Adding upstream version 5.10.209.upstream/5.10.209upstream

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

1 files changed, 1018 insertions, 0 deletions

diff --git a/net/llc/llc_conn.c b/net/llc/llc_conn.c
new file mode 100644
index 000000000..1144cda2a
--- /dev/null
+++ b/net/llc/llc_conn.c
@@ -0,0 +1,1018 @@
+/*
+ * llc_conn.c - Driver routines for connection component.
+ *
+ * Copyright (c) 1997 by Procom Technology, Inc.
+ *		 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ * This program can be redistributed or modified under the terms of the
+ * GNU General Public License as published by the Free Software Foundation.
+ * This program is distributed without any warranty or implied warranty
+ * of merchantability or fitness for a particular purpose.
+ *
+ * See the GNU General Public License for more details.
+ */
+
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <net/llc_sap.h>
+#include <net/llc_conn.h>
+#include <net/sock.h>
+#include <net/tcp_states.h>
+#include <net/llc_c_ev.h>
+#include <net/llc_c_ac.h>
+#include <net/llc_c_st.h>
+#include <net/llc_pdu.h>
+
+#if 0
+#define dprintk(args...) printk(KERN_DEBUG args)
+#else
+#define dprintk(args...)
+#endif
+
+static int llc_find_offset(int state, int ev_type);
+static void llc_conn_send_pdus(struct sock *sk);
+static int llc_conn_service(struct sock *sk, struct sk_buff *skb);
+static int llc_exec_conn_trans_actions(struct sock *sk,
+				       struct llc_conn_state_trans *trans,
+				       struct sk_buff *ev);
+static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
+							struct sk_buff *skb);
+
+/* Offset table on connection states transition diagram */
+static int llc_offset_table[NBR_CONN_STATES][NBR_CONN_EV];
+
+int sysctl_llc2_ack_timeout = LLC2_ACK_TIME * HZ;
+int sysctl_llc2_p_timeout = LLC2_P_TIME * HZ;
+int sysctl_llc2_rej_timeout = LLC2_REJ_TIME * HZ;
+int sysctl_llc2_busy_timeout = LLC2_BUSY_TIME * HZ;
+
+/**
+ *	llc_conn_state_process - sends event to connection state machine
+ *	@sk: connection
+ *	@skb: occurred event
+ *
+ *	Sends an event to connection state machine. After processing event
+ *	(executing it's actions and changing state), upper layer will be
+ *	indicated or confirmed, if needed. Returns 0 for success, 1 for
+ *	failure. The socket lock has to be held before calling this function.
+ *
+ *	This function always consumes a reference to the skb.
+ */
+int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
+{
+	int rc;
+	struct llc_sock *llc = llc_sk(skb->sk);
+	struct llc_conn_state_ev *ev = llc_conn_ev(skb);
+
+	ev->ind_prim = ev->cfm_prim = 0;
+	/*
+	 * Send event to state machine
+	 */
+	rc = llc_conn_service(skb->sk, skb);
+	if (unlikely(rc != 0)) {
+		printk(KERN_ERR "%s: llc_conn_service failed\n", __func__);
+		goto out_skb_put;
+	}
+
+	switch (ev->ind_prim) {
+	case LLC_DATA_PRIM:
+		skb_get(skb);
+		llc_save_primitive(sk, skb, LLC_DATA_PRIM);
+		if (unlikely(sock_queue_rcv_skb(sk, skb))) {
+			/*
+			 * shouldn't happen
+			 */
+			printk(KERN_ERR "%s: sock_queue_rcv_skb failed!\n",
+			       __func__);
+			kfree_skb(skb);
+		}
+		break;
+	case LLC_CONN_PRIM:
+		/*
+		 * Can't be sock_queue_rcv_skb, because we have to leave the
+		 * skb->sk pointing to the newly created struct sock in
+		 * llc_conn_handler. -acme
+		 */
+		skb_get(skb);
+		skb_queue_tail(&sk->sk_receive_queue, skb);
