
     asoc->unack_data++;
 
     return retval;
 }
 
 /* Compare two addresses to see if they match.  Wildcard addresses
  * only match themselves.
  */
 int sctp_cmp_addr_exact(const union sctp_addr *ss1,
             const union sctp_addr *ss2)
 {
     struct sctp_af *af;
 
     af = sctp_get_af_specific(ss1->sa.sa_family);
     if (unlikely(!af))
         return 0;
 
     return af->cmp_addr(ss1, ss2);
 }
 
 /* Return an ecne chunk to get prepended to a packet.
  * Note:  We are sly and return a shared, prealloced chunk.  FIXME:
  * No we don't, but we could/should.
  */
 struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
 {
     if (!asoc->need_ecne)
         return NULL;
 
     /* Send ECNE if needed.
      * Not being able to allocate a chunk here is not deadly.
      */
     return sctp_make_ecne(asoc, asoc->last_ecne_tsn);
 }
 
 /*
  * Find which transport this TSN was sent on.
  */
 struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
                          __u32 tsn)
 {
     struct sctp_transport *active;
     struct sctp_transport *match;
     struct sctp_transport *transport;
     struct sctp_chunk *chunk;
     __be32 key = htonl(tsn);
 
     match = NULL;
 
     /*
      * FIXME: In general, find a more efficient data structure for
      * searching.
      */
 
     /*
      * The general strategy is to search each transport's transmitted
      * list.   Return which transport this TSN lives on.
      *
      * Let's be hopeful and check the active_path first.
      * Another optimization would be to know if there is only one
      * outbound path and not have to look for the TSN at all.
      *
      */
 
     active = asoc->peer.active_path;
 
     list_for_each_entry(chunk, &active->transmitted,
             transmitted_list) {
 
         if (key == chunk->subh.data_hdr->tsn) {
             match = active;
             goto out;
         }
     }
 
     /* If not found, go search all the other transports. */
     list_for_each_entry(transport, &asoc->peer.transport_addr_list,
             transports) {
 
         if (transport == active)
             continue;
         list_for_each_entry(chunk, &transport->transmitted,
                 transmitted_list) {
             if (key == chunk->subh.data_hdr->tsn) {
                 match = transport;
                 goto out;
             }
         }
     }
 out:
     return match;
 }
 
 /* Do delayed input processing.  This is scheduled by sctp_rcv(). */
 static void sctp_assoc_bh_rcv(struct work_struct *work)
 {
     struct sctp_association *asoc =
         container_of(work, struct sctp_association,
                  base.inqueue.immediate);
     struct net *net = asoc->base.net;
     union sctp_subtype subtype;
     struct sctp_endpoint *ep;
     struct sctp_chunk *chunk;
     struct sctp_inq *inqueue;
     int first_time = 1; /* is this the first time through the loop */
     int error = 0;
     int state;
 
     /* The association should be held so we should be safe. */
     ep = asoc->ep;
 
     inqueue = &asoc->base.inqueue;
     sctp_association_hold(asoc);
     while (NULL != (chunk = sctp_inq_pop(inqueue))) {
         state = asoc->state;
         subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
 
         /* If the first chunk in the packet is AUTH, do special
          * processing specified in Section 6.3 of SCTP-AUTH spec
          */
         if (first_time && subtype.chunk == SCTP_CID_AUTH) {
             struct sctp_chunkhdr *next_hdr;
 
             next_hdr = sctp_inq_peek(inqueue);
             if (!next_hdr)
                 goto normal;
 
             /* If the next chunk is COOKIE-ECHO, skip the AUTH
              * chunk while saving a pointer to it so we can do
              * Authentication later (during cookie-echo
              * processing).
              */
             if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
                 chunk->auth_chunk = skb_clone(chunk->skb,
                                   GFP_ATOMIC);
                 chunk->auth = 1;
                 continue;
             }
         }
 
 normal:
         /* SCTP-AUTH, Section 6.3:
          *    The receiver has a list of chunk types which it expects
          *    to be received only after an AUTH-chunk.  This list has
          *    been sent to the peer during the association setup.  It
          *    MUST silently discard these chunks if they are not placed
          *    after an AUTH chunk in the packet.
          */
         if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
             continue;
 
