OSCL-LXR linux-6.0.1/​net/​tipc/​link.c	Source navigation Diff markup Identifier search General search
	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

 /*
  * net/tipc/link.c: TIPC link code
  *
  * Copyright (c) 1996-2007, 2012-2016, Ericsson AB
  * Copyright (c) 2004-2007, 2010-2013, Wind River Systems
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. Neither the names of the copyright holders nor the names of its
  *    contributors may be used to endorse or promote products derived from
  *    this software without specific prior written permission.
  *
  * Alternatively, this software may be distributed under the terms of the
  * GNU General Public License ("GPL") version 2 as published by the Free
  * Software Foundation.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core.h"
 #include "subscr.h"
 #include "link.h"
 #include "bcast.h"
 #include "socket.h"
 #include "name_distr.h"
 #include "discover.h"
 #include "netlink.h"
 #include "monitor.h"
 #include "trace.h"
 #include "crypto.h"
 
 #include <linux/pkt_sched.h>
 
 struct tipc_stats {
     u32 sent_pkts;
     u32 recv_pkts;
     u32 sent_states;
     u32 recv_states;
     u32 sent_probes;
     u32 recv_probes;
     u32 sent_nacks;
     u32 recv_nacks;
     u32 sent_acks;
     u32 sent_bundled;
     u32 sent_bundles;
     u32 recv_bundled;
     u32 recv_bundles;
     u32 retransmitted;
     u32 sent_fragmented;
     u32 sent_fragments;
     u32 recv_fragmented;
     u32 recv_fragments;
     u32 link_congs;     /* # port sends blocked by congestion */
     u32 deferred_recv;
     u32 duplicates;
     u32 max_queue_sz;   /* send queue size high water mark */
     u32 accu_queue_sz;  /* used for send queue size profiling */
     u32 queue_sz_counts;    /* used for send queue size profiling */
     u32 msg_length_counts;  /* used for message length profiling */
     u32 msg_lengths_total;  /* used for message length profiling */
     u32 msg_length_profile[7]; /* used for msg. length profiling */
 };
 
 /**
  * struct tipc_link - TIPC link data structure
  * @addr: network address of link's peer node
  * @name: link name character string
  * @media_addr: media address to use when sending messages over link
  * @timer: link timer
  * @net: pointer to namespace struct
  * @refcnt: reference counter for permanent references (owner node & timer)
  * @peer_session: link session # being used by peer end of link
  * @peer_bearer_id: bearer id used by link's peer endpoint
  * @bearer_id: local bearer id used by link
  * @tolerance: minimum link continuity loss needed to reset link [in ms]
  * @abort_limit: # of unacknowledged continuity probes needed to reset link
  * @state: current state of link FSM
  * @peer_caps: bitmap describing capabilities of peer node
  * @silent_intv_cnt: # of timer intervals without any reception from peer
  * @proto_msg: template for control messages generated by link
  * @pmsg: convenience pointer to "proto_msg" field
  * @priority: current link priority
  * @net_plane: current link network plane ('A' through 'H')
  * @mon_state: cookie with information needed by link monitor
  * @backlog_limit: backlog queue congestion thresholds (indexed by importance)
  * @exp_msg_count: # of tunnelled messages expected during link changeover
  * @reset_rcv_checkpt: seq # of last acknowledged message at time of link reset
  * @mtu: current maximum packet size for this link
  * @advertised_mtu: advertised own mtu when link is being established
  * @transmitq: queue for sent, non-acked messages
  * @backlogq: queue for messages waiting to be sent
  * @snt_nxt: next sequence number to use for outbound messages
  * @ackers: # of peers that needs to ack each packet before it can be released
  * @acked: # last packet acked by a certain peer. Used for broadcast.
  * @rcv_nxt: next sequence number to expect for inbound messages
  * @deferred_queue: deferred queue saved OOS b'cast message received from node
  * @unacked_window: # of inbound messages rx'd without ack'ing back to peer
  * @inputq: buffer queue for messages to be delivered upwards
  * @namedq: buffer queue for name table messages to be delivered upwards
  * @next_out: ptr to first unsent outbound message in queue
  * @wakeupq: linked list of wakeup msgs waiting for link congestion to abate
  * @long_msg_seq_no: next identifier to use for outbound fragmented messages
  * @reasm_buf: head of partially reassembled inbound message fragments
  * @bc_rcvr: marks that this is a broadcast receiver link
  * @stats: collects statistics regarding link activity
  * @session: session to be used by link
  * @snd_nxt_state: next send seq number
  * @rcv_nxt_state: next rcv seq number
  * @in_session: have received ACTIVATE_MSG from peer
  * @active: link is active
  * @if_name: associated interface name
  * @rst_cnt: link reset counter
  * @drop_point: seq number for failover handling (FIXME)
  * @failover_reasm_skb: saved failover msg ptr (FIXME)
  * @failover_deferdq: deferred message queue for failover processing (FIXME)
  * @transmq: the link's transmit queue
  * @backlog: link's backlog by priority (importance)
  * @snd_nxt: next sequence number to be used
  * @rcv_unacked: # messages read by user, but not yet acked back to peer
  * @deferdq: deferred receive queue
  * @window: sliding window size for congestion handling
  * @min_win: minimal send window to be used by link
  * @ssthresh: slow start threshold for congestion handling
  * @max_win: maximal send window to be used by link
  * @cong_acks: congestion acks for congestion avoidance (FIXME)
  * @checkpoint: seq number for congestion window size handling
  * @reasm_tnlmsg: fragmentation/reassembly area for tunnel protocol message
  * @last_gap: last gap ack blocks for bcast (FIXME)
  * @last_ga: ptr to gap ack blocks
  * @bc_rcvlink: the peer specific link used for broadcast reception
  * @bc_sndlink: the namespace global link used for broadcast sending
  * @nack_state: bcast nack state
  * @bc_peer_is_up: peer has acked the bcast init msg
  */
 struct tipc_link {
     u32 addr;
     char name[TIPC_MAX_LINK_NAME];
     struct net *net;
 
     /* Management and link supervision data */
     u16 peer_session;
     u16 session;
     u16 snd_nxt_state;
     u16 rcv_nxt_state;
     u32 peer_bearer_id;
     u32 bearer_id;
     u32 tolerance;
     u32 abort_limit;
     u32 state;
     u16 peer_caps;
     bool in_session;
     bool active;
     u32 silent_intv_cnt;
     char if_name[TIPC_MAX_IF_NAME];
     u32 priority;
     char net_plane;
     struct tipc_mon_state mon_state;
     u16 rst_cnt;
 
     /* Failover/synch */
     u16 drop_point;
     struct sk_buff *failover_reasm_skb;
     struct sk_buff_head failover_deferdq;
 
     /* Max packet negotiation */
     u16 mtu;
     u16 advertised_mtu;
 
     /* Sending */
     struct sk_buff_head transmq;
     struct sk_buff_head backlogq;
     struct {
         u16 len;
         u16 limit;
         struct sk_buff *target_bskb;
     } backlog[5];
     u16 snd_nxt;
 
     /* Reception */
     u16 rcv_nxt;
     u32 rcv_unacked;
     struct sk_buff_head deferdq;
     struct sk_buff_head *inputq;
     struct sk_buff_head *namedq;
 
     /* Congestion handling */
     struct sk_buff_head wakeupq;
     u16 window;
     u16 min_win;
     u16 ssthresh;
     u16 max_win;
     u16 cong_acks;
     u16 checkpoint;
 
     /* Fragmentation/reassembly */
     struct sk_buff *reasm_buf;
     struct sk_buff *reasm_tnlmsg;
 
     /* Broadcast */
     u16 ackers;
     u16 acked;
     u16 last_gap;
     struct tipc_gap_ack_blks *last_ga;
     struct tipc_link *bc_rcvlink;
     struct tipc_link *bc_sndlink;
     u8 nack_state;
     bool bc_peer_is_up;
 
     /* Statistics */
     struct tipc_stats stats;
 };
 
 /*
  * Error message prefixes
  */
 static const char *link_co_err = "Link tunneling error, ";
 static const char *link_rst_msg = "Resetting link ";
 
 /* Send states for broadcast NACKs
  */
 enum {
     BC_NACK_SND_CONDITIONAL,
     BC_NACK_SND_UNCONDITIONAL,
     BC_NACK_SND_SUPPRESS,
 };
 
 #define TIPC_BC_RETR_LIM  (jiffies + msecs_to_jiffies(10))
 #define TIPC_UC_RETR_TIME (jiffies + msecs_to_jiffies(1))
 
 /* Link FSM states:
  */
 enum {
     LINK_ESTABLISHED     = 0xe,
     LINK_ESTABLISHING    = 0xe  << 4,
     LINK_RESET           = 0x1  << 8,
     LINK_RESETTING       = 0x2  << 12,
     LINK_PEER_RESET      = 0xd  << 16,
     LINK_FAILINGOVER     = 0xf  << 20,
     LINK_SYNCHING        = 0xc  << 24
 };
 
 /* Link FSM state checking routines
  */
 static int link_is_up(struct tipc_link *l)
 {
     return l->state & (LINK_ESTABLISHED | LINK_SYNCHING);
 }
 
 static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
                    struct sk_buff_head *xmitq);
 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
                       bool probe_reply, u16 rcvgap,
                       int tolerance, int priority,
                       struct sk_buff_head *xmitq);
 static void link_print(struct tipc_link *l, const char *str);
 static int tipc_link_build_nack_msg(struct tipc_link *l,
                     struct sk_buff_head *xmitq);
 static void tipc_link_build_bc_init_msg(struct tipc_link *l,
                     struct sk_buff_head *xmitq);
 static u8 __tipc_build_gap_ack_blks(struct tipc_gap_ack_blks *ga,
                     struct tipc_link *l, u8 start_index);
 static u16 tipc_build_gap_ack_blks(struct tipc_link *l, struct tipc_msg *hdr);
 static int tipc_link_advance_transmq(struct tipc_link *l, struct tipc_link *r,
                      u16 acked, u16 gap,
                      struct tipc_gap_ack_blks *ga,
                      struct sk_buff_head *xmitq,
                      bool *retransmitted, int *rc);
 static void tipc_link_update_cwin(struct tipc_link *l, int released,
                   bool retransmitted);
 /*
  *  Simple non-static link routines (i.e. referenced outside this file)
  */
 bool tipc_link_is_up(struct tipc_link *l)
 {
     return link_is_up(l);
 }
 
 bool tipc_link_peer_is_down(struct tipc_link *l)
 {
     return l->state == LINK_PEER_RESET;
 }
 
 bool tipc_link_is_reset(struct tipc_link *l)
 {
     return l->state & (LINK_RESET | LINK_FAILINGOVER | LINK_ESTABLISHING);
 }
 
 bool tipc_link_is_establishing(struct tipc_link *l)
 {
     return l->state == LINK_ESTABLISHING;
 }
 
 bool tipc_link_is_synching(struct tipc_link *l)
 {
     return l->state == LINK_SYNCHING;
 }
 
 bool tipc_link_is_failingover(struct tipc_link *l)
 {
     return l->state == LINK_FAILINGOVER;
 }
 
 bool tipc_link_is_blocked(struct tipc_link *l)
 {
     return l->state & (LINK_RESETTING | LINK_PEER_RESET | LINK_FAILINGOVER);
 }
 
 static bool link_is_bc_sndlink(struct tipc_link *l)
 {
     return !l->bc_sndlink;
 }
 
 static bool link_is_bc_rcvlink(struct tipc_link *l)
 {
     return ((l->bc_rcvlink == l) && !link_is_bc_sndlink(l));
 }
 
 void tipc_link_set_active(struct tipc_link *l, bool active)
 {
     l->active = active;
 }
 
 u32 tipc_link_id(struct tipc_link *l)
 {
     return l->peer_bearer_id << 16 | l->bearer_id;
 }
 
 int tipc_link_min_win(struct tipc_link *l)
 {
     return l->min_win;
 }
 
 int tipc_link_max_win(struct tipc_link *l)
 {
     return l->max_win;
 }
 
 int tipc_link_prio(struct tipc_link *l)
 {
     return l->priority;
 }
 
 unsigned long tipc_link_tolerance(struct tipc_link *l)
 {
     return l->tolerance;
 }
 
 struct sk_buff_head *tipc_link_inputq(struct tipc_link *l)
 {
     return l->inputq;
 }
 
 char tipc_link_plane(struct tipc_link *l)
 {
     return l->net_plane;
 }
 
 struct net *tipc_link_net(struct tipc_link *l)
 {
     return l->net;
 }
 
 void tipc_link_update_caps(struct tipc_link *l, u16 capabilities)
 {
     l->peer_caps = capabilities;
 }
 
 void tipc_link_add_bc_peer(struct tipc_link *snd_l,
                struct tipc_link *uc_l,
                struct sk_buff_head *xmitq)
 {
     struct tipc_link *rcv_l = uc_l->bc_rcvlink;
 
     snd_l->ackers++;
     rcv_l->acked = snd_l->snd_nxt - 1;
     snd_l->state = LINK_ESTABLISHED;
     tipc_link_build_bc_init_msg(uc_l, xmitq);
 }
 
 void tipc_link_remove_bc_peer(struct tipc_link *snd_l,
                   struct tipc_link *rcv_l,
                   struct sk_buff_head *xmitq)
 {
     u16 ack = snd_l->snd_nxt - 1;
 
     snd_l->ackers--;
     rcv_l->bc_peer_is_up = true;
     rcv_l->state = LINK_ESTABLISHED;
     tipc_link_bc_ack_rcv(rcv_l, ack, 0, NULL, xmitq, NULL);
     trace_tipc_link_reset(rcv_l, TIPC_DUMP_ALL, "bclink removed!");
     tipc_link_reset(rcv_l);
     rcv_l->state = LINK_RESET;
     if (!snd_l->ackers) {
         trace_tipc_link_reset(snd_l, TIPC_DUMP_ALL, "zero ackers!");
         tipc_link_reset(snd_l);
         snd_l->state = LINK_RESET;
         __skb_queue_purge(xmitq);
     }
 }
 
