linux/net/llc/llc_conn.c
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   1/*
   2 * llc_conn.c - Driver routines for connection component.
   3 *
   4 * Copyright (c) 1997 by Procom Technology, Inc.
   5 *               2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6 *
   7 * This program can be redistributed or modified under the terms of the
   8 * GNU General Public License as published by the Free Software Foundation.
   9 * This program is distributed without any warranty or implied warranty
  10 * of merchantability or fitness for a particular purpose.
  11 *
  12 * See the GNU General Public License for more details.
  13 */
  14
  15#include <linux/init.h>
  16#include <net/llc_sap.h>
  17#include <net/llc_conn.h>
  18#include <net/sock.h>
  19#include <net/tcp_states.h>
  20#include <net/llc_c_ev.h>
  21#include <net/llc_c_ac.h>
  22#include <net/llc_c_st.h>
  23#include <net/llc_pdu.h>
  24
  25#if 0
  26#define dprintk(args...) printk(KERN_DEBUG args)
  27#else
  28#define dprintk(args...)
  29#endif
  30
  31static int llc_find_offset(int state, int ev_type);
  32static void llc_conn_send_pdus(struct sock *sk);
  33static int llc_conn_service(struct sock *sk, struct sk_buff *skb);
  34static int llc_exec_conn_trans_actions(struct sock *sk,
  35                                       struct llc_conn_state_trans *trans,
  36                                       struct sk_buff *ev);
  37static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
  38                                                        struct sk_buff *skb);
  39
  40/* Offset table on connection states transition diagram */
  41static int llc_offset_table[NBR_CONN_STATES][NBR_CONN_EV];
  42
  43int sysctl_llc2_ack_timeout = LLC2_ACK_TIME * HZ;
  44int sysctl_llc2_p_timeout = LLC2_P_TIME * HZ;
  45int sysctl_llc2_rej_timeout = LLC2_REJ_TIME * HZ;
  46int sysctl_llc2_busy_timeout = LLC2_BUSY_TIME * HZ;
  47
  48/**
  49 *      llc_conn_state_process - sends event to connection state machine
  50 *      @sk: connection
  51 *      @skb: occurred event
  52 *
  53 *      Sends an event to connection state machine. After processing event
  54 *      (executing it's actions and changing state), upper layer will be
  55 *      indicated or confirmed, if needed. Returns 0 for success, 1 for
  56 *      failure. The socket lock has to be held before calling this function.
  57 */
  58int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
  59{
  60        int rc;
  61        struct llc_sock *llc = llc_sk(skb->sk);
  62        struct llc_conn_state_ev *ev = llc_conn_ev(skb);
  63
  64        /*
  65         * We have to hold the skb, because llc_conn_service will kfree it in
  66         * the sending path and we need to look at the skb->cb, where we encode
  67         * llc_conn_state_ev.