+		sk->sk_state_change(sk);
+		break;
+	case LLC_DISC_PRIM:
+		sock_hold(sk);
+		if (sk->sk_type == SOCK_STREAM &&
+		    sk->sk_state == TCP_ESTABLISHED) {
+			sk->sk_shutdown       = SHUTDOWN_MASK;
+			sk->sk_socket->state  = SS_UNCONNECTED;
+			sk->sk_state          = TCP_CLOSE;
+			if (!sock_flag(sk, SOCK_DEAD)) {
+				sock_set_flag(sk, SOCK_DEAD);
+				sk->sk_state_change(sk);
+			}
+		}
+		sock_put(sk);
+		break;
+	case LLC_RESET_PRIM:
+		/*
+		 * FIXME:
+		 * RESET is not being notified to upper layers for now
+		 */
+		printk(KERN_INFO "%s: received a reset ind!\n", __func__);
+		break;
+	default:
+		if (ev->ind_prim)
+			printk(KERN_INFO "%s: received unknown %d prim!\n",
+				__func__, ev->ind_prim);
+		/* No indication */
+		break;
+	}
+
+	switch (ev->cfm_prim) {
+	case LLC_DATA_PRIM:
+		if (!llc_data_accept_state(llc->state))
+			sk->sk_write_space(sk);
+		else
+			rc = llc->failed_data_req = 1;
+		break;
+	case LLC_CONN_PRIM:
+		if (sk->sk_type == SOCK_STREAM &&
+		    sk->sk_state == TCP_SYN_SENT) {
+			if (ev->status) {
+				sk->sk_socket->state = SS_UNCONNECTED;
+				sk->sk_state         = TCP_CLOSE;
+			} else {
+				sk->sk_socket->state = SS_CONNECTED;
+				sk->sk_state         = TCP_ESTABLISHED;
+			}
+			sk->sk_state_change(sk);
+		}
+		break;
+	case LLC_DISC_PRIM:
+		sock_hold(sk);
+		if (sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_CLOSING) {
+			sk->sk_socket->state = SS_UNCONNECTED;
+			sk->sk_state         = TCP_CLOSE;
+			sk->sk_state_change(sk);
+		}
+		sock_put(sk);
+		break;
+	case LLC_RESET_PRIM:
+		/*
+		 * FIXME:
+		 * RESET is not being notified to upper layers for now
+		 */
+		printk(KERN_INFO "%s: received a reset conf!\n", __func__);
+		break;
+	default:
+		if (ev->cfm_prim)
+			printk(KERN_INFO "%s: received unknown %d prim!\n",
+					__func__, ev->cfm_prim);
+		/* No confirmation */
+		break;
+	}
+out_skb_put:
+	kfree_skb(skb);
+	return rc;
+}
+
+void llc_conn_send_pdu(struct sock *sk, struct sk_buff *skb)
+{
+	/* queue PDU to send to MAC layer */
+	skb_queue_tail(&sk->sk_write_queue, skb);
+	llc_conn_send_pdus(sk);
+}
+
+/**
+ *	llc_conn_rtn_pdu - sends received data pdu to upper layer
+ *	@sk: Active connection
+ *	@skb: Received data frame
+ *
+ *	Sends received data pdu to upper layer (by using indicate function).
+ *	Prepares service parameters (prim and prim_data). calling indication
+ *	function will be done in llc_conn_state_process.
+ */
+void llc_conn_rtn_pdu(struct sock *sk, struct sk_buff *skb)
+{
+	struct llc_conn_state_ev *ev = llc_conn_ev(skb);
+
+	ev->ind_prim = LLC_DATA_PRIM;
+}
+
+/**
+ *	llc_conn_resend_i_pdu_as_cmd - resend all all unacknowledged I PDUs
+ *	@sk: active connection
+ *	@nr: NR
+ *	@first_p_bit: p_bit value of first pdu
+ *
+ *	Resend all unacknowledged I PDUs, starting with the NR; send first as
+ *	command PDU with P bit equal first_p_bit; if more than one send
+ *	subsequent as command PDUs with P bit equal zero (0).
+ */
+void llc_conn_resend_i_pdu_as_cmd(struct sock *sk, u8 nr, u8 first_p_bit)
+{
+	struct sk_buff *skb;
+	struct llc_pdu_sn *pdu;
+	u16 nbr_unack_pdus;
+	struct llc_sock *llc;
+	u8 howmany_resend = 0;
+
+	llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
+	if (!nbr_unack_pdus)
+		goto out;
+	/*
+	 * Process unack PDUs only if unack queue is not empty; remove
+	 * appropriate PDUs, fix them up, and put them on mac_pdu_q.
