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32 results

socket.c

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  • socket.c 103.09 KiB
    /*
     * net/tipc/socket.c: TIPC socket API
     *
     * Copyright (c) 2001-2007, 2012-2017, Ericsson AB
     * Copyright (c) 2004-2008, 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 <linux/rhashtable.h>
    #include <linux/sched/signal.h>
    
    #include "core.h"
    #include "name_table.h"
    #include "node.h"
    #include "link.h"
    #include "name_distr.h"
    #include "socket.h"
    #include "bcast.h"
    #include "netlink.h"
    #include "group.h"
    #include "trace.h"
    
    #define NAGLE_START_INIT	4
    #define NAGLE_START_MAX		1024
    #define CONN_TIMEOUT_DEFAULT    8000    /* default connect timeout = 8s */
    #define CONN_PROBING_INTV	msecs_to_jiffies(3600000)  /* [ms] => 1 h */
    #define TIPC_FWD_MSG		1
    #define TIPC_MAX_PORT		0xffffffff
    #define TIPC_MIN_PORT		1
    #define TIPC_ACK_RATE		4       /* ACK at 1/4 of of rcv window size */
    
    enum {
    	TIPC_LISTEN = TCP_LISTEN,
    	TIPC_ESTABLISHED = TCP_ESTABLISHED,
    	TIPC_OPEN = TCP_CLOSE,
    	TIPC_DISCONNECTING = TCP_CLOSE_WAIT,
    	TIPC_CONNECTING = TCP_SYN_SENT,
    };
    
    struct sockaddr_pair {
    	struct sockaddr_tipc sock;
    	struct sockaddr_tipc member;
    };
    
    /**
     * struct tipc_sock - TIPC socket structure
     * @sk: socket - interacts with 'port' and with user via the socket API
     * @conn_type: TIPC type used when connection was established
     * @conn_instance: TIPC instance used when connection was established
     * @published: non-zero if port has one or more associated names
     * @max_pkt: maximum packet size "hint" used when building messages sent by port
     * @maxnagle: maximum size of msg which can be subject to nagle
     * @portid: unique port identity in TIPC socket hash table
     * @phdr: preformatted message header used when sending messages
     * #cong_links: list of congested links
     * @publications: list of publications for port
     * @blocking_link: address of the congested link we are currently sleeping on
     * @pub_count: total # of publications port has made during its lifetime
     * @conn_timeout: the time we can wait for an unresponded setup request
     * @dupl_rcvcnt: number of bytes counted twice, in both backlog and rcv queue
     * @cong_link_cnt: number of congested links
     * @snt_unacked: # messages sent by socket, and not yet acked by peer
     * @rcv_unacked: # messages read by user, but not yet acked back to peer
     * @peer: 'connected' peer for dgram/rdm
     * @node: hash table node
     * @mc_method: cookie for use between socket and broadcast layer
     * @rcu: rcu struct for tipc_sock
     */
    struct tipc_sock {
    	struct sock sk;
    	u32 conn_type;
    	u32 conn_instance;
    	int published;
    	u32 max_pkt;
    	u32 maxnagle;
    	u32 portid;
    	struct tipc_msg phdr;
    	struct list_head cong_links;
    	struct list_head publications;
    	u32 pub_count;
    	atomic_t dupl_rcvcnt;
    	u16 conn_timeout;
    	bool probe_unacked;
    	u16 cong_link_cnt;
    	u16 snt_unacked;
    	u16 snd_win;
    	u16 peer_caps;
    	u16 rcv_unacked;
    	u16 rcv_win;
    	struct sockaddr_tipc peer;
    	struct rhash_head node;
    	struct tipc_mc_method mc_method;
    	struct rcu_head rcu;
    	struct tipc_group *group;
    	u32 oneway;
    	u32 nagle_start;
    	u16 snd_backlog;
    	u16 msg_acc;
    	u16 pkt_cnt;
    	bool expect_ack;
    	bool nodelay;
    	bool group_is_open;
    };
    
    static int tipc_sk_backlog_rcv(struct sock *sk, struct sk_buff *skb);
    static void tipc_data_ready(struct sock *sk);
    static void tipc_write_space(struct sock *sk);
    static void tipc_sock_destruct(struct sock *sk);
    static int tipc_release(struct socket *sock);
    static int tipc_accept(struct socket *sock, struct socket *new_sock, int flags,
    		       bool kern);
    static void tipc_sk_timeout(struct timer_list *t);
    static int tipc_sk_publish(struct tipc_sock *tsk, uint scope,
    			   struct tipc_name_seq const *seq);
    static int tipc_sk_withdraw(struct tipc_sock *tsk, uint scope,
    			    struct tipc_name_seq const *seq);
    static int tipc_sk_leave(struct tipc_sock *tsk);
    static struct tipc_sock *tipc_sk_lookup(struct net *net, u32 portid);
    static int tipc_sk_insert(struct tipc_sock *tsk);
    static void tipc_sk_remove(struct tipc_sock *tsk);
    static int __tipc_sendstream(struct socket *sock, struct msghdr *m, size_t dsz);
    static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dsz);
    static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack);
    
    static const struct proto_ops packet_ops;
    static const struct proto_ops stream_ops;
    static const struct proto_ops msg_ops;
    static struct proto tipc_proto;
    static const struct rhashtable_params tsk_rht_params;
    
    static u32 tsk_own_node(struct tipc_sock *tsk)
    {
    	return msg_prevnode(&tsk->phdr);
    }
    
    static u32 tsk_peer_node(struct tipc_sock *tsk)
    {
    	return msg_destnode(&tsk->phdr);
    }
    
    static u32 tsk_peer_port(struct tipc_sock *tsk)
    {
    	return msg_destport(&tsk->phdr);
    }
    
    static  bool tsk_unreliable(struct tipc_sock *tsk)
    {
    	return msg_src_droppable(&tsk->phdr) != 0;
    }
    
    static void tsk_set_unreliable(struct tipc_sock *tsk, bool unreliable)
    {
    	msg_set_src_droppable(&tsk->phdr, unreliable ? 1 : 0);
    }
    
    static bool tsk_unreturnable(struct tipc_sock *tsk)
    {
    	return msg_dest_droppable(&tsk->phdr) != 0;
    }
    
    static void tsk_set_unreturnable(struct tipc_sock *tsk, bool unreturnable)
    {
    	msg_set_dest_droppable(&tsk->phdr, unreturnable ? 1 : 0);
    }
    
    static int tsk_importance(struct tipc_sock *tsk)
    {
    	return msg_importance(&tsk->phdr);
    }
    
    static struct tipc_sock *tipc_sk(const struct sock *sk)
    {
    	return container_of(sk, struct tipc_sock, sk);
    }
    
    int tsk_set_importance(struct sock *sk, int imp)
    {
    	if (imp > TIPC_CRITICAL_IMPORTANCE)
    		return -EINVAL;
    	msg_set_importance(&tipc_sk(sk)->phdr, (u32)imp);
    	return 0;
    }
    
    static bool tsk_conn_cong(struct tipc_sock *tsk)
    {
    	return tsk->snt_unacked > tsk->snd_win;
    }
    
    static u16 tsk_blocks(int len)
    {
    	return ((len / FLOWCTL_BLK_SZ) + 1);
    }
    
    /* tsk_blocks(): translate a buffer size in bytes to number of
     * advertisable blocks, taking into account the ratio truesize(len)/len
     * We can trust that this ratio is always < 4 for len >= FLOWCTL_BLK_SZ
     */
    static u16 tsk_adv_blocks(int len)
    {
    	return len / FLOWCTL_BLK_SZ / 4;
    }
    
    /* tsk_inc(): increment counter for sent or received data
     * - If block based flow control is not supported by peer we
     *   fall back to message based ditto, incrementing the counter
     */
    static u16 tsk_inc(struct tipc_sock *tsk, int msglen)
    {
    	if (likely(tsk->peer_caps & TIPC_BLOCK_FLOWCTL))
    		return ((msglen / FLOWCTL_BLK_SZ) + 1);
    	return 1;
    }
    
    /* tsk_set_nagle - enable/disable nagle property by manipulating maxnagle
     */
    static void tsk_set_nagle(struct tipc_sock *tsk)
    {
    	struct sock *sk = &tsk->sk;
    
    	tsk->maxnagle = 0;
    	if (sk->sk_type != SOCK_STREAM)
    		return;
    	if (tsk->nodelay)
    		return;
    	if (!(tsk->peer_caps & TIPC_NAGLE))
    		return;
    	/* Limit node local buffer size to avoid receive queue overflow */
    	if (tsk->max_pkt == MAX_MSG_SIZE)
    		tsk->maxnagle = 1500;
    	else
    		tsk->maxnagle = tsk->max_pkt;
    }
    
    /**
     * tsk_advance_rx_queue - discard first buffer in socket receive queue
     *
     * Caller must hold socket lock
     */
    static void tsk_advance_rx_queue(struct sock *sk)
    {
    	trace_tipc_sk_advance_rx(sk, NULL, TIPC_DUMP_SK_RCVQ, " ");
    	kfree_skb(__skb_dequeue(&sk->sk_receive_queue));
    }
    
    /* tipc_sk_respond() : send response message back to sender
     */
    static void tipc_sk_respond(struct sock *sk, struct sk_buff *skb, int err)
    {
    	u32 selector;
    	u32 dnode;
    	u32 onode = tipc_own_addr(sock_net(sk));
    
    	if (!tipc_msg_reverse(onode, &skb, err))
    		return;
    
    	trace_tipc_sk_rej_msg(sk, skb, TIPC_DUMP_NONE, "@sk_respond!");
    	dnode = msg_destnode(buf_msg(skb));
    	selector = msg_origport(buf_msg(skb));
    	tipc_node_xmit_skb(sock_net(sk), skb, dnode, selector);
    }
    
    /**
     * tsk_rej_rx_queue - reject all buffers in socket receive queue
     *
     * Caller must hold socket lock
     */
    static void tsk_rej_rx_queue(struct sock *sk, int error)
    {
    	struct sk_buff *skb;
    
    	while ((skb = __skb_dequeue(&sk->sk_receive_queue)))
    		tipc_sk_respond(sk, skb, error);
    }
    
    static bool tipc_sk_connected(struct sock *sk)
    {
    	return sk->sk_state == TIPC_ESTABLISHED;
    }
    
    /* tipc_sk_type_connectionless - check if the socket is datagram socket
     * @sk: socket
     *
     * Returns true if connection less, false otherwise
     */
    static bool tipc_sk_type_connectionless(struct sock *sk)
    {
    	return sk->sk_type == SOCK_RDM || sk->sk_type == SOCK_DGRAM;
    }
    
    /* tsk_peer_msg - verify if message was sent by connected port's peer
     *
     * Handles cases where the node's network address has changed from
     * the default of <0.0.0> to its configured setting.
     */
    static bool tsk_peer_msg(struct tipc_sock *tsk, struct tipc_msg *msg)
    {
    	struct sock *sk = &tsk->sk;
    	u32 self = tipc_own_addr(sock_net(sk));
    	u32 peer_port = tsk_peer_port(tsk);
    	u32 orig_node, peer_node;
    
    	if (unlikely(!tipc_sk_connected(sk)))
    		return false;
    
    	if (unlikely(msg_origport(msg) != peer_port))
    		return false;
    
    	orig_node = msg_orignode(msg);
    	peer_node = tsk_peer_node(tsk);
    
    	if (likely(orig_node == peer_node))
    		return true;
    
    	if (!orig_node && peer_node == self)
    		return true;
    
    	if (!peer_node && orig_node == self)
    		return true;
    
    	return false;
    }
    
    /* tipc_set_sk_state - set the sk_state of the socket
     * @sk: socket
     *
     * Caller must hold socket lock
     *
     * Returns 0 on success, errno otherwise
     */
    static int tipc_set_sk_state(struct sock *sk, int state)
    {
    	int oldsk_state = sk->sk_state;
    	int res = -EINVAL;
    
    	switch (state) {
    	case TIPC_OPEN:
    		res = 0;
    		break;
    	case TIPC_LISTEN:
    	case TIPC_CONNECTING:
    		if (oldsk_state == TIPC_OPEN)
    			res = 0;
    		break;
    	case TIPC_ESTABLISHED:
    		if (oldsk_state == TIPC_CONNECTING ||
    		    oldsk_state == TIPC_OPEN)
    			res = 0;
    		break;
    	case TIPC_DISCONNECTING:
    		if (oldsk_state == TIPC_CONNECTING ||
    		    oldsk_state == TIPC_ESTABLISHED)
    			res = 0;
    		break;
    	}
    
    	if (!res)
    		sk->sk_state = state;
    
    	return res;
    }
    
    static int tipc_sk_sock_err(struct socket *sock, long *timeout)
    {
    	struct sock *sk = sock->sk;
    	int err = sock_error(sk);
    	int typ = sock->type;
    
    	if (err)
    		return err;
    	if (typ == SOCK_STREAM || typ == SOCK_SEQPACKET) {
    		if (sk->sk_state == TIPC_DISCONNECTING)
    			return -EPIPE;
    		else if (!tipc_sk_connected(sk))
    			return -ENOTCONN;
    	}
    	if (!*timeout)
    		return -EAGAIN;
    	if (signal_pending(current))
    		return sock_intr_errno(*timeout);
    
    	return 0;
    }
    
    #define tipc_wait_for_cond(sock_, timeo_, condition_)			       \
    ({                                                                             \
    	DEFINE_WAIT_FUNC(wait_, woken_wake_function);                          \
    	struct sock *sk_;						       \
    	int rc_;							       \
    									       \
    	while ((rc_ = !(condition_))) {					       \
    		/* coupled with smp_wmb() in tipc_sk_proto_rcv() */            \
    		smp_rmb();                                                     \
    		sk_ = (sock_)->sk;					       \
    		rc_ = tipc_sk_sock_err((sock_), timeo_);		       \
    		if (rc_)						       \
    			break;						       \
    		add_wait_queue(sk_sleep(sk_), &wait_);                         \
    		release_sock(sk_);					       \
    		*(timeo_) = wait_woken(&wait_, TASK_INTERRUPTIBLE, *(timeo_)); \
    		sched_annotate_sleep();				               \
    		lock_sock(sk_);						       \
    		remove_wait_queue(sk_sleep(sk_), &wait_);		       \
    	}								       \
    	rc_;								       \
    })
    
    /**
     * tipc_sk_create - create a TIPC socket
     * @net: network namespace (must be default network)
     * @sock: pre-allocated socket structure
     * @protocol: protocol indicator (must be 0)
     * @kern: caused by kernel or by userspace?
     *
     * This routine creates additional data structures used by the TIPC socket,
     * initializes them, and links them together.
     *
     * Returns 0 on success, errno otherwise
     */
    static int tipc_sk_create(struct net *net, struct socket *sock,
    			  int protocol, int kern)
    {
    	const struct proto_ops *ops;
    	struct sock *sk;
    	struct tipc_sock *tsk;
    	struct tipc_msg *msg;
    
    	/* Validate arguments */
    	if (unlikely(protocol != 0))
    		return -EPROTONOSUPPORT;
    
    	switch (sock->type) {
    	case SOCK_STREAM:
    		ops = &stream_ops;
    		break;
    	case SOCK_SEQPACKET:
    		ops = &packet_ops;
    		break;
    	case SOCK_DGRAM:
    	case SOCK_RDM:
    		ops = &msg_ops;
    		break;
    	default:
    		return -EPROTOTYPE;
    	}
    
    	/* Allocate socket's protocol area */
    	sk = sk_alloc(net, AF_TIPC, GFP_KERNEL, &tipc_proto, kern);
    	if (sk == NULL)
    		return -ENOMEM;
    
    	tsk = tipc_sk(sk);
    	tsk->max_pkt = MAX_PKT_DEFAULT;
    	tsk->maxnagle = 0;
    	tsk->nagle_start = NAGLE_START_INIT;
    	INIT_LIST_HEAD(&tsk->publications);
    	INIT_LIST_HEAD(&tsk->cong_links);
    	msg = &tsk->phdr;
    
    	/* Finish initializing socket data structures */
    	sock->ops = ops;
    	sock_init_data(sock, sk);
    	tipc_set_sk_state(sk, TIPC_OPEN);
    	if (tipc_sk_insert(tsk)) {
    		pr_warn("Socket create failed; port number exhausted\n");
    		return -EINVAL;
    	}
    
    	/* Ensure tsk is visible before we read own_addr. */
    	smp_mb();
    
    	tipc_msg_init(tipc_own_addr(net), msg, TIPC_LOW_IMPORTANCE,
    		      TIPC_NAMED_MSG, NAMED_H_SIZE, 0);
    
    	msg_set_origport(msg, tsk->portid);
    	timer_setup(&sk->sk_timer, tipc_sk_timeout, 0);
    	sk->sk_shutdown = 0;
    	sk->sk_backlog_rcv = tipc_sk_backlog_rcv;
    	sk->sk_rcvbuf = sysctl_tipc_rmem[1];
    	sk->sk_data_ready = tipc_data_ready;
    	sk->sk_write_space = tipc_write_space;
    	sk->sk_destruct = tipc_sock_destruct;
    	tsk->conn_timeout = CONN_TIMEOUT_DEFAULT;
    	tsk->group_is_open = true;
    	atomic_set(&tsk->dupl_rcvcnt, 0);
    
    	/* Start out with safe limits until we receive an advertised window */
    	tsk->snd_win = tsk_adv_blocks(RCVBUF_MIN);
    	tsk->rcv_win = tsk->snd_win;
    
    	if (tipc_sk_type_connectionless(sk)) {
    		tsk_set_unreturnable(tsk, true);
    		if (sock->type == SOCK_DGRAM)
    			tsk_set_unreliable(tsk, true);
    	}
    	__skb_queue_head_init(&tsk->mc_method.deferredq);
    	trace_tipc_sk_create(sk, NULL, TIPC_DUMP_NONE, " ");
    	return 0;
    }
    
    static void tipc_sk_callback(struct rcu_head *head)
    {
    	struct tipc_sock *tsk = container_of(head, struct tipc_sock, rcu);
    
    	sock_put(&tsk->sk);
    }
    
    /* Caller should hold socket lock for the socket. */
    static void __tipc_shutdown(struct socket *sock, int error)
    {
    	struct sock *sk = sock->sk;
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct net *net = sock_net(sk);
    	long timeout = msecs_to_jiffies(CONN_TIMEOUT_DEFAULT);
    	u32 dnode = tsk_peer_node(tsk);
    	struct sk_buff *skb;
    