  68         */
  69        skb_get(skb);
  70        ev->ind_prim = ev->cfm_prim = 0;
  71        /*
  72         * Send event to state machine
  73         */
  74        rc = llc_conn_service(skb->sk, skb);
  75        if (unlikely(rc != 0)) {
  76                printk(KERN_ERR "%s: llc_conn_service failed\n", __func__);
  77                goto out_kfree_skb;
  78        }
  79
  80        if (unlikely(!ev->ind_prim && !ev->cfm_prim)) {
  81                /* indicate or confirm not required */
  82                /* XXX this is not very pretty, perhaps we should store
  83                 * XXX indicate/confirm-needed state in the llc_conn_state_ev
  84                 * XXX control block of the SKB instead? -DaveM
  85                 */
  86                if (!skb->next)
  87                        goto out_kfree_skb;
  88                goto out_skb_put;
  89        }
  90
  91        if (unlikely(ev->ind_prim && ev->cfm_prim)) /* Paranoia */
  92                skb_get(skb);
  93
  94        switch (ev->ind_prim) {
  95        case LLC_DATA_PRIM:
  96                llc_save_primitive(sk, skb, LLC_DATA_PRIM);
  97                if (unlikely(sock_queue_rcv_skb(sk, skb))) {
  98                        /*
  99                         * shouldn't happen
 100                         */
 101                        printk(KERN_ERR "%s: sock_queue_rcv_skb failed!\n",
 102                               __func__);
 103                        kfree_skb(skb);
 104                }
 105                break;
 106        case LLC_CONN_PRIM:
 107                /*
 108                 * Can't be sock_queue_rcv_skb, because we have to leave the
 109                 * skb->sk pointing to the newly created struct sock in
 110                 * llc_conn_handler. -acme
 111                 */
 112                skb_queue_tail(&sk->sk_receive_queue, skb);
 113                sk->sk_state_change(sk);
 114                break;
 115        case LLC_DISC_PRIM:
 116                sock_hold(sk);
 117                if (sk->sk_type == SOCK_STREAM &&
 118                    sk->sk_state == TCP_ESTABLISHED) {
 119                        sk->sk_shutdown       = SHUTDOWN_MASK;
 120                        sk->sk_socket->state  = SS_UNCONNECTED;
 121                        sk->sk_state          = TCP_CLOSE;
 122                        if (!sock_flag(sk, SOCK_DEAD)) {
 123                                sock_set_flag(sk, SOCK_DEAD);
 124                                sk->sk_state_change(sk);
 125                        }
 126                }
 127                kfree_skb(skb);
 128                sock_put(sk);
 129                break;
 130        case LLC_RESET_PRIM:
 131                /*
 132                 * FIXME:
 133                 * RESET is not being notified to upper layers for now
 134                 */
 135                printk(KERN_INFO "%s: received a reset ind!\n", __func__);
 136                kfree_skb(skb);
 137                break;
 138        default:
 139                if (ev->ind_prim) {
 140                        printk(KERN_INFO "%s: received unknown %d prim!\n",
 141                                __func__, ev->ind_prim);
 142                        kfree_skb(skb);
 143                }
 144                /* No indication */
 145                break;
 146        }
 147
 148        switch (ev->cfm_prim) {
 149        case LLC_DATA_PRIM:
 150                if (!llc_data_accept_state(llc->state))
 151                        sk->sk_write_space(sk);
 152                else
 153                        rc = llc->failed_data_req = 1;
 154                break;
 155        case LLC_CONN_PRIM:
 156                if (sk->sk_type == SOCK_STREAM &&
 157                    sk->sk_state == TCP_SYN_SENT) {
 158                        if (ev->status) {
 159                                sk->sk_socket->state = SS_UNCONNECTED;
 160                                sk->sk_state         = TCP_CLOSE;
 161                        } else {
 162                                sk->sk_socket->state = SS_CONNECTED;
 163                                sk->sk_state         = TCP_ESTABLISHED;
 164                        }
 165                        sk->sk_state_change(sk);
 166                }
 167                break;
 168        case LLC_DISC_PRIM:
 169                sock_hold(sk);
 170                if (sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_CLOSING) {
 171                        sk->sk_socket->state = SS_UNCONNECTED;
 172                        sk->sk_state         = TCP_CLOSE;
 173                        sk->sk_state_change(sk);
 174                }
 175                sock_put(sk);
 176                break;
 177        case LLC_RESET_PRIM:
 178                /*
 179                 * FIXME:
 180                 * RESET is not being notified to upper layers for now
 181                 */
 182                printk(KERN_INFO "%s: received a reset conf!\n", __func__);
 183                break;
 184        default:
 185                if (ev->cfm_prim) {
 186                        printk(KERN_INFO "%s: received unknown %d prim!\n",
 187                                        __func__, ev->cfm_prim);
 188                        break;
 189                }
 190                goto out_skb_put; /* No confirmation */
 191        }
 192out_kfree_skb:
 193        kfree_skb(skb);
 194out_skb_put:
 195        kfree_skb(skb);
 196        return rc;
 197}
 198
 199void llc_conn_send_pdu(struct sock *sk, struct sk_buff *skb)
 200{
 201        /* queue PDU to send to MAC layer */
 202        skb_queue_tail(&sk->sk_write_queue, skb);
 203        llc_conn_send_pdus(sk);
 204}
 205
 206/**
 207 *      llc_conn_rtn_pdu - sends received data pdu to upper layer
 208 *      @sk: Active connection
 209 *      @skb: Received data frame
 210 *
 211 *      Sends received data pdu to upper layer (by using indicate function).