+	 */
+	llc = llc_sk(sk);
+
+	while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
+		pdu = llc_pdu_sn_hdr(skb);
+		llc_pdu_set_cmd_rsp(skb, LLC_PDU_CMD);
+		llc_pdu_set_pf_bit(skb, first_p_bit);
+		skb_queue_tail(&sk->sk_write_queue, skb);
+		first_p_bit = 0;
+		llc->vS = LLC_I_GET_NS(pdu);
+		howmany_resend++;
+	}
+	if (howmany_resend > 0)
+		llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
+	/* any PDUs to re-send are queued up; start sending to MAC */
+	llc_conn_send_pdus(sk);
+out:;
+}
+
+/**
+ *	llc_conn_resend_i_pdu_as_rsp - Resend all unacknowledged I PDUs
+ *	@sk: active connection.
+ *	@nr: NR
+ *	@first_f_bit: f_bit value of first pdu.
+ *
+ *	Resend all unacknowledged I PDUs, starting with the NR; send first as
+ *	response PDU with F bit equal first_f_bit; if more than one send
+ *	subsequent as response PDUs with F bit equal zero (0).
+ */
+void llc_conn_resend_i_pdu_as_rsp(struct sock *sk, u8 nr, u8 first_f_bit)
+{
+	struct sk_buff *skb;
+	u16 nbr_unack_pdus;
+	struct llc_sock *llc = llc_sk(sk);
+	u8 howmany_resend = 0;
+
+	llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
+	if (!nbr_unack_pdus)
+		goto out;
+	/*
+	 * Process unack PDUs only if unack queue is not empty; remove
+	 * appropriate PDUs, fix them up, and put them on mac_pdu_q
+	 */
+	while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
+		struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
+
+		llc_pdu_set_cmd_rsp(skb, LLC_PDU_RSP);
+		llc_pdu_set_pf_bit(skb, first_f_bit);
+		skb_queue_tail(&sk->sk_write_queue, skb);
+		first_f_bit = 0;
+		llc->vS = LLC_I_GET_NS(pdu);
+		howmany_resend++;
+	}
+	if (howmany_resend > 0)
+		llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
+	/* any PDUs to re-send are queued up; start sending to MAC */
+	llc_conn_send_pdus(sk);
+out:;
+}
+
+/**
+ *	llc_conn_remove_acked_pdus - Removes acknowledged pdus from tx queue
+ *	@sk: active connection
+ *	@nr: NR
+ *	@how_many_unacked: size of pdu_unack_q after removing acked pdus
+ *
+ *	Removes acknowledged pdus from transmit queue (pdu_unack_q). Returns
+ *	the number of pdus that removed from queue.
+ */
+int llc_conn_remove_acked_pdus(struct sock *sk, u8 nr, u16 *how_many_unacked)
+{
+	int pdu_pos, i;
+	struct sk_buff *skb;
+	struct llc_pdu_sn *pdu;
+	int nbr_acked = 0;
+	struct llc_sock *llc = llc_sk(sk);
+	int q_len = skb_queue_len(&llc->pdu_unack_q);
+
+	if (!q_len)
+		goto out;
+	skb = skb_peek(&llc->pdu_unack_q);
+	pdu = llc_pdu_sn_hdr(skb);
+
+	/* finding position of last acked pdu in queue */
+	pdu_pos = ((int)LLC_2_SEQ_NBR_MODULO + (int)nr -
+			(int)LLC_I_GET_NS(pdu)) % LLC_2_SEQ_NBR_MODULO;
+
+	for (i = 0; i < pdu_pos && i < q_len; i++) {
+		skb = skb_dequeue(&llc->pdu_unack_q);
+		kfree_skb(skb);
+		nbr_acked++;
+	}
+out:
+	*how_many_unacked = skb_queue_len(&llc->pdu_unack_q);
+	return nbr_acked;
+}
+
+/**
+ *	llc_conn_send_pdus - Sends queued PDUs
+ *	@sk: active connection
+ *
+ *	Sends queued pdus to MAC layer for transmission.
+ */
+static void llc_conn_send_pdus(struct sock *sk)
+{
+	struct sk_buff *skb;
+
+	while ((skb = skb_dequeue(&sk->sk_write_queue)) != NULL) {
+		struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
+
+		if (LLC_PDU_TYPE_IS_I(pdu) &&
+		    !(skb->dev->flags & IFF_LOOPBACK)) {
+			struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
+
+			skb_queue_tail(&llc_sk(sk)->pdu_unack_q, skb);
+			if (!skb2)
+				break;
+			skb = skb2;
+		}
+		dev_queue_xmit(skb);
+	}
+}
+
+/**
+ *	llc_conn_service - finds transition and changes state of connection
+ *	@sk: connection
+ *	@skb: happened event
+ *
+ *	This function finds transition that matches with happened event, then
+ *	executes related actions and finally changes state of connection.