         /* Remember where the last DATA chunk came from so we
          * know where to send the SACK.
          */
         if (sctp_chunk_is_data(chunk))
             asoc->peer.last_data_from = chunk->transport;
         else {
             SCTP_INC_STATS(net, SCTP_MIB_INCTRLCHUNKS);
             asoc->stats.ictrlchunks++;
             if (chunk->chunk_hdr->type == SCTP_CID_SACK)
                 asoc->stats.isacks++;
         }
 
         if (chunk->transport)
             chunk->transport->last_time_heard = ktime_get();
 
         /* Run through the state machine. */
         error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype,
                    state, ep, asoc, chunk, GFP_ATOMIC);
 
         /* Check to see if the association is freed in response to
          * the incoming chunk.  If so, get out of the while loop.
          */
         if (asoc->base.dead)
             break;
 
         /* If there is an error on chunk, discard this packet. */
         if (error && chunk)
             chunk->pdiscard = 1;
 
         if (first_time)
             first_time = 0;
     }
     sctp_association_put(asoc);
 }
 
 /* This routine moves an association from its old sk to a new sk.  */
 void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
 {
     struct sctp_sock *newsp = sctp_sk(newsk);
     struct sock *oldsk = assoc->base.sk;
 
     /* Delete the association from the old endpoint's list of
      * associations.
      */
     list_del_init(&assoc->asocs);
 
     /* Decrement the backlog value for a TCP-style socket. */
     if (sctp_style(oldsk, TCP))
         sk_acceptq_removed(oldsk);
 
     /* Release references to the old endpoint and the sock.  */
     sctp_endpoint_put(assoc->ep);
     sock_put(assoc->base.sk);
 
     /* Get a reference to the new endpoint.  */
     assoc->ep = newsp->ep;
     sctp_endpoint_hold(assoc->ep);
 
     /* Get a reference to the new sock.  */
     assoc->base.sk = newsk;
     sock_hold(assoc->base.sk);
 
     /* Add the association to the new endpoint's list of associations.  */
     sctp_endpoint_add_asoc(newsp->ep, assoc);
 }
 
 /* Update an association (possibly from unexpected COOKIE-ECHO processing).  */
 int sctp_assoc_update(struct sctp_association *asoc,
               struct sctp_association *new)
 {
     struct sctp_transport *trans;
     struct list_head *pos, *temp;
 
     /* Copy in new parameters of peer. */
     asoc->c = new->c;
     asoc->peer.rwnd = new->peer.rwnd;
     asoc->peer.sack_needed = new->peer.sack_needed;
     asoc->peer.auth_capable = new->peer.auth_capable;
     asoc->peer.i = new->peer.i;
 
     if (!sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL,
                   asoc->peer.i.initial_tsn, GFP_ATOMIC))
         return -ENOMEM;
 
     /* Remove any peer addresses not present in the new association. */
     list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
         trans = list_entry(pos, struct sctp_transport, transports);
         if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr)) {
             sctp_assoc_rm_peer(asoc, trans);
             continue;
         }
 
         if (asoc->state >= SCTP_STATE_ESTABLISHED)
             sctp_transport_reset(trans);
     }
 
     /* If the case is A (association restart), use
      * initial_tsn as next_tsn. If the case is B, use
      * current next_tsn in case data sent to peer
      * has been discarded and needs retransmission.
      */
     if (asoc->state >= SCTP_STATE_ESTABLISHED) {
         asoc->next_tsn = new->next_tsn;
         asoc->ctsn_ack_point = new->ctsn_ack_point;
         asoc->adv_peer_ack_point = new->adv_peer_ack_point;
 
