C++ sock_put函数代码示例

static int mptp_release(struct socket *sock)
{
	struct sock *sk = sock->sk;
	struct mptp_sock *ssk = mptp_sk(sk);

	if (unlikely(!sk))
		return 0;

	mptp_unhash(ssk->src);

	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);

	synchronize_net();

	sock_orphan(sk);
	sock->sk = NULL;

	skb_queue_purge(&sk->sk_receive_queue);

	log_debug("mptp_release sock=%p\n", sk);
	sock_put(sk);

	return 0;
}

static void pep_sock_unhash(struct sock *sk)
{
	struct pep_sock *pn = pep_sk(sk);
	struct sock *skparent = NULL;

	lock_sock(sk);
	if ((1 << sk->sk_state) & ~(TCPF_CLOSE|TCPF_LISTEN)) {
		skparent = pn->listener;
		sk_del_node_init(sk);
		release_sock(sk);

		sk = skparent;
		pn = pep_sk(skparent);
		lock_sock(sk);
	}
	/* Unhash a listening sock only when it is closed
	 * and all of its active connected pipes are closed. */
	if (hlist_empty(&pn->hlist))
		pn_sock_unhash(&pn->pn_sk.sk);
	release_sock(sk);

	if (skparent)
		sock_put(skparent);
}

static int netlink_release(struct socket *sock)
{
	struct sock *sk = sock->sk;

	if (!sk)
		return 0;

	netlink_remove(sk);

	spin_lock(&sk->protinfo.af_netlink->cb_lock);
	if (sk->protinfo.af_netlink->cb) {
		sk->protinfo.af_netlink->cb->done(sk->protinfo.af_netlink->cb);
		netlink_destroy_callback(sk->protinfo.af_netlink->cb);
		sk->protinfo.af_netlink->cb = NULL;
		__sock_put(sk);
	}
	spin_unlock(&sk->protinfo.af_netlink->cb_lock);

	/* OK. Socket is unlinked, and, therefore,
	   no new packets will arrive */

	sock_orphan(sk);
	sock->sk = NULL;
	wake_up_interruptible_all(&sk->protinfo.af_netlink->wait);

	skb_queue_purge(&sk->write_queue);

	if (sk->protinfo.af_netlink->pid && !sk->protinfo.af_netlink->groups) {
		struct netlink_notify n = { protocol:sk->protocol,
		                            pid:sk->protinfo.af_netlink->pid };
		notifier_call_chain(&netlink_chain, NETLINK_URELEASE, &n);
	}	
	
	sock_put(sk);
	return 0;
}

/**
 *	__llc_lookup_established - Finds connection for the remote/local sap/mac
 *	@sap: SAP
 *	@daddr: address of remote LLC (MAC + SAP)
 *	@laddr: address of local LLC (MAC + SAP)
 *
 *	Search connection list of the SAP and finds connection using the remote
 *	mac, remote sap, local mac, and local sap. Returns pointer for
 *	connection found, %NULL otherwise.
 *	Caller has to make sure local_bh is disabled.
 */
static struct sock *__llc_lookup_established(struct llc_sap *sap,
					     struct llc_addr *daddr,
					     struct llc_addr *laddr)
{
	struct sock *rc;
	struct hlist_nulls_node *node;
	int slot = llc_sk_laddr_hashfn(sap, laddr);
	struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];

	rcu_read_lock();
again:
	sk_nulls_for_each_rcu(rc, node, laddr_hb) {
		if (llc_estab_match(sap, daddr, laddr, rc)) {
			/* Extra checks required by SLAB_DESTROY_BY_RCU */
			if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
				goto again;
			if (unlikely(llc_sk(rc)->sap != sap ||
				     !llc_estab_match(sap, daddr, laddr, rc))) {
				sock_put(rc);
				continue;
			}
			goto found;
		}
	}
	rc = NULL;
	/*
	 * if the nulls value we got at the end of this lookup is
	 * not the expected one, we must restart lookup.
	 * We probably met an item that was moved to another chain.
	 */
	if (unlikely(get_nulls_value(node) != slot))
		goto again;
found:
	rcu_read_unlock();
	return rc;
}