 212 *      Prepares service parameters (prim and prim_data). calling indication
 213 *      function will be done in llc_conn_state_process.
 214 */
 215void llc_conn_rtn_pdu(struct sock *sk, struct sk_buff *skb)
 216{
 217        struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 218
 219        ev->ind_prim = LLC_DATA_PRIM;
 220}
 221
 222/**
 223 *      llc_conn_resend_i_pdu_as_cmd - resend all all unacknowledged I PDUs
 224 *      @sk: active connection
 225 *      @nr: NR
 226 *      @first_p_bit: p_bit value of first pdu
 227 *
 228 *      Resend all unacknowledged I PDUs, starting with the NR; send first as
 229 *      command PDU with P bit equal first_p_bit; if more than one send
 230 *      subsequent as command PDUs with P bit equal zero (0).
 231 */
 232void llc_conn_resend_i_pdu_as_cmd(struct sock *sk, u8 nr, u8 first_p_bit)
 233{
 234        struct sk_buff *skb;
 235        struct llc_pdu_sn *pdu;
 236        u16 nbr_unack_pdus;
 237        struct llc_sock *llc;
 238        u8 howmany_resend = 0;
 239
 240        llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
 241        if (!nbr_unack_pdus)
 242                goto out;
 243        /*
 244         * Process unack PDUs only if unack queue is not empty; remove
 245         * appropriate PDUs, fix them up, and put them on mac_pdu_q.
 246         */
 247        llc = llc_sk(sk);
 248
 249        while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
 250                pdu = llc_pdu_sn_hdr(skb);
 251                llc_pdu_set_cmd_rsp(skb, LLC_PDU_CMD);
 252                llc_pdu_set_pf_bit(skb, first_p_bit);
 253                skb_queue_tail(&sk->sk_write_queue, skb);
 254                first_p_bit = 0;
 255                llc->vS = LLC_I_GET_NS(pdu);
 256                howmany_resend++;
 257        }
 258        if (howmany_resend > 0)
 259                llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
 260        /* any PDUs to re-send are queued up; start sending to MAC */
 261        llc_conn_send_pdus(sk);
 262out:;
 263}
 264
 265/**
 266 *      llc_conn_resend_i_pdu_as_rsp - Resend all unacknowledged I PDUs
 267 *      @sk: active connection.
 268 *      @nr: NR
 269 *      @first_f_bit: f_bit value of first pdu.
 270 *
 271 *      Resend all unacknowledged I PDUs, starting with the NR; send first as
 272 *      response PDU with F bit equal first_f_bit; if more than one send
 273 *      subsequent as response PDUs with F bit equal zero (0).