         /* Reinitialize SSN for both local streams
          * and peer's streams.
          */
         sctp_stream_clear(&asoc->stream);
 
         /* Flush the ULP reassembly and ordered queue.
          * Any data there will now be stale and will
          * cause problems.
          */
         sctp_ulpq_flush(&asoc->ulpq);
 
         /* reset the overall association error count so
          * that the restarted association doesn't get torn
          * down on the next retransmission timer.
          */
         asoc->overall_error_count = 0;
 
     } else {
         /* Add any peer addresses from the new association. */
         list_for_each_entry(trans, &new->peer.transport_addr_list,
                     transports)
             if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr) &&
                 !sctp_assoc_add_peer(asoc, &trans->ipaddr,
                          GFP_ATOMIC, trans->state))
                 return -ENOMEM;
 
         asoc->ctsn_ack_point = asoc->next_tsn - 1;
         asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
 
         if (sctp_state(asoc, COOKIE_WAIT))
             sctp_stream_update(&asoc->stream, &new->stream);
 
         /* get a new assoc id if we don't have one yet. */
         if (sctp_assoc_set_id(asoc, GFP_ATOMIC))
             return -ENOMEM;
     }
 
     /* SCTP-AUTH: Save the peer parameters from the new associations
      * and also move the association shared keys over
      */
     kfree(asoc->peer.peer_random);
     asoc->peer.peer_random = new->peer.peer_random;
     new->peer.peer_random = NULL;
 
     kfree(asoc->peer.peer_chunks);
     asoc->peer.peer_chunks = new->peer.peer_chunks;
     new->peer.peer_chunks = NULL;
 
     kfree(asoc->peer.peer_hmacs);
     asoc->peer.peer_hmacs = new->peer.peer_hmacs;
     new->peer.peer_hmacs = NULL;
 
     return sctp_auth_asoc_init_active_key(asoc, GFP_ATOMIC);
 }
 
 /* Update the retran path for sending a retransmitted packet.
  * See also RFC4960, 6.4. Multi-Homed SCTP Endpoints:
  *
  *   When there is outbound data to send and the primary path
  *   becomes inactive (e.g., due to failures), or where the
  *   SCTP user explicitly requests to send data to an
  *   inactive destination transport address, before reporting
  *   an error to its ULP, the SCTP endpoint should try to send
  *   the data to an alternate active destination transport
  *   address if one exists.
  *
  *   When retransmitting data that timed out, if the endpoint
  *   is multihomed, it should consider each source-destination
  *   address pair in its retransmission selection policy.
  *   When retransmitting timed-out data, the endpoint should
  *   attempt to pick the most divergent source-destination
  *   pair from the original source-destination pair to which
  *   the packet was transmitted.
  *
  *   Note: Rules for picking the most divergent source-destination
  *   pair are an implementation decision and are not specified
  *   within this document.
  *
  * Our basic strategy is to round-robin transports in priorities
  * according to sctp_trans_score() e.g., if no such
  * transport with state SCTP_ACTIVE exists, round-robin through
  * SCTP_UNKNOWN, etc. You get the picture.
  */
 static u8 sctp_trans_score(const struct sctp_transport *trans)
 {
     switch (trans->state) {
     case SCTP_ACTIVE:
         return 3;   /* best case */
     case SCTP_UNKNOWN:
         return 2;
     case SCTP_PF:
         return 1;
     default: /* case SCTP_INACTIVE */
         return 0;   /* worst case */
     }
 }
 
 static struct sctp_transport *sctp_trans_elect_tie(struct sctp_transport *trans1,
                            struct sctp_transport *trans2)
 {
     if (trans1->error_count > trans2->error_count) {
         return trans2;
     } else if (trans1->error_count == trans2->error_count &&
            ktime_after(trans2->last_time_heard,
                    trans1->last_time_heard)) {
         return trans2;
     } else {
         return trans1;
     }
 }
 
 static struct sctp_transport *sctp_trans_elect_best(struct sctp_transport *curr,
                             struct sctp_transport *best)
 {
     u8 score_curr, score_best;
 
     if (best == NULL || curr == best)
         return curr;
 
     score_curr = sctp_trans_score(curr);
     score_best = sctp_trans_score(best);
 