/**
 *	llc_ui_release - shutdown socket
 *	@sock: Socket to release.
 *
 *	Shutdown and deallocate an existing socket.
 */
static int llc_ui_release(struct socket *sock)
{
	struct sock *sk = sock->sk;
	struct llc_sock *llc;

	if (unlikely(sk == NULL))
		goto out;
	sock_hold(sk);
	lock_sock(sk);
	llc = llc_sk(sk);
	dprintk("%s: closing local(%02X) remote(%02X)\n", __func__,
		llc->laddr.lsap, llc->daddr.lsap);
	if (!llc_send_disc(sk))
		llc_ui_wait_for_disc(sk, sk->sk_rcvtimeo);
	if (!sock_flag(sk, SOCK_ZAPPED))
		llc_sap_remove_socket(llc->sap, sk);
	release_sock(sk);
	if (llc->dev)
		dev_put(llc->dev);
	sock_put(sk);
	llc_sk_free(sk);
out:
	return 0;
}

void skb_clone_tx_timestamp(struct sk_buff *skb)
{
	struct phy_device *phydev;
	struct sk_buff *clone;
	struct sock *sk = skb->sk;
	unsigned int type;

	if (!sk)
		return;

	type = classify(skb);

	switch (type) {
	case PTP_CLASS_V1_IPV4:
	case PTP_CLASS_V1_IPV6:
	case PTP_CLASS_V2_IPV4:
	case PTP_CLASS_V2_IPV6:
	case PTP_CLASS_V2_L2:
	case PTP_CLASS_V2_VLAN:
		phydev = skb->dev->phydev;
		if (likely(phydev->drv->txtstamp)) {
			if (!atomic_inc_not_zero(&sk->sk_refcnt))
				return;
			clone = skb_clone(skb, GFP_ATOMIC);
			if (!clone) {
				sock_put(sk);
				return;
			}
			clone->sk = sk;
			phydev->drv->txtstamp(phydev, clone, type);
		}
		break;
	default:
		break;
	}
}

void dccp_close(struct sock *sk, long timeout)
{
	struct sk_buff *skb;

	lock_sock(sk);

	sk->sk_shutdown = SHUTDOWN_MASK;

	if (sk->sk_state == DCCP_LISTEN) {
		dccp_set_state(sk, DCCP_CLOSED);

		/* Special case. */
		inet_csk_listen_stop(sk);

		goto adjudge_to_death;
	}

	/*
	 * We need to flush the recv. buffs.  We do this only on the
	 * descriptor close, not protocol-sourced closes, because the
	  *reader process may not have drained the data yet!
	 */
	/* FIXME: check for unread data */
	while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
		__kfree_skb(skb);
	}

	if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
		/* Check zero linger _after_ checking for unread data. */
		sk->sk_prot->disconnect(sk, 0);
	} else if (dccp_close_state(sk)) {
		dccp_send_close(sk, 1);
	}

	sk_stream_wait_close(sk, timeout);

adjudge_to_death:
	/*
	 * It is the last release_sock in its life. It will remove backlog.
	 */
	release_sock(sk);
	/*
	 * Now socket is owned by kernel and we acquire BH lock
	 * to finish close. No need to check for user refs.
	 */
	local_bh_disable();
	bh_lock_sock(sk);
	BUG_TRAP(!sock_owned_by_user(sk));

	sock_hold(sk);
	sock_orphan(sk);

	/*
	 * The last release_sock may have processed the CLOSE or RESET
	 * packet moving sock to CLOSED state, if not we have to fire
	 * the CLOSE/CLOSEREQ retransmission timer, see "8.3. Termination"
	 * in draft-ietf-dccp-spec-11. -acme
	 */
	if (sk->sk_state == DCCP_CLOSING) {
		/* FIXME: should start at 2 * RTT */
		/* Timer for repeating the CLOSE/CLOSEREQ until an answer. */
		inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
					  inet_csk(sk)->icsk_rto,
					  DCCP_RTO_MAX);
#if 0
		/* Yeah, we should use sk->sk_prot->orphan_count, etc */
		dccp_set_state(sk, DCCP_CLOSED);
#endif
	}

	atomic_inc(sk->sk_prot->orphan_count);
	if (sk->sk_state == DCCP_CLOSED)
		inet_csk_destroy_sock(sk);