 274 */
 275void llc_conn_resend_i_pdu_as_rsp(struct sock *sk, u8 nr, u8 first_f_bit)
 276{
 277        struct sk_buff *skb;
 278        u16 nbr_unack_pdus;
 279        struct llc_sock *llc = llc_sk(sk);
 280        u8 howmany_resend = 0;
 281
 282        llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
 283        if (!nbr_unack_pdus)
 284                goto out;
 285        /*
 286         * Process unack PDUs only if unack queue is not empty; remove
 287         * appropriate PDUs, fix them up, and put them on mac_pdu_q
 288         */
 289        while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
 290                struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 291
 292                llc_pdu_set_cmd_rsp(skb, LLC_PDU_RSP);
 293                llc_pdu_set_pf_bit(skb, first_f_bit);
 294                skb_queue_tail(&sk->sk_write_queue, skb);
 295                first_f_bit = 0;
 296                llc->vS = LLC_I_GET_NS(pdu);
 297                howmany_resend++;
 298        }
 299        if (howmany_resend > 0)
 300                llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
 301        /* any PDUs to re-send are queued up; start sending to MAC */
 302        llc_conn_send_pdus(sk);
 303out:;
 304}
 305
 306/**
 307 *      llc_conn_remove_acked_pdus - Removes acknowledged pdus from tx queue
 308 *      @sk: active connection
 309 *      nr: NR
 310 *      how_many_unacked: size of pdu_unack_q after removing acked pdus
 311 *
 312 *      Removes acknowledged pdus from transmit queue (pdu_unack_q). Returns
 313 *      the number of pdus that removed from queue.
 314 */
 315int llc_conn_remove_acked_pdus(struct sock *sk, u8 nr, u16 *how_many_unacked)
 316{
 317        int pdu_pos, i;
 318        struct sk_buff *skb;
 319        struct llc_pdu_sn *pdu;
 320        int nbr_acked = 0;
 321        struct llc_sock *llc = llc_sk(sk);
 322        int q_len = skb_queue_len(&llc->pdu_unack_q);
 323
 324        if (!q_len)
 325                goto out;
 326        skb = skb_peek(&llc->pdu_unack_q);
 327        pdu = llc_pdu_sn_hdr(skb);
 328
 329        /* finding position of last acked pdu in queue */
 330        pdu_pos = ((int)LLC_2_SEQ_NBR_MODULO + (int)nr -
 331                        (int)LLC_I_GET_NS(pdu)) % LLC_2_SEQ_NBR_MODULO;
 332
 333        for (i = 0; i < pdu_pos && i < q_len; i++) {
 334                skb = skb_dequeue(&llc->pdu_unack_q);
 335                kfree_skb(skb);
 336                nbr_acked++;
 337        }
 338out:
 339        *how_many_unacked = skb_queue_len(&llc->pdu_unack_q);
 340        return nbr_acked;
 341}
 342
 343/**
 344 *      llc_conn_send_pdus - Sends queued PDUs
 345 *      @sk: active connection
 346 *
 347 *      Sends queued pdus to MAC layer for transmission.
 348 */
 349static void llc_conn_send_pdus(struct sock *sk)
 350{
 351        struct sk_buff *skb;
 352
 353        while ((skb = skb_dequeue(&sk->sk_write_queue)) != NULL) {
 354                struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 355
 356                if (LLC_PDU_TYPE_IS_I(pdu) &&
 357                    !(skb->dev->flags & IFF_LOOPBACK)) {
 358                        struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
 359
 360                        skb_queue_tail(&llc_sk(sk)->pdu_unack_q, skb);
 361                        if (!skb2)
 362                                break;
 363                        skb = skb2;
 364                }
 365                dev_queue_xmit(skb);
 366        }
 367}
 368
 369/**
 370 *      llc_conn_service - finds transition and changes state of connection
 371 *      @sk: connection
 372 *      @skb: happened event
 373 *
 374 *      This function finds transition that matches with happened event, then
 375 *      executes related actions and finally changes state of connection.
 376 *      Returns 0 for success, 1 for failure.
 377 */
 378static int llc_conn_service(struct sock *sk, struct sk_buff *skb)
 379{
 380        int rc = 1;
 381        struct llc_sock *llc = llc_sk(sk);
 382        struct llc_conn_state_trans *trans;
 383
 384        if (llc->state > NBR_CONN_STATES)
 385                goto out;
 386        rc = 0;
 387        trans = llc_qualify_conn_ev(sk, skb);
 388        if (trans) {
 389                rc = llc_exec_conn_trans_actions(sk, trans, skb);
 390                if (!rc && trans->next_state != NO_STATE_CHANGE) {
 391                        llc->state = trans->next_state;
 392                        if (!llc_data_accept_state(llc->state))
 393                                sk->sk_state_change(sk);
 394                }
 395        }
 396out:
 397        return rc;
 398}
 399
 400/**
 401 *      llc_qualify_conn_ev - finds transition for event
 402 *      @sk: connection
 403 *      @skb: happened event
 404 *
 405 *      This function finds transition that matches with happened event.