 int tipc_link_bc_peers(struct tipc_link *l)
 {
     return l->ackers;
 }
 
 static u16 link_bc_rcv_gap(struct tipc_link *l)
 {
     struct sk_buff *skb = skb_peek(&l->deferdq);
     u16 gap = 0;
 
     if (more(l->snd_nxt, l->rcv_nxt))
         gap = l->snd_nxt - l->rcv_nxt;
     if (skb)
         gap = buf_seqno(skb) - l->rcv_nxt;
     return gap;
 }
 
 void tipc_link_set_mtu(struct tipc_link *l, int mtu)
 {
     l->mtu = mtu;
 }
 
 int tipc_link_mtu(struct tipc_link *l)
 {
     return l->mtu;
 }
 
 int tipc_link_mss(struct tipc_link *l)
 {
 #ifdef CONFIG_TIPC_CRYPTO
     return l->mtu - INT_H_SIZE - EMSG_OVERHEAD;
 #else
     return l->mtu - INT_H_SIZE;
 #endif
 }
 
 u16 tipc_link_rcv_nxt(struct tipc_link *l)
 {
     return l->rcv_nxt;
 }
 
 u16 tipc_link_acked(struct tipc_link *l)
 {
     return l->acked;
 }
 
 char *tipc_link_name(struct tipc_link *l)
 {
     return l->name;
 }
 
 u32 tipc_link_state(struct tipc_link *l)
 {
     return l->state;
 }
 
 /**
  * tipc_link_create - create a new link
  * @net: pointer to associated network namespace
  * @if_name: associated interface name
  * @bearer_id: id (index) of associated bearer
  * @tolerance: link tolerance to be used by link
  * @net_plane: network plane (A,B,c..) this link belongs to
  * @mtu: mtu to be advertised by link
  * @priority: priority to be used by link
  * @min_win: minimal send window to be used by link
  * @max_win: maximal send window to be used by link
  * @session: session to be used by link
  * @peer: node id of peer node
  * @peer_caps: bitmap describing peer node capabilities
  * @bc_sndlink: the namespace global link used for broadcast sending
  * @bc_rcvlink: the peer specific link used for broadcast reception
  * @inputq: queue to put messages ready for delivery
  * @namedq: queue to put binding table update messages ready for delivery
  * @link: return value, pointer to put the created link
  * @self: local unicast link id
  * @peer_id: 128-bit ID of peer
  *
  * Return: true if link was created, otherwise false
  */
 bool tipc_link_create(struct net *net, char *if_name, int bearer_id,
               int tolerance, char net_plane, u32 mtu, int priority,
               u32 min_win, u32 max_win, u32 session, u32 self,
               u32 peer, u8 *peer_id, u16 peer_caps,
               struct tipc_link *bc_sndlink,
               struct tipc_link *bc_rcvlink,
               struct sk_buff_head *inputq,
               struct sk_buff_head *namedq,
               struct tipc_link **link)
 {
     char peer_str[NODE_ID_STR_LEN] = {0,};
     char self_str[NODE_ID_STR_LEN] = {0,};
     struct tipc_link *l;
 
     l = kzalloc(sizeof(*l), GFP_ATOMIC);
     if (!l)
         return false;
     *link = l;
     l->session = session;
 
     /* Set link name for unicast links only */
     if (peer_id) {
         tipc_nodeid2string(self_str, tipc_own_id(net));
         if (strlen(self_str) > 16)
             sprintf(self_str, "%x", self);
         tipc_nodeid2string(peer_str, peer_id);
         if (strlen(peer_str) > 16)
             sprintf(peer_str, "%x", peer);
     }
     /* Peer i/f name will be completed by reset/activate message */
     snprintf(l->name, sizeof(l->name), "%s:%s-%s:unknown",
          self_str, if_name, peer_str);
 
     strcpy(l->if_name, if_name);
     l->addr = peer;
     l->peer_caps = peer_caps;
     l->net = net;
     l->in_session = false;
     l->bearer_id = bearer_id;
     l->tolerance = tolerance;
     if (bc_rcvlink)
         bc_rcvlink->tolerance = tolerance;
     l->net_plane = net_plane;
     l->advertised_mtu = mtu;
     l->mtu = mtu;
     l->priority = priority;
     tipc_link_set_queue_limits(l, min_win, max_win);
     l->ackers = 1;
     l->bc_sndlink = bc_sndlink;
     l->bc_rcvlink = bc_rcvlink;
     l->inputq = inputq;
     l->namedq = namedq;
     l->state = LINK_RESETTING;
     __skb_queue_head_init(&l->transmq);
     __skb_queue_head_init(&l->backlogq);
     __skb_queue_head_init(&l->deferdq);
     __skb_queue_head_init(&l->failover_deferdq);
     skb_queue_head_init(&l->wakeupq);
     skb_queue_head_init(l->inputq);
     return true;
 }
 
 /**
  * tipc_link_bc_create - create new link to be used for broadcast
  * @net: pointer to associated network namespace
  * @mtu: mtu to be used initially if no peers
  * @min_win: minimal send window to be used by link
  * @max_win: maximal send window to be used by link
  * @inputq: queue to put messages ready for delivery
  * @namedq: queue to put binding table update messages ready for delivery
  * @link: return value, pointer to put the created link
  * @ownnode: identity of own node
  * @peer: node id of peer node
  * @peer_id: 128-bit ID of peer
  * @peer_caps: bitmap describing peer node capabilities
  * @bc_sndlink: the namespace global link used for broadcast sending
  *
  * Return: true if link was created, otherwise false
  */
 bool tipc_link_bc_create(struct net *net, u32 ownnode, u32 peer, u8 *peer_id,
              int mtu, u32 min_win, u32 max_win, u16 peer_caps,
              struct sk_buff_head *inputq,
              struct sk_buff_head *namedq,
              struct tipc_link *bc_sndlink,
              struct tipc_link **link)
 {
     struct tipc_link *l;
 
     if (!tipc_link_create(net, "", MAX_BEARERS, 0, 'Z', mtu, 0, min_win,
                   max_win, 0, ownnode, peer, NULL, peer_caps,
                   bc_sndlink, NULL, inputq, namedq, link))
         return false;
 
     l = *link;
     if (peer_id) {
         char peer_str[NODE_ID_STR_LEN] = {0,};
 
         tipc_nodeid2string(peer_str, peer_id);
         if (strlen(peer_str) > 16)
             sprintf(peer_str, "%x", peer);
         /* Broadcast receiver link name: "broadcast-link:<peer>" */
         snprintf(l->name, sizeof(l->name), "%s:%s", tipc_bclink_name,
              peer_str);
     } else {
         strcpy(l->name, tipc_bclink_name);
     }
     trace_tipc_link_reset(l, TIPC_DUMP_ALL, "bclink created!");
     tipc_link_reset(l);
     l->state = LINK_RESET;
     l->ackers = 0;
     l->bc_rcvlink = l;
 
     /* Broadcast send link is always up */
     if (link_is_bc_sndlink(l))
         l->state = LINK_ESTABLISHED;
 
     /* Disable replicast if even a single peer doesn't support it */
     if (link_is_bc_rcvlink(l) && !(peer_caps & TIPC_BCAST_RCAST))
         tipc_bcast_toggle_rcast(net, false);
 
     return true;
 }
 
 /**
  * tipc_link_fsm_evt - link finite state machine
  * @l: pointer to link
  * @evt: state machine event to be processed
  */
 int tipc_link_fsm_evt(struct tipc_link *l, int evt)
 {
     int rc = 0;
     int old_state = l->state;
 
     switch (l->state) {
     case LINK_RESETTING:
         switch (evt) {
         case LINK_PEER_RESET_EVT:
             l->state = LINK_PEER_RESET;
             break;
         case LINK_RESET_EVT:
             l->state = LINK_RESET;
             break;
         case LINK_FAILURE_EVT:
         case LINK_FAILOVER_BEGIN_EVT:
         case LINK_ESTABLISH_EVT:
         case LINK_FAILOVER_END_EVT:
         case LINK_SYNCH_BEGIN_EVT:
         case LINK_SYNCH_END_EVT:
         default:
             goto illegal_evt;
         }
         break;
     case LINK_RESET:
         switch (evt) {
         case LINK_PEER_RESET_EVT:
             l->state = LINK_ESTABLISHING;
             break;
         case LINK_FAILOVER_BEGIN_EVT:
             l->state = LINK_FAILINGOVER;
             break;
         case LINK_FAILURE_EVT:
         case LINK_RESET_EVT:
         case LINK_ESTABLISH_EVT:
         case LINK_FAILOVER_END_EVT:
             break;
         case LINK_SYNCH_BEGIN_EVT:
         case LINK_SYNCH_END_EVT:
         default:
             goto illegal_evt;
         }
         break;
     case LINK_PEER_RESET:
         switch (evt) {
         case LINK_RESET_EVT:
             l->state = LINK_ESTABLISHING;
             break;
         case LINK_PEER_RESET_EVT:
         case LINK_ESTABLISH_EVT:
         case LINK_FAILURE_EVT:
             break;
         case LINK_SYNCH_BEGIN_EVT:
         case LINK_SYNCH_END_EVT:
         case LINK_FAILOVER_BEGIN_EVT:
         case LINK_FAILOVER_END_EVT:
         default:
             goto illegal_evt;
         }
         break;
     case LINK_FAILINGOVER:
         switch (evt) {
         case LINK_FAILOVER_END_EVT:
             l->state = LINK_RESET;
             break;
         case LINK_PEER_RESET_EVT:
         case LINK_RESET_EVT:
         case LINK_ESTABLISH_EVT:
         case LINK_FAILURE_EVT:
             break;
         case LINK_FAILOVER_BEGIN_EVT:
         case LINK_SYNCH_BEGIN_EVT:
         case LINK_SYNCH_END_EVT:
         default:
             goto illegal_evt;
         }
         break;
     case LINK_ESTABLISHING:
         switch (evt) {
         case LINK_ESTABLISH_EVT:
             l->state = LINK_ESTABLISHED;
             break;
         case LINK_FAILOVER_BEGIN_EVT:
             l->state = LINK_FAILINGOVER;
             break;
         case LINK_RESET_EVT:
             l->state = LINK_RESET;
             break;
         case LINK_FAILURE_EVT:
         case LINK_PEER_RESET_EVT:
         case LINK_SYNCH_BEGIN_EVT:
         case LINK_FAILOVER_END_EVT:
             break;
         case LINK_SYNCH_END_EVT:
         default:
             goto illegal_evt;
         }
         break;
     case LINK_ESTABLISHED:
         switch (evt) {
         case LINK_PEER_RESET_EVT:
             l->state = LINK_PEER_RESET;
             rc |= TIPC_LINK_DOWN_EVT;
             break;
         case LINK_FAILURE_EVT:
             l->state = LINK_RESETTING;
             rc |= TIPC_LINK_DOWN_EVT;
             break;
         case LINK_RESET_EVT:
             l->state = LINK_RESET;
             break;
         case LINK_ESTABLISH_EVT:
         case LINK_SYNCH_END_EVT:
             break;
         case LINK_SYNCH_BEGIN_EVT:
             l->state = LINK_SYNCHING;
             break;
         case LINK_FAILOVER_BEGIN_EVT:
         case LINK_FAILOVER_END_EVT:
         default:
             goto illegal_evt;
         }
         break;
     case LINK_SYNCHING:
         switch (evt) {
         case LINK_PEER_RESET_EVT:
             l->state = LINK_PEER_RESET;
             rc |= TIPC_LINK_DOWN_EVT;
             break;
         case LINK_FAILURE_EVT:
             l->state = LINK_RESETTING;
             rc |= TIPC_LINK_DOWN_EVT;
             break;
         case LINK_RESET_EVT:
             l->state = LINK_RESET;
             break;
         case LINK_ESTABLISH_EVT:
         case LINK_SYNCH_BEGIN_EVT:
             break;
         case LINK_SYNCH_END_EVT:
             l->state = LINK_ESTABLISHED;
             break;
         case LINK_FAILOVER_BEGIN_EVT:
         case LINK_FAILOVER_END_EVT:
         default:
             goto illegal_evt;
         }
         break;
     default:
         pr_err("Unknown FSM state %x in %s\n", l->state, l->name);
     }
     trace_tipc_link_fsm(l->name, old_state, l->state, evt);
     return rc;
 illegal_evt:
     pr_err("Illegal FSM event %x in state %x on link %s\n",
            evt, l->state, l->name);
     trace_tipc_link_fsm(l->name, old_state, l->state, evt);
     return rc;
 }
 
 /* link_profile_stats - update statistical profiling of traffic
  */
 static void link_profile_stats(struct tipc_link *l)
 {
     struct sk_buff *skb;
     struct tipc_msg *msg;
     int length;
 
     /* Update counters used in statistical profiling of send traffic */
     l->stats.accu_queue_sz += skb_queue_len(&l->transmq);
     l->stats.queue_sz_counts++;
 
     skb = skb_peek(&l->transmq);
     if (!skb)
         return;
     msg = buf_msg(skb);
     length = msg_size(msg);
 
     if (msg_user(msg) == MSG_FRAGMENTER) {
         if (msg_type(msg) != FIRST_FRAGMENT)
             return;
         length = msg_size(msg_inner_hdr(msg));
     }
     l->stats.msg_lengths_total += length;
     l->stats.msg_length_counts++;
     if (length <= 64)
         l->stats.msg_length_profile[0]++;
     else if (length <= 256)
         l->stats.msg_length_profile[1]++;
     else if (length <= 1024)
         l->stats.msg_length_profile[2]++;
     else if (length <= 4096)
         l->stats.msg_length_profile[3]++;
     else if (length <= 16384)
         l->stats.msg_length_profile[4]++;
     else if (length <= 32768)
         l->stats.msg_length_profile[5]++;
     else
         l->stats.msg_length_profile[6]++;
 }
 