	/* Otherwise, socket is reprieved until protocol close. */

	bh_unlock_sock(sk);
	local_bh_enable();
	sock_put(sk);
}

static int release(struct socket *sock)
{
	struct sock *sk = sock->sk;
	struct tipc_port *tport;
	struct sk_buff *buf;
	int res;

	/*
	 * 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;

	tport = tipc_sk_port(sk);
	lock_sock(sk);

	/*
	 * Reject all unreceived messages, except on an active connection
	 * (which disconnects locally & sends a 'FIN+' to peer)
	 */

	while (sock->state != SS_DISCONNECTING) {
		buf = __skb_dequeue(&sk->sk_receive_queue);
		if (buf == NULL)
			break;
		atomic_dec(&tipc_queue_size);
		if (TIPC_SKB_CB(buf)->handle != 0)
			kfree_skb(buf);
		else {
			if ((sock->state == SS_CONNECTING) ||
			    (sock->state == SS_CONNECTED)) {
				sock->state = SS_DISCONNECTING;
				tipc_disconnect(tport->ref);
			}
			tipc_reject_msg(buf, TIPC_ERR_NO_PORT);
		}
	}

	/*
	 * Delete TIPC port; this ensures no more messages are queued
	 * (also disconnects an active connection & sends a 'FIN-' to peer)
	 */

	res = tipc_deleteport(tport->ref);

	/* Discard any remaining (connection-based) messages in receive queue */

	discard_rx_queue(sk);

	/* Reject any messages that accumulated in backlog queue */

	sock->state = SS_DISCONNECTING;
	release_sock(sk);

	sock_put(sk);
	sock->sk = NULL;

	return res;
}

//.........这里部分代码省略.........
	if (!sk) {
		ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
		return;
	}

	if (sk->sk_state == DCCP_TIME_WAIT) {
		inet_twsk_put(inet_twsk(sk));
		return;
	}
	seq = dccp_hdr_seq(dh);
	if (sk->sk_state == DCCP_NEW_SYN_RECV)
		return dccp_req_err(sk, seq);

	bh_lock_sock(sk);
	/* If too many ICMPs get dropped on busy
	 * servers this needs to be solved differently.
	 */
	if (sock_owned_by_user(sk))
		NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);

	if (sk->sk_state == DCCP_CLOSED)
		goto out;

	dp = dccp_sk(sk);
	if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
	    !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
		NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
		goto out;
	}

	switch (type) {
	case ICMP_REDIRECT:
		dccp_do_redirect(skb, sk);
		goto out;
	case ICMP_SOURCE_QUENCH:
		/* Just silently ignore these. */
		goto out;
	case ICMP_PARAMETERPROB:
		err = EPROTO;
		break;
	case ICMP_DEST_UNREACH:
		if (code > NR_ICMP_UNREACH)
			goto out;

		if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
			if (!sock_owned_by_user(sk))
				dccp_do_pmtu_discovery(sk, iph, info);
			goto out;
		}

		err = icmp_err_convert[code].errno;
		break;
	case ICMP_TIME_EXCEEDED:
		err = EHOSTUNREACH;
		break;
	default:
		goto out;
	}

	switch (sk->sk_state) {
	case DCCP_REQUESTING:
	case DCCP_RESPOND:
		if (!sock_owned_by_user(sk)) {
			DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
			sk->sk_err = err;

			sk->sk_error_report(sk);

			dccp_done(sk);
		} else
			sk->sk_err_soft = err;
		goto out;
	}

	/* If we've already connected we will keep trying
	 * until we time out, or the user gives up.
	 *
	 * rfc1122 4.2.3.9 allows to consider as hard errors
	 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
	 * but it is obsoleted by pmtu discovery).
	 *
	 * Note, that in modern internet, where routing is unreliable
	 * and in each dark corner broken firewalls sit, sending random
	 * errors ordered by their masters even this two messages finally lose
	 * their original sense (even Linux sends invalid PORT_UNREACHs)
	 *
	 * Now we are in compliance with RFCs.
	 *							--ANK (980905)
	 */

	inet = inet_sk(sk);
	if (!sock_owned_by_user(sk) && inet->recverr) {
		sk->sk_err = err;
		sk->sk_error_report(sk);
	} else /* Only an error on timeout */
		sk->sk_err_soft = err;
out:
	bh_unlock_sock(sk);
	sock_put(sk);
}