 406 *      Returns pointer to found transition on success, %NULL otherwise.
 407 */
 408static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
 409                                                        struct sk_buff *skb)
 410{
 411        struct llc_conn_state_trans **next_trans;
 412        llc_conn_ev_qfyr_t *next_qualifier;
 413        struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 414        struct llc_sock *llc = llc_sk(sk);
 415        struct llc_conn_state *curr_state =
 416                                        &llc_conn_state_table[llc->state - 1];
 417
 418        /* search thru events for this state until
 419         * list exhausted or until no more
 420         */
 421        for (next_trans = curr_state->transitions +
 422                llc_find_offset(llc->state - 1, ev->type);
 423             (*next_trans)->ev; next_trans++) {
 424                if (!((*next_trans)->ev)(sk, skb)) {
 425                        /* got POSSIBLE event match; the event may require
 426                         * qualification based on the values of a number of
 427                         * state flags; if all qualifications are met (i.e.,
 428                         * if all qualifying functions return success, or 0,
 429                         * then this is THE event we're looking for
 430                         */
 431                        for (next_qualifier = (*next_trans)->ev_qualifiers;
 432                             next_qualifier && *next_qualifier &&
 433                             !(*next_qualifier)(sk, skb); next_qualifier++)
 434                                /* nothing */;
 435                        if (!next_qualifier || !*next_qualifier)
 436                                /* all qualifiers executed successfully; this is
 437                                 * our transition; return it so we can perform
 438                                 * the associated actions & change the state
 439                                 */
 440                                return *next_trans;
 441                }
 442        }
 443        return NULL;
 444}
 445
 446/**
 447 *      llc_exec_conn_trans_actions - executes related actions
 448 *      @sk: connection
 449 *      @trans: transition that it's actions must be performed
 450 *      @skb: event
 451 *
 452 *      Executes actions that is related to happened event. Returns 0 for
 453 *      success, 1 to indicate failure of at least one action.
 454 */
 455static int llc_exec_conn_trans_actions(struct sock *sk,
 456                                       struct llc_conn_state_trans *trans,
 457                                       struct sk_buff *skb)
 458{
 459        int rc = 0;
 460        llc_conn_action_t *next_action;
 461
 462        for (next_action = trans->ev_actions;
 463             next_action && *next_action; next_action++) {
 464                int rc2 = (*next_action)(sk, skb);
 465
 466                if (rc2 == 2) {
 467                        rc = rc2;
 468                        break;
 469                } else if (rc2)
 470                        rc = 1;
 471        }
 472        return rc;
 473}
 474
 475/**
 476 *      __llc_lookup_established - Finds connection for the remote/local sap/mac
 477 *      @sap: SAP
 478 *      @daddr: address of remote LLC (MAC + SAP)
 479 *      @laddr: address of local LLC (MAC + SAP)
 480 *
 481 *      Search connection list of the SAP and finds connection using the remote
 482 *      mac, remote sap, local mac, and local sap. Returns pointer for
 483 *      connection found, %NULL otherwise.
 484 *      Caller has to make sure local_bh is disabled.