 /**
  * tipc_link_too_silent - check if link is "too silent"
  * @l: tipc link to be checked
  *
  * Return: true if the link 'silent_intv_cnt' is about to reach the
  * 'abort_limit' value, otherwise false
  */
 bool tipc_link_too_silent(struct tipc_link *l)
 {
     return (l->silent_intv_cnt + 2 > l->abort_limit);
 }
 
 /* tipc_link_timeout - perform periodic task as instructed from node timeout
  */
 int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
 {
     int mtyp = 0;
     int rc = 0;
     bool state = false;
     bool probe = false;
     bool setup = false;
     u16 bc_snt = l->bc_sndlink->snd_nxt - 1;
     u16 bc_acked = l->bc_rcvlink->acked;
     struct tipc_mon_state *mstate = &l->mon_state;
 
     trace_tipc_link_timeout(l, TIPC_DUMP_NONE, " ");
     trace_tipc_link_too_silent(l, TIPC_DUMP_ALL, " ");
     switch (l->state) {
     case LINK_ESTABLISHED:
     case LINK_SYNCHING:
         mtyp = STATE_MSG;
         link_profile_stats(l);
         tipc_mon_get_state(l->net, l->addr, mstate, l->bearer_id);
         if (mstate->reset || (l->silent_intv_cnt > l->abort_limit))
             return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
         state = bc_acked != bc_snt;
         state |= l->bc_rcvlink->rcv_unacked;
         state |= l->rcv_unacked;
         state |= !skb_queue_empty(&l->transmq);
         probe = mstate->probing;
         probe |= l->silent_intv_cnt;
         if (probe || mstate->monitoring)
             l->silent_intv_cnt++;
         probe |= !skb_queue_empty(&l->deferdq);
         if (l->snd_nxt == l->checkpoint) {
             tipc_link_update_cwin(l, 0, 0);
             probe = true;
         }
         l->checkpoint = l->snd_nxt;
         break;
     case LINK_RESET:
         setup = l->rst_cnt++ <= 4;
         setup |= !(l->rst_cnt % 16);
         mtyp = RESET_MSG;
         break;
     case LINK_ESTABLISHING:
         setup = true;
         mtyp = ACTIVATE_MSG;
         break;
     case LINK_PEER_RESET:
     case LINK_RESETTING:
     case LINK_FAILINGOVER:
         break;
     default:
         break;
     }
 
     if (state || probe || setup)
         tipc_link_build_proto_msg(l, mtyp, probe, 0, 0, 0, 0, xmitq);
 
     return rc;
 }
 
 /**
  * link_schedule_user - schedule a message sender for wakeup after congestion
  * @l: congested link
  * @hdr: header of message that is being sent
  * Create pseudo msg to send back to user when congestion abates
  */
 static int link_schedule_user(struct tipc_link *l, struct tipc_msg *hdr)
 {
     u32 dnode = tipc_own_addr(l->net);
     u32 dport = msg_origport(hdr);
     struct sk_buff *skb;
 
     /* Create and schedule wakeup pseudo message */
     skb = tipc_msg_create(SOCK_WAKEUP, 0, INT_H_SIZE, 0,
                   dnode, l->addr, dport, 0, 0);
     if (!skb)
         return -ENOBUFS;
     msg_set_dest_droppable(buf_msg(skb), true);
     TIPC_SKB_CB(skb)->chain_imp = msg_importance(hdr);
     skb_queue_tail(&l->wakeupq, skb);
     l->stats.link_congs++;
     trace_tipc_link_conges(l, TIPC_DUMP_ALL, "wakeup scheduled!");
     return -ELINKCONG;
 }
 
 /**
  * link_prepare_wakeup - prepare users for wakeup after congestion
  * @l: congested link
  * Wake up a number of waiting users, as permitted by available space
  * in the send queue
  */
 static void link_prepare_wakeup(struct tipc_link *l)
 {
     struct sk_buff_head *wakeupq = &l->wakeupq;
     struct sk_buff_head *inputq = l->inputq;
     struct sk_buff *skb, *tmp;
     struct sk_buff_head tmpq;
     int avail[5] = {0,};
     int imp = 0;
 
     __skb_queue_head_init(&tmpq);
 
     for (; imp <= TIPC_SYSTEM_IMPORTANCE; imp++)
         avail[imp] = l->backlog[imp].limit - l->backlog[imp].len;
 
     skb_queue_walk_safe(wakeupq, skb, tmp) {
         imp = TIPC_SKB_CB(skb)->chain_imp;
         if (avail[imp] <= 0)
             continue;
         avail[imp]--;
         __skb_unlink(skb, wakeupq);
         __skb_queue_tail(&tmpq, skb);
     }
 
     spin_lock_bh(&inputq->lock);
     skb_queue_splice_tail(&tmpq, inputq);
     spin_unlock_bh(&inputq->lock);
 
 }
 
 /**
  * tipc_link_set_skb_retransmit_time - set the time at which retransmission of
  *                                     the given skb should be next attempted
  * @skb: skb to set a future retransmission time for
  * @l: link the skb will be transmitted on
  */
 static void tipc_link_set_skb_retransmit_time(struct sk_buff *skb,
                           struct tipc_link *l)
 {
     if (link_is_bc_sndlink(l))
         TIPC_SKB_CB(skb)->nxt_retr = TIPC_BC_RETR_LIM;
     else
         TIPC_SKB_CB(skb)->nxt_retr = TIPC_UC_RETR_TIME;
 }
 
 void tipc_link_reset(struct tipc_link *l)
 {
     struct sk_buff_head list;
     u32 imp;
 
     __skb_queue_head_init(&list);
 
     l->in_session = false;
     /* Force re-synch of peer session number before establishing */
     l->peer_session--;
     l->session++;
     l->mtu = l->advertised_mtu;
 
     spin_lock_bh(&l->wakeupq.lock);
     skb_queue_splice_init(&l->wakeupq, &list);
     spin_unlock_bh(&l->wakeupq.lock);
 
     spin_lock_bh(&l->inputq->lock);
     skb_queue_splice_init(&list, l->inputq);
     spin_unlock_bh(&l->inputq->lock);
 
     __skb_queue_purge(&l->transmq);
     __skb_queue_purge(&l->deferdq);
     __skb_queue_purge(&l->backlogq);
     __skb_queue_purge(&l->failover_deferdq);
     for (imp = 0; imp <= TIPC_SYSTEM_IMPORTANCE; imp++) {
         l->backlog[imp].len = 0;
         l->backlog[imp].target_bskb = NULL;
     }
     kfree_skb(l->reasm_buf);
     kfree_skb(l->reasm_tnlmsg);
     kfree_skb(l->failover_reasm_skb);
     l->reasm_buf = NULL;
     l->reasm_tnlmsg = NULL;
     l->failover_reasm_skb = NULL;
     l->rcv_unacked = 0;
     l->snd_nxt = 1;
     l->rcv_nxt = 1;
     l->snd_nxt_state = 1;
     l->rcv_nxt_state = 1;
     l->acked = 0;
     l->last_gap = 0;
     kfree(l->last_ga);
     l->last_ga = NULL;
     l->silent_intv_cnt = 0;
     l->rst_cnt = 0;
     l->bc_peer_is_up = false;
     memset(&l->mon_state, 0, sizeof(l->mon_state));
     tipc_link_reset_stats(l);
 }
 
 /**
  * tipc_link_xmit(): enqueue buffer list according to queue situation
  * @l: link to use
  * @list: chain of buffers containing message
  * @xmitq: returned list of packets to be sent by caller
  *
  * Consumes the buffer chain.
  * Messages at TIPC_SYSTEM_IMPORTANCE are always accepted
  * Return: 0 if success, or errno: -ELINKCONG, -EMSGSIZE or -ENOBUFS
  */
 int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
            struct sk_buff_head *xmitq)
 {
     struct sk_buff_head *backlogq = &l->backlogq;
     struct sk_buff_head *transmq = &l->transmq;
     struct sk_buff *skb, *_skb;
     u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
     u16 ack = l->rcv_nxt - 1;
     u16 seqno = l->snd_nxt;
     int pkt_cnt = skb_queue_len(list);
     unsigned int mss = tipc_link_mss(l);
     unsigned int cwin = l->window;
     unsigned int mtu = l->mtu;
     struct tipc_msg *hdr;
     bool new_bundle;
     int rc = 0;
     int imp;
 
     if (pkt_cnt <= 0)
         return 0;
 
     hdr = buf_msg(skb_peek(list));
     if (unlikely(msg_size(hdr) > mtu)) {
         pr_warn("Too large msg, purging xmit list %d %d %d %d %d!\n",
             skb_queue_len(list), msg_user(hdr),
             msg_type(hdr), msg_size(hdr), mtu);
         __skb_queue_purge(list);
         return -EMSGSIZE;
     }
 
     imp = msg_importance(hdr);
     /* Allow oversubscription of one data msg per source at congestion */
     if (unlikely(l->backlog[imp].len >= l->backlog[imp].limit)) {
         if (imp == TIPC_SYSTEM_IMPORTANCE) {
             pr_warn("%s<%s>, link overflow", link_rst_msg, l->name);
             return -ENOBUFS;
         }
         rc = link_schedule_user(l, hdr);
     }
 
     if (pkt_cnt > 1) {
         l->stats.sent_fragmented++;
         l->stats.sent_fragments += pkt_cnt;
     }
 
     /* Prepare each packet for sending, and add to relevant queue: */
     while ((skb = __skb_dequeue(list))) {
         if (likely(skb_queue_len(transmq) < cwin)) {
             hdr = buf_msg(skb);
             msg_set_seqno(hdr, seqno);
             msg_set_ack(hdr, ack);
             msg_set_bcast_ack(hdr, bc_ack);
             _skb = skb_clone(skb, GFP_ATOMIC);
             if (!_skb) {
                 kfree_skb(skb);
                 __skb_queue_purge(list);
                 return -ENOBUFS;
             }
             __skb_queue_tail(transmq, skb);
             tipc_link_set_skb_retransmit_time(skb, l);
             __skb_queue_tail(xmitq, _skb);
             TIPC_SKB_CB(skb)->ackers = l->ackers;
             l->rcv_unacked = 0;
             l->stats.sent_pkts++;
             seqno++;
             continue;
         }
         if (tipc_msg_try_bundle(l->backlog[imp].target_bskb, &skb,
                     mss, l->addr, &new_bundle)) {
             if (skb) {
                 /* Keep a ref. to the skb for next try */
                 l->backlog[imp].target_bskb = skb;
                 l->backlog[imp].len++;
                 __skb_queue_tail(backlogq, skb);
             } else {
                 if (new_bundle) {
                     l->stats.sent_bundles++;
                     l->stats.sent_bundled++;
                 }
                 l->stats.sent_bundled++;
             }
             continue;
         }
         l->backlog[imp].target_bskb = NULL;
         l->backlog[imp].len += (1 + skb_queue_len(list));
         __skb_queue_tail(backlogq, skb);
         skb_queue_splice_tail_init(list, backlogq);
     }
     l->snd_nxt = seqno;
     return rc;
 }
 
 static void tipc_link_update_cwin(struct tipc_link *l, int released,
                   bool retransmitted)
 {
     int bklog_len = skb_queue_len(&l->backlogq);
     struct sk_buff_head *txq = &l->transmq;
     int txq_len = skb_queue_len(txq);
     u16 cwin = l->window;
 
     /* Enter fast recovery */
     if (unlikely(retransmitted)) {
         l->ssthresh = max_t(u16, l->window / 2, 300);
         l->window = min_t(u16, l->ssthresh, l->window);
         return;
     }
     /* Enter slow start */
     if (unlikely(!released)) {
         l->ssthresh = max_t(u16, l->window / 2, 300);
         l->window = l->min_win;
         return;
     }
     /* Don't increase window if no pressure on the transmit queue */
     if (txq_len + bklog_len < cwin)
         return;
 
     /* Don't increase window if there are holes the transmit queue */
     if (txq_len && l->snd_nxt - buf_seqno(skb_peek(txq)) != txq_len)
         return;
 
     l->cong_acks += released;
 
     /* Slow start  */
     if (cwin <= l->ssthresh) {
         l->window = min_t(u16, cwin + released, l->max_win);
         return;
     }
     /* Congestion avoidance */
     if (l->cong_acks < cwin)
         return;
     l->window = min_t(u16, ++cwin, l->max_win);
     l->cong_acks = 0;
 }
 
 static void tipc_link_advance_backlog(struct tipc_link *l,
                       struct sk_buff_head *xmitq)
 {
     u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
     struct sk_buff_head *txq = &l->transmq;
     struct sk_buff *skb, *_skb;
     u16 ack = l->rcv_nxt - 1;
     u16 seqno = l->snd_nxt;
     struct tipc_msg *hdr;
     u16 cwin = l->window;
     u32 imp;
 
     while (skb_queue_len(txq) < cwin) {
         skb = skb_peek(&l->backlogq);
         if (!skb)
             break;
         _skb = skb_clone(skb, GFP_ATOMIC);
         if (!_skb)
             break;
         __skb_dequeue(&l->backlogq);
         hdr = buf_msg(skb);
         imp = msg_importance(hdr);
         l->backlog[imp].len--;
         if (unlikely(skb == l->backlog[imp].target_bskb))
             l->backlog[imp].target_bskb = NULL;
         __skb_queue_tail(&l->transmq, skb);
         tipc_link_set_skb_retransmit_time(skb, l);
 
         __skb_queue_tail(xmitq, _skb);
         TIPC_SKB_CB(skb)->ackers = l->ackers;
         msg_set_seqno(hdr, seqno);
         msg_set_ack(hdr, ack);
         msg_set_bcast_ack(hdr, bc_ack);
         l->rcv_unacked = 0;
         l->stats.sent_pkts++;
         seqno++;
     }
     l->snd_nxt = seqno;
 }
 