static void vxlan_sock_put(struct sk_buff *skb)
{
	sock_put(skb->sk);
}

//.........这里部分代码省略.........
	tcp_sw_conn->rx_hash.tfm = crypto_alloc_hash("crc32c", 0,
						     CRYPTO_ALG_ASYNC);
	tcp_sw_conn->rx_hash.flags = 0;
	if (IS_ERR(tcp_sw_conn->rx_hash.tfm))
		goto free_tx_tfm;
	tcp_conn->rx_hash = &tcp_sw_conn->rx_hash;

	return cls_conn;

free_tx_tfm:
	crypto_free_hash(tcp_sw_conn->tx_hash.tfm);
free_conn:
	iscsi_conn_printk(KERN_ERR, conn,
			  "Could not create connection due to crc32c "
			  "loading error. Make sure the crc32c "
			  "module is built as a module or into the "
			  "kernel\n");
	iscsi_tcp_conn_teardown(cls_conn);
	return NULL;
}

static void iscsi_sw_tcp_release_conn(struct iscsi_conn *conn)
{
	struct iscsi_session *session = conn->session;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
	struct socket *sock = tcp_sw_conn->sock;

	if (!sock)
		return;

	sock_hold(sock->sk);
	iscsi_sw_tcp_conn_restore_callbacks(tcp_sw_conn);
	sock_put(sock->sk);

	spin_lock_bh(&session->lock);
	tcp_sw_conn->sock = NULL;
	spin_unlock_bh(&session->lock);
	sockfd_put(sock);
}

static void iscsi_sw_tcp_conn_destroy(struct iscsi_cls_conn *cls_conn)
{
	struct iscsi_conn *conn = cls_conn->dd_data;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;

	iscsi_sw_tcp_release_conn(conn);

	if (tcp_sw_conn->tx_hash.tfm)
		crypto_free_hash(tcp_sw_conn->tx_hash.tfm);
	if (tcp_sw_conn->rx_hash.tfm)
		crypto_free_hash(tcp_sw_conn->rx_hash.tfm);

	iscsi_tcp_conn_teardown(cls_conn);
}

static void iscsi_sw_tcp_conn_stop(struct iscsi_cls_conn *cls_conn, int flag)
{
	struct iscsi_conn *conn = cls_conn->dd_data;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;

	/* userspace may have goofed up and not bound us */
	if (!tcp_sw_conn->sock)
		return;

void dccp_close(struct sock *sk, long timeout)
{
	struct dccp_sock *dp = dccp_sk(sk);
	struct sk_buff *skb;
	u32 data_was_unread = 0;
	int state;

	lock_sock(sk);

	sk->sk_shutdown = SHUTDOWN_MASK;

	if (sk->sk_state == DCCP_LISTEN) {
		dccp_set_state(sk, DCCP_CLOSED);

		/* Special case. */
		inet_csk_listen_stop(sk);

		goto adjudge_to_death;
	}

	sk_stop_timer(sk, &dp->dccps_xmit_timer);

	/*
	 * We need to flush the recv. buffs.  We do this only on the
	 * descriptor close, not protocol-sourced closes, because the
	  *reader process may not have drained the data yet!
	 */
	while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
		data_was_unread += skb->len;
		__kfree_skb(skb);
	}

	if (data_was_unread) {
		/* Unread data was tossed, send an appropriate Reset Code */
		DCCP_WARN("ABORT with %u bytes unread\n", data_was_unread);
		dccp_send_reset(sk, DCCP_RESET_CODE_ABORTED);
		dccp_set_state(sk, DCCP_CLOSED);
	} else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
		/* Check zero linger _after_ checking for unread data. */
		sk->sk_prot->disconnect(sk, 0);
	} else if (sk->sk_state != DCCP_CLOSED) {
		/*
		 * Normal connection termination. May need to wait if there are
		 * still packets in the TX queue that are delayed by the CCID.
		 */
		dccp_flush_write_queue(sk, &timeout);
		dccp_terminate_connection(sk);
	}