    	/* Avoid that hi-prio shutdown msgs bypass msgs in link wakeup queue */
    	tipc_wait_for_cond(sock, &timeout, (!tsk->cong_link_cnt &&
    					    !tsk_conn_cong(tsk)));
    
    	/* Push out delayed messages if in Nagle mode */
    	tipc_sk_push_backlog(tsk, false);
    	/* Remove pending SYN */
    	__skb_queue_purge(&sk->sk_write_queue);
    
    	/* Remove partially received buffer if any */
    	skb = skb_peek(&sk->sk_receive_queue);
    	if (skb && TIPC_SKB_CB(skb)->bytes_read) {
    		__skb_unlink(skb, &sk->sk_receive_queue);
    		kfree_skb(skb);
    	}
    
    	/* Reject all unreceived messages if connectionless */
    	if (tipc_sk_type_connectionless(sk)) {
    		tsk_rej_rx_queue(sk, error);
    		return;
    	}
    
    	switch (sk->sk_state) {
    	case TIPC_CONNECTING:
    	case TIPC_ESTABLISHED:
    		tipc_set_sk_state(sk, TIPC_DISCONNECTING);
    		tipc_node_remove_conn(net, dnode, tsk->portid);
    		/* Send a FIN+/- to its peer */
    		skb = __skb_dequeue(&sk->sk_receive_queue);
    		if (skb) {
    			__skb_queue_purge(&sk->sk_receive_queue);
    			tipc_sk_respond(sk, skb, error);
    			break;
    		}
    		skb = tipc_msg_create(TIPC_CRITICAL_IMPORTANCE,
    				      TIPC_CONN_MSG, SHORT_H_SIZE, 0, dnode,
    				      tsk_own_node(tsk), tsk_peer_port(tsk),
    				      tsk->portid, error);
    		if (skb)
    			tipc_node_xmit_skb(net, skb, dnode, tsk->portid);
    		break;
    	case TIPC_LISTEN:
    		/* Reject all SYN messages */
    		tsk_rej_rx_queue(sk, error);
    		break;
    	default:
    		__skb_queue_purge(&sk->sk_receive_queue);
    		break;
    	}
    }
    
    /**
     * tipc_release - destroy a TIPC socket
     * @sock: socket to destroy
     *
     * This routine cleans up any messages that are still queued on the socket.
     * For DGRAM and RDM socket types, all queued messages are rejected.
     * For SEQPACKET and STREAM socket types, the first message is rejected
     * and any others are discarded.  (If the first message on a STREAM socket
     * is partially-read, it is discarded and the next one is rejected instead.)
     *
     * NOTE: Rejected messages are not necessarily returned to the sender!  They
     * are returned or discarded according to the "destination droppable" setting
     * specified for the message by the sender.
     *
     * Returns 0 on success, errno otherwise
     */
    static int tipc_release(struct socket *sock)
    {
    	struct sock *sk = sock->sk;
    	struct tipc_sock *tsk;
    
    	/*
    	 * Exit if socket isn't fully initialized (occurs when a failed accept()
    	 * releases a pre-allocated child socket that was never used)
    	 */
    	if (sk == NULL)
    		return 0;
    
    	tsk = tipc_sk(sk);
    	lock_sock(sk);
    
    	trace_tipc_sk_release(sk, NULL, TIPC_DUMP_ALL, " ");
    	__tipc_shutdown(sock, TIPC_ERR_NO_PORT);
    	sk->sk_shutdown = SHUTDOWN_MASK;
    	tipc_sk_leave(tsk);
    	tipc_sk_withdraw(tsk, 0, NULL);
    	__skb_queue_purge(&tsk->mc_method.deferredq);
    	sk_stop_timer(sk, &sk->sk_timer);
    	tipc_sk_remove(tsk);
    
    	sock_orphan(sk);
    	/* Reject any messages that accumulated in backlog queue */
    	release_sock(sk);
    	tipc_dest_list_purge(&tsk->cong_links);
    	tsk->cong_link_cnt = 0;
    	call_rcu(&tsk->rcu, tipc_sk_callback);
    	sock->sk = NULL;
    
    	return 0;
    }
    
    /**
     * tipc_bind - associate or disassocate TIPC name(s) with a socket
     * @sock: socket structure
     * @uaddr: socket address describing name(s) and desired operation
     * @uaddr_len: size of socket address data structure
     *
     * Name and name sequence binding is indicated using a positive scope value;
     * a negative scope value unbinds the specified name.  Specifying no name
     * (i.e. a socket address length of 0) unbinds all names from the socket.
     *
     * Returns 0 on success, errno otherwise
     *
     * NOTE: This routine doesn't need to take the socket lock since it doesn't
     *       access any non-constant socket information.
     */
    static int tipc_bind(struct socket *sock, struct sockaddr *uaddr,
    		     int uaddr_len)
    {
    	struct sock *sk = sock->sk;
    	struct sockaddr_tipc *addr = (struct sockaddr_tipc *)uaddr;
    	struct tipc_sock *tsk = tipc_sk(sk);
    	int res = -EINVAL;
    
    	lock_sock(sk);
    	if (unlikely(!uaddr_len)) {
    		res = tipc_sk_withdraw(tsk, 0, NULL);
    		goto exit;
    	}
    	if (tsk->group) {
    		res = -EACCES;
    		goto exit;
    	}
    	if (uaddr_len < sizeof(struct sockaddr_tipc)) {
    		res = -EINVAL;
    		goto exit;
    	}
    	if (addr->family != AF_TIPC) {
    		res = -EAFNOSUPPORT;
    		goto exit;
    	}
    
    	if (addr->addrtype == TIPC_ADDR_NAME)
    		addr->addr.nameseq.upper = addr->addr.nameseq.lower;
    	else if (addr->addrtype != TIPC_ADDR_NAMESEQ) {
    		res = -EAFNOSUPPORT;
    		goto exit;
    	}
    
    	if ((addr->addr.nameseq.type < TIPC_RESERVED_TYPES) &&
    	    (addr->addr.nameseq.type != TIPC_TOP_SRV) &&
    	    (addr->addr.nameseq.type != TIPC_CFG_SRV)) {
    		res = -EACCES;
    		goto exit;
    	}
    
    	res = (addr->scope >= 0) ?
    		tipc_sk_publish(tsk, addr->scope, &addr->addr.nameseq) :
    		tipc_sk_withdraw(tsk, -addr->scope, &addr->addr.nameseq);
    exit:
    	release_sock(sk);
    	return res;
    }
    
    /**
     * tipc_getname - get port ID of socket or peer socket
     * @sock: socket structure
     * @uaddr: area for returned socket address
     * @uaddr_len: area for returned length of socket address
     * @peer: 0 = own ID, 1 = current peer ID, 2 = current/former peer ID
     *
     * Returns 0 on success, errno otherwise
     *
     * NOTE: This routine doesn't need to take the socket lock since it only
     *       accesses socket information that is unchanging (or which changes in
     *       a completely predictable manner).
     */
    static int tipc_getname(struct socket *sock, struct sockaddr *uaddr,
    			int peer)
    {
    	struct sockaddr_tipc *addr = (struct sockaddr_tipc *)uaddr;
    	struct sock *sk = sock->sk;
    	struct tipc_sock *tsk = tipc_sk(sk);
    
    	memset(addr, 0, sizeof(*addr));
    	if (peer) {
    		if ((!tipc_sk_connected(sk)) &&
    		    ((peer != 2) || (sk->sk_state != TIPC_DISCONNECTING)))
    			return -ENOTCONN;
    		addr->addr.id.ref = tsk_peer_port(tsk);
    		addr->addr.id.node = tsk_peer_node(tsk);
    	} else {
    		addr->addr.id.ref = tsk->portid;
    		addr->addr.id.node = tipc_own_addr(sock_net(sk));
    	}
    
    	addr->addrtype = TIPC_ADDR_ID;
    	addr->family = AF_TIPC;
    	addr->scope = 0;
    	addr->addr.name.domain = 0;
    
    	return sizeof(*addr);
    }
    
    /**
     * tipc_poll - read and possibly block on pollmask
     * @file: file structure associated with the socket
     * @sock: socket for which to calculate the poll bits
     * @wait: ???
     *
     * Returns pollmask value
     *
     * COMMENTARY:
     * It appears that the usual socket locking mechanisms are not useful here
     * since the pollmask info is potentially out-of-date the moment this routine
     * exits.  TCP and other protocols seem to rely on higher level poll routines
     * to handle any preventable race conditions, so TIPC will do the same ...
     *
     * IMPORTANT: The fact that a read or write operation is indicated does NOT
     * imply that the operation will succeed, merely that it should be performed
     * and will not block.
     */
    static __poll_t tipc_poll(struct file *file, struct socket *sock,
    			      poll_table *wait)
    {
    	struct sock *sk = sock->sk;
    	struct tipc_sock *tsk = tipc_sk(sk);
    	__poll_t revents = 0;
    
    	sock_poll_wait(file, sock, wait);
    	trace_tipc_sk_poll(sk, NULL, TIPC_DUMP_ALL, " ");
    
    	if (sk->sk_shutdown & RCV_SHUTDOWN)
    		revents |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM;
    	if (sk->sk_shutdown == SHUTDOWN_MASK)
    		revents |= EPOLLHUP;
    
    	switch (sk->sk_state) {
    	case TIPC_ESTABLISHED:
    		if (!tsk->cong_link_cnt && !tsk_conn_cong(tsk))
    			revents |= EPOLLOUT;
    		/* fall through */
    	case TIPC_LISTEN:
    	case TIPC_CONNECTING:
    		if (!skb_queue_empty_lockless(&sk->sk_receive_queue))
    			revents |= EPOLLIN | EPOLLRDNORM;
    		break;
    	case TIPC_OPEN:
    		if (tsk->group_is_open && !tsk->cong_link_cnt)
    			revents |= EPOLLOUT;
    		if (!tipc_sk_type_connectionless(sk))
    			break;
    		if (skb_queue_empty_lockless(&sk->sk_receive_queue))
    			break;
    		revents |= EPOLLIN | EPOLLRDNORM;
    		break;
    	case TIPC_DISCONNECTING:
    		revents = EPOLLIN | EPOLLRDNORM | EPOLLHUP;
    		break;
    	}
    	return revents;
    }
    
    /**
     * tipc_sendmcast - send multicast message
     * @sock: socket structure
     * @seq: destination address
     * @msg: message to send
     * @dlen: length of data to send
     * @timeout: timeout to wait for wakeup
     *
     * Called from function tipc_sendmsg(), which has done all sanity checks
     * Returns the number of bytes sent on success, or errno
     */
    static int tipc_sendmcast(struct  socket *sock, struct tipc_name_seq *seq,
    			  struct msghdr *msg, size_t dlen, long timeout)
    {
    	struct sock *sk = sock->sk;
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct tipc_msg *hdr = &tsk->phdr;
    	struct net *net = sock_net(sk);
    	int mtu = tipc_bcast_get_mtu(net);
    	struct tipc_mc_method *method = &tsk->mc_method;
    	struct sk_buff_head pkts;
    	struct tipc_nlist dsts;
    	int rc;
    
    	if (tsk->group)
    		return -EACCES;
    
    	/* Block or return if any destination link is congested */
    	rc = tipc_wait_for_cond(sock, &timeout, !tsk->cong_link_cnt);
    	if (unlikely(rc))
    		return rc;
    
    	/* Lookup destination nodes */
    	tipc_nlist_init(&dsts, tipc_own_addr(net));
    	tipc_nametbl_lookup_dst_nodes(net, seq->type, seq->lower,
    				      seq->upper, &dsts);
    	if (!dsts.local && !dsts.remote)
    		return -EHOSTUNREACH;
    
    	/* Build message header */
    	msg_set_type(hdr, TIPC_MCAST_MSG);
    	msg_set_hdr_sz(hdr, MCAST_H_SIZE);
    	msg_set_lookup_scope(hdr, TIPC_CLUSTER_SCOPE);
    	msg_set_destport(hdr, 0);
    	msg_set_destnode(hdr, 0);
    	msg_set_nametype(hdr, seq->type);
    	msg_set_namelower(hdr, seq->lower);
    	msg_set_nameupper(hdr, seq->upper);
    
    	/* Build message as chain of buffers */
    	__skb_queue_head_init(&pkts);
    	rc = tipc_msg_build(hdr, msg, 0, dlen, mtu, &pkts);
    
    	/* Send message if build was successful */
    	if (unlikely(rc == dlen)) {
    		trace_tipc_sk_sendmcast(sk, skb_peek(&pkts),
    					TIPC_DUMP_SK_SNDQ, " ");
    		rc = tipc_mcast_xmit(net, &pkts, method, &dsts,
    				     &tsk->cong_link_cnt);
    	}
    
    	tipc_nlist_purge(&dsts);
    
    	return rc ? rc : dlen;
    }
    
    /**
     * tipc_send_group_msg - send a message to a member in the group
     * @net: network namespace
     * @m: message to send
     * @mb: group member
     * @dnode: destination node
     * @dport: destination port
     * @dlen: total length of message data
     */
    static int tipc_send_group_msg(struct net *net, struct tipc_sock *tsk,
    			       struct msghdr *m, struct tipc_member *mb,
    			       u32 dnode, u32 dport, int dlen)
    {
    	u16 bc_snd_nxt = tipc_group_bc_snd_nxt(tsk->group);
    	struct tipc_mc_method *method = &tsk->mc_method;
    	int blks = tsk_blocks(GROUP_H_SIZE + dlen);
    	struct tipc_msg *hdr = &tsk->phdr;
    	struct sk_buff_head pkts;
    	int mtu, rc;
    
    	/* Complete message header */
    	msg_set_type(hdr, TIPC_GRP_UCAST_MSG);
    	msg_set_hdr_sz(hdr, GROUP_H_SIZE);
    	msg_set_destport(hdr, dport);
    	msg_set_destnode(hdr, dnode);
    	msg_set_grp_bc_seqno(hdr, bc_snd_nxt);
    
    	/* Build message as chain of buffers */
    	__skb_queue_head_init(&pkts);
    	mtu = tipc_node_get_mtu(net, dnode, tsk->portid, false);
    	rc = tipc_msg_build(hdr, m, 0, dlen, mtu, &pkts);
    	if (unlikely(rc != dlen))
    		return rc;
    
    	/* Send message */
    	rc = tipc_node_xmit(net, &pkts, dnode, tsk->portid);
    	if (unlikely(rc == -ELINKCONG)) {
    		tipc_dest_push(&tsk->cong_links, dnode, 0);
    		tsk->cong_link_cnt++;
    	}
    
    	/* Update send window */
    	tipc_group_update_member(mb, blks);
    
    	/* A broadcast sent within next EXPIRE period must follow same path */
    	method->rcast = true;
    	method->mandatory = true;
    	return dlen;
    }
    
    /**
     * tipc_send_group_unicast - send message to a member in the group
     * @sock: socket structure
     * @m: message to send
     * @dlen: total length of message data
     * @timeout: timeout to wait for wakeup
     *
     * Called from function tipc_sendmsg(), which has done all sanity checks
     * Returns the number of bytes sent on success, or errno
     */
    static int tipc_send_group_unicast(struct socket *sock, struct msghdr *m,
    				   int dlen, long timeout)
    {
    	struct sock *sk = sock->sk;
    	DECLARE_SOCKADDR(struct sockaddr_tipc *, dest, m->msg_name);
    	int blks = tsk_blocks(GROUP_H_SIZE + dlen);
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct net *net = sock_net(sk);
    	struct tipc_member *mb = NULL;
    	u32 node, port;
    	int rc;
    
    	node = dest->addr.id.node;
    	port = dest->addr.id.ref;
    	if (!port && !node)
    		return -EHOSTUNREACH;
    
    	/* Block or return if destination link or member is congested */
    	rc = tipc_wait_for_cond(sock, &timeout,
    				!tipc_dest_find(&tsk->cong_links, node, 0) &&
    				tsk->group &&
    				!tipc_group_cong(tsk->group, node, port, blks,
    						 &mb));
    	if (unlikely(rc))
    		return rc;
    
    	if (unlikely(!mb))
    		return -EHOSTUNREACH;
    
    	rc = tipc_send_group_msg(net, tsk, m, mb, node, port, dlen);
    
    	return rc ? rc : dlen;
    }
    
    /**
     * tipc_send_group_anycast - send message to any member with given identity
     * @sock: socket structure
     * @m: message to send
     * @dlen: total length of message data
     * @timeout: timeout to wait for wakeup
     *
     * Called from function tipc_sendmsg(), which has done all sanity checks
     * Returns the number of bytes sent on success, or errno
     */
    static int tipc_send_group_anycast(struct socket *sock, struct msghdr *m,
    				   int dlen, long timeout)
    {
    	DECLARE_SOCKADDR(struct sockaddr_tipc *, dest, m->msg_name);
    	struct sock *sk = sock->sk;
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct list_head *cong_links = &tsk->cong_links;
    	int blks = tsk_blocks(GROUP_H_SIZE + dlen);
    	struct tipc_msg *hdr = &tsk->phdr;
    	struct tipc_member *first = NULL;
    	struct tipc_member *mbr = NULL;
    	struct net *net = sock_net(sk);
    	u32 node, port, exclude;
    	struct list_head dsts;
    	u32 type, inst, scope;
    	int lookups = 0;
    	int dstcnt, rc;
    	bool cong;
    
    	INIT_LIST_HEAD(&dsts);
    
    	type = msg_nametype(hdr);
    	inst = dest->addr.name.name.instance;
    	scope = msg_lookup_scope(hdr);
    
    	while (++lookups < 4) {
    		exclude = tipc_group_exclude(tsk->group);
    
    		first = NULL;
    
    		/* Look for a non-congested destination member, if any */
    		while (1) {
    			if (!tipc_nametbl_lookup(net, type, inst, scope, &dsts,
    						 &dstcnt, exclude, false))
    				return -EHOSTUNREACH;
    			tipc_dest_pop(&dsts, &node, &port);
    			cong = tipc_group_cong(tsk->group, node, port, blks,
    					       &mbr);
    			if (!cong)
    				break;
    			if (mbr == first)
    				break;
    			if (!first)
    				first = mbr;
    		}
    