 /**
  * link_retransmit_failure() - Detect repeated retransmit failures
  * @l: tipc link sender
  * @r: tipc link receiver (= l in case of unicast)
  * @rc: returned code
  *
  * Return: true if the repeated retransmit failures happens, otherwise
  * false
  */
 static bool link_retransmit_failure(struct tipc_link *l, struct tipc_link *r,
                     int *rc)
 {
     struct sk_buff *skb = skb_peek(&l->transmq);
     struct tipc_msg *hdr;
 
     if (!skb)
         return false;
 
     if (!TIPC_SKB_CB(skb)->retr_cnt)
         return false;
 
     if (!time_after(jiffies, TIPC_SKB_CB(skb)->retr_stamp +
             msecs_to_jiffies(r->tolerance * 10)))
         return false;
 
     hdr = buf_msg(skb);
     if (link_is_bc_sndlink(l) && !less(r->acked, msg_seqno(hdr)))
         return false;
 
     pr_warn("Retransmission failure on link <%s>\n", l->name);
     link_print(l, "State of link ");
     pr_info("Failed msg: usr %u, typ %u, len %u, err %u\n",
         msg_user(hdr), msg_type(hdr), msg_size(hdr), msg_errcode(hdr));
     pr_info("sqno %u, prev: %x, dest: %x\n",
         msg_seqno(hdr), msg_prevnode(hdr), msg_destnode(hdr));
     pr_info("retr_stamp %d, retr_cnt %d\n",
         jiffies_to_msecs(TIPC_SKB_CB(skb)->retr_stamp),
         TIPC_SKB_CB(skb)->retr_cnt);
 
     trace_tipc_list_dump(&l->transmq, true, "retrans failure!");
     trace_tipc_link_dump(l, TIPC_DUMP_NONE, "retrans failure!");
     trace_tipc_link_dump(r, TIPC_DUMP_NONE, "retrans failure!");
 
     if (link_is_bc_sndlink(l)) {
         r->state = LINK_RESET;
         *rc |= TIPC_LINK_DOWN_EVT;
     } else {
         *rc |= tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
     }
 
     return true;
 }
 
 /* tipc_data_input - deliver data and name distr msgs to upper layer
  *
  * Consumes buffer if message is of right type
  * Node lock must be held
  */
 static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb,
                 struct sk_buff_head *inputq)
 {
     struct sk_buff_head *mc_inputq = l->bc_rcvlink->inputq;
     struct tipc_msg *hdr = buf_msg(skb);
 
     switch (msg_user(hdr)) {
     case TIPC_LOW_IMPORTANCE:
     case TIPC_MEDIUM_IMPORTANCE:
     case TIPC_HIGH_IMPORTANCE:
     case TIPC_CRITICAL_IMPORTANCE:
         if (unlikely(msg_in_group(hdr) || msg_mcast(hdr))) {
             skb_queue_tail(mc_inputq, skb);
             return true;
         }
         fallthrough;
     case CONN_MANAGER:
         skb_queue_tail(inputq, skb);
         return true;
     case GROUP_PROTOCOL:
         skb_queue_tail(mc_inputq, skb);
         return true;
     case NAME_DISTRIBUTOR:
         l->bc_rcvlink->state = LINK_ESTABLISHED;
         skb_queue_tail(l->namedq, skb);
         return true;
     case MSG_BUNDLER:
     case TUNNEL_PROTOCOL:
     case MSG_FRAGMENTER:
     case BCAST_PROTOCOL:
         return false;
 #ifdef CONFIG_TIPC_CRYPTO
     case MSG_CRYPTO:
         if (sysctl_tipc_key_exchange_enabled &&
             TIPC_SKB_CB(skb)->decrypted) {
             tipc_crypto_msg_rcv(l->net, skb);
             return true;
         }
         fallthrough;
 #endif
     default:
         pr_warn("Dropping received illegal msg type\n");
         kfree_skb(skb);
         return true;
     }
 }
 
 /* tipc_link_input - process packet that has passed link protocol check
  *
  * Consumes buffer
  */
 static int tipc_link_input(struct tipc_link *l, struct sk_buff *skb,
                struct sk_buff_head *inputq,
                struct sk_buff **reasm_skb)
 {
     struct tipc_msg *hdr = buf_msg(skb);
     struct sk_buff *iskb;
     struct sk_buff_head tmpq;
     int usr = msg_user(hdr);
     int pos = 0;
 
     if (usr == MSG_BUNDLER) {
         skb_queue_head_init(&tmpq);
         l->stats.recv_bundles++;
         l->stats.recv_bundled += msg_msgcnt(hdr);
         while (tipc_msg_extract(skb, &iskb, &pos))
             tipc_data_input(l, iskb, &tmpq);
         tipc_skb_queue_splice_tail(&tmpq, inputq);
         return 0;
     } else if (usr == MSG_FRAGMENTER) {
         l->stats.recv_fragments++;
         if (tipc_buf_append(reasm_skb, &skb)) {
             l->stats.recv_fragmented++;
             tipc_data_input(l, skb, inputq);
         } else if (!*reasm_skb && !link_is_bc_rcvlink(l)) {
             pr_warn_ratelimited("Unable to build fragment list\n");
             return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
         }
         return 0;
     } else if (usr == BCAST_PROTOCOL) {
         tipc_bcast_lock(l->net);
         tipc_link_bc_init_rcv(l->bc_rcvlink, hdr);
         tipc_bcast_unlock(l->net);
     }
 
     kfree_skb(skb);
     return 0;
 }
 
 /* tipc_link_tnl_rcv() - receive TUNNEL_PROTOCOL message, drop or process the
  *           inner message along with the ones in the old link's
  *           deferdq
  * @l: tunnel link
  * @skb: TUNNEL_PROTOCOL message
  * @inputq: queue to put messages ready for delivery
  */
 static int tipc_link_tnl_rcv(struct tipc_link *l, struct sk_buff *skb,
                  struct sk_buff_head *inputq)
 {
     struct sk_buff **reasm_skb = &l->failover_reasm_skb;
     struct sk_buff **reasm_tnlmsg = &l->reasm_tnlmsg;
     struct sk_buff_head *fdefq = &l->failover_deferdq;
     struct tipc_msg *hdr = buf_msg(skb);
     struct sk_buff *iskb;
     int ipos = 0;
     int rc = 0;
     u16 seqno;
 
     if (msg_type(hdr) == SYNCH_MSG) {
         kfree_skb(skb);
         return 0;
     }
 
     /* Not a fragment? */
     if (likely(!msg_nof_fragms(hdr))) {
         if (unlikely(!tipc_msg_extract(skb, &iskb, &ipos))) {
             pr_warn_ratelimited("Unable to extract msg, defq: %d\n",
                         skb_queue_len(fdefq));
             return 0;
         }
         kfree_skb(skb);
     } else {
         /* Set fragment type for buf_append */
         if (msg_fragm_no(hdr) == 1)
             msg_set_type(hdr, FIRST_FRAGMENT);
         else if (msg_fragm_no(hdr) < msg_nof_fragms(hdr))
             msg_set_type(hdr, FRAGMENT);
         else
             msg_set_type(hdr, LAST_FRAGMENT);
 
         if (!tipc_buf_append(reasm_tnlmsg, &skb)) {
             /* Successful but non-complete reassembly? */
             if (*reasm_tnlmsg || link_is_bc_rcvlink(l))
                 return 0;
             pr_warn_ratelimited("Unable to reassemble tunnel msg\n");
             return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
         }
         iskb = skb;
     }
 
     do {
         seqno = buf_seqno(iskb);
         if (unlikely(less(seqno, l->drop_point))) {
             kfree_skb(iskb);
             continue;
         }
         if (unlikely(seqno != l->drop_point)) {
             __tipc_skb_queue_sorted(fdefq, seqno, iskb);
             continue;
         }
 
         l->drop_point++;
         if (!tipc_data_input(l, iskb, inputq))
             rc |= tipc_link_input(l, iskb, inputq, reasm_skb);
         if (unlikely(rc))
             break;
     } while ((iskb = __tipc_skb_dequeue(fdefq, l->drop_point)));
 
     return rc;
 }
 
 /**
  * tipc_get_gap_ack_blks - get Gap ACK blocks from PROTOCOL/STATE_MSG
  * @ga: returned pointer to the Gap ACK blocks if any
  * @l: the tipc link
  * @hdr: the PROTOCOL/STATE_MSG header
  * @uc: desired Gap ACK blocks type, i.e. unicast (= 1) or broadcast (= 0)
  *
  * Return: the total Gap ACK blocks size
  */
 u16 tipc_get_gap_ack_blks(struct tipc_gap_ack_blks **ga, struct tipc_link *l,
               struct tipc_msg *hdr, bool uc)
 {
     struct tipc_gap_ack_blks *p;
     u16 sz = 0;
 
     /* Does peer support the Gap ACK blocks feature? */
     if (l->peer_caps & TIPC_GAP_ACK_BLOCK) {
         p = (struct tipc_gap_ack_blks *)msg_data(hdr);
         sz = ntohs(p->len);
         /* Sanity check */
         if (sz == struct_size(p, gacks, p->ugack_cnt + p->bgack_cnt)) {
             /* Good, check if the desired type exists */
             if ((uc && p->ugack_cnt) || (!uc && p->bgack_cnt))
                 goto ok;
         /* Backward compatible: peer might not support bc, but uc? */
         } else if (uc && sz == struct_size(p, gacks, p->ugack_cnt)) {
             if (p->ugack_cnt) {
                 p->bgack_cnt = 0;
                 goto ok;
             }
         }
     }
     /* Other cases: ignore! */
     p = NULL;
 
 ok:
     *ga = p;
     return sz;
 }
 
 static u8 __tipc_build_gap_ack_blks(struct tipc_gap_ack_blks *ga,
                     struct tipc_link *l, u8 start_index)
 {
     struct tipc_gap_ack *gacks = &ga->gacks[start_index];
     struct sk_buff *skb = skb_peek(&l->deferdq);
     u16 expect, seqno = 0;
     u8 n = 0;
 
     if (!skb)
         return 0;
 
     expect = buf_seqno(skb);
     skb_queue_walk(&l->deferdq, skb) {
         seqno = buf_seqno(skb);
         if (unlikely(more(seqno, expect))) {
             gacks[n].ack = htons(expect - 1);
             gacks[n].gap = htons(seqno - expect);
             if (++n >= MAX_GAP_ACK_BLKS / 2) {
                 pr_info_ratelimited("Gacks on %s: %d, ql: %d!\n",
                             l->name, n,
                             skb_queue_len(&l->deferdq));
                 return n;
             }
         } else if (unlikely(less(seqno, expect))) {
             pr_warn("Unexpected skb in deferdq!\n");
             continue;
         }
         expect = seqno + 1;
     }
 
     /* last block */
     gacks[n].ack = htons(seqno);
     gacks[n].gap = 0;
     n++;
     return n;
 }
 
 /* tipc_build_gap_ack_blks - build Gap ACK blocks
  * @l: tipc unicast link
  * @hdr: the tipc message buffer to store the Gap ACK blocks after built
  *
  * The function builds Gap ACK blocks for both the unicast & broadcast receiver
  * links of a certain peer, the buffer after built has the network data format
  * as found at the struct tipc_gap_ack_blks definition.
  *
  * returns the actual allocated memory size
  */
 static u16 tipc_build_gap_ack_blks(struct tipc_link *l, struct tipc_msg *hdr)
 {
     struct tipc_link *bcl = l->bc_rcvlink;
     struct tipc_gap_ack_blks *ga;
     u16 len;
 
     ga = (struct tipc_gap_ack_blks *)msg_data(hdr);
 
     /* Start with broadcast link first */
     tipc_bcast_lock(bcl->net);
     msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
     msg_set_bc_gap(hdr, link_bc_rcv_gap(bcl));
     ga->bgack_cnt = __tipc_build_gap_ack_blks(ga, bcl, 0);
     tipc_bcast_unlock(bcl->net);
 
     /* Now for unicast link, but an explicit NACK only (???) */
     ga->ugack_cnt = (msg_seq_gap(hdr)) ?
             __tipc_build_gap_ack_blks(ga, l, ga->bgack_cnt) : 0;
 
     /* Total len */
     len = struct_size(ga, gacks, ga->bgack_cnt + ga->ugack_cnt);
     ga->len = htons(len);
     return len;
 }
 
 /* tipc_link_advance_transmq - advance TIPC link transmq queue by releasing
  *                 acked packets, also doing retransmissions if
  *                 gaps found
  * @l: tipc link with transmq queue to be advanced
  * @r: tipc link "receiver" i.e. in case of broadcast (= "l" if unicast)
  * @acked: seqno of last packet acked by peer without any gaps before
  * @gap: # of gap packets
  * @ga: buffer pointer to Gap ACK blocks from peer
  * @xmitq: queue for accumulating the retransmitted packets if any
  * @retransmitted: returned boolean value if a retransmission is really issued
  * @rc: returned code e.g. TIPC_LINK_DOWN_EVT if a repeated retransmit failures
  *      happens (- unlikely case)
  *
  * Return: the number of packets released from the link transmq
  */
 static int tipc_link_advance_transmq(struct tipc_link *l, struct tipc_link *r,
                      u16 acked, u16 gap,
                      struct tipc_gap_ack_blks *ga,
                      struct sk_buff_head *xmitq,
                      bool *retransmitted, int *rc)
 {
     struct tipc_gap_ack_blks *last_ga = r->last_ga, *this_ga = NULL;
     struct tipc_gap_ack *gacks = NULL;
     struct sk_buff *skb, *_skb, *tmp;
     struct tipc_msg *hdr;
     u32 qlen = skb_queue_len(&l->transmq);
     u16 nacked = acked, ngap = gap, gack_cnt = 0;
     u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
     u16 ack = l->rcv_nxt - 1;
     u16 seqno, n = 0;
     u16 end = r->acked, start = end, offset = r->last_gap;
     u16 si = (last_ga) ? last_ga->start_index : 0;
     bool is_uc = !link_is_bc_sndlink(l);
     bool bc_has_acked = false;
 
     trace_tipc_link_retrans(r, acked + 1, acked + gap, &l->transmq);
 