	/*
	 * Flush write queue. This may be necessary in several cases:
	 * - we have been closed by the peer but still have application data;
	 * - abortive termination (unread data or zero linger time),
	 * - normal termination but queue could not be flushed within time limit
	 */
	__skb_queue_purge(&sk->sk_write_queue);

	sk_stream_wait_close(sk, timeout);

adjudge_to_death:
	state = sk->sk_state;
	sock_hold(sk);
	sock_orphan(sk);

	/*
	 * It is the last release_sock in its life. It will remove backlog.
	 */
	release_sock(sk);
	/*
	 * Now socket is owned by kernel and we acquire BH lock
	 * to finish close. No need to check for user refs.
	 */
	local_bh_disable();
	bh_lock_sock(sk);
	WARN_ON(sock_owned_by_user(sk));

	percpu_counter_inc(sk->sk_prot->orphan_count);

	/* Have we already been destroyed by a softirq or backlog? */
	if (state != DCCP_CLOSED && sk->sk_state == DCCP_CLOSED)
		goto out;

	if (sk->sk_state == DCCP_CLOSED)
		inet_csk_destroy_sock(sk);

	/* Otherwise, socket is reprieved until protocol close. */

out:
	bh_unlock_sock(sk);
	local_bh_enable();
	sock_put(sk);
}

static int
MksckPageDescIoctl(struct socket *sock,
		   unsigned int cmd,
		   unsigned long arg)
{
	struct sock *mksck = NULL;
	struct sock *sk = sock->sk;
	struct MksckPageDescInfo *mpdi;
	unsigned long ul[2];
	int retval = 0;

	switch (cmd) {
	case MKSCK_DETACH:
		lock_sock(sk);
		mpdi = sk->sk_protinfo;

		if (copy_from_user(ul, (void *)arg, sizeof(ul))) {
			retval = -EFAULT;

		} else if (!mpdi || !sk->sk_user_data) {
			retval = -EINVAL;
		} else {
			uint32 flags = calc_vm_prot_bits(ul[0]);

			ul[0] = 0;
			while (mpdi) {
				struct MksckPageDescInfo *next = mpdi->next;

				ul[0] += MksckPageDescManage(mpdi->descs,
							     mpdi->pages,
							     MANAGE_COUNT);
				mpdi->mapCounts = ul[1];
				mpdi = next;
			}
			if (copy_to_user((void *)arg, ul, sizeof(ul[0]))) {
				retval = -EFAULT;
			} else {
				mpdi = sk->sk_protinfo;
				mpdi->flags = flags;
				mksck = (struct sock *)sk->sk_user_data;
				sk->sk_user_data = NULL;
			}
		}

		release_sock(sk);

		sk = mksck;
		if (sk) {
			lock_sock(sk);
			sock_kfree_s(sk, sk->sk_user_data, sizeof(int));
			sk->sk_user_data = NULL;
			release_sock(sk);
			sock_put(sk);
		}
		break;
	default:
		retval = -EINVAL;
		break;
	}
	return retval;
}

//.........这里部分代码省略.........
		NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);

	if (sk->sk_state == DCCP_CLOSED)
		goto out;

	dp = dccp_sk(sk);
	seq = dccp_hdr_seq(dh);
	if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
	    !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
		NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
		goto out;
	}

	np = inet6_sk(sk);

	if (type == NDISC_REDIRECT) {
		struct dst_entry *dst = __sk_dst_check(sk, np->dst_cookie);

		if (dst)
			dst->ops->redirect(dst, sk, skb);
		goto out;
	}

	if (type == ICMPV6_PKT_TOOBIG) {
		struct dst_entry *dst = NULL;

		if (!ip6_sk_accept_pmtu(sk))
			goto out;

		if (sock_owned_by_user(sk))
			goto out;
		if ((1 << sk->sk_state) & (DCCPF_LISTEN | DCCPF_CLOSED))
			goto out;

		dst = inet6_csk_update_pmtu(sk, ntohl(info));
		if (!dst)
			goto out;

		if (inet_csk(sk)->icsk_pmtu_cookie > dst_mtu(dst))
			dccp_sync_mss(sk, dst_mtu(dst));
		goto out;
	}

	icmpv6_err_convert(type, code, &err);