+ *	Returns 0 for success, 1 for failure.
+ */
+static int llc_conn_service(struct sock *sk, struct sk_buff *skb)
+{
+	int rc = 1;
+	struct llc_sock *llc = llc_sk(sk);
+	struct llc_conn_state_trans *trans;
+
+	if (llc->state > NBR_CONN_STATES)
+		goto out;
+	rc = 0;
+	trans = llc_qualify_conn_ev(sk, skb);
+	if (trans) {
+		rc = llc_exec_conn_trans_actions(sk, trans, skb);
+		if (!rc && trans->next_state != NO_STATE_CHANGE) {
+			llc->state = trans->next_state;
+			if (!llc_data_accept_state(llc->state))
+				sk->sk_state_change(sk);
+		}
+	}
+out:
+	return rc;
+}
+
+/**
+ *	llc_qualify_conn_ev - finds transition for event
+ *	@sk: connection
+ *	@skb: happened event
+ *
+ *	This function finds transition that matches with happened event.
+ *	Returns pointer to found transition on success, %NULL otherwise.
+ */
+static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
+							struct sk_buff *skb)
+{
+	struct llc_conn_state_trans **next_trans;
+	const llc_conn_ev_qfyr_t *next_qualifier;
+	struct llc_conn_state_ev *ev = llc_conn_ev(skb);
+	struct llc_sock *llc = llc_sk(sk);
+	struct llc_conn_state *curr_state =
+					&llc_conn_state_table[llc->state - 1];
+
+	/* search thru events for this state until
+	 * list exhausted or until no more
+	 */
+	for (next_trans = curr_state->transitions +
+		llc_find_offset(llc->state - 1, ev->type);
+	     (*next_trans)->ev; next_trans++) {
+		if (!((*next_trans)->ev)(sk, skb)) {
+			/* got POSSIBLE event match; the event may require
+			 * qualification based on the values of a number of
+			 * state flags; if all qualifications are met (i.e.,
+			 * if all qualifying functions return success, or 0,
+			 * then this is THE event we're looking for
+			 */
+			for (next_qualifier = (*next_trans)->ev_qualifiers;
+			     next_qualifier && *next_qualifier &&
+			     !(*next_qualifier)(sk, skb); next_qualifier++)
+				/* nothing */;
+			if (!next_qualifier || !*next_qualifier)
+				/* all qualifiers executed successfully; this is
+				 * our transition; return it so we can perform
+				 * the associated actions & change the state
+				 */
+				return *next_trans;
+		}
+	}
+	return NULL;
+}
+
+/**
+ *	llc_exec_conn_trans_actions - executes related actions
+ *	@sk: connection
+ *	@trans: transition that it's actions must be performed
+ *	@skb: event
+ *
+ *	Executes actions that is related to happened event. Returns 0 for
+ *	success, 1 to indicate failure of at least one action.
+ */
+static int llc_exec_conn_trans_actions(struct sock *sk,
+				       struct llc_conn_state_trans *trans,
+				       struct sk_buff *skb)
+{
+	int rc = 0;
+	const llc_conn_action_t *next_action;
+
+	for (next_action = trans->ev_actions;
+	     next_action && *next_action; next_action++) {
+		int rc2 = (*next_action)(sk, skb);
+
+		if (rc2 == 2) {
+			rc = rc2;
+			break;
+		} else if (rc2)
+			rc = 1;
+	}
+	return rc;
+}
+
+static inline bool llc_estab_match(const struct llc_sap *sap,
+				   const struct llc_addr *daddr,
+				   const struct llc_addr *laddr,
+				   const struct sock *sk)
+{
+	struct llc_sock *llc = llc_sk(sk);
+
+	return llc->laddr.lsap == laddr->lsap &&
+		llc->daddr.lsap == daddr->lsap &&
+		ether_addr_equal(llc->laddr.mac, laddr->mac) &&
+		ether_addr_equal(llc->daddr.mac, daddr->mac);
+}
+
+/**
+ *	__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_TYPESAFE_BY_RCU */
+			if (unlikely(!refcount_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;
+}
+
+struct sock *llc_lookup_established(struct llc_sap *sap,
+				    struct llc_addr *daddr,
+				    struct llc_addr *laddr)
+{
+	struct sock *sk;
+
+	local_bh_disable();
+	sk = __llc_lookup_established(sap, daddr, laddr);
+	local_bh_enable();
+	return sk;
+}
+
+static inline bool llc_listener_match(const struct llc_sap *sap,
+				      const struct llc_addr *laddr,
+				      const struct sock *sk)
+{
+	struct llc_sock *llc = llc_sk(sk);
+
+	return sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_LISTEN &&
+		llc->laddr.lsap == laddr->lsap &&
+		ether_addr_equal(llc->laddr.mac, laddr->mac);
+}
+
+static struct sock *__llc_lookup_listener(struct llc_sap *sap,
+					  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_listener_match(sap, laddr, rc)) {
+			/* Extra checks required by SLAB_TYPESAFE_BY_RCU */
+			if (unlikely(!refcount_inc_not_zero(&rc->sk_refcnt)))
+				goto again;
+			if (unlikely(llc_sk(rc)->sap != sap ||
+				     !llc_listener_match(sap, 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_lookup_listener - Finds listener for local MAC + SAP
+ *	@sap: SAP
+ *	@laddr: address of local LLC (MAC + SAP)
+ *
+ *	Search connection list of the SAP and finds connection listening on
+ *	local mac, and local sap. Returns pointer for parent socket found,
+ *	%NULL otherwise.