     /* Determine Gap ACK blocks if any for the particular link */
     if (ga && is_uc) {
         /* Get the Gap ACKs, uc part */
         gack_cnt = ga->ugack_cnt;
         gacks = &ga->gacks[ga->bgack_cnt];
     } else if (ga) {
         /* Copy the Gap ACKs, bc part, for later renewal if needed */
         this_ga = kmemdup(ga, struct_size(ga, gacks, ga->bgack_cnt),
                   GFP_ATOMIC);
         if (likely(this_ga)) {
             this_ga->start_index = 0;
             /* Start with the bc Gap ACKs */
             gack_cnt = this_ga->bgack_cnt;
             gacks = &this_ga->gacks[0];
         } else {
             /* Hmm, we can get in trouble..., simply ignore it */
             pr_warn_ratelimited("Ignoring bc Gap ACKs, no memory\n");
         }
     }
 
     /* Advance the link transmq */
     skb_queue_walk_safe(&l->transmq, skb, tmp) {
         seqno = buf_seqno(skb);
 
 next_gap_ack:
         if (less_eq(seqno, nacked)) {
             if (is_uc)
                 goto release;
             /* Skip packets peer has already acked */
             if (!more(seqno, r->acked))
                 continue;
             /* Get the next of last Gap ACK blocks */
             while (more(seqno, end)) {
                 if (!last_ga || si >= last_ga->bgack_cnt)
                     break;
                 start = end + offset + 1;
                 end = ntohs(last_ga->gacks[si].ack);
                 offset = ntohs(last_ga->gacks[si].gap);
                 si++;
                 WARN_ONCE(more(start, end) ||
                       (!offset &&
                        si < last_ga->bgack_cnt) ||
                       si > MAX_GAP_ACK_BLKS,
                       "Corrupted Gap ACK: %d %d %d %d %d\n",
                       start, end, offset, si,
                       last_ga->bgack_cnt);
             }
             /* Check against the last Gap ACK block */
             if (in_range(seqno, start, end))
                 continue;
             /* Update/release the packet peer is acking */
             bc_has_acked = true;
             if (--TIPC_SKB_CB(skb)->ackers)
                 continue;
 release:
             /* release skb */
             __skb_unlink(skb, &l->transmq);
             kfree_skb(skb);
         } else if (less_eq(seqno, nacked + ngap)) {
             /* First gap: check if repeated retrans failures? */
             if (unlikely(seqno == acked + 1 &&
                      link_retransmit_failure(l, r, rc))) {
                 /* Ignore this bc Gap ACKs if any */
                 kfree(this_ga);
                 this_ga = NULL;
                 break;
             }
             /* retransmit skb if unrestricted*/
             if (time_before(jiffies, TIPC_SKB_CB(skb)->nxt_retr))
                 continue;
             tipc_link_set_skb_retransmit_time(skb, l);
             _skb = pskb_copy(skb, GFP_ATOMIC);
             if (!_skb)
                 continue;
             hdr = buf_msg(_skb);
             msg_set_ack(hdr, ack);
             msg_set_bcast_ack(hdr, bc_ack);
             _skb->priority = TC_PRIO_CONTROL;
             __skb_queue_tail(xmitq, _skb);
             l->stats.retransmitted++;
             if (!is_uc)
                 r->stats.retransmitted++;
             *retransmitted = true;
             /* Increase actual retrans counter & mark first time */
             if (!TIPC_SKB_CB(skb)->retr_cnt++)
                 TIPC_SKB_CB(skb)->retr_stamp = jiffies;
         } else {
             /* retry with Gap ACK blocks if any */
             if (n >= gack_cnt)
                 break;
             nacked = ntohs(gacks[n].ack);
             ngap = ntohs(gacks[n].gap);
             n++;
             goto next_gap_ack;
         }
     }
 
     /* Renew last Gap ACK blocks for bc if needed */
     if (bc_has_acked) {
         if (this_ga) {
             kfree(last_ga);
             r->last_ga = this_ga;
             r->last_gap = gap;
         } else if (last_ga) {
             if (less(acked, start)) {
                 si--;
                 offset = start - acked - 1;
             } else if (less(acked, end)) {
                 acked = end;
             }
             if (si < last_ga->bgack_cnt) {
                 last_ga->start_index = si;
                 r->last_gap = offset;
             } else {
                 kfree(last_ga);
                 r->last_ga = NULL;
                 r->last_gap = 0;
             }
         } else {
             r->last_gap = 0;
         }
         r->acked = acked;
     } else {
         kfree(this_ga);
     }
 
     return qlen - skb_queue_len(&l->transmq);
 }
 
 /* tipc_link_build_state_msg: prepare link state message for transmission
  *
  * Note that sending of broadcast ack is coordinated among nodes, to reduce
  * risk of ack storms towards the sender
  */
 int tipc_link_build_state_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
 {
     if (!l)
         return 0;
 
     /* Broadcast ACK must be sent via a unicast link => defer to caller */
     if (link_is_bc_rcvlink(l)) {
         if (((l->rcv_nxt ^ tipc_own_addr(l->net)) & 0xf) != 0xf)
             return 0;
         l->rcv_unacked = 0;
 
         /* Use snd_nxt to store peer's snd_nxt in broadcast rcv link */
         l->snd_nxt = l->rcv_nxt;
         return TIPC_LINK_SND_STATE;
     }
     /* Unicast ACK */
     l->rcv_unacked = 0;
     l->stats.sent_acks++;
     tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, 0, xmitq);
     return 0;
 }
 
 /* tipc_link_build_reset_msg: prepare link RESET or ACTIVATE message
  */
 void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
 {
     int mtyp = RESET_MSG;
     struct sk_buff *skb;
 
     if (l->state == LINK_ESTABLISHING)
         mtyp = ACTIVATE_MSG;
 
     tipc_link_build_proto_msg(l, mtyp, 0, 0, 0, 0, 0, xmitq);
 
     /* Inform peer that this endpoint is going down if applicable */
     skb = skb_peek_tail(xmitq);
     if (skb && (l->state == LINK_RESET))
         msg_set_peer_stopping(buf_msg(skb), 1);
 }
 
 /* tipc_link_build_nack_msg: prepare link nack message for transmission
  * Note that sending of broadcast NACK is coordinated among nodes, to
  * reduce the risk of NACK storms towards the sender
  */
 static int tipc_link_build_nack_msg(struct tipc_link *l,
                     struct sk_buff_head *xmitq)
 {
     u32 def_cnt = ++l->stats.deferred_recv;
     struct sk_buff_head *dfq = &l->deferdq;
     u32 defq_len = skb_queue_len(dfq);
     int match1, match2;
 
     if (link_is_bc_rcvlink(l)) {
         match1 = def_cnt & 0xf;
         match2 = tipc_own_addr(l->net) & 0xf;
         if (match1 == match2)
             return TIPC_LINK_SND_STATE;
         return 0;
     }
 
     if (defq_len >= 3 && !((defq_len - 3) % 16)) {
         u16 rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
 
         tipc_link_build_proto_msg(l, STATE_MSG, 0, 0,
                       rcvgap, 0, 0, xmitq);
     }
     return 0;
 }
 
 /* tipc_link_rcv - process TIPC packets/messages arriving from off-node
  * @l: the link that should handle the message
  * @skb: TIPC packet
  * @xmitq: queue to place packets to be sent after this call
  */
 int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
           struct sk_buff_head *xmitq)
 {
     struct sk_buff_head *defq = &l->deferdq;
     struct tipc_msg *hdr = buf_msg(skb);
     u16 seqno, rcv_nxt, win_lim;
     int released = 0;
     int rc = 0;
 
     /* Verify and update link state */
     if (unlikely(msg_user(hdr) == LINK_PROTOCOL))
         return tipc_link_proto_rcv(l, skb, xmitq);
 
     /* Don't send probe at next timeout expiration */
     l->silent_intv_cnt = 0;
 
     do {
         hdr = buf_msg(skb);
         seqno = msg_seqno(hdr);
         rcv_nxt = l->rcv_nxt;
         win_lim = rcv_nxt + TIPC_MAX_LINK_WIN;
 
         if (unlikely(!link_is_up(l))) {
             if (l->state == LINK_ESTABLISHING)
                 rc = TIPC_LINK_UP_EVT;
             kfree_skb(skb);
             break;
         }
 
         /* Drop if outside receive window */
         if (unlikely(less(seqno, rcv_nxt) || more(seqno, win_lim))) {
             l->stats.duplicates++;
             kfree_skb(skb);
             break;
         }
         released += tipc_link_advance_transmq(l, l, msg_ack(hdr), 0,
                               NULL, NULL, NULL, NULL);
 
         /* Defer delivery if sequence gap */
         if (unlikely(seqno != rcv_nxt)) {
             if (!__tipc_skb_queue_sorted(defq, seqno, skb))
                 l->stats.duplicates++;
             rc |= tipc_link_build_nack_msg(l, xmitq);
             break;
         }
 
         /* Deliver packet */
         l->rcv_nxt++;
         l->stats.recv_pkts++;
 
         if (unlikely(msg_user(hdr) == TUNNEL_PROTOCOL))
             rc |= tipc_link_tnl_rcv(l, skb, l->inputq);
         else if (!tipc_data_input(l, skb, l->inputq))
             rc |= tipc_link_input(l, skb, l->inputq, &l->reasm_buf);
         if (unlikely(++l->rcv_unacked >= TIPC_MIN_LINK_WIN))
             rc |= tipc_link_build_state_msg(l, xmitq);
         if (unlikely(rc & ~TIPC_LINK_SND_STATE))
             break;
     } while ((skb = __tipc_skb_dequeue(defq, l->rcv_nxt)));
 
     /* Forward queues and wake up waiting users */
     if (released) {
         tipc_link_update_cwin(l, released, 0);
         tipc_link_advance_backlog(l, xmitq);
         if (unlikely(!skb_queue_empty(&l->wakeupq)))
             link_prepare_wakeup(l);
     }
     return rc;
 }
 
 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
                       bool probe_reply, u16 rcvgap,
                       int tolerance, int priority,
                       struct sk_buff_head *xmitq)
 {
     struct tipc_mon_state *mstate = &l->mon_state;
     struct sk_buff_head *dfq = &l->deferdq;
     struct tipc_link *bcl = l->bc_rcvlink;
     struct tipc_msg *hdr;
     struct sk_buff *skb;
     bool node_up = link_is_up(bcl);
     u16 glen = 0, bc_rcvgap = 0;
     int dlen = 0;
     void *data;
 
     /* Don't send protocol message during reset or link failover */
     if (tipc_link_is_blocked(l))
         return;
 
     if (!tipc_link_is_up(l) && (mtyp == STATE_MSG))
         return;
 
     if ((probe || probe_reply) && !skb_queue_empty(dfq))
         rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
 
     skb = tipc_msg_create(LINK_PROTOCOL, mtyp, INT_H_SIZE,
                   tipc_max_domain_size + MAX_GAP_ACK_BLKS_SZ,
                   l->addr, tipc_own_addr(l->net), 0, 0, 0);
     if (!skb)
         return;
 
     hdr = buf_msg(skb);
     data = msg_data(hdr);
     msg_set_session(hdr, l->session);
     msg_set_bearer_id(hdr, l->bearer_id);
     msg_set_net_plane(hdr, l->net_plane);
     msg_set_next_sent(hdr, l->snd_nxt);
     msg_set_ack(hdr, l->rcv_nxt - 1);
     msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
     msg_set_bc_ack_invalid(hdr, !node_up);
     msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
     msg_set_link_tolerance(hdr, tolerance);
     msg_set_linkprio(hdr, priority);
     msg_set_redundant_link(hdr, node_up);
     msg_set_seq_gap(hdr, 0);
     msg_set_seqno(hdr, l->snd_nxt + U16_MAX / 2);
 
     if (mtyp == STATE_MSG) {
         if (l->peer_caps & TIPC_LINK_PROTO_SEQNO)
             msg_set_seqno(hdr, l->snd_nxt_state++);
         msg_set_seq_gap(hdr, rcvgap);
         bc_rcvgap = link_bc_rcv_gap(bcl);
         msg_set_bc_gap(hdr, bc_rcvgap);
         msg_set_probe(hdr, probe);
         msg_set_is_keepalive(hdr, probe || probe_reply);
         if (l->peer_caps & TIPC_GAP_ACK_BLOCK)
             glen = tipc_build_gap_ack_blks(l, hdr);
         tipc_mon_prep(l->net, data + glen, &dlen, mstate, l->bearer_id);
         msg_set_size(hdr, INT_H_SIZE + glen + dlen);
         skb_trim(skb, INT_H_SIZE + glen + dlen);
         l->stats.sent_states++;
         l->rcv_unacked = 0;
     } else {
         /* RESET_MSG or ACTIVATE_MSG */
         if (mtyp == ACTIVATE_MSG) {
             msg_set_dest_session_valid(hdr, 1);
             msg_set_dest_session(hdr, l->peer_session);
         }
         msg_set_max_pkt(hdr, l->advertised_mtu);
         strcpy(data, l->if_name);
         msg_set_size(hdr, INT_H_SIZE + TIPC_MAX_IF_NAME);
         skb_trim(skb, INT_H_SIZE + TIPC_MAX_IF_NAME);
     }
     if (probe)
         l->stats.sent_probes++;
     if (rcvgap)
         l->stats.sent_nacks++;
     if (bc_rcvgap)
         bcl->stats.sent_nacks++;
     skb->priority = TC_PRIO_CONTROL;
     __skb_queue_tail(xmitq, skb);
     trace_tipc_proto_build(skb, false, l->name);
 }
 
 void tipc_link_create_dummy_tnl_msg(struct tipc_link *l,
                     struct sk_buff_head *xmitq)
 {
     u32 onode = tipc_own_addr(l->net);
     struct tipc_msg *hdr, *ihdr;
     struct sk_buff_head tnlq;
     struct sk_buff *skb;
     u32 dnode = l->addr;
 