	/* Might be for an request_sock */
	switch (sk->sk_state) {
		struct request_sock *req, **prev;
	case DCCP_LISTEN:
		if (sock_owned_by_user(sk))
			goto out;

		req = inet6_csk_search_req(sk, &prev, dh->dccph_dport,
					   &hdr->daddr, &hdr->saddr,
					   inet6_iif(skb));
		if (req == NULL)
			goto out;

		/*
		 * ICMPs are not backlogged, hence we cannot get an established
		 * socket here.
		 */
		WARN_ON(req->sk != NULL);

		if (!between48(seq, dccp_rsk(req)->dreq_iss,
				    dccp_rsk(req)->dreq_gss)) {
			NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
			goto out;
		}

		inet_csk_reqsk_queue_drop(sk, req, prev);
		goto out;

	case DCCP_REQUESTING:
	case DCCP_RESPOND:  /* Cannot happen.
			       It can, it SYNs are crossed. --ANK */
		if (!sock_owned_by_user(sk)) {
			DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
			sk->sk_err = err;
			/*
			 * Wake people up to see the error
			 * (see connect in sock.c)
			 */
			sk->sk_error_report(sk);
			dccp_done(sk);
		} else
			sk->sk_err_soft = err;
		goto out;
	}

	if (!sock_owned_by_user(sk) && np->recverr) {
		sk->sk_err = err;
		sk->sk_error_report(sk);
	} else
		sk->sk_err_soft = err;

out:
	bh_unlock_sock(sk);
	sock_put(sk);
}

static int dccp_v6_rcv(struct sk_buff *skb)
{
	const struct dccp_hdr *dh;
	struct sock *sk;
	int min_cov;

	/* Step 1: Check header basics */

	if (dccp_invalid_packet(skb))
		goto discard_it;

	/* Step 1: If header checksum is incorrect, drop packet and return. */
	if (dccp_v6_csum_finish(skb, &ipv6_hdr(skb)->saddr,
				     &ipv6_hdr(skb)->daddr)) {
		DCCP_WARN("dropped packet with invalid checksum\n");
		goto discard_it;
	}

	dh = dccp_hdr(skb);

	DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
	DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;

	if (dccp_packet_without_ack(skb))
		DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
	else
		DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);

	/* Step 2:
	 *	Look up flow ID in table and get corresponding socket */
	sk = __inet6_lookup_skb(&dccp_hashinfo, skb,
			        dh->dccph_sport, dh->dccph_dport);
	/*
	 * Step 2:
	 *	If no socket ...
	 */
	if (sk == NULL) {
		dccp_pr_debug("failed to look up flow ID in table and "
			      "get corresponding socket\n");
		goto no_dccp_socket;
	}

	/*
	 * Step 2:
	 *	... or S.state == TIMEWAIT,
	 *		Generate Reset(No Connection) unless P.type == Reset
	 *		Drop packet and return
	 */
	if (sk->sk_state == DCCP_TIME_WAIT) {
		dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
		inet_twsk_put(inet_twsk(sk));
		goto no_dccp_socket;
	}

	/*
	 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
	 *	o if MinCsCov = 0, only packets with CsCov = 0 are accepted
	 *	o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
	 */
	min_cov = dccp_sk(sk)->dccps_pcrlen;
	if (dh->dccph_cscov  &&  (min_cov == 0 || dh->dccph_cscov < min_cov))  {
		dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
			      dh->dccph_cscov, min_cov);
		/* FIXME: send Data Dropped option (see also dccp_v4_rcv) */
		goto discard_and_relse;
	}

	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
		goto discard_and_relse;

	return sk_receive_skb(sk, skb, 1) ? -1 : 0;

no_dccp_socket:
	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
		goto discard_it;
	/*
	 * Step 2:
	 *	If no socket ...
	 *		Generate Reset(No Connection) unless P.type == Reset
	 *		Drop packet and return
	 */
	if (dh->dccph_type != DCCP_PKT_RESET) {
		DCCP_SKB_CB(skb)->dccpd_reset_code =
					DCCP_RESET_CODE_NO_CONNECTION;
		dccp_v6_ctl_send_reset(sk, skb);
	}

discard_it:
	kfree_skb(skb);
	return 0;

discard_and_relse:
	sock_put(sk);
	goto discard_it;
}