    		/* Start over if destination was not in member list */
    		if (unlikely(!mbr))
    			continue;
    
    		if (likely(!cong && !tipc_dest_find(cong_links, node, 0)))
    			break;
    
    		/* Block or return if destination link or member is congested */
    		rc = tipc_wait_for_cond(sock, &timeout,
    					!tipc_dest_find(cong_links, node, 0) &&
    					tsk->group &&
    					!tipc_group_cong(tsk->group, node, port,
    							 blks, &mbr));
    		if (unlikely(rc))
    			return rc;
    
    		/* Send, unless destination disappeared while waiting */
    		if (likely(mbr))
    			break;
    	}
    
    	if (unlikely(lookups >= 4))
    		return -EHOSTUNREACH;
    
    	rc = tipc_send_group_msg(net, tsk, m, mbr, node, port, dlen);
    
    	return rc ? rc : dlen;
    }
    
    /**
     * tipc_send_group_bcast - send message to all members in communication group
     * @sk: socket structure
     * @m: message to send
     * @dlen: total length of message data
     * @timeout: timeout to wait for wakeup
     *
     * Called from function tipc_sendmsg(), which has done all sanity checks
     * Returns the number of bytes sent on success, or errno
     */
    static int tipc_send_group_bcast(struct socket *sock, struct msghdr *m,
    				 int dlen, long timeout)
    {
    	DECLARE_SOCKADDR(struct sockaddr_tipc *, dest, m->msg_name);
    	struct sock *sk = sock->sk;
    	struct net *net = sock_net(sk);
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct tipc_nlist *dsts;
    	struct tipc_mc_method *method = &tsk->mc_method;
    	bool ack = method->mandatory && method->rcast;
    	int blks = tsk_blocks(MCAST_H_SIZE + dlen);
    	struct tipc_msg *hdr = &tsk->phdr;
    	int mtu = tipc_bcast_get_mtu(net);
    	struct sk_buff_head pkts;
    	int rc = -EHOSTUNREACH;
    
    	/* Block or return if any destination link or member is congested */
    	rc = tipc_wait_for_cond(sock, &timeout,
    				!tsk->cong_link_cnt && tsk->group &&
    				!tipc_group_bc_cong(tsk->group, blks));
    	if (unlikely(rc))
    		return rc;
    
    	dsts = tipc_group_dests(tsk->group);
    	if (!dsts->local && !dsts->remote)
    		return -EHOSTUNREACH;
    
    	/* Complete message header */
    	if (dest) {
    		msg_set_type(hdr, TIPC_GRP_MCAST_MSG);
    		msg_set_nameinst(hdr, dest->addr.name.name.instance);
    	} else {
    		msg_set_type(hdr, TIPC_GRP_BCAST_MSG);
    		msg_set_nameinst(hdr, 0);
    	}
    	msg_set_hdr_sz(hdr, GROUP_H_SIZE);
    	msg_set_destport(hdr, 0);
    	msg_set_destnode(hdr, 0);
    	msg_set_grp_bc_seqno(hdr, tipc_group_bc_snd_nxt(tsk->group));
    
    	/* Avoid getting stuck with repeated forced replicasts */
    	msg_set_grp_bc_ack_req(hdr, ack);
    
    	/* Build message as chain of buffers */
    	__skb_queue_head_init(&pkts);
    	rc = tipc_msg_build(hdr, m, 0, dlen, mtu, &pkts);
    	if (unlikely(rc != dlen))
    		return rc;
    
    	/* Send message */
    	rc = tipc_mcast_xmit(net, &pkts, method, dsts, &tsk->cong_link_cnt);
    	if (unlikely(rc))
    		return rc;
    
    	/* Update broadcast sequence number and send windows */
    	tipc_group_update_bc_members(tsk->group, blks, ack);
    
    	/* Broadcast link is now free to choose method for next broadcast */
    	method->mandatory = false;
    	method->expires = jiffies;
    
    	return dlen;
    }
    
    /**
     * tipc_send_group_mcast - send message to all members with given identity
     * @sock: socket structure
     * @m: message to send
     * @dlen: total length of message data
     * @timeout: timeout to wait for wakeup
     *
     * Called from function tipc_sendmsg(), which has done all sanity checks
     * Returns the number of bytes sent on success, or errno
     */
    static int tipc_send_group_mcast(struct socket *sock, struct msghdr *m,
    				 int dlen, long timeout)
    {
    	struct sock *sk = sock->sk;
    	DECLARE_SOCKADDR(struct sockaddr_tipc *, dest, m->msg_name);
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct tipc_group *grp = tsk->group;
    	struct tipc_msg *hdr = &tsk->phdr;
    	struct net *net = sock_net(sk);
    	u32 type, inst, scope, exclude;
    	struct list_head dsts;
    	u32 dstcnt;
    
    	INIT_LIST_HEAD(&dsts);
    
    	type = msg_nametype(hdr);
    	inst = dest->addr.name.name.instance;
    	scope = msg_lookup_scope(hdr);
    	exclude = tipc_group_exclude(grp);
    
    	if (!tipc_nametbl_lookup(net, type, inst, scope, &dsts,
    				 &dstcnt, exclude, true))
    		return -EHOSTUNREACH;
    
    	if (dstcnt == 1) {
    		tipc_dest_pop(&dsts, &dest->addr.id.node, &dest->addr.id.ref);
    		return tipc_send_group_unicast(sock, m, dlen, timeout);
    	}
    
    	tipc_dest_list_purge(&dsts);
    	return tipc_send_group_bcast(sock, m, dlen, timeout);
    }
    
    /**
     * tipc_sk_mcast_rcv - Deliver multicast messages to all destination sockets
     * @arrvq: queue with arriving messages, to be cloned after destination lookup
     * @inputq: queue with cloned messages, delivered to socket after dest lookup
     *
     * Multi-threaded: parallel calls with reference to same queues may occur
     */
    void tipc_sk_mcast_rcv(struct net *net, struct sk_buff_head *arrvq,
    		       struct sk_buff_head *inputq)
    {
    	u32 self = tipc_own_addr(net);
    	u32 type, lower, upper, scope;
    	struct sk_buff *skb, *_skb;
    	u32 portid, onode;
    	struct sk_buff_head tmpq;
    	struct list_head dports;
    	struct tipc_msg *hdr;
    	int user, mtyp, hlen;
    	bool exact;
    
    	__skb_queue_head_init(&tmpq);
    	INIT_LIST_HEAD(&dports);
    
    	skb = tipc_skb_peek(arrvq, &inputq->lock);
    	for (; skb; skb = tipc_skb_peek(arrvq, &inputq->lock)) {
    		hdr = buf_msg(skb);
    		user = msg_user(hdr);
    		mtyp = msg_type(hdr);
    		hlen = skb_headroom(skb) + msg_hdr_sz(hdr);
    		onode = msg_orignode(hdr);
    		type = msg_nametype(hdr);
    
    		if (mtyp == TIPC_GRP_UCAST_MSG || user == GROUP_PROTOCOL) {
    			spin_lock_bh(&inputq->lock);
    			if (skb_peek(arrvq) == skb) {
    				__skb_dequeue(arrvq);
    				__skb_queue_tail(inputq, skb);
    			}
    			kfree_skb(skb);
    			spin_unlock_bh(&inputq->lock);
    			continue;
    		}
    
    		/* Group messages require exact scope match */
    		if (msg_in_group(hdr)) {
    			lower = 0;
    			upper = ~0;
    			scope = msg_lookup_scope(hdr);
    			exact = true;
    		} else {
    			/* TIPC_NODE_SCOPE means "any scope" in this context */
    			if (onode == self)
    				scope = TIPC_NODE_SCOPE;
    			else
    				scope = TIPC_CLUSTER_SCOPE;
    			exact = false;
    			lower = msg_namelower(hdr);
    			upper = msg_nameupper(hdr);
    		}
    
    		/* Create destination port list: */
    		tipc_nametbl_mc_lookup(net, type, lower, upper,
    				       scope, exact, &dports);
    
    		/* Clone message per destination */
    		while (tipc_dest_pop(&dports, NULL, &portid)) {
    			_skb = __pskb_copy(skb, hlen, GFP_ATOMIC);
    			if (_skb) {
    				msg_set_destport(buf_msg(_skb), portid);
    				__skb_queue_tail(&tmpq, _skb);
    				continue;
    			}
    			pr_warn("Failed to clone mcast rcv buffer\n");
    		}
    		/* Append to inputq if not already done by other thread */
    		spin_lock_bh(&inputq->lock);
    		if (skb_peek(arrvq) == skb) {
    			skb_queue_splice_tail_init(&tmpq, inputq);
    			kfree_skb(__skb_dequeue(arrvq));
    		}
    		spin_unlock_bh(&inputq->lock);
    		__skb_queue_purge(&tmpq);
    		kfree_skb(skb);
    	}
    	tipc_sk_rcv(net, inputq);
    }
    
    /* tipc_sk_push_backlog(): send accumulated buffers in socket write queue
     *                         when socket is in Nagle mode
     */
    static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack)
    {
    	struct sk_buff_head *txq = &tsk->sk.sk_write_queue;
    	struct sk_buff *skb = skb_peek_tail(txq);
    	struct net *net = sock_net(&tsk->sk);
    	u32 dnode = tsk_peer_node(tsk);
    	int rc;
    
    	if (nagle_ack) {
    		tsk->pkt_cnt += skb_queue_len(txq);
    		if (!tsk->pkt_cnt || tsk->msg_acc / tsk->pkt_cnt < 2) {
    			tsk->oneway = 0;
    			if (tsk->nagle_start < NAGLE_START_MAX)
    				tsk->nagle_start *= 2;
    			tsk->expect_ack = false;
    			pr_debug("tsk %10u: bad nagle %u -> %u, next start %u!\n",
    				 tsk->portid, tsk->msg_acc, tsk->pkt_cnt,
    				 tsk->nagle_start);
    		} else {
    			tsk->nagle_start = NAGLE_START_INIT;
    			if (skb) {
    				msg_set_ack_required(buf_msg(skb));
    				tsk->expect_ack = true;
    			} else {
    				tsk->expect_ack = false;
    			}
    		}
    		tsk->msg_acc = 0;
    		tsk->pkt_cnt = 0;
    	}
    
    	if (!skb || tsk->cong_link_cnt)
    		return;
    
    	/* Do not send SYN again after congestion */
    	if (msg_is_syn(buf_msg(skb)))
    		return;
    
    	if (tsk->msg_acc)
    		tsk->pkt_cnt += skb_queue_len(txq);
    	tsk->snt_unacked += tsk->snd_backlog;
    	tsk->snd_backlog = 0;
    	rc = tipc_node_xmit(net, txq, dnode, tsk->portid);
    	if (rc == -ELINKCONG)
    		tsk->cong_link_cnt = 1;
    }
    
    /**
     * tipc_sk_conn_proto_rcv - receive a connection mng protocol message
     * @tsk: receiving socket
     * @skb: pointer to message buffer.
     */
    static void tipc_sk_conn_proto_rcv(struct tipc_sock *tsk, struct sk_buff *skb,
    				   struct sk_buff_head *inputq,
    				   struct sk_buff_head *xmitq)
    {
    	struct tipc_msg *hdr = buf_msg(skb);
    	u32 onode = tsk_own_node(tsk);
    	struct sock *sk = &tsk->sk;
    	int mtyp = msg_type(hdr);
    	bool was_cong;
    
    	/* Ignore if connection cannot be validated: */
    	if (!tsk_peer_msg(tsk, hdr)) {
    		trace_tipc_sk_drop_msg(sk, skb, TIPC_DUMP_NONE, "@proto_rcv!");
    		goto exit;
    	}
    
    	if (unlikely(msg_errcode(hdr))) {
    		tipc_set_sk_state(sk, TIPC_DISCONNECTING);
    		tipc_node_remove_conn(sock_net(sk), tsk_peer_node(tsk),
    				      tsk_peer_port(tsk));
    		sk->sk_state_change(sk);
    
    		/* State change is ignored if socket already awake,
    		 * - convert msg to abort msg and add to inqueue
    		 */
    		msg_set_user(hdr, TIPC_CRITICAL_IMPORTANCE);
    		msg_set_type(hdr, TIPC_CONN_MSG);
    		msg_set_size(hdr, BASIC_H_SIZE);
    		msg_set_hdr_sz(hdr, BASIC_H_SIZE);
    		__skb_queue_tail(inputq, skb);
    		return;
    	}
    
    	tsk->probe_unacked = false;
    
    	if (mtyp == CONN_PROBE) {
    		msg_set_type(hdr, CONN_PROBE_REPLY);
    		if (tipc_msg_reverse(onode, &skb, TIPC_OK))
    			__skb_queue_tail(xmitq, skb);
    		return;
    	} else if (mtyp == CONN_ACK) {
    		was_cong = tsk_conn_cong(tsk);
    		tipc_sk_push_backlog(tsk, msg_nagle_ack(hdr));
    		tsk->snt_unacked -= msg_conn_ack(hdr);
    		if (tsk->peer_caps & TIPC_BLOCK_FLOWCTL)
    			tsk->snd_win = msg_adv_win(hdr);
    		if (was_cong && !tsk_conn_cong(tsk))
    			sk->sk_write_space(sk);
    	} else if (mtyp != CONN_PROBE_REPLY) {
    		pr_warn("Received unknown CONN_PROTO msg\n");
    	}
    exit:
    	kfree_skb(skb);
    }
    
    /**
     * tipc_sendmsg - send message in connectionless manner
     * @sock: socket structure
     * @m: message to send
     * @dsz: amount of user data to be sent
     *
     * Message must have an destination specified explicitly.
     * Used for SOCK_RDM and SOCK_DGRAM messages,
     * and for 'SYN' messages on SOCK_SEQPACKET and SOCK_STREAM connections.
     * (Note: 'SYN+' is prohibited on SOCK_STREAM.)
     *
     * Returns the number of bytes sent on success, or errno otherwise
     */
    static int tipc_sendmsg(struct socket *sock,
    			struct msghdr *m, size_t dsz)
    {
    	struct sock *sk = sock->sk;
    	int ret;
    
    	lock_sock(sk);
    	ret = __tipc_sendmsg(sock, m, dsz);
    	release_sock(sk);
    
    	return ret;
    }
    
    static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dlen)
    {
    	struct sock *sk = sock->sk;
    	struct net *net = sock_net(sk);
    	struct tipc_sock *tsk = tipc_sk(sk);
    	DECLARE_SOCKADDR(struct sockaddr_tipc *, dest, m->msg_name);
    	long timeout = sock_sndtimeo(sk, m->msg_flags & MSG_DONTWAIT);
    	struct list_head *clinks = &tsk->cong_links;
    	bool syn = !tipc_sk_type_connectionless(sk);
    	struct tipc_group *grp = tsk->group;
    	struct tipc_msg *hdr = &tsk->phdr;
    	struct tipc_name_seq *seq;
    	struct sk_buff_head pkts;
    	u32 dport = 0, dnode = 0;
    	u32 type = 0, inst = 0;
    	int mtu, rc;
    
    	if (unlikely(dlen > TIPC_MAX_USER_MSG_SIZE))
    		return -EMSGSIZE;
    
    	if (likely(dest)) {
    		if (unlikely(m->msg_namelen < sizeof(*dest)))
    			return -EINVAL;
    		if (unlikely(dest->family != AF_TIPC))
    			return -EINVAL;
    	}
    
    	if (grp) {
    		if (!dest)
    			return tipc_send_group_bcast(sock, m, dlen, timeout);
    		if (dest->addrtype == TIPC_ADDR_NAME)
    			return tipc_send_group_anycast(sock, m, dlen, timeout);
    		if (dest->addrtype == TIPC_ADDR_ID)
    			return tipc_send_group_unicast(sock, m, dlen, timeout);
    		if (dest->addrtype == TIPC_ADDR_MCAST)
    			return tipc_send_group_mcast(sock, m, dlen, timeout);
    		return -EINVAL;
    	}
    
    	if (unlikely(!dest)) {
    		dest = &tsk->peer;
    		if (!syn && dest->family != AF_TIPC)
    			return -EDESTADDRREQ;
    	}
    
    	if (unlikely(syn)) {
    		if (sk->sk_state == TIPC_LISTEN)
    			return -EPIPE;
    		if (sk->sk_state != TIPC_OPEN)
    			return -EISCONN;
    		if (tsk->published)
    			return -EOPNOTSUPP;
    		if (dest->addrtype == TIPC_ADDR_NAME) {
    			tsk->conn_type = dest->addr.name.name.type;
    			tsk->conn_instance = dest->addr.name.name.instance;
    		}
    		msg_set_syn(hdr, 1);
    	}
    
    	seq = &dest->addr.nameseq;
    	if (dest->addrtype == TIPC_ADDR_MCAST)
    		return tipc_sendmcast(sock, seq, m, dlen, timeout);
    
    	if (dest->addrtype == TIPC_ADDR_NAME) {
    		type = dest->addr.name.name.type;
    		inst = dest->addr.name.name.instance;
    		dnode = dest->addr.name.domain;
    		dport = tipc_nametbl_translate(net, type, inst, &dnode);
    		if (unlikely(!dport && !dnode))
    			return -EHOSTUNREACH;
    	} else if (dest->addrtype == TIPC_ADDR_ID) {
    		dnode = dest->addr.id.node;
    	} else {
    		return -EINVAL;
    	}
    
    	/* Block or return if destination link is congested */
    	rc = tipc_wait_for_cond(sock, &timeout,
    				!tipc_dest_find(clinks, dnode, 0));
    	if (unlikely(rc))
    		return rc;
    
    	if (dest->addrtype == TIPC_ADDR_NAME) {
    		msg_set_type(hdr, TIPC_NAMED_MSG);
    		msg_set_hdr_sz(hdr, NAMED_H_SIZE);
    		msg_set_nametype(hdr, type);
    		msg_set_nameinst(hdr, inst);
    		msg_set_lookup_scope(hdr, tipc_node2scope(dnode));
    		msg_set_destnode(hdr, dnode);
    		msg_set_destport(hdr, dport);
    	} else { /* TIPC_ADDR_ID */
    		msg_set_type(hdr, TIPC_DIRECT_MSG);
    		msg_set_lookup_scope(hdr, 0);
    		msg_set_destnode(hdr, dnode);
    		msg_set_destport(hdr, dest->addr.id.ref);
    		msg_set_hdr_sz(hdr, BASIC_H_SIZE);
    	}
    