+ *	Caller has to make sure local_bh is disabled.
+ */
+static struct sock *llc_lookup_listener(struct llc_sap *sap,
+					struct llc_addr *laddr)
+{
+	static struct llc_addr null_addr;
+	struct sock *rc = __llc_lookup_listener(sap, laddr);
+
+	if (!rc)
+		rc = __llc_lookup_listener(sap, &null_addr);
+
+	return rc;
+}
+
+static struct sock *__llc_lookup(struct llc_sap *sap,
+				 struct llc_addr *daddr,
+				 struct llc_addr *laddr)
+{
+	struct sock *sk = __llc_lookup_established(sap, daddr, laddr);
+
+	return sk ? : llc_lookup_listener(sap, laddr);
+}
+
+/**
+ *	llc_data_accept_state - designates if in this state data can be sent.
+ *	@state: state of connection.
+ *
+ *	Returns 0 if data can be sent, 1 otherwise.
+ */
+u8 llc_data_accept_state(u8 state)
+{
+	return state != LLC_CONN_STATE_NORMAL && state != LLC_CONN_STATE_BUSY &&
+	       state != LLC_CONN_STATE_REJ;
+}
+
+/**
+ *	llc_find_next_offset - finds offset for next category of transitions
+ *	@state: state table.
+ *	@offset: start offset.
+ *
+ *	Finds offset of next category of transitions in transition table.
+ *	Returns the start index of next category.
+ */
+static u16 __init llc_find_next_offset(struct llc_conn_state *state, u16 offset)
+{
+	u16 cnt = 0;
+	struct llc_conn_state_trans **next_trans;
+
+	for (next_trans = state->transitions + offset;
+	     (*next_trans)->ev; next_trans++)
+		++cnt;
+	return cnt;
+}
+
+/**
+ *	llc_build_offset_table - builds offset table of connection
+ *
+ *	Fills offset table of connection state transition table
+ *	(llc_offset_table).
+ */
+void __init llc_build_offset_table(void)
+{
+	struct llc_conn_state *curr_state;
+	int state, ev_type, next_offset;
+
+	for (state = 0; state < NBR_CONN_STATES; state++) {
+		curr_state = &llc_conn_state_table[state];
+		next_offset = 0;
+		for (ev_type = 0; ev_type < NBR_CONN_EV; ev_type++) {
+			llc_offset_table[state][ev_type] = next_offset;
+			next_offset += llc_find_next_offset(curr_state,
+							    next_offset) + 1;
+		}
+	}
+}
+
+/**
+ *	llc_find_offset - finds start offset of category of transitions
+ *	@state: state of connection
+ *	@ev_type: type of happened event
+ *
+ *	Finds start offset of desired category of transitions. Returns the
+ *	desired start offset.
+ */
+static int llc_find_offset(int state, int ev_type)
+{
+	int rc = 0;
+	/* at this stage, llc_offset_table[..][2] is not important. it is for
+	 * init_pf_cycle and I don't know what is it.