     __skb_queue_head_init(&tnlq);
     skb = tipc_msg_create(TUNNEL_PROTOCOL, FAILOVER_MSG,
                   INT_H_SIZE, BASIC_H_SIZE,
                   dnode, onode, 0, 0, 0);
     if (!skb) {
         pr_warn("%sunable to create tunnel packet\n", link_co_err);
         return;
     }
 
     hdr = buf_msg(skb);
     msg_set_msgcnt(hdr, 1);
     msg_set_bearer_id(hdr, l->peer_bearer_id);
 
     ihdr = (struct tipc_msg *)msg_data(hdr);
     tipc_msg_init(onode, ihdr, TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
               BASIC_H_SIZE, dnode);
     msg_set_errcode(ihdr, TIPC_ERR_NO_PORT);
     __skb_queue_tail(&tnlq, skb);
     tipc_link_xmit(l, &tnlq, xmitq);
 }
 
 /* tipc_link_tnl_prepare(): prepare and return a list of tunnel packets
  * with contents of the link's transmit and backlog queues.
  */
 void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
                int mtyp, struct sk_buff_head *xmitq)
 {
     struct sk_buff_head *fdefq = &tnl->failover_deferdq;
     struct sk_buff *skb, *tnlskb;
     struct tipc_msg *hdr, tnlhdr;
     struct sk_buff_head *queue = &l->transmq;
     struct sk_buff_head tmpxq, tnlq, frags;
     u16 pktlen, pktcnt, seqno = l->snd_nxt;
     bool pktcnt_need_update = false;
     u16 syncpt;
     int rc;
 
     if (!tnl)
         return;
 
     __skb_queue_head_init(&tnlq);
     /* Link Synching:
      * From now on, send only one single ("dummy") SYNCH message
      * to peer. The SYNCH message does not contain any data, just
      * a header conveying the synch point to the peer.
      */
     if (mtyp == SYNCH_MSG && (tnl->peer_caps & TIPC_TUNNEL_ENHANCED)) {
         tnlskb = tipc_msg_create(TUNNEL_PROTOCOL, SYNCH_MSG,
                      INT_H_SIZE, 0, l->addr,
                      tipc_own_addr(l->net),
                      0, 0, 0);
         if (!tnlskb) {
             pr_warn("%sunable to create dummy SYNCH_MSG\n",
                 link_co_err);
             return;
         }
 
         hdr = buf_msg(tnlskb);
         syncpt = l->snd_nxt + skb_queue_len(&l->backlogq) - 1;
         msg_set_syncpt(hdr, syncpt);
         msg_set_bearer_id(hdr, l->peer_bearer_id);
         __skb_queue_tail(&tnlq, tnlskb);
         tipc_link_xmit(tnl, &tnlq, xmitq);
         return;
     }
 
     __skb_queue_head_init(&tmpxq);
     __skb_queue_head_init(&frags);
     /* At least one packet required for safe algorithm => add dummy */
     skb = tipc_msg_create(TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
                   BASIC_H_SIZE, 0, l->addr, tipc_own_addr(l->net),
                   0, 0, TIPC_ERR_NO_PORT);
     if (!skb) {
         pr_warn("%sunable to create tunnel packet\n", link_co_err);
         return;
     }
     __skb_queue_tail(&tnlq, skb);
     tipc_link_xmit(l, &tnlq, &tmpxq);
     __skb_queue_purge(&tmpxq);
 
     /* Initialize reusable tunnel packet header */
     tipc_msg_init(tipc_own_addr(l->net), &tnlhdr, TUNNEL_PROTOCOL,
               mtyp, INT_H_SIZE, l->addr);
     if (mtyp == SYNCH_MSG)
         pktcnt = l->snd_nxt - buf_seqno(skb_peek(&l->transmq));
     else
         pktcnt = skb_queue_len(&l->transmq);
     pktcnt += skb_queue_len(&l->backlogq);
     msg_set_msgcnt(&tnlhdr, pktcnt);
     msg_set_bearer_id(&tnlhdr, l->peer_bearer_id);
 tnl:
     /* Wrap each packet into a tunnel packet */
     skb_queue_walk(queue, skb) {
         hdr = buf_msg(skb);
         if (queue == &l->backlogq)
             msg_set_seqno(hdr, seqno++);
         pktlen = msg_size(hdr);
 
         /* Tunnel link MTU is not large enough? This could be
          * due to:
          * 1) Link MTU has just changed or set differently;
          * 2) Or FAILOVER on the top of a SYNCH message
          *
          * The 2nd case should not happen if peer supports
          * TIPC_TUNNEL_ENHANCED
          */
         if (pktlen > tnl->mtu - INT_H_SIZE) {
             if (mtyp == FAILOVER_MSG &&
                 (tnl->peer_caps & TIPC_TUNNEL_ENHANCED)) {
                 rc = tipc_msg_fragment(skb, &tnlhdr, tnl->mtu,
                                &frags);
                 if (rc) {
                     pr_warn("%sunable to frag msg: rc %d\n",
                         link_co_err, rc);
                     return;
                 }
                 pktcnt += skb_queue_len(&frags) - 1;
                 pktcnt_need_update = true;
                 skb_queue_splice_tail_init(&frags, &tnlq);
                 continue;
             }
             /* Unluckily, peer doesn't have TIPC_TUNNEL_ENHANCED
              * => Just warn it and return!
              */
             pr_warn_ratelimited("%stoo large msg <%d, %d>: %d!\n",
                         link_co_err, msg_user(hdr),
                         msg_type(hdr), msg_size(hdr));
             return;
         }
 
         msg_set_size(&tnlhdr, pktlen + INT_H_SIZE);
         tnlskb = tipc_buf_acquire(pktlen + INT_H_SIZE, GFP_ATOMIC);
         if (!tnlskb) {
             pr_warn("%sunable to send packet\n", link_co_err);
             return;
         }
         skb_copy_to_linear_data(tnlskb, &tnlhdr, INT_H_SIZE);
         skb_copy_to_linear_data_offset(tnlskb, INT_H_SIZE, hdr, pktlen);
         __skb_queue_tail(&tnlq, tnlskb);
     }
     if (queue != &l->backlogq) {
         queue = &l->backlogq;
         goto tnl;
     }
 
     if (pktcnt_need_update)
         skb_queue_walk(&tnlq, skb) {
             hdr = buf_msg(skb);
             msg_set_msgcnt(hdr, pktcnt);
         }
 
     tipc_link_xmit(tnl, &tnlq, xmitq);
 
     if (mtyp == FAILOVER_MSG) {
         tnl->drop_point = l->rcv_nxt;
         tnl->failover_reasm_skb = l->reasm_buf;
         l->reasm_buf = NULL;
 
         /* Failover the link's deferdq */
         if (unlikely(!skb_queue_empty(fdefq))) {
             pr_warn("Link failover deferdq not empty: %d!\n",
                 skb_queue_len(fdefq));
             __skb_queue_purge(fdefq);
         }
         skb_queue_splice_init(&l->deferdq, fdefq);
     }
 }
 
 /**
  * tipc_link_failover_prepare() - prepare tnl for link failover
  *
  * This is a special version of the precursor - tipc_link_tnl_prepare(),
  * see the tipc_node_link_failover() for details
  *
  * @l: failover link
  * @tnl: tunnel link
  * @xmitq: queue for messages to be xmited
  */
 void tipc_link_failover_prepare(struct tipc_link *l, struct tipc_link *tnl,
                 struct sk_buff_head *xmitq)
 {
     struct sk_buff_head *fdefq = &tnl->failover_deferdq;
 
     tipc_link_create_dummy_tnl_msg(tnl, xmitq);
 
     /* This failover link endpoint was never established before,
      * so it has not received anything from peer.
      * Otherwise, it must be a normal failover situation or the
      * node has entered SELF_DOWN_PEER_LEAVING and both peer nodes
      * would have to start over from scratch instead.
      */
     tnl->drop_point = 1;
     tnl->failover_reasm_skb = NULL;
 
     /* Initiate the link's failover deferdq */
     if (unlikely(!skb_queue_empty(fdefq))) {
         pr_warn("Link failover deferdq not empty: %d!\n",
             skb_queue_len(fdefq));
         __skb_queue_purge(fdefq);
     }
 }
 
 /* tipc_link_validate_msg(): validate message against current link state
  * Returns true if message should be accepted, otherwise false
  */
 bool tipc_link_validate_msg(struct tipc_link *l, struct tipc_msg *hdr)
 {
     u16 curr_session = l->peer_session;
     u16 session = msg_session(hdr);
     int mtyp = msg_type(hdr);
 
     if (msg_user(hdr) != LINK_PROTOCOL)
         return true;
 
     switch (mtyp) {
     case RESET_MSG:
         if (!l->in_session)
             return true;
         /* Accept only RESET with new session number */
         return more(session, curr_session);
     case ACTIVATE_MSG:
         if (!l->in_session)
             return true;
         /* Accept only ACTIVATE with new or current session number */
         return !less(session, curr_session);
     case STATE_MSG:
         /* Accept only STATE with current session number */
         if (!l->in_session)
             return false;
         if (session != curr_session)
             return false;
         /* Extra sanity check */
         if (!link_is_up(l) && msg_ack(hdr))
             return false;
         if (!(l->peer_caps & TIPC_LINK_PROTO_SEQNO))
             return true;
         /* Accept only STATE with new sequence number */
         return !less(msg_seqno(hdr), l->rcv_nxt_state);
     default:
         return false;
     }
 }
 
 /* tipc_link_proto_rcv(): receive link level protocol message :
  * Note that network plane id propagates through the network, and may
  * change at any time. The node with lowest numerical id determines
  * network plane
  */
 static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
                    struct sk_buff_head *xmitq)
 {
     struct tipc_msg *hdr = buf_msg(skb);
     struct tipc_gap_ack_blks *ga = NULL;
     bool reply = msg_probe(hdr), retransmitted = false;
     u32 dlen = msg_data_sz(hdr), glen = 0;
     u16 peers_snd_nxt =  msg_next_sent(hdr);
     u16 peers_tol = msg_link_tolerance(hdr);
     u16 peers_prio = msg_linkprio(hdr);
     u16 gap = msg_seq_gap(hdr);
     u16 ack = msg_ack(hdr);
     u16 rcv_nxt = l->rcv_nxt;
     u16 rcvgap = 0;
     int mtyp = msg_type(hdr);
     int rc = 0, released;
     char *if_name;
     void *data;
 
     trace_tipc_proto_rcv(skb, false, l->name);
 
     if (dlen > U16_MAX)
         goto exit;
 
     if (tipc_link_is_blocked(l) || !xmitq)
         goto exit;
 
     if (tipc_own_addr(l->net) > msg_prevnode(hdr))
         l->net_plane = msg_net_plane(hdr);
 
     skb_linearize(skb);
     hdr = buf_msg(skb);
     data = msg_data(hdr);
 
     if (!tipc_link_validate_msg(l, hdr)) {
         trace_tipc_skb_dump(skb, false, "PROTO invalid (1)!");
         trace_tipc_link_dump(l, TIPC_DUMP_NONE, "PROTO invalid (1)!");
         goto exit;
     }
 
     switch (mtyp) {
     case RESET_MSG:
     case ACTIVATE_MSG:
         /* Complete own link name with peer's interface name */
         if_name =  strrchr(l->name, ':') + 1;
         if (sizeof(l->name) - (if_name - l->name) <= TIPC_MAX_IF_NAME)
             break;
         if (msg_data_sz(hdr) < TIPC_MAX_IF_NAME)
             break;
         strncpy(if_name, data, TIPC_MAX_IF_NAME);
 
         /* Update own tolerance if peer indicates a non-zero value */
         if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL)) {
             l->tolerance = peers_tol;
             l->bc_rcvlink->tolerance = peers_tol;
         }
         /* Update own priority if peer's priority is higher */
         if (in_range(peers_prio, l->priority + 1, TIPC_MAX_LINK_PRI))
             l->priority = peers_prio;
 
         /* If peer is going down we want full re-establish cycle */
         if (msg_peer_stopping(hdr)) {
             rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
             break;
         }
 
         /* If this endpoint was re-created while peer was ESTABLISHING
          * it doesn't know current session number. Force re-synch.
          */
         if (mtyp == ACTIVATE_MSG && msg_dest_session_valid(hdr) &&
             l->session != msg_dest_session(hdr)) {
             if (less(l->session, msg_dest_session(hdr)))
                 l->session = msg_dest_session(hdr) + 1;
             break;
         }
 
         /* ACTIVATE_MSG serves as PEER_RESET if link is already down */
         if (mtyp == RESET_MSG || !link_is_up(l))
             rc = tipc_link_fsm_evt(l, LINK_PEER_RESET_EVT);
 
         /* ACTIVATE_MSG takes up link if it was already locally reset */
         if (mtyp == ACTIVATE_MSG && l->state == LINK_ESTABLISHING)
             rc = TIPC_LINK_UP_EVT;
 
         l->peer_session = msg_session(hdr);
         l->in_session = true;
         l->peer_bearer_id = msg_bearer_id(hdr);
         if (l->mtu > msg_max_pkt(hdr))
             l->mtu = msg_max_pkt(hdr);
         break;
 
     case STATE_MSG:
         /* Validate Gap ACK blocks, drop if invalid */
         glen = tipc_get_gap_ack_blks(&ga, l, hdr, true);
         if (glen > dlen)
             break;
 
         l->rcv_nxt_state = msg_seqno(hdr) + 1;
 