    	__skb_queue_head_init(&pkts);
    	mtu = tipc_node_get_mtu(net, dnode, tsk->portid, true);
    	rc = tipc_msg_build(hdr, m, 0, dlen, mtu, &pkts);
    	if (unlikely(rc != dlen))
    		return rc;
    	if (unlikely(syn && !tipc_msg_skb_clone(&pkts, &sk->sk_write_queue))) {
    		__skb_queue_purge(&pkts);
    		return -ENOMEM;
    	}
    
    	trace_tipc_sk_sendmsg(sk, skb_peek(&pkts), TIPC_DUMP_SK_SNDQ, " ");
    	rc = tipc_node_xmit(net, &pkts, dnode, tsk->portid);
    	if (unlikely(rc == -ELINKCONG)) {
    		tipc_dest_push(clinks, dnode, 0);
    		tsk->cong_link_cnt++;
    		rc = 0;
    	}
    
    	if (unlikely(syn && !rc))
    		tipc_set_sk_state(sk, TIPC_CONNECTING);
    
    	return rc ? rc : dlen;
    }
    
    /**
     * tipc_sendstream - send stream-oriented data
     * @sock: socket structure
     * @m: data to send
     * @dsz: total length of data to be transmitted
     *
     * Used for SOCK_STREAM data.
     *
     * Returns the number of bytes sent on success (or partial success),
     * or errno if no data sent
     */
    static int tipc_sendstream(struct socket *sock, struct msghdr *m, size_t dsz)
    {
    	struct sock *sk = sock->sk;
    	int ret;
    
    	lock_sock(sk);
    	ret = __tipc_sendstream(sock, m, dsz);
    	release_sock(sk);
    
    	return ret;
    }
    
    static int __tipc_sendstream(struct socket *sock, struct msghdr *m, size_t dlen)
    {
    	struct sock *sk = sock->sk;
    	DECLARE_SOCKADDR(struct sockaddr_tipc *, dest, m->msg_name);
    	long timeout = sock_sndtimeo(sk, m->msg_flags & MSG_DONTWAIT);
    	struct sk_buff_head *txq = &sk->sk_write_queue;
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct tipc_msg *hdr = &tsk->phdr;
    	struct net *net = sock_net(sk);
    	struct sk_buff *skb;
    	u32 dnode = tsk_peer_node(tsk);
    	int maxnagle = tsk->maxnagle;
    	int maxpkt = tsk->max_pkt;
    	int send, sent = 0;
    	int blocks, rc = 0;
    
    	if (unlikely(dlen > INT_MAX))
    		return -EMSGSIZE;
    
    	/* Handle implicit connection setup */
    	if (unlikely(dest)) {
    		rc = __tipc_sendmsg(sock, m, dlen);
    		if (dlen && dlen == rc) {
    			tsk->peer_caps = tipc_node_get_capabilities(net, dnode);
    			tsk->snt_unacked = tsk_inc(tsk, dlen + msg_hdr_sz(hdr));
    		}
    		return rc;
    	}
    
    	do {
    		rc = tipc_wait_for_cond(sock, &timeout,
    					(!tsk->cong_link_cnt &&
    					 !tsk_conn_cong(tsk) &&
    					 tipc_sk_connected(sk)));
    		if (unlikely(rc))
    			break;
    		send = min_t(size_t, dlen - sent, TIPC_MAX_USER_MSG_SIZE);
    		blocks = tsk->snd_backlog;
    		if (tsk->oneway++ >= tsk->nagle_start && send <= maxnagle) {
    			rc = tipc_msg_append(hdr, m, send, maxnagle, txq);
    			if (unlikely(rc < 0))
    				break;
    			blocks += rc;
    			tsk->msg_acc++;
    			if (blocks <= 64 && tsk->expect_ack) {
    				tsk->snd_backlog = blocks;
    				sent += send;
    				break;
    			} else if (blocks > 64) {
    				tsk->pkt_cnt += skb_queue_len(txq);
    			} else {
    				skb = skb_peek_tail(txq);
    				if (skb) {
    					msg_set_ack_required(buf_msg(skb));
    					tsk->expect_ack = true;
    				} else {
    					tsk->expect_ack = false;
    				}
    				tsk->msg_acc = 0;
    				tsk->pkt_cnt = 0;
    			}
    		} else {
    			rc = tipc_msg_build(hdr, m, sent, send, maxpkt, txq);
    			if (unlikely(rc != send))
    				break;
    			blocks += tsk_inc(tsk, send + MIN_H_SIZE);
    		}
    		trace_tipc_sk_sendstream(sk, skb_peek(txq),
    					 TIPC_DUMP_SK_SNDQ, " ");
    		rc = tipc_node_xmit(net, txq, dnode, tsk->portid);
    		if (unlikely(rc == -ELINKCONG)) {
    			tsk->cong_link_cnt = 1;
    			rc = 0;
    		}
    		if (likely(!rc)) {
    			tsk->snt_unacked += blocks;
    			tsk->snd_backlog = 0;
    			sent += send;
    		}
    	} while (sent < dlen && !rc);
    
    	return sent ? sent : rc;
    }
    
    /**
     * tipc_send_packet - send a connection-oriented message
     * @sock: socket structure
     * @m: message to send
     * @dsz: length of data to be transmitted
     *
     * Used for SOCK_SEQPACKET messages.
     *
     * Returns the number of bytes sent on success, or errno otherwise
     */
    static int tipc_send_packet(struct socket *sock, struct msghdr *m, size_t dsz)
    {
    	if (dsz > TIPC_MAX_USER_MSG_SIZE)
    		return -EMSGSIZE;
    
    	return tipc_sendstream(sock, m, dsz);
    }
    
    /* tipc_sk_finish_conn - complete the setup of a connection
     */
    static void tipc_sk_finish_conn(struct tipc_sock *tsk, u32 peer_port,
    				u32 peer_node)
    {
    	struct sock *sk = &tsk->sk;
    	struct net *net = sock_net(sk);
    	struct tipc_msg *msg = &tsk->phdr;
    
    	msg_set_syn(msg, 0);
    	msg_set_destnode(msg, peer_node);
    	msg_set_destport(msg, peer_port);
    	msg_set_type(msg, TIPC_CONN_MSG);
    	msg_set_lookup_scope(msg, 0);
    	msg_set_hdr_sz(msg, SHORT_H_SIZE);
    
    	sk_reset_timer(sk, &sk->sk_timer, jiffies + CONN_PROBING_INTV);
    	tipc_set_sk_state(sk, TIPC_ESTABLISHED);
    	tipc_node_add_conn(net, peer_node, tsk->portid, peer_port);
    	tsk->max_pkt = tipc_node_get_mtu(net, peer_node, tsk->portid, true);
    	tsk->peer_caps = tipc_node_get_capabilities(net, peer_node);
    	tsk_set_nagle(tsk);
    	__skb_queue_purge(&sk->sk_write_queue);
    	if (tsk->peer_caps & TIPC_BLOCK_FLOWCTL)
    		return;
    
    	/* Fall back to message based flow control */
    	tsk->rcv_win = FLOWCTL_MSG_WIN;
    	tsk->snd_win = FLOWCTL_MSG_WIN;
    }
    
    /**
     * tipc_sk_set_orig_addr - capture sender's address for received message
     * @m: descriptor for message info
     * @hdr: received message header
     *
     * Note: Address is not captured if not requested by receiver.
     */
    static void tipc_sk_set_orig_addr(struct msghdr *m, struct sk_buff *skb)
    {
    	DECLARE_SOCKADDR(struct sockaddr_pair *, srcaddr, m->msg_name);
    	struct tipc_msg *hdr = buf_msg(skb);
    
    	if (!srcaddr)
    		return;
    
    	srcaddr->sock.family = AF_TIPC;
    	srcaddr->sock.addrtype = TIPC_ADDR_ID;
    	srcaddr->sock.scope = 0;
    	srcaddr->sock.addr.id.ref = msg_origport(hdr);
    	srcaddr->sock.addr.id.node = msg_orignode(hdr);
    	srcaddr->sock.addr.name.domain = 0;
    	m->msg_namelen = sizeof(struct sockaddr_tipc);
    
    	if (!msg_in_group(hdr))
    		return;
    
    	/* Group message users may also want to know sending member's id */
    	srcaddr->member.family = AF_TIPC;
    	srcaddr->member.addrtype = TIPC_ADDR_NAME;
    	srcaddr->member.scope = 0;
    	srcaddr->member.addr.name.name.type = msg_nametype(hdr);
    	srcaddr->member.addr.name.name.instance = TIPC_SKB_CB(skb)->orig_member;
    	srcaddr->member.addr.name.domain = 0;
    	m->msg_namelen = sizeof(*srcaddr);
    }
    
    /**
     * tipc_sk_anc_data_recv - optionally capture ancillary data for received message
     * @m: descriptor for message info
     * @skb: received message buffer
     * @tsk: TIPC port associated with message
     *
     * Note: Ancillary data is not captured if not requested by receiver.
     *
     * Returns 0 if successful, otherwise errno
     */
    static int tipc_sk_anc_data_recv(struct msghdr *m, struct sk_buff *skb,
    				 struct tipc_sock *tsk)
    {
    	struct tipc_msg *msg;
    	u32 anc_data[3];
    	u32 err;
    	u32 dest_type;
    	int has_name;
    	int res;
    
    	if (likely(m->msg_controllen == 0))
    		return 0;
    	msg = buf_msg(skb);
    
    	/* Optionally capture errored message object(s) */
    	err = msg ? msg_errcode(msg) : 0;
    	if (unlikely(err)) {
    		anc_data[0] = err;
    		anc_data[1] = msg_data_sz(msg);
    		res = put_cmsg(m, SOL_TIPC, TIPC_ERRINFO, 8, anc_data);
    		if (res)
    			return res;
    		if (anc_data[1]) {
    			if (skb_linearize(skb))
    				return -ENOMEM;
    			msg = buf_msg(skb);
    			res = put_cmsg(m, SOL_TIPC, TIPC_RETDATA, anc_data[1],
    				       msg_data(msg));
    			if (res)
    				return res;
    		}
    	}
    
    	/* Optionally capture message destination object */
    	dest_type = msg ? msg_type(msg) : TIPC_DIRECT_MSG;
    	switch (dest_type) {
    	case TIPC_NAMED_MSG:
    		has_name = 1;
    		anc_data[0] = msg_nametype(msg);
    		anc_data[1] = msg_namelower(msg);
    		anc_data[2] = msg_namelower(msg);
    		break;
    	case TIPC_MCAST_MSG:
    		has_name = 1;
    		anc_data[0] = msg_nametype(msg);
    		anc_data[1] = msg_namelower(msg);
    		anc_data[2] = msg_nameupper(msg);
    		break;
    	case TIPC_CONN_MSG:
    		has_name = (tsk->conn_type != 0);
    		anc_data[0] = tsk->conn_type;
    		anc_data[1] = tsk->conn_instance;
    		anc_data[2] = tsk->conn_instance;
    		break;
    	default:
    		has_name = 0;
    	}
    	if (has_name) {
    		res = put_cmsg(m, SOL_TIPC, TIPC_DESTNAME, 12, anc_data);
    		if (res)
    			return res;
    	}
    
    	return 0;
    }
    
    static struct sk_buff *tipc_sk_build_ack(struct tipc_sock *tsk)
    {
    	struct sock *sk = &tsk->sk;
    	struct sk_buff *skb = NULL;
    	struct tipc_msg *msg;
    	u32 peer_port = tsk_peer_port(tsk);
    	u32 dnode = tsk_peer_node(tsk);
    
    	if (!tipc_sk_connected(sk))
    		return NULL;
    	skb = tipc_msg_create(CONN_MANAGER, CONN_ACK, INT_H_SIZE, 0,
    			      dnode, tsk_own_node(tsk), peer_port,
    			      tsk->portid, TIPC_OK);
    	if (!skb)
    		return NULL;
    	msg = buf_msg(skb);
    	msg_set_conn_ack(msg, tsk->rcv_unacked);
    	tsk->rcv_unacked = 0;
    
    	/* Adjust to and advertize the correct window limit */
    	if (tsk->peer_caps & TIPC_BLOCK_FLOWCTL) {
    		tsk->rcv_win = tsk_adv_blocks(tsk->sk.sk_rcvbuf);
    		msg_set_adv_win(msg, tsk->rcv_win);
    	}
    	return skb;
    }
    
    static void tipc_sk_send_ack(struct tipc_sock *tsk)
    {
    	struct sk_buff *skb;
    
    	skb = tipc_sk_build_ack(tsk);
    	if (!skb)
    		return;
    
    	tipc_node_xmit_skb(sock_net(&tsk->sk), skb, tsk_peer_node(tsk),
    			   msg_link_selector(buf_msg(skb)));
    }
    
    static int tipc_wait_for_rcvmsg(struct socket *sock, long *timeop)
    {
    	struct sock *sk = sock->sk;
    	DEFINE_WAIT_FUNC(wait, woken_wake_function);
    	long timeo = *timeop;
    	int err = sock_error(sk);
    
    	if (err)
    		return err;
    
    	for (;;) {
    		if (timeo && skb_queue_empty(&sk->sk_receive_queue)) {
    			if (sk->sk_shutdown & RCV_SHUTDOWN) {
    				err = -ENOTCONN;
    				break;
    			}
    			add_wait_queue(sk_sleep(sk), &wait);
    			release_sock(sk);
    			timeo = wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
    			sched_annotate_sleep();
    			lock_sock(sk);
    			remove_wait_queue(sk_sleep(sk), &wait);
    		}
    		err = 0;
    		if (!skb_queue_empty(&sk->sk_receive_queue))
    			break;
    		err = -EAGAIN;
    		if (!timeo)
    			break;
    		err = sock_intr_errno(timeo);
    		if (signal_pending(current))
    			break;
    
    		err = sock_error(sk);
    		if (err)
    			break;
    	}
    	*timeop = timeo;
    	return err;
    }
    
    /**
     * tipc_recvmsg - receive packet-oriented message
     * @m: descriptor for message info
     * @buflen: length of user buffer area
     * @flags: receive flags
     *
     * Used for SOCK_DGRAM, SOCK_RDM, and SOCK_SEQPACKET messages.
     * If the complete message doesn't fit in user area, truncate it.
     *
     * Returns size of returned message data, errno otherwise
     */
    static int tipc_recvmsg(struct socket *sock, struct msghdr *m,
    			size_t buflen,	int flags)
    {
    	struct sock *sk = sock->sk;
    	bool connected = !tipc_sk_type_connectionless(sk);
    	struct tipc_sock *tsk = tipc_sk(sk);
    	int rc, err, hlen, dlen, copy;
    	struct sk_buff_head xmitq;
    	struct tipc_msg *hdr;
    	struct sk_buff *skb;
    	bool grp_evt;
    	long timeout;
    
    	/* Catch invalid receive requests */
    	if (unlikely(!buflen))
    		return -EINVAL;
    
    	lock_sock(sk);
    	if (unlikely(connected && sk->sk_state == TIPC_OPEN)) {
    		rc = -ENOTCONN;
    		goto exit;
    	}
    	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
    
    	/* Step rcv queue to first msg with data or error; wait if necessary */
    	do {
    		rc = tipc_wait_for_rcvmsg(sock, &timeout);
    		if (unlikely(rc))
    			goto exit;
    		skb = skb_peek(&sk->sk_receive_queue);
    		hdr = buf_msg(skb);
    		dlen = msg_data_sz(hdr);
    		hlen = msg_hdr_sz(hdr);
    		err = msg_errcode(hdr);
    		grp_evt = msg_is_grp_evt(hdr);
    		if (likely(dlen || err))
    			break;
    		tsk_advance_rx_queue(sk);
    	} while (1);
    
    	/* Collect msg meta data, including error code and rejected data */
    	tipc_sk_set_orig_addr(m, skb);
    	rc = tipc_sk_anc_data_recv(m, skb, tsk);
    	if (unlikely(rc))
    		goto exit;
    	hdr = buf_msg(skb);
    
    	/* Capture data if non-error msg, otherwise just set return value */
    	if (likely(!err)) {
    		copy = min_t(int, dlen, buflen);
    		if (unlikely(copy != dlen))
    			m->msg_flags |= MSG_TRUNC;
    		rc = skb_copy_datagram_msg(skb, hlen, m, copy);
    	} else {
    		copy = 0;
    		rc = 0;
    		if (err != TIPC_CONN_SHUTDOWN && connected && !m->msg_control)
    			rc = -ECONNRESET;
    	}
    	if (unlikely(rc))
    		goto exit;
    
    	/* Mark message as group event if applicable */
    	if (unlikely(grp_evt)) {
    		if (msg_grp_evt(hdr) == TIPC_WITHDRAWN)
    			m->msg_flags |= MSG_EOR;
    		m->msg_flags |= MSG_OOB;
    		copy = 0;
    	}
    
    	/* Caption of data or error code/rejected data was successful */
    	if (unlikely(flags & MSG_PEEK))
    		goto exit;
    
    	/* Send group flow control advertisement when applicable */
    	if (tsk->group && msg_in_group(hdr) && !grp_evt) {
    		__skb_queue_head_init(&xmitq);
    		tipc_group_update_rcv_win(tsk->group, tsk_blocks(hlen + dlen),
    					  msg_orignode(hdr), msg_origport(hdr),
    					  &xmitq);
    		tipc_node_distr_xmit(sock_net(sk), &xmitq);
    	}
    
    	tsk_advance_rx_queue(sk);
    
    	if (likely(!connected))
    		goto exit;
    
    	/* Send connection flow control advertisement when applicable */
    	tsk->rcv_unacked += tsk_inc(tsk, hlen + dlen);
    	if (tsk->rcv_unacked >= tsk->rcv_win / TIPC_ACK_RATE)
    		tipc_sk_send_ack(tsk);
    exit:
    	release_sock(sk);
    	return rc ? rc : copy;
    }
    