 485 */
 486static struct sock *__llc_lookup_established(struct llc_sap *sap,
 487                                             struct llc_addr *daddr,
 488                                             struct llc_addr *laddr)
 489{
 490        struct sock *rc;
 491        struct hlist_node *node;
 492
 493        read_lock(&sap->sk_list.lock);
 494        sk_for_each(rc, node, &sap->sk_list.list) {
 495                struct llc_sock *llc = llc_sk(rc);
 496
 497                if (llc->laddr.lsap == laddr->lsap &&
 498                    llc->daddr.lsap == daddr->lsap &&
 499                    llc_mac_match(llc->laddr.mac, laddr->mac) &&
 500                    llc_mac_match(llc->daddr.mac, daddr->mac)) {
 501                        sock_hold(rc);
 502                        goto found;
 503                }
 504        }
 505        rc = NULL;
 506found:
 507        read_unlock(&sap->sk_list.lock);
 508        return rc;
 509}
 510
 511struct sock *llc_lookup_established(struct llc_sap *sap,
 512                                    struct llc_addr *daddr,
 513                                    struct llc_addr *laddr)
 514{
 515        struct sock *sk;
 516
 517        local_bh_disable();
 518        sk = __llc_lookup_established(sap, daddr, laddr);
 519        local_bh_enable();
 520        return sk;
 521}
 522
 523/**
 524 *      llc_lookup_listener - Finds listener for local MAC + SAP
 525 *      @sap: SAP
 526 *      @laddr: address of local LLC (MAC + SAP)
 527 *
 528 *      Search connection list of the SAP and finds connection listening on
 529 *      local mac, and local sap. Returns pointer for parent socket found,
 530 *      %NULL otherwise.
 531 *      Caller has to make sure local_bh is disabled.
 532 */
 533static struct sock *llc_lookup_listener(struct llc_sap *sap,
 534                                        struct llc_addr *laddr)
 535{
 536        struct sock *rc;
 537        struct hlist_node *node;
 538
 539        read_lock(&sap->sk_list.lock);
 540        sk_for_each(rc, node, &sap->sk_list.list) {
 541                struct llc_sock *llc = llc_sk(rc);
 542
 543                if (rc->sk_type == SOCK_STREAM && rc->sk_state == TCP_LISTEN &&
 544                    llc->laddr.lsap == laddr->lsap &&
 545                    (llc_mac_match(llc->laddr.mac, laddr->mac) ||
 546                     llc_mac_null(llc->laddr.mac))) {
 547                        sock_hold(rc);
 548                        goto found;
 549                }
 550        }
 551        rc = NULL;
 552found:
 553        read_unlock(&sap->sk_list.lock);
 554        return rc;
 555}
 556
 557static struct sock *__llc_lookup(struct llc_sap *sap,
 558                                 struct llc_addr *daddr,
 559                                 struct llc_addr *laddr)
 560{
 561        struct sock *sk = __llc_lookup_established(sap, daddr, laddr);
 562
 563        return sk ? : llc_lookup_listener(sap, laddr);
 564}
 565
 566/**
 567 *      llc_data_accept_state - designates if in this state data can be sent.
 568 *      @state: state of connection.
 569 *
 570 *      Returns 0 if data can be sent, 1 otherwise.
 571 */
 572u8 llc_data_accept_state(u8 state)
 573{
 574        return state != LLC_CONN_STATE_NORMAL && state != LLC_CONN_STATE_BUSY &&
 575               state != LLC_CONN_STATE_REJ;
 576}
 577
 578/**
 579 *      llc_find_next_offset - finds offset for next category of transitions
 580 *      @state: state table.
 581 *      @offset: start offset.
 582 *
 583 *      Finds offset of next category of transitions in transition table.
 584 *      Returns the start index of next category.
 585 */
 586static u16 __init llc_find_next_offset(struct llc_conn_state *state, u16 offset)
 587{
 588        u16 cnt = 0;
 589        struct llc_conn_state_trans **next_trans;
 590
 591        for (next_trans = state->transitions + offset;
 592             (*next_trans)->ev; next_trans++)
 593                ++cnt;
 594        return cnt;
 595}
 596
 597/**
 598 *      llc_build_offset_table - builds offset table of connection
 599 *
 600 *      Fills offset table of connection state transition table
 601 *      (llc_offset_table).