+	 */
+	switch (ev_type) {
+	case LLC_CONN_EV_TYPE_PRIM:
+		rc = llc_offset_table[state][0]; break;
+	case LLC_CONN_EV_TYPE_PDU:
+		rc = llc_offset_table[state][4]; break;
+	case LLC_CONN_EV_TYPE_SIMPLE:
+		rc = llc_offset_table[state][1]; break;
+	case LLC_CONN_EV_TYPE_P_TMR:
+	case LLC_CONN_EV_TYPE_ACK_TMR:
+	case LLC_CONN_EV_TYPE_REJ_TMR:
+	case LLC_CONN_EV_TYPE_BUSY_TMR:
+		rc = llc_offset_table[state][3]; break;
+	}
+	return rc;
+}
+
+/**
+ *	llc_sap_add_socket - adds a socket to a SAP
+ *	@sap: SAP
+ *	@sk: socket
+ *
+ *	This function adds a socket to the hash tables of a SAP.
+ */
+void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk)
+{
+	struct llc_sock *llc = llc_sk(sk);
+	struct hlist_head *dev_hb = llc_sk_dev_hash(sap, llc->dev->ifindex);
+	struct hlist_nulls_head *laddr_hb = llc_sk_laddr_hash(sap, &llc->laddr);
+
+	llc_sap_hold(sap);
+	llc_sk(sk)->sap = sap;
+
+	spin_lock_bh(&sap->sk_lock);
+	sock_set_flag(sk, SOCK_RCU_FREE);
+	sap->sk_count++;
+	sk_nulls_add_node_rcu(sk, laddr_hb);
+	hlist_add_head(&llc->dev_hash_node, dev_hb);
+	spin_unlock_bh(&sap->sk_lock);
+}
+
+/**
+ *	llc_sap_remove_socket - removes a socket from SAP
+ *	@sap: SAP
+ *	@sk: socket
+ *
+ *	This function removes a connection from the hash tables of a SAP if
+ *	the connection was in this list.
+ */
+void llc_sap_remove_socket(struct llc_sap *sap, struct sock *sk)
+{
+	struct llc_sock *llc = llc_sk(sk);
+
+	spin_lock_bh(&sap->sk_lock);
+	sk_nulls_del_node_init_rcu(sk);
+	hlist_del(&llc->dev_hash_node);
+	sap->sk_count--;
+	spin_unlock_bh(&sap->sk_lock);
+	llc_sap_put(sap);
+}
+
+/**
+ *	llc_conn_rcv - sends received pdus to the connection state machine
+ *	@sk: current connection structure.
+ *	@skb: received frame.
+ *
+ *	Sends received pdus to the connection state machine.
+ */
+static int llc_conn_rcv(struct sock *sk, struct sk_buff *skb)
+{
+	struct llc_conn_state_ev *ev = llc_conn_ev(skb);
+
+	ev->type   = LLC_CONN_EV_TYPE_PDU;
+	ev->reason = 0;
+	return llc_conn_state_process(sk, skb);
+}
+
+static struct sock *llc_create_incoming_sock(struct sock *sk,
+					     struct net_device *dev,
+					     struct llc_addr *saddr,
+					     struct llc_addr *daddr)
+{
+	struct sock *newsk = llc_sk_alloc(sock_net(sk), sk->sk_family, GFP_ATOMIC,
+					  sk->sk_prot, 0);
+	struct llc_sock *newllc, *llc = llc_sk(sk);
+
+	if (!newsk)
+		goto out;
+	newllc = llc_sk(newsk);
+	memcpy(&newllc->laddr, daddr, sizeof(newllc->laddr));
+	memcpy(&newllc->daddr, saddr, sizeof(newllc->daddr));
+	newllc->dev = dev;
+	dev_hold(dev);
+	llc_sap_add_socket(llc->sap, newsk);
+	llc_sap_hold(llc->sap);
+out:
+	return newsk;
+}
+
+void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
+{
+	struct llc_addr saddr, daddr;
+	struct sock *sk;
+
+	llc_pdu_decode_sa(skb, saddr.mac);
+	llc_pdu_decode_ssap(skb, &saddr.lsap);
+	llc_pdu_decode_da(skb, daddr.mac);
+	llc_pdu_decode_dsap(skb, &daddr.lsap);
+
+	sk = __llc_lookup(sap, &saddr, &daddr);
+	if (!sk)
+		goto drop;
+
+	bh_lock_sock(sk);
+	/*
+	 * This has to be done here and not at the upper layer ->accept
+	 * method because of the way the PROCOM state machine works:
+	 * it needs to set several state variables (see, for instance,
+	 * llc_adm_actions_2 in net/llc/llc_c_st.c) and send a packet to