    /**
     * tipc_recvstream - receive stream-oriented data
     * @m: descriptor for message info
     * @buflen: total size of user buffer area
     * @flags: receive flags
     *
     * Used for SOCK_STREAM messages only.  If not enough data is available
     * will optionally wait for more; never truncates data.
     *
     * Returns size of returned message data, errno otherwise
     */
    static int tipc_recvstream(struct socket *sock, struct msghdr *m,
    			   size_t buflen, int flags)
    {
    	struct sock *sk = sock->sk;
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct sk_buff *skb;
    	struct tipc_msg *hdr;
    	struct tipc_skb_cb *skb_cb;
    	bool peek = flags & MSG_PEEK;
    	int offset, required, copy, copied = 0;
    	int hlen, dlen, err, rc;
    	long timeout;
    
    	/* Catch invalid receive attempts */
    	if (unlikely(!buflen))
    		return -EINVAL;
    
    	lock_sock(sk);
    
    	if (unlikely(sk->sk_state == TIPC_OPEN)) {
    		rc = -ENOTCONN;
    		goto exit;
    	}
    	required = sock_rcvlowat(sk, flags & MSG_WAITALL, buflen);
    	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
    
    	do {
    		/* Look at first msg in receive queue; wait if necessary */
    		rc = tipc_wait_for_rcvmsg(sock, &timeout);
    		if (unlikely(rc))
    			break;
    		skb = skb_peek(&sk->sk_receive_queue);
    		skb_cb = TIPC_SKB_CB(skb);
    		hdr = buf_msg(skb);
    		dlen = msg_data_sz(hdr);
    		hlen = msg_hdr_sz(hdr);
    		err = msg_errcode(hdr);
    
    		/* Discard any empty non-errored (SYN-) message */
    		if (unlikely(!dlen && !err)) {
    			tsk_advance_rx_queue(sk);
    			continue;
    		}
    
    		/* Collect msg meta data, incl. error code and rejected data */
    		if (!copied) {
    			tipc_sk_set_orig_addr(m, skb);
    			rc = tipc_sk_anc_data_recv(m, skb, tsk);
    			if (rc)
    				break;
    			hdr = buf_msg(skb);
    		}
    
    		/* Copy data if msg ok, otherwise return error/partial data */
    		if (likely(!err)) {
    			offset = skb_cb->bytes_read;
    			copy = min_t(int, dlen - offset, buflen - copied);
    			rc = skb_copy_datagram_msg(skb, hlen + offset, m, copy);
    			if (unlikely(rc))
    				break;
    			copied += copy;
    			offset += copy;
    			if (unlikely(offset < dlen)) {
    				if (!peek)
    					skb_cb->bytes_read = offset;
    				break;
    			}
    		} else {
    			rc = 0;
    			if ((err != TIPC_CONN_SHUTDOWN) && !m->msg_control)
    				rc = -ECONNRESET;
    			if (copied || rc)
    				break;
    		}
    
    		if (unlikely(peek))
    			break;
    
    		tsk_advance_rx_queue(sk);
    
    		/* Send connection flow control advertisement when applicable */
    		tsk->rcv_unacked += tsk_inc(tsk, hlen + dlen);
    		if (tsk->rcv_unacked >= tsk->rcv_win / TIPC_ACK_RATE)
    			tipc_sk_send_ack(tsk);
    
    		/* Exit if all requested data or FIN/error received */
    		if (copied == buflen || err)
    			break;
    
    	} while (!skb_queue_empty(&sk->sk_receive_queue) || copied < required);
    exit:
    	release_sock(sk);
    	return copied ? copied : rc;
    }
    
    /**
     * tipc_write_space - wake up thread if port congestion is released
     * @sk: socket
     */
    static void tipc_write_space(struct sock *sk)
    {
    	struct socket_wq *wq;
    
    	rcu_read_lock();
    	wq = rcu_dereference(sk->sk_wq);
    	if (skwq_has_sleeper(wq))
    		wake_up_interruptible_sync_poll(&wq->wait, EPOLLOUT |
    						EPOLLWRNORM | EPOLLWRBAND);
    	rcu_read_unlock();
    }
    
    /**
     * tipc_data_ready - wake up threads to indicate messages have been received
     * @sk: socket
     * @len: the length of messages
     */
    static void tipc_data_ready(struct sock *sk)
    {
    	struct socket_wq *wq;
    
    	rcu_read_lock();
    	wq = rcu_dereference(sk->sk_wq);
    	if (skwq_has_sleeper(wq))
    		wake_up_interruptible_sync_poll(&wq->wait, EPOLLIN |
    						EPOLLRDNORM | EPOLLRDBAND);
    	rcu_read_unlock();
    }
    
    static void tipc_sock_destruct(struct sock *sk)
    {
    	__skb_queue_purge(&sk->sk_receive_queue);
    }
    
    static void tipc_sk_proto_rcv(struct sock *sk,
    			      struct sk_buff_head *inputq,
    			      struct sk_buff_head *xmitq)
    {
    	struct sk_buff *skb = __skb_dequeue(inputq);
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct tipc_msg *hdr = buf_msg(skb);
    	struct tipc_group *grp = tsk->group;
    	bool wakeup = false;
    
    	switch (msg_user(hdr)) {
    	case CONN_MANAGER:
    		tipc_sk_conn_proto_rcv(tsk, skb, inputq, xmitq);
    		return;
    	case SOCK_WAKEUP:
    		tipc_dest_del(&tsk->cong_links, msg_orignode(hdr), 0);
    		/* coupled with smp_rmb() in tipc_wait_for_cond() */
    		smp_wmb();
    		tsk->cong_link_cnt--;
    		wakeup = true;
    		tipc_sk_push_backlog(tsk, false);
    		break;
    	case GROUP_PROTOCOL:
    		tipc_group_proto_rcv(grp, &wakeup, hdr, inputq, xmitq);
    		break;
    	case TOP_SRV:
    		tipc_group_member_evt(tsk->group, &wakeup, &sk->sk_rcvbuf,
    				      hdr, inputq, xmitq);
    		break;
    	default:
    		break;
    	}
    
    	if (wakeup)
    		sk->sk_write_space(sk);
    
    	kfree_skb(skb);
    }
    
    /**
     * tipc_sk_filter_connect - check incoming message for a connection-based socket
     * @tsk: TIPC socket
     * @skb: pointer to message buffer.
     * @xmitq: for Nagle ACK if any
     * Returns true if message should be added to receive queue, false otherwise
     */
    static bool tipc_sk_filter_connect(struct tipc_sock *tsk, struct sk_buff *skb,
    				   struct sk_buff_head *xmitq)
    {
    	struct sock *sk = &tsk->sk;
    	struct net *net = sock_net(sk);
    	struct tipc_msg *hdr = buf_msg(skb);
    	bool con_msg = msg_connected(hdr);
    	u32 pport = tsk_peer_port(tsk);
    	u32 pnode = tsk_peer_node(tsk);
    	u32 oport = msg_origport(hdr);
    	u32 onode = msg_orignode(hdr);
    	int err = msg_errcode(hdr);
    	unsigned long delay;
    
    	if (unlikely(msg_mcast(hdr)))
    		return false;
    	tsk->oneway = 0;
    
    	switch (sk->sk_state) {
    	case TIPC_CONNECTING:
    		/* Setup ACK */
    		if (likely(con_msg)) {
    			if (err)
    				break;
    			tipc_sk_finish_conn(tsk, oport, onode);
    			msg_set_importance(&tsk->phdr, msg_importance(hdr));
    			/* ACK+ message with data is added to receive queue */
    			if (msg_data_sz(hdr))
    				return true;
    			/* Empty ACK-, - wake up sleeping connect() and drop */
    			sk->sk_state_change(sk);
    			msg_set_dest_droppable(hdr, 1);
    			return false;
    		}
    		/* Ignore connectionless message if not from listening socket */
    		if (oport != pport || onode != pnode)
    			return false;
    
    		/* Rejected SYN */
    		if (err != TIPC_ERR_OVERLOAD)
    			break;
    
    		/* Prepare for new setup attempt if we have a SYN clone */
    		if (skb_queue_empty(&sk->sk_write_queue))
    			break;
    		get_random_bytes(&delay, 2);
    		delay %= (tsk->conn_timeout / 4);
    		delay = msecs_to_jiffies(delay + 100);
    		sk_reset_timer(sk, &sk->sk_timer, jiffies + delay);
    		return false;
    	case TIPC_OPEN:
    	case TIPC_DISCONNECTING:
    		return false;
    	case TIPC_LISTEN:
    		/* Accept only SYN message */
    		if (!msg_is_syn(hdr) &&
    		    tipc_node_get_capabilities(net, onode) & TIPC_SYN_BIT)
    			return false;
    		if (!con_msg && !err)
    			return true;
    		return false;
    	case TIPC_ESTABLISHED:
    		if (!skb_queue_empty(&sk->sk_write_queue))
    			tipc_sk_push_backlog(tsk, false);
    		/* Accept only connection-based messages sent by peer */
    		if (likely(con_msg && !err && pport == oport &&
    			   pnode == onode)) {
    			if (msg_ack_required(hdr)) {
    				struct sk_buff *skb;
    
    				skb = tipc_sk_build_ack(tsk);
    				if (skb) {
    					msg_set_nagle_ack(buf_msg(skb));
    					__skb_queue_tail(xmitq, skb);
    				}
    			}
    			return true;
    		}
    		if (!tsk_peer_msg(tsk, hdr))
    			return false;
    		if (!err)
    			return true;
    		tipc_set_sk_state(sk, TIPC_DISCONNECTING);
    		tipc_node_remove_conn(net, pnode, tsk->portid);
    		sk->sk_state_change(sk);
    		return true;
    	default:
    		pr_err("Unknown sk_state %u\n", sk->sk_state);
    	}
    	/* Abort connection setup attempt */
    	tipc_set_sk_state(sk, TIPC_DISCONNECTING);
    	sk->sk_err = ECONNREFUSED;
    	sk->sk_state_change(sk);
    	return true;
    }
    
    /**
     * rcvbuf_limit - get proper overload limit of socket receive queue
     * @sk: socket
     * @skb: message
     *
     * For connection oriented messages, irrespective of importance,
     * default queue limit is 2 MB.
     *
     * For connectionless messages, queue limits are based on message
     * importance as follows:
     *
     * TIPC_LOW_IMPORTANCE       (2 MB)
     * TIPC_MEDIUM_IMPORTANCE    (4 MB)
     * TIPC_HIGH_IMPORTANCE      (8 MB)
     * TIPC_CRITICAL_IMPORTANCE  (16 MB)
     *
     * Returns overload limit according to corresponding message importance
     */
    static unsigned int rcvbuf_limit(struct sock *sk, struct sk_buff *skb)
    {
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct tipc_msg *hdr = buf_msg(skb);
    
    	if (unlikely(msg_in_group(hdr)))
    		return READ_ONCE(sk->sk_rcvbuf);
    
    	if (unlikely(!msg_connected(hdr)))
    		return READ_ONCE(sk->sk_rcvbuf) << msg_importance(hdr);
    
    	if (likely(tsk->peer_caps & TIPC_BLOCK_FLOWCTL))
    		return READ_ONCE(sk->sk_rcvbuf);
    
    	return FLOWCTL_MSG_LIM;
    }
    
    /**
     * tipc_sk_filter_rcv - validate incoming message
     * @sk: socket
     * @skb: pointer to message.
     *
     * Enqueues message on receive queue if acceptable; optionally handles
     * disconnect indication for a connected socket.
     *
     * Called with socket lock already taken
     *
     */
    static void tipc_sk_filter_rcv(struct sock *sk, struct sk_buff *skb,
    			       struct sk_buff_head *xmitq)
    {
    	bool sk_conn = !tipc_sk_type_connectionless(sk);
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct tipc_group *grp = tsk->group;
    	struct tipc_msg *hdr = buf_msg(skb);
    	struct net *net = sock_net(sk);
    	struct sk_buff_head inputq;
    	int mtyp = msg_type(hdr);
    	int limit, err = TIPC_OK;
    
    	trace_tipc_sk_filter_rcv(sk, skb, TIPC_DUMP_ALL, " ");
    	TIPC_SKB_CB(skb)->bytes_read = 0;
    	__skb_queue_head_init(&inputq);
    	__skb_queue_tail(&inputq, skb);
    
    	if (unlikely(!msg_isdata(hdr)))
    		tipc_sk_proto_rcv(sk, &inputq, xmitq);
    
    	if (unlikely(grp))
    		tipc_group_filter_msg(grp, &inputq, xmitq);
    
    	if (unlikely(!grp) && mtyp == TIPC_MCAST_MSG)
    		tipc_mcast_filter_msg(net, &tsk->mc_method.deferredq, &inputq);
    
    	/* Validate and add to receive buffer if there is space */
    	while ((skb = __skb_dequeue(&inputq))) {
    		hdr = buf_msg(skb);
    		limit = rcvbuf_limit(sk, skb);
    		if ((sk_conn && !tipc_sk_filter_connect(tsk, skb, xmitq)) ||
    		    (!sk_conn && msg_connected(hdr)) ||
    		    (!grp && msg_in_group(hdr)))
    			err = TIPC_ERR_NO_PORT;
    		else if (sk_rmem_alloc_get(sk) + skb->truesize >= limit) {
    			trace_tipc_sk_dump(sk, skb, TIPC_DUMP_ALL,
    					   "err_overload2!");
    			atomic_inc(&sk->sk_drops);
    			err = TIPC_ERR_OVERLOAD;
    		}
    
    		if (unlikely(err)) {
    			if (tipc_msg_reverse(tipc_own_addr(net), &skb, err)) {
    				trace_tipc_sk_rej_msg(sk, skb, TIPC_DUMP_NONE,
    						      "@filter_rcv!");
    				__skb_queue_tail(xmitq, skb);
    			}
    			err = TIPC_OK;
    			continue;
    		}
    		__skb_queue_tail(&sk->sk_receive_queue, skb);
    		skb_set_owner_r(skb, sk);
    		trace_tipc_sk_overlimit2(sk, skb, TIPC_DUMP_ALL,
    					 "rcvq >90% allocated!");
    		sk->sk_data_ready(sk);
    	}
    }
    
    /**
     * tipc_sk_backlog_rcv - handle incoming message from backlog queue
     * @sk: socket
     * @skb: message
     *
     * Caller must hold socket lock
     */
    static int tipc_sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
    {
    	unsigned int before = sk_rmem_alloc_get(sk);
    	struct sk_buff_head xmitq;
    	unsigned int added;
    
    	__skb_queue_head_init(&xmitq);
    
    	tipc_sk_filter_rcv(sk, skb, &xmitq);
    	added = sk_rmem_alloc_get(sk) - before;
    	atomic_add(added, &tipc_sk(sk)->dupl_rcvcnt);
    
    	/* Send pending response/rejected messages, if any */
    	tipc_node_distr_xmit(sock_net(sk), &xmitq);
    	return 0;
    }
    
    /**
     * tipc_sk_enqueue - extract all buffers with destination 'dport' from
     *                   inputq and try adding them to socket or backlog queue
     * @inputq: list of incoming buffers with potentially different destinations
     * @sk: socket where the buffers should be enqueued
     * @dport: port number for the socket
     *
     * Caller must hold socket lock
     */
    static void tipc_sk_enqueue(struct sk_buff_head *inputq, struct sock *sk,
    			    u32 dport, struct sk_buff_head *xmitq)
    {
    	unsigned long time_limit = jiffies + 2;
    	struct sk_buff *skb;
    	unsigned int lim;
    	atomic_t *dcnt;
    	u32 onode;
    
    	while (skb_queue_len(inputq)) {
    		if (unlikely(time_after_eq(jiffies, time_limit)))
    			return;
    
    		skb = tipc_skb_dequeue(inputq, dport);
    		if (unlikely(!skb))
    			return;
    
    		/* Add message directly to receive queue if possible */
    		if (!sock_owned_by_user(sk)) {
    			tipc_sk_filter_rcv(sk, skb, xmitq);
    			continue;
    		}
    
    		/* Try backlog, compensating for double-counted bytes */
    		dcnt = &tipc_sk(sk)->dupl_rcvcnt;
    		if (!sk->sk_backlog.len)
    			atomic_set(dcnt, 0);
    		lim = rcvbuf_limit(sk, skb) + atomic_read(dcnt);
    		if (likely(!sk_add_backlog(sk, skb, lim))) {
    			trace_tipc_sk_overlimit1(sk, skb, TIPC_DUMP_ALL,
    						 "bklg & rcvq >90% allocated!");
    			continue;
    		}
    
    		trace_tipc_sk_dump(sk, skb, TIPC_DUMP_ALL, "err_overload!");
    		/* Overload => reject message back to sender */
    		onode = tipc_own_addr(sock_net(sk));
    		atomic_inc(&sk->sk_drops);
    		if (tipc_msg_reverse(onode, &skb, TIPC_ERR_OVERLOAD)) {
    			trace_tipc_sk_rej_msg(sk, skb, TIPC_DUMP_ALL,
    					      "@sk_enqueue!");
    			__skb_queue_tail(xmitq, skb);
    		}
    		break;
    	}
    }
    
    /**
     * tipc_sk_rcv - handle a chain of incoming buffers
     * @inputq: buffer list containing the buffers
     * Consumes all buffers in list until inputq is empty
     * Note: may be called in multiple threads referring to the same queue
     */
    void tipc_sk_rcv(struct net *net, struct sk_buff_head *inputq)
    {
    	struct sk_buff_head xmitq;
    	u32 dnode, dport = 0;
    	int err;
    	struct tipc_sock *tsk;
    	struct sock *sk;
    	struct sk_buff *skb;
    
    	__skb_queue_head_init(&xmitq);
    	while (skb_queue_len(inputq)) {
    		dport = tipc_skb_peek_port(inputq, dport);
    		tsk = tipc_sk_lookup(net, dport);
    
    		if (likely(tsk)) {
    			sk = &tsk->sk;
    			if (likely(spin_trylock_bh(&sk->sk_lock.slock))) {
    				tipc_sk_enqueue(inputq, sk, dport, &xmitq);
    				spin_unlock_bh(&sk->sk_lock.slock);
    			}
    			/* Send pending response/rejected messages, if any */
    			tipc_node_distr_xmit(sock_net(sk), &xmitq);
    			sock_put(sk);
    			continue;
    		}
    		/* No destination socket => dequeue skb if still there */
    		skb = tipc_skb_dequeue(inputq, dport);
    		if (!skb)
    			return;
    