         /* Update own tolerance if peer indicates a non-zero value */
         if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL)) {
             l->tolerance = peers_tol;
             l->bc_rcvlink->tolerance = peers_tol;
         }
         /* Update own prio if peer indicates a different value */
         if ((peers_prio != l->priority) &&
             in_range(peers_prio, 1, TIPC_MAX_LINK_PRI)) {
             l->priority = peers_prio;
             rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
         }
 
         l->silent_intv_cnt = 0;
         l->stats.recv_states++;
         if (msg_probe(hdr))
             l->stats.recv_probes++;
 
         if (!link_is_up(l)) {
             if (l->state == LINK_ESTABLISHING)
                 rc = TIPC_LINK_UP_EVT;
             break;
         }
 
         tipc_mon_rcv(l->net, data + glen, dlen - glen, l->addr,
                  &l->mon_state, l->bearer_id);
 
         /* Send NACK if peer has sent pkts we haven't received yet */
         if ((reply || msg_is_keepalive(hdr)) &&
             more(peers_snd_nxt, rcv_nxt) &&
             !tipc_link_is_synching(l) &&
             skb_queue_empty(&l->deferdq))
             rcvgap = peers_snd_nxt - l->rcv_nxt;
         if (rcvgap || reply)
             tipc_link_build_proto_msg(l, STATE_MSG, 0, reply,
                           rcvgap, 0, 0, xmitq);
 
         released = tipc_link_advance_transmq(l, l, ack, gap, ga, xmitq,
                              &retransmitted, &rc);
         if (gap)
             l->stats.recv_nacks++;
         if (released || retransmitted)
             tipc_link_update_cwin(l, released, retransmitted);
         if (released)
             tipc_link_advance_backlog(l, xmitq);
         if (unlikely(!skb_queue_empty(&l->wakeupq)))
             link_prepare_wakeup(l);
     }
 exit:
     kfree_skb(skb);
     return rc;
 }
 
 /* tipc_link_build_bc_proto_msg() - create broadcast protocol message
  */
 static bool tipc_link_build_bc_proto_msg(struct tipc_link *l, bool bcast,
                      u16 peers_snd_nxt,
                      struct sk_buff_head *xmitq)
 {
     struct sk_buff *skb;
     struct tipc_msg *hdr;
     struct sk_buff *dfrd_skb = skb_peek(&l->deferdq);
     u16 ack = l->rcv_nxt - 1;
     u16 gap_to = peers_snd_nxt - 1;
 
     skb = tipc_msg_create(BCAST_PROTOCOL, STATE_MSG, INT_H_SIZE,
                   0, l->addr, tipc_own_addr(l->net), 0, 0, 0);
     if (!skb)
         return false;
     hdr = buf_msg(skb);
     msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
     msg_set_bcast_ack(hdr, ack);
     msg_set_bcgap_after(hdr, ack);
     if (dfrd_skb)
         gap_to = buf_seqno(dfrd_skb) - 1;
     msg_set_bcgap_to(hdr, gap_to);
     msg_set_non_seq(hdr, bcast);
     __skb_queue_tail(xmitq, skb);
     return true;
 }
 
 /* tipc_link_build_bc_init_msg() - synchronize broadcast link endpoints.
  *
  * Give a newly added peer node the sequence number where it should
  * start receiving and acking broadcast packets.
  */
 static void tipc_link_build_bc_init_msg(struct tipc_link *l,
                     struct sk_buff_head *xmitq)
 {
     struct sk_buff_head list;
 
     __skb_queue_head_init(&list);
     if (!tipc_link_build_bc_proto_msg(l->bc_rcvlink, false, 0, &list))
         return;
     msg_set_bc_ack_invalid(buf_msg(skb_peek(&list)), true);
     tipc_link_xmit(l, &list, xmitq);
 }
 
 /* tipc_link_bc_init_rcv - receive initial broadcast synch data from peer
  */
 void tipc_link_bc_init_rcv(struct tipc_link *l, struct tipc_msg *hdr)
 {
     int mtyp = msg_type(hdr);
     u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
 
     if (link_is_up(l))
         return;
 
     if (msg_user(hdr) == BCAST_PROTOCOL) {
         l->rcv_nxt = peers_snd_nxt;
         l->state = LINK_ESTABLISHED;
         return;
     }
 
     if (l->peer_caps & TIPC_BCAST_SYNCH)
         return;
 
     if (msg_peer_node_is_up(hdr))
         return;
 
     /* Compatibility: accept older, less safe initial synch data */
     if ((mtyp == RESET_MSG) || (mtyp == ACTIVATE_MSG))
         l->rcv_nxt = peers_snd_nxt;
 }
 
 /* tipc_link_bc_sync_rcv - update rcv link according to peer's send state
  */
 int tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
               struct sk_buff_head *xmitq)
 {
     u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
     int rc = 0;
 
     if (!link_is_up(l))
         return rc;
 
     if (!msg_peer_node_is_up(hdr))
         return rc;
 
     /* Open when peer acknowledges our bcast init msg (pkt #1) */
     if (msg_ack(hdr))
         l->bc_peer_is_up = true;
 
     if (!l->bc_peer_is_up)
         return rc;
 
     /* Ignore if peers_snd_nxt goes beyond receive window */
     if (more(peers_snd_nxt, l->rcv_nxt + l->window))
         return rc;
 
     l->snd_nxt = peers_snd_nxt;
     if (link_bc_rcv_gap(l))
         rc |= TIPC_LINK_SND_STATE;
 
     /* Return now if sender supports nack via STATE messages */
     if (l->peer_caps & TIPC_BCAST_STATE_NACK)
         return rc;
 
     /* Otherwise, be backwards compatible */
 
     if (!more(peers_snd_nxt, l->rcv_nxt)) {
         l->nack_state = BC_NACK_SND_CONDITIONAL;
         return 0;
     }
 
     /* Don't NACK if one was recently sent or peeked */
     if (l->nack_state == BC_NACK_SND_SUPPRESS) {
         l->nack_state = BC_NACK_SND_UNCONDITIONAL;
         return 0;
     }
 
     /* Conditionally delay NACK sending until next synch rcv */
     if (l->nack_state == BC_NACK_SND_CONDITIONAL) {
         l->nack_state = BC_NACK_SND_UNCONDITIONAL;
         if ((peers_snd_nxt - l->rcv_nxt) < TIPC_MIN_LINK_WIN)
             return 0;
     }
 
     /* Send NACK now but suppress next one */
     tipc_link_build_bc_proto_msg(l, true, peers_snd_nxt, xmitq);
     l->nack_state = BC_NACK_SND_SUPPRESS;
     return 0;
 }
 
 int tipc_link_bc_ack_rcv(struct tipc_link *r, u16 acked, u16 gap,
              struct tipc_gap_ack_blks *ga,
              struct sk_buff_head *xmitq,
              struct sk_buff_head *retrq)
 {
     struct tipc_link *l = r->bc_sndlink;
     bool unused = false;
     int rc = 0;
 
     if (!link_is_up(r) || !r->bc_peer_is_up)
         return 0;
 
     if (gap) {
         l->stats.recv_nacks++;
         r->stats.recv_nacks++;
     }
 
     if (less(acked, r->acked) || (acked == r->acked && !gap && !ga))
         return 0;
 
     trace_tipc_link_bc_ack(r, acked, gap, &l->transmq);
     tipc_link_advance_transmq(l, r, acked, gap, ga, retrq, &unused, &rc);
 
     tipc_link_advance_backlog(l, xmitq);
     if (unlikely(!skb_queue_empty(&l->wakeupq)))
         link_prepare_wakeup(l);
 
     return rc;
 }
 
 /* tipc_link_bc_nack_rcv(): receive broadcast nack message
  * This function is here for backwards compatibility, since
  * no BCAST_PROTOCOL/STATE messages occur from TIPC v2.5.
  */
 int tipc_link_bc_nack_rcv(struct tipc_link *l, struct sk_buff *skb,
               struct sk_buff_head *xmitq)
 {
     struct tipc_msg *hdr = buf_msg(skb);
     u32 dnode = msg_destnode(hdr);
     int mtyp = msg_type(hdr);
     u16 acked = msg_bcast_ack(hdr);
     u16 from = acked + 1;
     u16 to = msg_bcgap_to(hdr);
     u16 peers_snd_nxt = to + 1;
     int rc = 0;
 
     kfree_skb(skb);
 
     if (!tipc_link_is_up(l) || !l->bc_peer_is_up)
         return 0;
 
     if (mtyp != STATE_MSG)
         return 0;
 
     if (dnode == tipc_own_addr(l->net)) {
         rc = tipc_link_bc_ack_rcv(l, acked, to - acked, NULL, xmitq,
                       xmitq);
         l->stats.recv_nacks++;
         return rc;
     }
 
     /* Msg for other node => suppress own NACK at next sync if applicable */
     if (more(peers_snd_nxt, l->rcv_nxt) && !less(l->rcv_nxt, from))
         l->nack_state = BC_NACK_SND_SUPPRESS;
 
     return 0;
 }
 
 void tipc_link_set_queue_limits(struct tipc_link *l, u32 min_win, u32 max_win)
 {
     int max_bulk = TIPC_MAX_PUBL / (l->mtu / ITEM_SIZE);
 
     l->min_win = min_win;
     l->ssthresh = max_win;
     l->max_win = max_win;
     l->window = min_win;
     l->backlog[TIPC_LOW_IMPORTANCE].limit      = min_win * 2;
     l->backlog[TIPC_MEDIUM_IMPORTANCE].limit   = min_win * 4;
     l->backlog[TIPC_HIGH_IMPORTANCE].limit     = min_win * 6;
     l->backlog[TIPC_CRITICAL_IMPORTANCE].limit = min_win * 8;
     l->backlog[TIPC_SYSTEM_IMPORTANCE].limit   = max_bulk;
 }
 
 /**
  * tipc_link_reset_stats - reset link statistics
  * @l: pointer to link
  */
 void tipc_link_reset_stats(struct tipc_link *l)
 {
     memset(&l->stats, 0, sizeof(l->stats));
 }
 
 static void link_print(struct tipc_link *l, const char *str)
 {
     struct sk_buff *hskb = skb_peek(&l->transmq);
     u16 head = hskb ? msg_seqno(buf_msg(hskb)) : l->snd_nxt - 1;
     u16 tail = l->snd_nxt - 1;
 
     pr_info("%s Link <%s> state %x\n", str, l->name, l->state);
     pr_info("XMTQ: %u [%u-%u], BKLGQ: %u, SNDNX: %u, RCVNX: %u\n",
         skb_queue_len(&l->transmq), head, tail,
         skb_queue_len(&l->backlogq), l->snd_nxt, l->rcv_nxt);
 }
 
 /* Parse and validate nested (link) properties valid for media, bearer and link
  */
 int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[])
 {
     int err;
 
     err = nla_parse_nested_deprecated(props, TIPC_NLA_PROP_MAX, prop,
                       tipc_nl_prop_policy, NULL);
     if (err)
         return err;
 
     if (props[TIPC_NLA_PROP_PRIO]) {
         u32 prio;
 
         prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
         if (prio > TIPC_MAX_LINK_PRI)
             return -EINVAL;
     }
 
     if (props[TIPC_NLA_PROP_TOL]) {
         u32 tol;
 
         tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
         if ((tol < TIPC_MIN_LINK_TOL) || (tol > TIPC_MAX_LINK_TOL))
             return -EINVAL;
     }
 
     if (props[TIPC_NLA_PROP_WIN]) {
         u32 max_win;
 
         max_win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
         if (max_win < TIPC_DEF_LINK_WIN || max_win > TIPC_MAX_LINK_WIN)
             return -EINVAL;
     }
 
     return 0;
 }
 
 static int __tipc_nl_add_stats(struct sk_buff *skb, struct tipc_stats *s)
 {
     int i;
     struct nlattr *stats;
 
     struct nla_map {
         u32 key;
         u32 val;
     };
 
     struct nla_map map[] = {
         {TIPC_NLA_STATS_RX_INFO, 0},
         {TIPC_NLA_STATS_RX_FRAGMENTS, s->recv_fragments},
         {TIPC_NLA_STATS_RX_FRAGMENTED, s->recv_fragmented},
         {TIPC_NLA_STATS_RX_BUNDLES, s->recv_bundles},
         {TIPC_NLA_STATS_RX_BUNDLED, s->recv_bundled},
         {TIPC_NLA_STATS_TX_INFO, 0},
         {TIPC_NLA_STATS_TX_FRAGMENTS, s->sent_fragments},
         {TIPC_NLA_STATS_TX_FRAGMENTED, s->sent_fragmented},
         {TIPC_NLA_STATS_TX_BUNDLES, s->sent_bundles},
         {TIPC_NLA_STATS_TX_BUNDLED, s->sent_bundled},
         {TIPC_NLA_STATS_MSG_PROF_TOT, (s->msg_length_counts) ?
             s->msg_length_counts : 1},
         {TIPC_NLA_STATS_MSG_LEN_CNT, s->msg_length_counts},
         {TIPC_NLA_STATS_MSG_LEN_TOT, s->msg_lengths_total},
         {TIPC_NLA_STATS_MSG_LEN_P0, s->msg_length_profile[0]},
         {TIPC_NLA_STATS_MSG_LEN_P1, s->msg_length_profile[1]},
         {TIPC_NLA_STATS_MSG_LEN_P2, s->msg_length_profile[2]},
         {TIPC_NLA_STATS_MSG_LEN_P3, s->msg_length_profile[3]},
         {TIPC_NLA_STATS_MSG_LEN_P4, s->msg_length_profile[4]},
         {TIPC_NLA_STATS_MSG_LEN_P5, s->msg_length_profile[5]},
         {TIPC_NLA_STATS_MSG_LEN_P6, s->msg_length_profile[6]},
         {TIPC_NLA_STATS_RX_STATES, s->recv_states},
         {TIPC_NLA_STATS_RX_PROBES, s->recv_probes},
         {TIPC_NLA_STATS_RX_NACKS, s->recv_nacks},
         {TIPC_NLA_STATS_RX_DEFERRED, s->deferred_recv},
         {TIPC_NLA_STATS_TX_STATES, s->sent_states},
         {TIPC_NLA_STATS_TX_PROBES, s->sent_probes},
         {TIPC_NLA_STATS_TX_NACKS, s->sent_nacks},
         {TIPC_NLA_STATS_TX_ACKS, s->sent_acks},
         {TIPC_NLA_STATS_RETRANSMITTED, s->retransmitted},
         {TIPC_NLA_STATS_DUPLICATES, s->duplicates},
         {TIPC_NLA_STATS_LINK_CONGS, s->link_congs},
         {TIPC_NLA_STATS_MAX_QUEUE, s->max_queue_sz},
         {TIPC_NLA_STATS_AVG_QUEUE, s->queue_sz_counts ?
             (s->accu_queue_sz / s->queue_sz_counts) : 0}
     };
 