+	 * the originator of the new connection, and this state has to be
+	 * in the newly created struct sock private area. -acme
+	 */
+	if (unlikely(sk->sk_state == TCP_LISTEN)) {
+		struct sock *newsk = llc_create_incoming_sock(sk, skb->dev,
+							      &saddr, &daddr);
+		if (!newsk)
+			goto drop_unlock;
+		skb_set_owner_r(skb, newsk);
+	} else {
+		/*
+		 * Can't be skb_set_owner_r, this will be done at the
+		 * llc_conn_state_process function, later on, when we will use
+		 * skb_queue_rcv_skb to send it to upper layers, this is
+		 * another trick required to cope with how the PROCOM state
+		 * machine works. -acme
+		 */
+		skb_orphan(skb);
+		sock_hold(sk);
+		skb->sk = sk;
+		skb->destructor = sock_efree;
+	}
+	if (!sock_owned_by_user(sk))
+		llc_conn_rcv(sk, skb);
+	else {
+		dprintk("%s: adding to backlog...\n", __func__);
+		llc_set_backlog_type(skb, LLC_PACKET);
+		if (sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)))
+			goto drop_unlock;
+	}
+out:
+	bh_unlock_sock(sk);
+	sock_put(sk);
+	return;
+drop:
+	kfree_skb(skb);
+	return;
+drop_unlock:
+	kfree_skb(skb);
+	goto out;
+}
+
+#undef LLC_REFCNT_DEBUG
+#ifdef LLC_REFCNT_DEBUG
+static atomic_t llc_sock_nr;
+#endif
+
+/**
+ *	llc_backlog_rcv - Processes rx frames and expired timers.
+ *	@sk: LLC sock (p8022 connection)
+ *	@skb: queued rx frame or event
+ *
+ *	This function processes frames that has received and timers that has
+ *	expired during sending an I pdu (refer to data_req_handler).  frames
+ *	queue by llc_rcv function (llc_mac.c) and timers queue by timer
+ *	callback functions(llc_c_ac.c).
+ */
+static int llc_backlog_rcv(struct sock *sk, struct sk_buff *skb)
+{
+	int rc = 0;
+	struct llc_sock *llc = llc_sk(sk);
+
+	if (likely(llc_backlog_type(skb) == LLC_PACKET)) {
+		if (likely(llc->state > 1)) /* not closed */
+			rc = llc_conn_rcv(sk, skb);
+		else
+			goto out_kfree_skb;
+	} else if (llc_backlog_type(skb) == LLC_EVENT) {
+		/* timer expiration event */
+		if (likely(llc->state > 1))  /* not closed */
+			rc = llc_conn_state_process(sk, skb);
+		else
+			goto out_kfree_skb;
+	} else {
+		printk(KERN_ERR "%s: invalid skb in backlog\n", __func__);
+		goto out_kfree_skb;
+	}
+out:
+	return rc;
+out_kfree_skb:
+	kfree_skb(skb);
+	goto out;
+}
+
+/**
+ *     llc_sk_init - Initializes a socket with default llc values.
+ *     @sk: socket to initialize.
+ *
+ *     Initializes a socket with default llc values.
+ */
+static void llc_sk_init(struct sock *sk)
+{
+	struct llc_sock *llc = llc_sk(sk);
+
+	llc->state    = LLC_CONN_STATE_ADM;
+	llc->inc_cntr = llc->dec_cntr = 2;
+	llc->dec_step = llc->connect_step = 1;
+
+	timer_setup(&llc->ack_timer.timer, llc_conn_ack_tmr_cb, 0);
+	llc->ack_timer.expire	      = sysctl_llc2_ack_timeout;
+
+	timer_setup(&llc->pf_cycle_timer.timer, llc_conn_pf_cycle_tmr_cb, 0);
+	llc->pf_cycle_timer.expire	   = sysctl_llc2_p_timeout;
+
+	timer_setup(&llc->rej_sent_timer.timer, llc_conn_rej_tmr_cb, 0);
+	llc->rej_sent_timer.expire	   = sysctl_llc2_rej_timeout;
+
+	timer_setup(&llc->busy_state_timer.timer, llc_conn_busy_tmr_cb, 0);
+	llc->busy_state_timer.expire	     = sysctl_llc2_busy_timeout;
+
+	llc->n2 = 2;   /* max retransmit */
+	llc->k  = 2;   /* tx win size, will adjust dynam */