     /* First, try a score-based selection if both transport states
      * differ. If we're in a tie, lets try to make a more clever
      * decision here based on error counts and last time heard.
      */
     if (score_curr > score_best)
         return curr;
     else if (score_curr == score_best)
         return sctp_trans_elect_tie(best, curr);
     else
         return best;
 }
 
 void sctp_assoc_update_retran_path(struct sctp_association *asoc)
 {
     struct sctp_transport *trans = asoc->peer.retran_path;
     struct sctp_transport *trans_next = NULL;
 
     /* We're done as we only have the one and only path. */
     if (asoc->peer.transport_count == 1)
         return;
     /* If active_path and retran_path are the same and active,
      * then this is the only active path. Use it.
      */
     if (asoc->peer.active_path == asoc->peer.retran_path &&
         asoc->peer.active_path->state == SCTP_ACTIVE)
         return;
 
     /* Iterate from retran_path's successor back to retran_path. */
     for (trans = list_next_entry(trans, transports); 1;
          trans = list_next_entry(trans, transports)) {
         /* Manually skip the head element. */
         if (&trans->transports == &asoc->peer.transport_addr_list)
             continue;
         if (trans->state == SCTP_UNCONFIRMED)
             continue;
         trans_next = sctp_trans_elect_best(trans, trans_next);
         /* Active is good enough for immediate return. */
         if (trans_next->state == SCTP_ACTIVE)
             break;
         /* We've reached the end, time to update path. */
         if (trans == asoc->peer.retran_path)
             break;
     }
 
     asoc->peer.retran_path = trans_next;
 
     pr_debug("%s: association:%p updated new path to addr:%pISpc\n",
          __func__, asoc, &asoc->peer.retran_path->ipaddr.sa);
 }
 
 static void sctp_select_active_and_retran_path(struct sctp_association *asoc)
 {
     struct sctp_transport *trans, *trans_pri = NULL, *trans_sec = NULL;
     struct sctp_transport *trans_pf = NULL;
 
     /* Look for the two most recently used active transports. */
     list_for_each_entry(trans, &asoc->peer.transport_addr_list,
                 transports) {
         /* Skip uninteresting transports. */
         if (trans->state == SCTP_INACTIVE ||
             trans->state == SCTP_UNCONFIRMED)
             continue;
         /* Keep track of the best PF transport from our
          * list in case we don't find an active one.
          */
         if (trans->state == SCTP_PF) {
             trans_pf = sctp_trans_elect_best(trans, trans_pf);
             continue;
         }
         /* For active transports, pick the most recent ones. */
         if (trans_pri == NULL ||
             ktime_after(trans->last_time_heard,
                 trans_pri->last_time_heard)) {
             trans_sec = trans_pri;
             trans_pri = trans;
         } else if (trans_sec == NULL ||
                ktime_after(trans->last_time_heard,
                        trans_sec->last_time_heard)) {
             trans_sec = trans;
         }
     }
 
     /* RFC 2960 6.4 Multi-Homed SCTP Endpoints
      *
      * By default, an endpoint should always transmit to the primary
      * path, unless the SCTP user explicitly specifies the
      * destination transport address (and possibly source transport
      * address) to use. [If the primary is active but not most recent,
      * bump the most recently used transport.]
      */
     if ((asoc->peer.primary_path->state == SCTP_ACTIVE ||
          asoc->peer.primary_path->state == SCTP_UNKNOWN) &&
          asoc->peer.primary_path != trans_pri) {
         trans_sec = trans_pri;
         trans_pri = asoc->peer.primary_path;
     }
 