    		/* Try secondary lookup if unresolved named message */
    		err = TIPC_ERR_NO_PORT;
    		if (tipc_msg_lookup_dest(net, skb, &err))
    			goto xmit;
    
    		/* Prepare for message rejection */
    		if (!tipc_msg_reverse(tipc_own_addr(net), &skb, err))
    			continue;
    
    		trace_tipc_sk_rej_msg(NULL, skb, TIPC_DUMP_NONE, "@sk_rcv!");
    xmit:
    		dnode = msg_destnode(buf_msg(skb));
    		tipc_node_xmit_skb(net, skb, dnode, dport);
    	}
    }
    
    static int tipc_wait_for_connect(struct socket *sock, long *timeo_p)
    {
    	DEFINE_WAIT_FUNC(wait, woken_wake_function);
    	struct sock *sk = sock->sk;
    	int done;
    
    	do {
    		int err = sock_error(sk);
    		if (err)
    			return err;
    		if (!*timeo_p)
    			return -ETIMEDOUT;
    		if (signal_pending(current))
    			return sock_intr_errno(*timeo_p);
    		if (sk->sk_state == TIPC_DISCONNECTING)
    			break;
    
    		add_wait_queue(sk_sleep(sk), &wait);
    		done = sk_wait_event(sk, timeo_p, tipc_sk_connected(sk),
    				     &wait);
    		remove_wait_queue(sk_sleep(sk), &wait);
    	} while (!done);
    	return 0;
    }
    
    static bool tipc_sockaddr_is_sane(struct sockaddr_tipc *addr)
    {
    	if (addr->family != AF_TIPC)
    		return false;
    	if (addr->addrtype == TIPC_SERVICE_RANGE)
    		return (addr->addr.nameseq.lower <= addr->addr.nameseq.upper);
    	return (addr->addrtype == TIPC_SERVICE_ADDR ||
    		addr->addrtype == TIPC_SOCKET_ADDR);
    }
    
    /**
     * tipc_connect - establish a connection to another TIPC port
     * @sock: socket structure
     * @dest: socket address for destination port
     * @destlen: size of socket address data structure
     * @flags: file-related flags associated with socket
     *
     * Returns 0 on success, errno otherwise
     */
    static int tipc_connect(struct socket *sock, struct sockaddr *dest,
    			int destlen, int flags)
    {
    	struct sock *sk = sock->sk;
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct sockaddr_tipc *dst = (struct sockaddr_tipc *)dest;
    	struct msghdr m = {NULL,};
    	long timeout = (flags & O_NONBLOCK) ? 0 : tsk->conn_timeout;
    	int previous;
    	int res = 0;
    
    	if (destlen != sizeof(struct sockaddr_tipc))
    		return -EINVAL;
    
    	lock_sock(sk);
    
    	if (tsk->group) {
    		res = -EINVAL;
    		goto exit;
    	}
    
    	if (dst->family == AF_UNSPEC) {
    		memset(&tsk->peer, 0, sizeof(struct sockaddr_tipc));
    		if (!tipc_sk_type_connectionless(sk))
    			res = -EINVAL;
    		goto exit;
    	}
    	if (!tipc_sockaddr_is_sane(dst)) {
    		res = -EINVAL;
    		goto exit;
    	}
    	/* DGRAM/RDM connect(), just save the destaddr */
    	if (tipc_sk_type_connectionless(sk)) {
    		memcpy(&tsk->peer, dest, destlen);
    		goto exit;
    	} else if (dst->addrtype == TIPC_SERVICE_RANGE) {
    		res = -EINVAL;
    		goto exit;
    	}
    
    	previous = sk->sk_state;
    
    	switch (sk->sk_state) {
    	case TIPC_OPEN:
    		/* Send a 'SYN-' to destination */
    		m.msg_name = dest;
    		m.msg_namelen = destlen;
    
    		/* If connect is in non-blocking case, set MSG_DONTWAIT to
    		 * indicate send_msg() is never blocked.
    		 */
    		if (!timeout)
    			m.msg_flags = MSG_DONTWAIT;
    
    		res = __tipc_sendmsg(sock, &m, 0);
    		if ((res < 0) && (res != -EWOULDBLOCK))
    			goto exit;
    
    		/* Just entered TIPC_CONNECTING state; the only
    		 * difference is that return value in non-blocking
    		 * case is EINPROGRESS, rather than EALREADY.
    		 */
    		res = -EINPROGRESS;
    		/* fall through */
    	case TIPC_CONNECTING:
    		if (!timeout) {
    			if (previous == TIPC_CONNECTING)
    				res = -EALREADY;
    			goto exit;
    		}
    		timeout = msecs_to_jiffies(timeout);
    		/* Wait until an 'ACK' or 'RST' arrives, or a timeout occurs */
    		res = tipc_wait_for_connect(sock, &timeout);
    		break;
    	case TIPC_ESTABLISHED:
    		res = -EISCONN;
    		break;
    	default:
    		res = -EINVAL;
    	}
    
    exit:
    	release_sock(sk);
    	return res;
    }
    
    /**
     * tipc_listen - allow socket to listen for incoming connections
     * @sock: socket structure
     * @len: (unused)
     *
     * Returns 0 on success, errno otherwise
     */
    static int tipc_listen(struct socket *sock, int len)
    {
    	struct sock *sk = sock->sk;
    	int res;
    
    	lock_sock(sk);
    	res = tipc_set_sk_state(sk, TIPC_LISTEN);
    	release_sock(sk);
    
    	return res;
    }
    
    static int tipc_wait_for_accept(struct socket *sock, long timeo)
    {
    	struct sock *sk = sock->sk;
    	DEFINE_WAIT(wait);
    	int err;
    
    	/* True wake-one mechanism for incoming connections: only
    	 * one process gets woken up, not the 'whole herd'.
    	 * Since we do not 'race & poll' for established sockets
    	 * anymore, the common case will execute the loop only once.
    	*/
    	for (;;) {
    		prepare_to_wait_exclusive(sk_sleep(sk), &wait,
    					  TASK_INTERRUPTIBLE);
    		if (timeo && skb_queue_empty(&sk->sk_receive_queue)) {
    			release_sock(sk);
    			timeo = schedule_timeout(timeo);
    			lock_sock(sk);
    		}
    		err = 0;
    		if (!skb_queue_empty(&sk->sk_receive_queue))
    			break;
    		err = -EAGAIN;
    		if (!timeo)
    			break;
    		err = sock_intr_errno(timeo);
    		if (signal_pending(current))
    			break;
    	}
    	finish_wait(sk_sleep(sk), &wait);
    	return err;
    }
    
    /**
     * tipc_accept - wait for connection request
     * @sock: listening socket
     * @newsock: new socket that is to be connected
     * @flags: file-related flags associated with socket
     *
     * Returns 0 on success, errno otherwise
     */
    static int tipc_accept(struct socket *sock, struct socket *new_sock, int flags,
    		       bool kern)
    {
    	struct sock *new_sk, *sk = sock->sk;
    	struct sk_buff *buf;
    	struct tipc_sock *new_tsock;
    	struct tipc_msg *msg;
    	long timeo;
    	int res;
    
    	lock_sock(sk);
    
    	if (sk->sk_state != TIPC_LISTEN) {
    		res = -EINVAL;
    		goto exit;
    	}
    	timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
    	res = tipc_wait_for_accept(sock, timeo);
    	if (res)
    		goto exit;
    
    	buf = skb_peek(&sk->sk_receive_queue);
    
    	res = tipc_sk_create(sock_net(sock->sk), new_sock, 0, kern);
    	if (res)
    		goto exit;
    	security_sk_clone(sock->sk, new_sock->sk);
    
    	new_sk = new_sock->sk;
    	new_tsock = tipc_sk(new_sk);
    	msg = buf_msg(buf);
    
    	/* we lock on new_sk; but lockdep sees the lock on sk */
    	lock_sock_nested(new_sk, SINGLE_DEPTH_NESTING);
    
    	/*
    	 * Reject any stray messages received by new socket
    	 * before the socket lock was taken (very, very unlikely)
    	 */
    	tsk_rej_rx_queue(new_sk, TIPC_ERR_NO_PORT);
    
    	/* Connect new socket to it's peer */
    	tipc_sk_finish_conn(new_tsock, msg_origport(msg), msg_orignode(msg));
    
    	tsk_set_importance(new_sk, msg_importance(msg));
    	if (msg_named(msg)) {
    		new_tsock->conn_type = msg_nametype(msg);
    		new_tsock->conn_instance = msg_nameinst(msg);
    	}
    
    	/*
    	 * Respond to 'SYN-' by discarding it & returning 'ACK'-.
    	 * Respond to 'SYN+' by queuing it on new socket.
    	 */
    	if (!msg_data_sz(msg)) {
    		struct msghdr m = {NULL,};
    
    		tsk_advance_rx_queue(sk);
    		__tipc_sendstream(new_sock, &m, 0);
    	} else {
    		__skb_dequeue(&sk->sk_receive_queue);
    		__skb_queue_head(&new_sk->sk_receive_queue, buf);
    		skb_set_owner_r(buf, new_sk);
    	}
    	release_sock(new_sk);
    exit:
    	release_sock(sk);
    	return res;
    }
    
    /**
     * tipc_shutdown - shutdown socket connection
     * @sock: socket structure
     * @how: direction to close (must be SHUT_RDWR)
     *
     * Terminates connection (if necessary), then purges socket's receive queue.
     *
     * Returns 0 on success, errno otherwise
     */
    static int tipc_shutdown(struct socket *sock, int how)
    {
    	struct sock *sk = sock->sk;
    	int res;
    
    	if (how != SHUT_RDWR)
    		return -EINVAL;
    
    	lock_sock(sk);
    
    	trace_tipc_sk_shutdown(sk, NULL, TIPC_DUMP_ALL, " ");
    	__tipc_shutdown(sock, TIPC_CONN_SHUTDOWN);
    	sk->sk_shutdown = SEND_SHUTDOWN;
    
    	if (sk->sk_state == TIPC_DISCONNECTING) {
    		/* Discard any unreceived messages */
    		__skb_queue_purge(&sk->sk_receive_queue);
    
    		/* Wake up anyone sleeping in poll */
    		sk->sk_state_change(sk);
    		res = 0;
    	} else {
    		res = -ENOTCONN;
    	}
    
    	release_sock(sk);
    	return res;
    }
    
    static void tipc_sk_check_probing_state(struct sock *sk,
    					struct sk_buff_head *list)
    {
    	struct tipc_sock *tsk = tipc_sk(sk);
    	u32 pnode = tsk_peer_node(tsk);
    	u32 pport = tsk_peer_port(tsk);
    	u32 self = tsk_own_node(tsk);
    	u32 oport = tsk->portid;
    	struct sk_buff *skb;
    
    	if (tsk->probe_unacked) {
    		tipc_set_sk_state(sk, TIPC_DISCONNECTING);
    		sk->sk_err = ECONNABORTED;
    		tipc_node_remove_conn(sock_net(sk), pnode, pport);
    		sk->sk_state_change(sk);
    		return;
    	}
    	/* Prepare new probe */
    	skb = tipc_msg_create(CONN_MANAGER, CONN_PROBE, INT_H_SIZE, 0,
    			      pnode, self, pport, oport, TIPC_OK);
    	if (skb)
    		__skb_queue_tail(list, skb);
    	tsk->probe_unacked = true;
    	sk_reset_timer(sk, &sk->sk_timer, jiffies + CONN_PROBING_INTV);
    }
    
    static void tipc_sk_retry_connect(struct sock *sk, struct sk_buff_head *list)
    {
    	struct tipc_sock *tsk = tipc_sk(sk);
    
    	/* Try again later if dest link is congested */
    	if (tsk->cong_link_cnt) {
    		sk_reset_timer(sk, &sk->sk_timer, msecs_to_jiffies(100));
    		return;
    	}
    	/* Prepare SYN for retransmit */
    	tipc_msg_skb_clone(&sk->sk_write_queue, list);
    }
    
    static void tipc_sk_timeout(struct timer_list *t)
    {
    	struct sock *sk = from_timer(sk, t, sk_timer);
    	struct tipc_sock *tsk = tipc_sk(sk);
    	u32 pnode = tsk_peer_node(tsk);
    	struct sk_buff_head list;
    	int rc = 0;
    
    	__skb_queue_head_init(&list);
    	bh_lock_sock(sk);
    
    	/* Try again later if socket is busy */
    	if (sock_owned_by_user(sk)) {
    		sk_reset_timer(sk, &sk->sk_timer, jiffies + HZ / 20);
    		bh_unlock_sock(sk);
    		sock_put(sk);
    		return;
    	}
    
    	if (sk->sk_state == TIPC_ESTABLISHED)
    		tipc_sk_check_probing_state(sk, &list);
    	else if (sk->sk_state == TIPC_CONNECTING)
    		tipc_sk_retry_connect(sk, &list);
    
    	bh_unlock_sock(sk);
    
    	if (!skb_queue_empty(&list))
    		rc = tipc_node_xmit(sock_net(sk), &list, pnode, tsk->portid);
    
    	/* SYN messages may cause link congestion */
    	if (rc == -ELINKCONG) {
    		tipc_dest_push(&tsk->cong_links, pnode, 0);
    		tsk->cong_link_cnt = 1;
    	}
    	sock_put(sk);
    }
    
    static int tipc_sk_publish(struct tipc_sock *tsk, uint scope,
    			   struct tipc_name_seq const *seq)
    {
    	struct sock *sk = &tsk->sk;
    	struct net *net = sock_net(sk);
    	struct publication *publ;
    	u32 key;
    
    	if (scope != TIPC_NODE_SCOPE)
    		scope = TIPC_CLUSTER_SCOPE;
    
    	if (tipc_sk_connected(sk))
    		return -EINVAL;
    	key = tsk->portid + tsk->pub_count + 1;
    	if (key == tsk->portid)
    		return -EADDRINUSE;
    
    	publ = tipc_nametbl_publish(net, seq->type, seq->lower, seq->upper,
    				    scope, tsk->portid, key);
    	if (unlikely(!publ))
    		return -EINVAL;
    
    	list_add(&publ->binding_sock, &tsk->publications);
    	tsk->pub_count++;
    	tsk->published = 1;
    	return 0;
    }
    
    static int tipc_sk_withdraw(struct tipc_sock *tsk, uint scope,
    			    struct tipc_name_seq const *seq)
    {
    	struct net *net = sock_net(&tsk->sk);
    	struct publication *publ;
    	struct publication *safe;
    	int rc = -EINVAL;
    
    	if (scope != TIPC_NODE_SCOPE)
    		scope = TIPC_CLUSTER_SCOPE;
    
    	list_for_each_entry_safe(publ, safe, &tsk->publications, binding_sock) {
    		if (seq) {
    			if (publ->scope != scope)
    				continue;
    			if (publ->type != seq->type)
    				continue;
    			if (publ->lower != seq->lower)
    				continue;
    			if (publ->upper != seq->upper)
    				break;
    			tipc_nametbl_withdraw(net, publ->type, publ->lower,
    					      publ->upper, publ->key);
    			rc = 0;
    			break;
    		}
    		tipc_nametbl_withdraw(net, publ->type, publ->lower,
    				      publ->upper, publ->key);
    		rc = 0;
    	}
    	if (list_empty(&tsk->publications))
    		tsk->published = 0;
    	return rc;
    }
    
    /* tipc_sk_reinit: set non-zero address in all existing sockets
     *                 when we go from standalone to network mode.
     */
    void tipc_sk_reinit(struct net *net)
    {
    	struct tipc_net *tn = net_generic(net, tipc_net_id);
    	struct rhashtable_iter iter;
    	struct tipc_sock *tsk;
    	struct tipc_msg *msg;
    
    	rhashtable_walk_enter(&tn->sk_rht, &iter);
    
    	do {
    		rhashtable_walk_start(&iter);
    
    		while ((tsk = rhashtable_walk_next(&iter)) && !IS_ERR(tsk)) {
    			sock_hold(&tsk->sk);
    			rhashtable_walk_stop(&iter);
    			lock_sock(&tsk->sk);
    			msg = &tsk->phdr;
    			msg_set_prevnode(msg, tipc_own_addr(net));
    			msg_set_orignode(msg, tipc_own_addr(net));
    			release_sock(&tsk->sk);
    			rhashtable_walk_start(&iter);
    			sock_put(&tsk->sk);
    		}
    
    		rhashtable_walk_stop(&iter);
    	} while (tsk == ERR_PTR(-EAGAIN));
    
    	rhashtable_walk_exit(&iter);
    }
    
    static struct tipc_sock *tipc_sk_lookup(struct net *net, u32 portid)
    {
    	struct tipc_net *tn = net_generic(net, tipc_net_id);
    	struct tipc_sock *tsk;
    
    	rcu_read_lock();
    	tsk = rhashtable_lookup(&tn->sk_rht, &portid, tsk_rht_params);
    	if (tsk)
    		sock_hold(&tsk->sk);
    	rcu_read_unlock();
    
    	return tsk;
    }
    
    static int tipc_sk_insert(struct tipc_sock *tsk)
    {
    	struct sock *sk = &tsk->sk;
    	struct net *net = sock_net(sk);
    	struct tipc_net *tn = net_generic(net, tipc_net_id);
    	u32 remaining = (TIPC_MAX_PORT - TIPC_MIN_PORT) + 1;
    	u32 portid = prandom_u32() % remaining + TIPC_MIN_PORT;
    
    	while (remaining--) {
    		portid++;
    		if ((portid < TIPC_MIN_PORT) || (portid > TIPC_MAX_PORT))
    			portid = TIPC_MIN_PORT;
    		tsk->portid = portid;
    		sock_hold(&tsk->sk);
    		if (!rhashtable_lookup_insert_fast(&tn->sk_rht, &tsk->node,
    						   tsk_rht_params))
    			return 0;
    		sock_put(&tsk->sk);
    	}
    
    	return -1;
    }
    
    static void tipc_sk_remove(struct tipc_sock *tsk)
    {
    	struct sock *sk = &tsk->sk;
    	struct tipc_net *tn = net_generic(sock_net(sk), tipc_net_id);
    
    	if (!rhashtable_remove_fast(&tn->sk_rht, &tsk->node, tsk_rht_params)) {
    		WARN_ON(refcount_read(&sk->sk_refcnt) == 1);
    		__sock_put(sk);
    	}
    }
    
    static const struct rhashtable_params tsk_rht_params = {
    	.nelem_hint = 192,
    	.head_offset = offsetof(struct tipc_sock, node),
    	.key_offset = offsetof(struct tipc_sock, portid),
    	.key_len = sizeof(u32), /* portid */
    	.max_size = 1048576,
    	.min_size = 256,
    	.automatic_shrinking = true,
    };
    
    int tipc_sk_rht_init(struct net *net)
    {
    	struct tipc_net *tn = net_generic(net, tipc_net_id);
    
    	return rhashtable_init(&tn->sk_rht, &tsk_rht_params);
    }
    
    void tipc_sk_rht_destroy(struct net *net)
    {
    	struct tipc_net *tn = net_generic(net, tipc_net_id);
    
