llc_conn.c

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/*
 * llc_conn.c - Driver routines for connection component.
 *
 * Copyright (c) 1997 by Procom Technology, Inc.
 *       2001-2003 by Arnaldo Carvalho de Melo <[email protected]>
 *
 * 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;

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);

    /*
     * We have to hold the skb, because llc_conn_service will kfree it in
     * the sending path and we need to look at the skb->cb, where we encode
     * llc_conn_state_ev.
     */
    skb_get(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_kfree_skb;
    }

    if (unlikely(!ev->ind_prim && !ev->cfm_prim)) {
        /* indicate or confirm not required */
        if (!skb->next)
            goto out_kfree_skb;
        goto out_skb_put;
    }

    if (unlikely(ev->ind_prim && ev->cfm_prim)) /* Paranoia */
        skb_get(skb);

    switch (ev->ind_prim) {
    case LLC_DATA_PRIM:
        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_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);
            }
        }
        kfree_skb(skb);
        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__);
        kfree_skb(skb);
        break;
    default:
        if (ev->ind_prim) {
            printk(KERN_INFO "%s: received unknown %d prim!\n",
                __func__, ev->ind_prim);
            kfree_skb(skb);
        }
        /* 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);
            break;
        }
        goto out_skb_put; /* No confirmation */
    }
out_kfree_skb:
    kfree_skb(skb);
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);
}

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;
}

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:;
}

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:;
}

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;
}

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);
    }
}

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;
}

static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
                            struct sk_buff *skb)
{
    struct llc_conn_state_trans **next_trans;
    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;
}

static int llc_exec_conn_trans_actions(struct sock *sk,
                       struct llc_conn_state_trans *trans,
                       struct sk_buff *skb)
{
    int rc = 0;
    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 &&
        llc_mac_match(llc->laddr.mac, laddr->mac) &&
        llc_mac_match(llc->daddr.mac, daddr->mac);
}

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;
}

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 &&
        llc_mac_match(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_DESTROY_BY_RCU */
            if (unlikely(!atomic_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;
}

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);
}

u8 llc_data_accept_state(u8 state)
{
    return state != LLC_CONN_STATE_NORMAL && state != LLC_CONN_STATE_BUSY &&
           state != LLC_CONN_STATE_REJ;
}

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;
}

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;
        }
    }
}

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;
}

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);
    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);
}

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);
}

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);
    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->sk = sk;
    }
    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, 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

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;
}

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;

    setup_timer(&llc->ack_timer.timer, llc_conn_ack_tmr_cb,
            (unsigned long)sk);
    llc->ack_timer.expire         = sysctl_llc2_ack_timeout;

    setup_timer(&llc->pf_cycle_timer.timer, llc_conn_pf_cycle_tmr_cb,
            (unsigned long)sk);
    llc->pf_cycle_timer.expire     = sysctl_llc2_p_timeout;

    setup_timer(&llc->rej_sent_timer.timer, llc_conn_rej_tmr_cb,
            (unsigned long)sk);
    llc->rej_sent_timer.expire     = sysctl_llc2_rej_timeout;

    setup_timer(&llc->busy_state_timer.timer, llc_conn_busy_tmr_cb,
            (unsigned long)sk);
    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;
}

struct sock *llc_sk_alloc(struct net *net, int family, gfp_t priority, struct proto *prot)
{
    struct sock *sk = sk_alloc(net, family, priority, prot);

    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_free(struct sock *sk)
{
    struct llc_sock *llc = llc_sk(sk);

    llc->state = LLC_CONN_OUT_OF_SVC;
    /* Stop all (possibly) running timers */
    llc_conn_ac_stop_all_timers(sk, NULL);
#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 (atomic_read(&sk->sk_refcnt) != 1) {
        printk(KERN_DEBUG "Destruction of LLC sock %p delayed in %s, cnt=%d\n",
            sk, __func__, atomic_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);
}

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;
}