     /* We did not find anything useful for a possible retransmission
      * path; either primary path that we found is the same as
      * the current one, or we didn't generally find an active one.
      */
     if (trans_sec == NULL)
         trans_sec = trans_pri;
 
     /* If we failed to find a usable transport, just camp on the
      * active or pick a PF iff it's the better choice.
      */
     if (trans_pri == NULL) {
         trans_pri = sctp_trans_elect_best(asoc->peer.active_path, trans_pf);
         trans_sec = trans_pri;
     }
 
     /* Set the active and retran transports. */
     asoc->peer.active_path = trans_pri;
     asoc->peer.retran_path = trans_sec;
 }
 
 struct sctp_transport *
 sctp_assoc_choose_alter_transport(struct sctp_association *asoc,
                   struct sctp_transport *last_sent_to)
 {
     /* If this is the first time packet is sent, use the active path,
      * else use the retran path. If the last packet was sent over the
      * retran path, update the retran path and use it.
      */
     if (last_sent_to == NULL) {
         return asoc->peer.active_path;
     } else {
         if (last_sent_to == asoc->peer.retran_path)
             sctp_assoc_update_retran_path(asoc);
 
         return asoc->peer.retran_path;
     }
 }
 
 void sctp_assoc_update_frag_point(struct sctp_association *asoc)
 {
     int frag = sctp_mtu_payload(sctp_sk(asoc->base.sk), asoc->pathmtu,
                     sctp_datachk_len(&asoc->stream));
 
     if (asoc->user_frag)
         frag = min_t(int, frag, asoc->user_frag);
 
     frag = min_t(int, frag, SCTP_MAX_CHUNK_LEN -
                 sctp_datachk_len(&asoc->stream));
 
     asoc->frag_point = SCTP_TRUNC4(frag);
 }
 
 void sctp_assoc_set_pmtu(struct sctp_association *asoc, __u32 pmtu)
 {
     if (asoc->pathmtu != pmtu) {
         asoc->pathmtu = pmtu;
         sctp_assoc_update_frag_point(asoc);
     }
 
     pr_debug("%s: asoc:%p, pmtu:%d, frag_point:%d\n", __func__, asoc,
          asoc->pathmtu, asoc->frag_point);
 }
 
 /* Update the association's pmtu and frag_point by going through all the
  * transports. This routine is called when a transport's PMTU has changed.
  */
 void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
 {
     struct sctp_transport *t;
     __u32 pmtu = 0;
 
     if (!asoc)
         return;
 
     /* Get the lowest pmtu of all the transports. */
     list_for_each_entry(t, &asoc->peer.transport_addr_list, transports) {
         if (t->pmtu_pending && t->dst) {
             sctp_transport_update_pmtu(t,
                            atomic_read(&t->mtu_info));
             t->pmtu_pending = 0;
         }
         if (!pmtu || (t->pathmtu < pmtu))
             pmtu = t->pathmtu;
     }
 
     sctp_assoc_set_pmtu(asoc, pmtu);
 }
 
 /* Should we send a SACK to update our peer? */
 static inline bool sctp_peer_needs_update(struct sctp_association *asoc)
 {
     struct net *net = asoc->base.net;
 
     switch (asoc->state) {
     case SCTP_STATE_ESTABLISHED:
     case SCTP_STATE_SHUTDOWN_PENDING:
     case SCTP_STATE_SHUTDOWN_RECEIVED:
     case SCTP_STATE_SHUTDOWN_SENT:
         if ((asoc->rwnd > asoc->a_rwnd) &&
             ((asoc->rwnd - asoc->a_rwnd) >= max_t(__u32,
                (asoc->base.sk->sk_rcvbuf >> net->sctp.rwnd_upd_shift),
                asoc->pathmtu)))
             return true;
         break;
     default:
         break;
     }
     return false;
 }
 