    	/* Wait for socket readers to complete */
    	synchronize_net();
    
    	rhashtable_destroy(&tn->sk_rht);
    }
    
    static int tipc_sk_join(struct tipc_sock *tsk, struct tipc_group_req *mreq)
    {
    	struct net *net = sock_net(&tsk->sk);
    	struct tipc_group *grp = tsk->group;
    	struct tipc_msg *hdr = &tsk->phdr;
    	struct tipc_name_seq seq;
    	int rc;
    
    	if (mreq->type < TIPC_RESERVED_TYPES)
    		return -EACCES;
    	if (mreq->scope > TIPC_NODE_SCOPE)
    		return -EINVAL;
    	if (grp)
    		return -EACCES;
    	grp = tipc_group_create(net, tsk->portid, mreq, &tsk->group_is_open);
    	if (!grp)
    		return -ENOMEM;
    	tsk->group = grp;
    	msg_set_lookup_scope(hdr, mreq->scope);
    	msg_set_nametype(hdr, mreq->type);
    	msg_set_dest_droppable(hdr, true);
    	seq.type = mreq->type;
    	seq.lower = mreq->instance;
    	seq.upper = seq.lower;
    	tipc_nametbl_build_group(net, grp, mreq->type, mreq->scope);
    	rc = tipc_sk_publish(tsk, mreq->scope, &seq);
    	if (rc) {
    		tipc_group_delete(net, grp);
    		tsk->group = NULL;
    		return rc;
    	}
    	/* Eliminate any risk that a broadcast overtakes sent JOINs */
    	tsk->mc_method.rcast = true;
    	tsk->mc_method.mandatory = true;
    	tipc_group_join(net, grp, &tsk->sk.sk_rcvbuf);
    	return rc;
    }
    
    static int tipc_sk_leave(struct tipc_sock *tsk)
    {
    	struct net *net = sock_net(&tsk->sk);
    	struct tipc_group *grp = tsk->group;
    	struct tipc_name_seq seq;
    	int scope;
    
    	if (!grp)
    		return -EINVAL;
    	tipc_group_self(grp, &seq, &scope);
    	tipc_group_delete(net, grp);
    	tsk->group = NULL;
    	tipc_sk_withdraw(tsk, scope, &seq);
    	return 0;
    }
    
    /**
     * tipc_setsockopt - set socket option
     * @sock: socket structure
     * @lvl: option level
     * @opt: option identifier
     * @ov: pointer to new option value
     * @ol: length of option value
     *
     * For stream sockets only, accepts and ignores all IPPROTO_TCP options
     * (to ease compatibility).
     *
     * Returns 0 on success, errno otherwise
     */
    static int tipc_setsockopt(struct socket *sock, int lvl, int opt,
    			   char __user *ov, unsigned int ol)
    {
    	struct sock *sk = sock->sk;
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct tipc_group_req mreq;
    	u32 value = 0;
    	int res = 0;
    
    	if ((lvl == IPPROTO_TCP) && (sock->type == SOCK_STREAM))
    		return 0;
    	if (lvl != SOL_TIPC)
    		return -ENOPROTOOPT;
    
    	switch (opt) {
    	case TIPC_IMPORTANCE:
    	case TIPC_SRC_DROPPABLE:
    	case TIPC_DEST_DROPPABLE:
    	case TIPC_CONN_TIMEOUT:
    	case TIPC_NODELAY:
    		if (ol < sizeof(value))
    			return -EINVAL;
    		if (get_user(value, (u32 __user *)ov))
    			return -EFAULT;
    		break;
    	case TIPC_GROUP_JOIN:
    		if (ol < sizeof(mreq))
    			return -EINVAL;
    		if (copy_from_user(&mreq, ov, sizeof(mreq)))
    			return -EFAULT;
    		break;
    	default:
    		if (ov || ol)
    			return -EINVAL;
    	}
    
    	lock_sock(sk);
    
    	switch (opt) {
    	case TIPC_IMPORTANCE:
    		res = tsk_set_importance(sk, value);
    		break;
    	case TIPC_SRC_DROPPABLE:
    		if (sock->type != SOCK_STREAM)
    			tsk_set_unreliable(tsk, value);
    		else
    			res = -ENOPROTOOPT;
    		break;
    	case TIPC_DEST_DROPPABLE:
    		tsk_set_unreturnable(tsk, value);
    		break;
    	case TIPC_CONN_TIMEOUT:
    		tipc_sk(sk)->conn_timeout = value;
    		break;
    	case TIPC_MCAST_BROADCAST:
    		tsk->mc_method.rcast = false;
    		tsk->mc_method.mandatory = true;
    		break;
    	case TIPC_MCAST_REPLICAST:
    		tsk->mc_method.rcast = true;
    		tsk->mc_method.mandatory = true;
    		break;
    	case TIPC_GROUP_JOIN:
    		res = tipc_sk_join(tsk, &mreq);
    		break;
    	case TIPC_GROUP_LEAVE:
    		res = tipc_sk_leave(tsk);
    		break;
    	case TIPC_NODELAY:
    		tsk->nodelay = !!value;
    		tsk_set_nagle(tsk);
    		break;
    	default:
    		res = -EINVAL;
    	}
    
    	release_sock(sk);
    
    	return res;
    }
    
    /**
     * tipc_getsockopt - get socket option
     * @sock: socket structure
     * @lvl: option level
     * @opt: option identifier
     * @ov: receptacle for option value
     * @ol: receptacle for length of option value
     *
     * For stream sockets only, returns 0 length result for all IPPROTO_TCP options
     * (to ease compatibility).
     *
     * Returns 0 on success, errno otherwise
     */
    static int tipc_getsockopt(struct socket *sock, int lvl, int opt,
    			   char __user *ov, int __user *ol)
    {
    	struct sock *sk = sock->sk;
    	struct tipc_sock *tsk = tipc_sk(sk);
    	struct tipc_name_seq seq;
    	int len, scope;
    	u32 value;
    	int res;
    
    	if ((lvl == IPPROTO_TCP) && (sock->type == SOCK_STREAM))
    		return put_user(0, ol);
    	if (lvl != SOL_TIPC)
    		return -ENOPROTOOPT;
    	res = get_user(len, ol);
    	if (res)
    		return res;
    
    	lock_sock(sk);
    
    	switch (opt) {
    	case TIPC_IMPORTANCE:
    		value = tsk_importance(tsk);
    		break;
    	case TIPC_SRC_DROPPABLE:
    		value = tsk_unreliable(tsk);
    		break;
    	case TIPC_DEST_DROPPABLE:
    		value = tsk_unreturnable(tsk);
    		break;
    	case TIPC_CONN_TIMEOUT:
    		value = tsk->conn_timeout;
    		/* no need to set "res", since already 0 at this point */
    		break;
    	case TIPC_NODE_RECVQ_DEPTH:
    		value = 0; /* was tipc_queue_size, now obsolete */
    		break;
    	case TIPC_SOCK_RECVQ_DEPTH:
    		value = skb_queue_len(&sk->sk_receive_queue);
    		break;
    	case TIPC_SOCK_RECVQ_USED:
    		value = sk_rmem_alloc_get(sk);
    		break;
    	case TIPC_GROUP_JOIN:
    		seq.type = 0;
    		if (tsk->group)
    			tipc_group_self(tsk->group, &seq, &scope);
    		value = seq.type;
    		break;
    	default:
    		res = -EINVAL;
    	}
    
    	release_sock(sk);
    
    	if (res)
    		return res;	/* "get" failed */
    
    	if (len < sizeof(value))
    		return -EINVAL;
    
    	if (copy_to_user(ov, &value, sizeof(value)))
    		return -EFAULT;
    
    	return put_user(sizeof(value), ol);
    }
    
    static int tipc_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
    {
    	struct net *net = sock_net(sock->sk);
    	struct tipc_sioc_nodeid_req nr = {0};
    	struct tipc_sioc_ln_req lnr;
    	void __user *argp = (void __user *)arg;
    
    	switch (cmd) {
    	case SIOCGETLINKNAME:
    		if (copy_from_user(&lnr, argp, sizeof(lnr)))
    			return -EFAULT;
    		if (!tipc_node_get_linkname(net,
    					    lnr.bearer_id & 0xffff, lnr.peer,
    					    lnr.linkname, TIPC_MAX_LINK_NAME)) {
    			if (copy_to_user(argp, &lnr, sizeof(lnr)))
    				return -EFAULT;
    			return 0;
    		}
    		return -EADDRNOTAVAIL;
    	case SIOCGETNODEID:
    		if (copy_from_user(&nr, argp, sizeof(nr)))
    			return -EFAULT;
    		if (!tipc_node_get_id(net, nr.peer, nr.node_id))
    			return -EADDRNOTAVAIL;
    		if (copy_to_user(argp, &nr, sizeof(nr)))
    			return -EFAULT;
    		return 0;
    	default:
    		return -ENOIOCTLCMD;
    	}
    }
    
    static int tipc_socketpair(struct socket *sock1, struct socket *sock2)
    {
    	struct tipc_sock *tsk2 = tipc_sk(sock2->sk);
    	struct tipc_sock *tsk1 = tipc_sk(sock1->sk);
    	u32 onode = tipc_own_addr(sock_net(sock1->sk));
    
    	tsk1->peer.family = AF_TIPC;
    	tsk1->peer.addrtype = TIPC_ADDR_ID;
    	tsk1->peer.scope = TIPC_NODE_SCOPE;
    	tsk1->peer.addr.id.ref = tsk2->portid;
    	tsk1->peer.addr.id.node = onode;
    	tsk2->peer.family = AF_TIPC;
    	tsk2->peer.addrtype = TIPC_ADDR_ID;
    	tsk2->peer.scope = TIPC_NODE_SCOPE;
    	tsk2->peer.addr.id.ref = tsk1->portid;
    	tsk2->peer.addr.id.node = onode;
    
    	tipc_sk_finish_conn(tsk1, tsk2->portid, onode);
    	tipc_sk_finish_conn(tsk2, tsk1->portid, onode);
    	return 0;
    }
    
    /* Protocol switches for the various types of TIPC sockets */
    
    static const struct proto_ops msg_ops = {
    	.owner		= THIS_MODULE,
    	.family		= AF_TIPC,
    	.release	= tipc_release,
    	.bind		= tipc_bind,
    	.connect	= tipc_connect,
    	.socketpair	= tipc_socketpair,
    	.accept		= sock_no_accept,
    	.getname	= tipc_getname,
    	.poll		= tipc_poll,
    	.ioctl		= tipc_ioctl,
    	.listen		= sock_no_listen,
    	.shutdown	= tipc_shutdown,
    	.setsockopt	= tipc_setsockopt,
    	.getsockopt	= tipc_getsockopt,
    	.sendmsg	= tipc_sendmsg,
    	.recvmsg	= tipc_recvmsg,
    	.mmap		= sock_no_mmap,
    	.sendpage	= sock_no_sendpage
    };
    
    static const struct proto_ops packet_ops = {
    	.owner		= THIS_MODULE,
    	.family		= AF_TIPC,
    	.release	= tipc_release,
    	.bind		= tipc_bind,
    	.connect	= tipc_connect,
    	.socketpair	= tipc_socketpair,
    	.accept		= tipc_accept,
    	.getname	= tipc_getname,
    	.poll		= tipc_poll,
    	.ioctl		= tipc_ioctl,
    	.listen		= tipc_listen,
    	.shutdown	= tipc_shutdown,
    	.setsockopt	= tipc_setsockopt,
    	.getsockopt	= tipc_getsockopt,
    	.sendmsg	= tipc_send_packet,
    	.recvmsg	= tipc_recvmsg,
    	.mmap		= sock_no_mmap,
    	.sendpage	= sock_no_sendpage
    };
    
    static const struct proto_ops stream_ops = {
    	.owner		= THIS_MODULE,
    	.family		= AF_TIPC,
    	.release	= tipc_release,
    	.bind		= tipc_bind,
    	.connect	= tipc_connect,
    	.socketpair	= tipc_socketpair,
    	.accept		= tipc_accept,
    	.getname	= tipc_getname,
    	.poll		= tipc_poll,
    	.ioctl		= tipc_ioctl,
    	.listen		= tipc_listen,
    	.shutdown	= tipc_shutdown,
    	.setsockopt	= tipc_setsockopt,
    	.getsockopt	= tipc_getsockopt,
    	.sendmsg	= tipc_sendstream,
    	.recvmsg	= tipc_recvstream,
    	.mmap		= sock_no_mmap,
    	.sendpage	= sock_no_sendpage
    };
    
    static const struct net_proto_family tipc_family_ops = {
    	.owner		= THIS_MODULE,
    	.family		= AF_TIPC,
    	.create		= tipc_sk_create
    };
    
    static struct proto tipc_proto = {
    	.name		= "TIPC",
    	.owner		= THIS_MODULE,
    	.obj_size	= sizeof(struct tipc_sock),
    	.sysctl_rmem	= sysctl_tipc_rmem
    };
    
    /**
     * tipc_socket_init - initialize TIPC socket interface
     *
     * Returns 0 on success, errno otherwise
     */
    int tipc_socket_init(void)
    {
    	int res;
    
    	res = proto_register(&tipc_proto, 1);
    	if (res) {
    		pr_err("Failed to register TIPC protocol type\n");
    		goto out;
    	}
    
    	res = sock_register(&tipc_family_ops);
    	if (res) {
    		pr_err("Failed to register TIPC socket type\n");
    		proto_unregister(&tipc_proto);
    		goto out;
    	}
     out:
    	return res;
    }
    
    /**
     * tipc_socket_stop - stop TIPC socket interface
     */
    void tipc_socket_stop(void)
    {
    	sock_unregister(tipc_family_ops.family);
    	proto_unregister(&tipc_proto);
    }
    
    /* Caller should hold socket lock for the passed tipc socket. */
    static int __tipc_nl_add_sk_con(struct sk_buff *skb, struct tipc_sock *tsk)
    {
    	u32 peer_node;
    	u32 peer_port;
    	struct nlattr *nest;
    
    	peer_node = tsk_peer_node(tsk);
    	peer_port = tsk_peer_port(tsk);
    
    	nest = nla_nest_start_noflag(skb, TIPC_NLA_SOCK_CON);
    	if (!nest)
    		return -EMSGSIZE;
    
    	if (nla_put_u32(skb, TIPC_NLA_CON_NODE, peer_node))
    		goto msg_full;
    	if (nla_put_u32(skb, TIPC_NLA_CON_SOCK, peer_port))
    		goto msg_full;
    
    	if (tsk->conn_type != 0) {
    		if (nla_put_flag(skb, TIPC_NLA_CON_FLAG))
    			goto msg_full;
    		if (nla_put_u32(skb, TIPC_NLA_CON_TYPE, tsk->conn_type))
    			goto msg_full;
    		if (nla_put_u32(skb, TIPC_NLA_CON_INST, tsk->conn_instance))
    			goto msg_full;
    	}
    	nla_nest_end(skb, nest);
    
    	return 0;
    
    msg_full:
    	nla_nest_cancel(skb, nest);
    
    	return -EMSGSIZE;
    }
    
    static int __tipc_nl_add_sk_info(struct sk_buff *skb, struct tipc_sock
    			  *tsk)
    {
    	struct net *net = sock_net(skb->sk);
    	struct sock *sk = &tsk->sk;
    
    	if (nla_put_u32(skb, TIPC_NLA_SOCK_REF, tsk->portid) ||
    	    nla_put_u32(skb, TIPC_NLA_SOCK_ADDR, tipc_own_addr(net)))
    		return -EMSGSIZE;
    
    	if (tipc_sk_connected(sk)) {
    		if (__tipc_nl_add_sk_con(skb, tsk))
    			return -EMSGSIZE;
    	} else if (!list_empty(&tsk->publications)) {
    		if (nla_put_flag(skb, TIPC_NLA_SOCK_HAS_PUBL))
    			return -EMSGSIZE;
    	}
    	return 0;
    }
    