     stats = nla_nest_start_noflag(skb, TIPC_NLA_LINK_STATS);
     if (!stats)
         return -EMSGSIZE;
 
     for (i = 0; i <  ARRAY_SIZE(map); i++)
         if (nla_put_u32(skb, map[i].key, map[i].val))
             goto msg_full;
 
     nla_nest_end(skb, stats);
 
     return 0;
 msg_full:
     nla_nest_cancel(skb, stats);
 
     return -EMSGSIZE;
 }
 
 /* Caller should hold appropriate locks to protect the link */
 int __tipc_nl_add_link(struct net *net, struct tipc_nl_msg *msg,
                struct tipc_link *link, int nlflags)
 {
     u32 self = tipc_own_addr(net);
     struct nlattr *attrs;
     struct nlattr *prop;
     void *hdr;
     int err;
 
     hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
               nlflags, TIPC_NL_LINK_GET);
     if (!hdr)
         return -EMSGSIZE;
 
     attrs = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK);
     if (!attrs)
         goto msg_full;
 
     if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, link->name))
         goto attr_msg_full;
     if (nla_put_u32(msg->skb, TIPC_NLA_LINK_DEST, tipc_cluster_mask(self)))
         goto attr_msg_full;
     if (nla_put_u32(msg->skb, TIPC_NLA_LINK_MTU, link->mtu))
         goto attr_msg_full;
     if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, link->stats.recv_pkts))
         goto attr_msg_full;
     if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, link->stats.sent_pkts))
         goto attr_msg_full;
 
     if (tipc_link_is_up(link))
         if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
             goto attr_msg_full;
     if (link->active)
         if (nla_put_flag(msg->skb, TIPC_NLA_LINK_ACTIVE))
             goto attr_msg_full;
 
     prop = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK_PROP);
     if (!prop)
         goto attr_msg_full;
     if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
         goto prop_msg_full;
     if (nla_put_u32(msg->skb, TIPC_NLA_PROP_TOL, link->tolerance))
         goto prop_msg_full;
     if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN,
             link->window))
         goto prop_msg_full;
     if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
         goto prop_msg_full;
     nla_nest_end(msg->skb, prop);
 
     err = __tipc_nl_add_stats(msg->skb, &link->stats);
     if (err)
         goto attr_msg_full;
 
     nla_nest_end(msg->skb, attrs);
     genlmsg_end(msg->skb, hdr);
 
     return 0;
 
 prop_msg_full:
     nla_nest_cancel(msg->skb, prop);
 attr_msg_full:
     nla_nest_cancel(msg->skb, attrs);
 msg_full:
     genlmsg_cancel(msg->skb, hdr);
 
     return -EMSGSIZE;
 }
 
 static int __tipc_nl_add_bc_link_stat(struct sk_buff *skb,
                       struct tipc_stats *stats)
 {
     int i;
     struct nlattr *nest;
 
     struct nla_map {
         __u32 key;
         __u32 val;
     };
 
     struct nla_map map[] = {
         {TIPC_NLA_STATS_RX_INFO, stats->recv_pkts},
         {TIPC_NLA_STATS_RX_FRAGMENTS, stats->recv_fragments},
         {TIPC_NLA_STATS_RX_FRAGMENTED, stats->recv_fragmented},
         {TIPC_NLA_STATS_RX_BUNDLES, stats->recv_bundles},
         {TIPC_NLA_STATS_RX_BUNDLED, stats->recv_bundled},
         {TIPC_NLA_STATS_TX_INFO, stats->sent_pkts},
         {TIPC_NLA_STATS_TX_FRAGMENTS, stats->sent_fragments},
         {TIPC_NLA_STATS_TX_FRAGMENTED, stats->sent_fragmented},
         {TIPC_NLA_STATS_TX_BUNDLES, stats->sent_bundles},
         {TIPC_NLA_STATS_TX_BUNDLED, stats->sent_bundled},
         {TIPC_NLA_STATS_RX_NACKS, stats->recv_nacks},
         {TIPC_NLA_STATS_RX_DEFERRED, stats->deferred_recv},
         {TIPC_NLA_STATS_TX_NACKS, stats->sent_nacks},
         {TIPC_NLA_STATS_TX_ACKS, stats->sent_acks},
         {TIPC_NLA_STATS_RETRANSMITTED, stats->retransmitted},
         {TIPC_NLA_STATS_DUPLICATES, stats->duplicates},
         {TIPC_NLA_STATS_LINK_CONGS, stats->link_congs},
         {TIPC_NLA_STATS_MAX_QUEUE, stats->max_queue_sz},
         {TIPC_NLA_STATS_AVG_QUEUE, stats->queue_sz_counts ?
             (stats->accu_queue_sz / stats->queue_sz_counts) : 0}
     };
 
     nest = nla_nest_start_noflag(skb, TIPC_NLA_LINK_STATS);
     if (!nest)
         return -EMSGSIZE;
 
     for (i = 0; i <  ARRAY_SIZE(map); i++)
         if (nla_put_u32(skb, map[i].key, map[i].val))
             goto msg_full;
 
     nla_nest_end(skb, nest);
 
     return 0;
 msg_full:
     nla_nest_cancel(skb, nest);
 
     return -EMSGSIZE;
 }
 
 int tipc_nl_add_bc_link(struct net *net, struct tipc_nl_msg *msg,
             struct tipc_link *bcl)
 {
     int err;
     void *hdr;
     struct nlattr *attrs;
     struct nlattr *prop;
     u32 bc_mode = tipc_bcast_get_mode(net);
     u32 bc_ratio = tipc_bcast_get_broadcast_ratio(net);
 
     if (!bcl)
         return 0;
 
     tipc_bcast_lock(net);
 
     hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
               NLM_F_MULTI, TIPC_NL_LINK_GET);
     if (!hdr) {
         tipc_bcast_unlock(net);
         return -EMSGSIZE;
     }
 
     attrs = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK);
     if (!attrs)
         goto msg_full;
 
     /* The broadcast link is always up */
     if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
         goto attr_msg_full;
 
     if (nla_put_flag(msg->skb, TIPC_NLA_LINK_BROADCAST))
         goto attr_msg_full;
     if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, bcl->name))
         goto attr_msg_full;
     if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, 0))
         goto attr_msg_full;
     if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, 0))
         goto attr_msg_full;
 
     prop = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK_PROP);
     if (!prop)
         goto attr_msg_full;
     if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, bcl->max_win))
         goto prop_msg_full;
     if (nla_put_u32(msg->skb, TIPC_NLA_PROP_BROADCAST, bc_mode))
         goto prop_msg_full;
     if (bc_mode & BCLINK_MODE_SEL)
         if (nla_put_u32(msg->skb, TIPC_NLA_PROP_BROADCAST_RATIO,
                 bc_ratio))
             goto prop_msg_full;
     nla_nest_end(msg->skb, prop);
 
     err = __tipc_nl_add_bc_link_stat(msg->skb, &bcl->stats);
     if (err)
         goto attr_msg_full;
 
     tipc_bcast_unlock(net);
     nla_nest_end(msg->skb, attrs);
     genlmsg_end(msg->skb, hdr);
 
     return 0;
 
 prop_msg_full:
     nla_nest_cancel(msg->skb, prop);
 attr_msg_full:
     nla_nest_cancel(msg->skb, attrs);
 msg_full:
     tipc_bcast_unlock(net);
     genlmsg_cancel(msg->skb, hdr);
 
     return -EMSGSIZE;
 }
 
 void tipc_link_set_tolerance(struct tipc_link *l, u32 tol,
                  struct sk_buff_head *xmitq)
 {
     l->tolerance = tol;
     if (l->bc_rcvlink)
         l->bc_rcvlink->tolerance = tol;
     if (link_is_up(l))
         tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, tol, 0, xmitq);
 }
 
 void tipc_link_set_prio(struct tipc_link *l, u32 prio,
             struct sk_buff_head *xmitq)
 {
     l->priority = prio;
     tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, prio, xmitq);
 }
 
 void tipc_link_set_abort_limit(struct tipc_link *l, u32 limit)
 {
     l->abort_limit = limit;
 }
 
 /**
  * tipc_link_dump - dump TIPC link data
  * @l: tipc link to be dumped
  * @dqueues: bitmask to decide if any link queue to be dumped?
  *           - TIPC_DUMP_NONE: don't dump link queues
  *           - TIPC_DUMP_TRANSMQ: dump link transmq queue
  *           - TIPC_DUMP_BACKLOGQ: dump link backlog queue
  *           - TIPC_DUMP_DEFERDQ: dump link deferd queue
  *           - TIPC_DUMP_INPUTQ: dump link input queue
  *           - TIPC_DUMP_WAKEUP: dump link wakeup queue
  *           - TIPC_DUMP_ALL: dump all the link queues above
  * @buf: returned buffer of dump data in format
  */
 int tipc_link_dump(struct tipc_link *l, u16 dqueues, char *buf)
 {
     int i = 0;
     size_t sz = (dqueues) ? LINK_LMAX : LINK_LMIN;
     struct sk_buff_head *list;
     struct sk_buff *hskb, *tskb;
     u32 len;
 
     if (!l) {
         i += scnprintf(buf, sz, "link data: (null)\n");
         return i;
     }
 
     i += scnprintf(buf, sz, "link data: %x", l->addr);
     i += scnprintf(buf + i, sz - i, " %x", l->state);
     i += scnprintf(buf + i, sz - i, " %u", l->in_session);
     i += scnprintf(buf + i, sz - i, " %u", l->session);
     i += scnprintf(buf + i, sz - i, " %u", l->peer_session);
     i += scnprintf(buf + i, sz - i, " %u", l->snd_nxt);
     i += scnprintf(buf + i, sz - i, " %u", l->rcv_nxt);
     i += scnprintf(buf + i, sz - i, " %u", l->snd_nxt_state);
     i += scnprintf(buf + i, sz - i, " %u", l->rcv_nxt_state);
     i += scnprintf(buf + i, sz - i, " %x", l->peer_caps);
     i += scnprintf(buf + i, sz - i, " %u", l->silent_intv_cnt);
     i += scnprintf(buf + i, sz - i, " %u", l->rst_cnt);
     i += scnprintf(buf + i, sz - i, " %u", 0);
     i += scnprintf(buf + i, sz - i, " %u", 0);
     i += scnprintf(buf + i, sz - i, " %u", l->acked);
 
     list = &l->transmq;
     len = skb_queue_len(list);
     hskb = skb_peek(list);
     tskb = skb_peek_tail(list);
     i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
                (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
                (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
 
     list = &l->deferdq;
     len = skb_queue_len(list);
     hskb = skb_peek(list);
     tskb = skb_peek_tail(list);
     i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
                (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
                (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
 
     list = &l->backlogq;
     len = skb_queue_len(list);
     hskb = skb_peek(list);
     tskb = skb_peek_tail(list);
     i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
                (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
                (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
 
     list = l->inputq;
     len = skb_queue_len(list);
     hskb = skb_peek(list);
     tskb = skb_peek_tail(list);
     i += scnprintf(buf + i, sz - i, " | %u %u %u\n", len,
                (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
                (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
 
     if (dqueues & TIPC_DUMP_TRANSMQ) {
         i += scnprintf(buf + i, sz - i, "transmq: ");
         i += tipc_list_dump(&l->transmq, false, buf + i);
     }
     if (dqueues & TIPC_DUMP_BACKLOGQ) {
         i += scnprintf(buf + i, sz - i,
                    "backlogq: <%u %u %u %u %u>, ",
                    l->backlog[TIPC_LOW_IMPORTANCE].len,
                    l->backlog[TIPC_MEDIUM_IMPORTANCE].len,
                    l->backlog[TIPC_HIGH_IMPORTANCE].len,
                    l->backlog[TIPC_CRITICAL_IMPORTANCE].len,
                    l->backlog[TIPC_SYSTEM_IMPORTANCE].len);
         i += tipc_list_dump(&l->backlogq, false, buf + i);
     }
     if (dqueues & TIPC_DUMP_DEFERDQ) {
         i += scnprintf(buf + i, sz - i, "deferdq: ");
         i += tipc_list_dump(&l->deferdq, false, buf + i);
     }
     if (dqueues & TIPC_DUMP_INPUTQ) {
         i += scnprintf(buf + i, sz - i, "inputq: ");
         i += tipc_list_dump(l->inputq, false, buf + i);
     }
     if (dqueues & TIPC_DUMP_WAKEUP) {
         i += scnprintf(buf + i, sz - i, "wakeup: ");
         i += tipc_list_dump(&l->wakeupq, false, buf + i);
     }
 
     return i;
 }