 /* Increase asoc's rwnd by len and send any window update SACK if needed. */
 void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned int len)
 {
     struct sctp_chunk *sack;
     struct timer_list *timer;
 
     if (asoc->rwnd_over) {
         if (asoc->rwnd_over >= len) {
             asoc->rwnd_over -= len;
         } else {
             asoc->rwnd += (len - asoc->rwnd_over);
             asoc->rwnd_over = 0;
         }
     } else {
         asoc->rwnd += len;
     }
 
     /* If we had window pressure, start recovering it
      * once our rwnd had reached the accumulated pressure
      * threshold.  The idea is to recover slowly, but up
      * to the initial advertised window.
      */
     if (asoc->rwnd_press) {
         int change = min(asoc->pathmtu, asoc->rwnd_press);
         asoc->rwnd += change;
         asoc->rwnd_press -= change;
     }
 
     pr_debug("%s: asoc:%p rwnd increased by %d to (%u, %u) - %u\n",
          __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
          asoc->a_rwnd);
 
     /* Send a window update SACK if the rwnd has increased by at least the
      * minimum of the association's PMTU and half of the receive buffer.
      * The algorithm used is similar to the one described in
      * Section 4.2.3.3 of RFC 1122.
      */
     if (sctp_peer_needs_update(asoc)) {
         asoc->a_rwnd = asoc->rwnd;
 
         pr_debug("%s: sending window update SACK- asoc:%p rwnd:%u "
              "a_rwnd:%u\n", __func__, asoc, asoc->rwnd,
              asoc->a_rwnd);
 
         sack = sctp_make_sack(asoc);
         if (!sack)
             return;
 
         asoc->peer.sack_needed = 0;
 
         sctp_outq_tail(&asoc->outqueue, sack, GFP_ATOMIC);
 
         /* Stop the SACK timer.  */
         timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
         if (del_timer(timer))
             sctp_association_put(asoc);
     }
 }
 
 /* Decrease asoc's rwnd by len. */
 void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned int len)
 {
     int rx_count;
     int over = 0;
 
     if (unlikely(!asoc->rwnd || asoc->rwnd_over))
         pr_debug("%s: association:%p has asoc->rwnd:%u, "
              "asoc->rwnd_over:%u!\n", __func__, asoc,
              asoc->rwnd, asoc->rwnd_over);
 
     if (asoc->ep->rcvbuf_policy)
         rx_count = atomic_read(&asoc->rmem_alloc);
     else
         rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
 
     /* If we've reached or overflowed our receive buffer, announce
      * a 0 rwnd if rwnd would still be positive.  Store the
      * potential pressure overflow so that the window can be restored
      * back to original value.
      */
     if (rx_count >= asoc->base.sk->sk_rcvbuf)
         over = 1;
 
     if (asoc->rwnd >= len) {
         asoc->rwnd -= len;
         if (over) {
             asoc->rwnd_press += asoc->rwnd;
             asoc->rwnd = 0;
         }
     } else {
         asoc->rwnd_over += len - asoc->rwnd;
         asoc->rwnd = 0;
     }
 
     pr_debug("%s: asoc:%p rwnd decreased by %d to (%u, %u, %u)\n",
          __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
          asoc->rwnd_press);
 }
 
 /* Build the bind address list for the association based on info from the
  * local endpoint and the remote peer.
  */
 int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
                      enum sctp_scope scope, gfp_t gfp)
 {
     struct sock *sk = asoc->base.sk;
     int flags;
 
     /* Use scoping rules to determine the subset of addresses from
      * the endpoint.
      */
     flags = (PF_INET6 == sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
     if (!inet_v6_ipv6only(sk))
         flags |= SCTP_ADDR4_ALLOWED;
     if (asoc->peer.ipv4_address)
         flags |= SCTP_ADDR4_PEERSUPP;
     if (asoc->peer.ipv6_address)
         flags |= SCTP_ADDR6_PEERSUPP;
 
     return sctp_bind_addr_copy(asoc->base.net,
                    &asoc->base.bind_addr,
                    &asoc->ep->base.bind_addr,
                    scope, gfp, flags);
 }
 