    /* Caller should hold socket lock for the passed tipc socket. */
    static int __tipc_nl_add_sk(struct sk_buff *skb, struct netlink_callback *cb,
    			    struct tipc_sock *tsk)
    {
    	struct nlattr *attrs;
    	void *hdr;
    
    	hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
    			  &tipc_genl_family, NLM_F_MULTI, TIPC_NL_SOCK_GET);
    	if (!hdr)
    		goto msg_cancel;
    
    	attrs = nla_nest_start_noflag(skb, TIPC_NLA_SOCK);
    	if (!attrs)
    		goto genlmsg_cancel;
    
    	if (__tipc_nl_add_sk_info(skb, tsk))
    		goto attr_msg_cancel;
    
    	nla_nest_end(skb, attrs);
    	genlmsg_end(skb, hdr);
    
    	return 0;
    
    attr_msg_cancel:
    	nla_nest_cancel(skb, attrs);
    genlmsg_cancel:
    	genlmsg_cancel(skb, hdr);
    msg_cancel:
    	return -EMSGSIZE;
    }
    
    int tipc_nl_sk_walk(struct sk_buff *skb, struct netlink_callback *cb,
    		    int (*skb_handler)(struct sk_buff *skb,
    				       struct netlink_callback *cb,
    				       struct tipc_sock *tsk))
    {
    	struct rhashtable_iter *iter = (void *)cb->args[4];
    	struct tipc_sock *tsk;
    	int err;
    
    	rhashtable_walk_start(iter);
    	while ((tsk = rhashtable_walk_next(iter)) != NULL) {
    		if (IS_ERR(tsk)) {
    			err = PTR_ERR(tsk);
    			if (err == -EAGAIN) {
    				err = 0;
    				continue;
    			}
    			break;
    		}
    
    		sock_hold(&tsk->sk);
    		rhashtable_walk_stop(iter);
    		lock_sock(&tsk->sk);
    		err = skb_handler(skb, cb, tsk);
    		if (err) {
    			release_sock(&tsk->sk);
    			sock_put(&tsk->sk);
    			goto out;
    		}
    		release_sock(&tsk->sk);
    		rhashtable_walk_start(iter);
    		sock_put(&tsk->sk);
    	}
    	rhashtable_walk_stop(iter);
    out:
    	return skb->len;
    }
    EXPORT_SYMBOL(tipc_nl_sk_walk);
    
    int tipc_dump_start(struct netlink_callback *cb)
    {
    	return __tipc_dump_start(cb, sock_net(cb->skb->sk));
    }
    EXPORT_SYMBOL(tipc_dump_start);
    
    int __tipc_dump_start(struct netlink_callback *cb, struct net *net)
    {
    	/* tipc_nl_name_table_dump() uses cb->args[0...3]. */
    	struct rhashtable_iter *iter = (void *)cb->args[4];
    	struct tipc_net *tn = tipc_net(net);
    
    	if (!iter) {
    		iter = kmalloc(sizeof(*iter), GFP_KERNEL);
    		if (!iter)
    			return -ENOMEM;
    
    		cb->args[4] = (long)iter;
    	}
    
    	rhashtable_walk_enter(&tn->sk_rht, iter);
    	return 0;
    }
    
    int tipc_dump_done(struct netlink_callback *cb)
    {
    	struct rhashtable_iter *hti = (void *)cb->args[4];
    
    	rhashtable_walk_exit(hti);
    	kfree(hti);
    	return 0;
    }
    EXPORT_SYMBOL(tipc_dump_done);
    
    int tipc_sk_fill_sock_diag(struct sk_buff *skb, struct netlink_callback *cb,
    			   struct tipc_sock *tsk, u32 sk_filter_state,
    			   u64 (*tipc_diag_gen_cookie)(struct sock *sk))
    {
    	struct sock *sk = &tsk->sk;
    	struct nlattr *attrs;
    	struct nlattr *stat;
    
    	/*filter response w.r.t sk_state*/
    	if (!(sk_filter_state & (1 << sk->sk_state)))
    		return 0;
    
    	attrs = nla_nest_start_noflag(skb, TIPC_NLA_SOCK);
    	if (!attrs)
    		goto msg_cancel;
    
    	if (__tipc_nl_add_sk_info(skb, tsk))
    		goto attr_msg_cancel;
    
    	if (nla_put_u32(skb, TIPC_NLA_SOCK_TYPE, (u32)sk->sk_type) ||
    	    nla_put_u32(skb, TIPC_NLA_SOCK_TIPC_STATE, (u32)sk->sk_state) ||
    	    nla_put_u32(skb, TIPC_NLA_SOCK_INO, sock_i_ino(sk)) ||
    	    nla_put_u32(skb, TIPC_NLA_SOCK_UID,
    			from_kuid_munged(sk_user_ns(NETLINK_CB(cb->skb).sk),
    					 sock_i_uid(sk))) ||
    	    nla_put_u64_64bit(skb, TIPC_NLA_SOCK_COOKIE,
    			      tipc_diag_gen_cookie(sk),
    			      TIPC_NLA_SOCK_PAD))
    		goto attr_msg_cancel;
    
    	stat = nla_nest_start_noflag(skb, TIPC_NLA_SOCK_STAT);
    	if (!stat)
    		goto attr_msg_cancel;
    
    	if (nla_put_u32(skb, TIPC_NLA_SOCK_STAT_RCVQ,
    			skb_queue_len(&sk->sk_receive_queue)) ||
    	    nla_put_u32(skb, TIPC_NLA_SOCK_STAT_SENDQ,
    			skb_queue_len(&sk->sk_write_queue)) ||
    	    nla_put_u32(skb, TIPC_NLA_SOCK_STAT_DROP,
    			atomic_read(&sk->sk_drops)))
    		goto stat_msg_cancel;
    
    	if (tsk->cong_link_cnt &&
    	    nla_put_flag(skb, TIPC_NLA_SOCK_STAT_LINK_CONG))
    		goto stat_msg_cancel;
    
    	if (tsk_conn_cong(tsk) &&
    	    nla_put_flag(skb, TIPC_NLA_SOCK_STAT_CONN_CONG))
    		goto stat_msg_cancel;
    
    	nla_nest_end(skb, stat);
    
    	if (tsk->group)
    		if (tipc_group_fill_sock_diag(tsk->group, skb))
    			goto stat_msg_cancel;
    
    	nla_nest_end(skb, attrs);
    
    	return 0;
    
    stat_msg_cancel:
    	nla_nest_cancel(skb, stat);
    attr_msg_cancel:
    	nla_nest_cancel(skb, attrs);
    msg_cancel:
    	return -EMSGSIZE;
    }
    EXPORT_SYMBOL(tipc_sk_fill_sock_diag);
    
    int tipc_nl_sk_dump(struct sk_buff *skb, struct netlink_callback *cb)
    {
    	return tipc_nl_sk_walk(skb, cb, __tipc_nl_add_sk);
    }
    
    /* Caller should hold socket lock for the passed tipc socket. */
    static int __tipc_nl_add_sk_publ(struct sk_buff *skb,
    				 struct netlink_callback *cb,
    				 struct publication *publ)
    {
    	void *hdr;
    	struct nlattr *attrs;
    
    	hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
    			  &tipc_genl_family, NLM_F_MULTI, TIPC_NL_PUBL_GET);
    	if (!hdr)
    		goto msg_cancel;
    
    	attrs = nla_nest_start_noflag(skb, TIPC_NLA_PUBL);
    	if (!attrs)
    		goto genlmsg_cancel;
    
    	if (nla_put_u32(skb, TIPC_NLA_PUBL_KEY, publ->key))
    		goto attr_msg_cancel;
    	if (nla_put_u32(skb, TIPC_NLA_PUBL_TYPE, publ->type))
    		goto attr_msg_cancel;
    	if (nla_put_u32(skb, TIPC_NLA_PUBL_LOWER, publ->lower))
    		goto attr_msg_cancel;
    	if (nla_put_u32(skb, TIPC_NLA_PUBL_UPPER, publ->upper))
    		goto attr_msg_cancel;
    
    	nla_nest_end(skb, attrs);
    	genlmsg_end(skb, hdr);
    
    	return 0;
    
    attr_msg_cancel:
    	nla_nest_cancel(skb, attrs);
    genlmsg_cancel:
    	genlmsg_cancel(skb, hdr);
    msg_cancel:
    	return -EMSGSIZE;
    }
    
    /* Caller should hold socket lock for the passed tipc socket. */
    static int __tipc_nl_list_sk_publ(struct sk_buff *skb,
    				  struct netlink_callback *cb,
    				  struct tipc_sock *tsk, u32 *last_publ)
    {
    	int err;
    	struct publication *p;
    
    	if (*last_publ) {
    		list_for_each_entry(p, &tsk->publications, binding_sock) {
    			if (p->key == *last_publ)
    				break;
    		}
    		if (p->key != *last_publ) {
    			/* We never set seq or call nl_dump_check_consistent()
    			 * this means that setting prev_seq here will cause the
    			 * consistence check to fail in the netlink callback
    			 * handler. Resulting in the last NLMSG_DONE message
    			 * having the NLM_F_DUMP_INTR flag set.
    			 */
    			cb->prev_seq = 1;
    			*last_publ = 0;
    			return -EPIPE;
    		}
    	} else {
    		p = list_first_entry(&tsk->publications, struct publication,
    				     binding_sock);
    	}
    
    	list_for_each_entry_from(p, &tsk->publications, binding_sock) {
    		err = __tipc_nl_add_sk_publ(skb, cb, p);
    		if (err) {
    			*last_publ = p->key;
    			return err;
    		}
    	}
    	*last_publ = 0;
    
    	return 0;
    }
    
    int tipc_nl_publ_dump(struct sk_buff *skb, struct netlink_callback *cb)
    {
    	int err;
    	u32 tsk_portid = cb->args[0];
    	u32 last_publ = cb->args[1];
    	u32 done = cb->args[2];
    	struct net *net = sock_net(skb->sk);
    	struct tipc_sock *tsk;
    
    	if (!tsk_portid) {
    		struct nlattr **attrs = genl_dumpit_info(cb)->attrs;
    		struct nlattr *sock[TIPC_NLA_SOCK_MAX + 1];
    
    		if (!attrs[TIPC_NLA_SOCK])
    			return -EINVAL;
    
    		err = nla_parse_nested_deprecated(sock, TIPC_NLA_SOCK_MAX,
    						  attrs[TIPC_NLA_SOCK],
    						  tipc_nl_sock_policy, NULL);
    		if (err)
    			return err;
    
    		if (!sock[TIPC_NLA_SOCK_REF])
    			return -EINVAL;
    
    		tsk_portid = nla_get_u32(sock[TIPC_NLA_SOCK_REF]);
    	}
    
    	if (done)
    		return 0;
    
    	tsk = tipc_sk_lookup(net, tsk_portid);
    	if (!tsk)
    		return -EINVAL;
    
    	lock_sock(&tsk->sk);
    	err = __tipc_nl_list_sk_publ(skb, cb, tsk, &last_publ);
    	if (!err)
    		done = 1;
    	release_sock(&tsk->sk);
    	sock_put(&tsk->sk);
    
    	cb->args[0] = tsk_portid;
    	cb->args[1] = last_publ;
    	cb->args[2] = done;
    
    	return skb->len;
    }
    
    /**
     * tipc_sk_filtering - check if a socket should be traced
     * @sk: the socket to be examined
     * @sysctl_tipc_sk_filter[]: the socket tuple for filtering,
     *  (portid, sock type, name type, name lower, name upper)
     *
     * Returns true if the socket meets the socket tuple data
     * (value 0 = 'any') or when there is no tuple set (all = 0),
     * otherwise false
     */
    bool tipc_sk_filtering(struct sock *sk)
    {
    	struct tipc_sock *tsk;
    	struct publication *p;
    	u32 _port, _sktype, _type, _lower, _upper;
    	u32 type = 0, lower = 0, upper = 0;
    
    	if (!sk)
    		return true;
    
    	tsk = tipc_sk(sk);
    
    	_port = sysctl_tipc_sk_filter[0];
    	_sktype = sysctl_tipc_sk_filter[1];
    	_type = sysctl_tipc_sk_filter[2];
    	_lower = sysctl_tipc_sk_filter[3];
    	_upper = sysctl_tipc_sk_filter[4];
    
    	if (!_port && !_sktype && !_type && !_lower && !_upper)
    		return true;
    
    	if (_port)
    		return (_port == tsk->portid);
    
    	if (_sktype && _sktype != sk->sk_type)
    		return false;
    
    	if (tsk->published) {
    		p = list_first_entry_or_null(&tsk->publications,
    					     struct publication, binding_sock);
    		if (p) {
    			type = p->type;
    			lower = p->lower;
    			upper = p->upper;
    		}
    	}
    
    	if (!tipc_sk_type_connectionless(sk)) {
    		type = tsk->conn_type;
    		lower = tsk->conn_instance;
    		upper = tsk->conn_instance;
    	}
    
    	if ((_type && _type != type) || (_lower && _lower != lower) ||
    	    (_upper && _upper != upper))
    		return false;
    
    	return true;
    }
    
    u32 tipc_sock_get_portid(struct sock *sk)
    {
    	return (sk) ? (tipc_sk(sk))->portid : 0;
    }
    
    /**
     * tipc_sk_overlimit1 - check if socket rx queue is about to be overloaded,
     *			both the rcv and backlog queues are considered
     * @sk: tipc sk to be checked
     * @skb: tipc msg to be checked
     *
     * Returns true if the socket rx queue allocation is > 90%, otherwise false
     */
    
    bool tipc_sk_overlimit1(struct sock *sk, struct sk_buff *skb)
    {
    	atomic_t *dcnt = &tipc_sk(sk)->dupl_rcvcnt;
    	unsigned int lim = rcvbuf_limit(sk, skb) + atomic_read(dcnt);
    	unsigned int qsize = sk->sk_backlog.len + sk_rmem_alloc_get(sk);
    
    	return (qsize > lim * 90 / 100);
    }
    
    /**
     * tipc_sk_overlimit2 - check if socket rx queue is about to be overloaded,
     *			only the rcv queue is considered
     * @sk: tipc sk to be checked
     * @skb: tipc msg to be checked
     *
     * Returns true if the socket rx queue allocation is > 90%, otherwise false
     */
    
    bool tipc_sk_overlimit2(struct sock *sk, struct sk_buff *skb)
    {
    	unsigned int lim = rcvbuf_limit(sk, skb);
    	unsigned int qsize = sk_rmem_alloc_get(sk);
    
    	return (qsize > lim * 90 / 100);
    }
    
    /**
     * tipc_sk_dump - dump TIPC socket
     * @sk: tipc sk to be dumped
     * @dqueues: bitmask to decide if any socket queue to be dumped?
     *           - TIPC_DUMP_NONE: don't dump socket queues
     *           - TIPC_DUMP_SK_SNDQ: dump socket send queue
     *           - TIPC_DUMP_SK_RCVQ: dump socket rcv queue
     *           - TIPC_DUMP_SK_BKLGQ: dump socket backlog queue
     *           - TIPC_DUMP_ALL: dump all the socket queues above
     * @buf: returned buffer of dump data in format
     */
    int tipc_sk_dump(struct sock *sk, u16 dqueues, char *buf)
    {
    	int i = 0;
    	size_t sz = (dqueues) ? SK_LMAX : SK_LMIN;
    	struct tipc_sock *tsk;
    	struct publication *p;
    	bool tsk_connected;
    
    	if (!sk) {
    		i += scnprintf(buf, sz, "sk data: (null)\n");
    		return i;
    	}
    
    	tsk = tipc_sk(sk);
    	tsk_connected = !tipc_sk_type_connectionless(sk);
    
    	i += scnprintf(buf, sz, "sk data: %u", sk->sk_type);
    	i += scnprintf(buf + i, sz - i, " %d", sk->sk_state);
    	i += scnprintf(buf + i, sz - i, " %x", tsk_own_node(tsk));
    	i += scnprintf(buf + i, sz - i, " %u", tsk->portid);
    	i += scnprintf(buf + i, sz - i, " | %u", tsk_connected);
    	if (tsk_connected) {
    		i += scnprintf(buf + i, sz - i, " %x", tsk_peer_node(tsk));
    		i += scnprintf(buf + i, sz - i, " %u", tsk_peer_port(tsk));
    		i += scnprintf(buf + i, sz - i, " %u", tsk->conn_type);
    		i += scnprintf(buf + i, sz - i, " %u", tsk->conn_instance);
    	}
    	i += scnprintf(buf + i, sz - i, " | %u", tsk->published);
    	if (tsk->published) {
    		p = list_first_entry_or_null(&tsk->publications,
    					     struct publication, binding_sock);
    		i += scnprintf(buf + i, sz - i, " %u", (p) ? p->type : 0);
    		i += scnprintf(buf + i, sz - i, " %u", (p) ? p->lower : 0);
    		i += scnprintf(buf + i, sz - i, " %u", (p) ? p->upper : 0);
    	}
    	i += scnprintf(buf + i, sz - i, " | %u", tsk->snd_win);
    	i += scnprintf(buf + i, sz - i, " %u", tsk->rcv_win);
    	i += scnprintf(buf + i, sz - i, " %u", tsk->max_pkt);
    	i += scnprintf(buf + i, sz - i, " %x", tsk->peer_caps);
    	i += scnprintf(buf + i, sz - i, " %u", tsk->cong_link_cnt);
    	i += scnprintf(buf + i, sz - i, " %u", tsk->snt_unacked);
    	i += scnprintf(buf + i, sz - i, " %u", tsk->rcv_unacked);
    	i += scnprintf(buf + i, sz - i, " %u", atomic_read(&tsk->dupl_rcvcnt));
    	i += scnprintf(buf + i, sz - i, " %u", sk->sk_shutdown);
    	i += scnprintf(buf + i, sz - i, " | %d", sk_wmem_alloc_get(sk));
    	i += scnprintf(buf + i, sz - i, " %d", sk->sk_sndbuf);
    	i += scnprintf(buf + i, sz - i, " | %d", sk_rmem_alloc_get(sk));
    	i += scnprintf(buf + i, sz - i, " %d", sk->sk_rcvbuf);
    	i += scnprintf(buf + i, sz - i, " | %d\n", READ_ONCE(sk->sk_backlog.len));
    
    	if (dqueues & TIPC_DUMP_SK_SNDQ) {
    		i += scnprintf(buf + i, sz - i, "sk_write_queue: ");
    		i += tipc_list_dump(&sk->sk_write_queue, false, buf + i);
    	}
    
    	if (dqueues & TIPC_DUMP_SK_RCVQ) {
    		i += scnprintf(buf + i, sz - i, "sk_receive_queue: ");
    		i += tipc_list_dump(&sk->sk_receive_queue, false, buf + i);
    	}
    
    	if (dqueues & TIPC_DUMP_SK_BKLGQ) {
    		i += scnprintf(buf + i, sz - i, "sk_backlog:\n  head ");
    		i += tipc_skb_dump(sk->sk_backlog.head, false, buf + i);
    		if (sk->sk_backlog.tail != sk->sk_backlog.head) {
    			i += scnprintf(buf + i, sz - i, "  tail ");
    			i += tipc_skb_dump(sk->sk_backlog.tail, false,
    					   buf + i);
    		}
    	}
    
    	return i;
    }