+	llc->rw = 128; /* rx win size (opt and equal to
+			* tx_win of remote LLC) */
+	skb_queue_head_init(&llc->pdu_unack_q);
+	sk->sk_backlog_rcv = llc_backlog_rcv;
+}
+
+/**
+ *	llc_sk_alloc - Allocates LLC sock
+ *	@net: network namespace
+ *	@family: upper layer protocol family
+ *	@priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
+ *
+ *	Allocates a LLC sock and initializes it. Returns the new LLC sock
+ *	or %NULL if there's no memory available for one
+ */
+struct sock *llc_sk_alloc(struct net *net, int family, gfp_t priority, struct proto *prot, int kern)
+{
+	struct sock *sk = sk_alloc(net, family, priority, prot, kern);
+
+	if (!sk)
+		goto out;
+	llc_sk_init(sk);
+	sock_init_data(NULL, sk);
+#ifdef LLC_REFCNT_DEBUG
+	atomic_inc(&llc_sock_nr);
+	printk(KERN_DEBUG "LLC socket %p created in %s, now we have %d alive\n", sk,
+		__func__, atomic_read(&llc_sock_nr));
+#endif
+out:
+	return sk;
+}
+
+void llc_sk_stop_all_timers(struct sock *sk, bool sync)
+{
+	struct llc_sock *llc = llc_sk(sk);
+
+	if (sync) {
+		del_timer_sync(&llc->pf_cycle_timer.timer);
+		del_timer_sync(&llc->ack_timer.timer);
+		del_timer_sync(&llc->rej_sent_timer.timer);
+		del_timer_sync(&llc->busy_state_timer.timer);
+	} else {
+		del_timer(&llc->pf_cycle_timer.timer);
+		del_timer(&llc->ack_timer.timer);
+		del_timer(&llc->rej_sent_timer.timer);
+		del_timer(&llc->busy_state_timer.timer);
+	}
+
+	llc->ack_must_be_send = 0;
+	llc->ack_pf = 0;
+}
+
+/**
+ *	llc_sk_free - Frees a LLC socket
+ *	@sk: - socket to free
+ *
+ *	Frees a LLC socket
+ */
+void llc_sk_free(struct sock *sk)
+{
+	struct llc_sock *llc = llc_sk(sk);
+
+	llc->state = LLC_CONN_OUT_OF_SVC;
+	/* Stop all (possibly) running timers */
+	llc_sk_stop_all_timers(sk, true);
+#ifdef DEBUG_LLC_CONN_ALLOC
+	printk(KERN_INFO "%s: unackq=%d, txq=%d\n", __func__,
+		skb_queue_len(&llc->pdu_unack_q),
+		skb_queue_len(&sk->sk_write_queue));
+#endif
+	skb_queue_purge(&sk->sk_receive_queue);
+	skb_queue_purge(&sk->sk_write_queue);
+	skb_queue_purge(&llc->pdu_unack_q);
+#ifdef LLC_REFCNT_DEBUG
+	if (refcount_read(&sk->sk_refcnt) != 1) {
+		printk(KERN_DEBUG "Destruction of LLC sock %p delayed in %s, cnt=%d\n",
+			sk, __func__, refcount_read(&sk->sk_refcnt));
+		printk(KERN_DEBUG "%d LLC sockets are still alive\n",
+			atomic_read(&llc_sock_nr));
+	} else {
+		atomic_dec(&llc_sock_nr);
+		printk(KERN_DEBUG "LLC socket %p released in %s, %d are still alive\n", sk,
+			__func__, atomic_read(&llc_sock_nr));
+	}
+#endif
+	sock_put(sk);
+}
+
+/**
+ *	llc_sk_reset - resets a connection
+ *	@sk: LLC socket to reset
+ *
+ *	Resets a connection to the out of service state. Stops its timers
+ *	and frees any frames in the queues of the connection.
+ */
+void llc_sk_reset(struct sock *sk)
+{
+	struct llc_sock *llc = llc_sk(sk);
+
+	llc_conn_ac_stop_all_timers(sk, NULL);
+	skb_queue_purge(&sk->sk_write_queue);
+	skb_queue_purge(&llc->pdu_unack_q);
+	llc->remote_busy_flag	= 0;
+	llc->cause_flag		= 0;
+	llc->retry_count	= 0;
+	llc_conn_set_p_flag(sk, 0);
+	llc->f_flag		= 0;
+	llc->s_flag		= 0;
+	llc->ack_pf		= 0;
+	llc->first_pdu_Ns	= 0;
+	llc->ack_must_be_send	= 0;
+	llc->dec_step		= 1;
+	llc->inc_cntr		= 2;
+	llc->dec_cntr		= 2;
+	llc->X			= 0;
+	llc->failed_data_req	= 0 ;
+	llc->last_nr		= 0;
+}