 /* Build the association's bind address list from the cookie.  */
 int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
                      struct sctp_cookie *cookie,
                      gfp_t gfp)
 {
     int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
     int var_size3 = cookie->raw_addr_list_len;
     __u8 *raw = (__u8 *)cookie->peer_init + var_size2;
 
     return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
                       asoc->ep->base.bind_addr.port, gfp);
 }
 
 /* Lookup laddr in the bind address list of an association. */
 int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
                 const union sctp_addr *laddr)
 {
     int found = 0;
 
     if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
         sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
                  sctp_sk(asoc->base.sk)))
         found = 1;
 
     return found;
 }
 
 /* Set an association id for a given association */
 int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
 {
     bool preload = gfpflags_allow_blocking(gfp);
     int ret;
 
     /* If the id is already assigned, keep it. */
     if (asoc->assoc_id)
         return 0;
 
     if (preload)
         idr_preload(gfp);
     spin_lock_bh(&sctp_assocs_id_lock);
     /* 0, 1, 2 are used as SCTP_FUTURE_ASSOC, SCTP_CURRENT_ASSOC and
      * SCTP_ALL_ASSOC, so an available id must be > SCTP_ALL_ASSOC.
      */
     ret = idr_alloc_cyclic(&sctp_assocs_id, asoc, SCTP_ALL_ASSOC + 1, 0,
                    GFP_NOWAIT);
     spin_unlock_bh(&sctp_assocs_id_lock);
     if (preload)
         idr_preload_end();
     if (ret < 0)
         return ret;
 
     asoc->assoc_id = (sctp_assoc_t)ret;
     return 0;
 }
 
 /* Free the ASCONF queue */
 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc)
 {
     struct sctp_chunk *asconf;
     struct sctp_chunk *tmp;
 
     list_for_each_entry_safe(asconf, tmp, &asoc->addip_chunk_list, list) {
         list_del_init(&asconf->list);
         sctp_chunk_free(asconf);
     }
 }
 
 /* Free asconf_ack cache */
 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc)
 {
     struct sctp_chunk *ack;
     struct sctp_chunk *tmp;
 
     list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
                 transmitted_list) {
         list_del_init(&ack->transmitted_list);
         sctp_chunk_free(ack);
     }
 }
 
 /* Clean up the ASCONF_ACK queue */
 void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc)
 {
     struct sctp_chunk *ack;
     struct sctp_chunk *tmp;
 
     /* We can remove all the entries from the queue up to
      * the "Peer-Sequence-Number".
      */
     list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
                 transmitted_list) {
         if (ack->subh.addip_hdr->serial ==
                 htonl(asoc->peer.addip_serial))
             break;
 
         list_del_init(&ack->transmitted_list);
         sctp_chunk_free(ack);
     }
 }
 
 /* Find the ASCONF_ACK whose serial number matches ASCONF */
 struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
                     const struct sctp_association *asoc,
                     __be32 serial)
 {
     struct sctp_chunk *ack;
 
     /* Walk through the list of cached ASCONF-ACKs and find the
      * ack chunk whose serial number matches that of the request.
      */
     list_for_each_entry(ack, &asoc->asconf_ack_list, transmitted_list) {
         if (sctp_chunk_pending(ack))
             continue;
         if (ack->subh.addip_hdr->serial == serial) {
             sctp_chunk_hold(ack);
             return ack;
         }
     }
 
     return NULL;
 }
 
 void sctp_asconf_queue_teardown(struct sctp_association *asoc)
 {
     /* Free any cached ASCONF_ACK chunk. */
     sctp_assoc_free_asconf_acks(asoc);
 
     /* Free the ASCONF queue. */
     sctp_assoc_free_asconf_queue(asoc);
 
     /* Free any cached ASCONF chunk. */
     if (asoc->addip_last_asconf)
         sctp_chunk_free(asoc->addip_last_asconf);
 }

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