 602 */
 603void __init llc_build_offset_table(void)
 604{
 605        struct llc_conn_state *curr_state;
 606        int state, ev_type, next_offset;
 607
 608        for (state = 0; state < NBR_CONN_STATES; state++) {
 609                curr_state = &llc_conn_state_table[state];
 610                next_offset = 0;
 611                for (ev_type = 0; ev_type < NBR_CONN_EV; ev_type++) {
 612                        llc_offset_table[state][ev_type] = next_offset;
 613                        next_offset += llc_find_next_offset(curr_state,
 614                                                            next_offset) + 1;
 615                }
 616        }
 617}
 618
 619/**
 620 *      llc_find_offset - finds start offset of category of transitions
 621 *      @state: state of connection
 622 *      @ev_type: type of happened event
 623 *
 624 *      Finds start offset of desired category of transitions. Returns the
 625 *      desired start offset.
 626 */
 627static int llc_find_offset(int state, int ev_type)
 628{
 629        int rc = 0;
 630        /* at this stage, llc_offset_table[..][2] is not important. it is for
 631         * init_pf_cycle and I don't know what is it.
 632         */
 633        switch (ev_type) {
 634        case LLC_CONN_EV_TYPE_PRIM:
 635                rc = llc_offset_table[state][0]; break;
 636        case LLC_CONN_EV_TYPE_PDU:
 637                rc = llc_offset_table[state][4]; break;
 638        case LLC_CONN_EV_TYPE_SIMPLE:
 639                rc = llc_offset_table[state][1]; break;
 640        case LLC_CONN_EV_TYPE_P_TMR:
 641        case LLC_CONN_EV_TYPE_ACK_TMR:
 642        case LLC_CONN_EV_TYPE_REJ_TMR:
 643        case LLC_CONN_EV_TYPE_BUSY_TMR:
 644                rc = llc_offset_table[state][3]; break;
 645        }
 646        return rc;
 647}
 648
 649/**
 650 *      llc_sap_add_socket - adds a socket to a SAP
 651 *      @sap: SAP
 652 *      @sk: socket
 653 *
 654 *      This function adds a socket to sk_list of a SAP.
 655 */
 656void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk)
 657{
 658        llc_sap_hold(sap);
 659        write_lock_bh(&sap->sk_list.lock);
 660        llc_sk(sk)->sap = sap;
 661        sk_add_node(sk, &sap->sk_list.list);
 662        write_unlock_bh(&sap->sk_list.lock);
 663}
 664
 665/**
 666 *      llc_sap_remove_socket - removes a socket from SAP
 667 *      @sap: SAP
 668 *      @sk: socket
 669 *
 670 *      This function removes a connection from sk_list.list of a SAP if
 671 *      the connection was in this list.
 672 */
 673void llc_sap_remove_socket(struct llc_sap *sap, struct sock *sk)
 674{
 675        write_lock_bh(&sap->sk_list.lock);
 676        sk_del_node_init(sk);
 677        write_unlock_bh(&sap->sk_list.lock);
 678        llc_sap_put(sap);
 679}
 680
 681/**
 682 *      llc_conn_rcv - sends received pdus to the connection state machine
 683 *      @sk: current connection structure.
 684 *      @skb: received frame.
 685 *
 686 *      Sends received pdus to the connection state machine.
 687 */
 688static int llc_conn_rcv(struct sock* sk, struct sk_buff *skb)
 689{
 690        struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 691
 692        ev->type   = LLC_CONN_EV_TYPE_PDU;
 693        ev->reason = 0;
 694        return llc_conn_state_process(sk, skb);
 695}
 696
 697static struct sock *llc_create_incoming_sock(struct sock *sk,
 698                                             struct net_device *dev,
 699                                             struct llc_addr *saddr,
 700                                             struct llc_addr *daddr)
 701{
 702        struct sock *newsk = llc_sk_alloc(sock_net(sk), sk->sk_family, GFP_ATOMIC,
 703                                          sk->sk_prot);
 704        struct llc_sock *newllc, *llc = llc_sk(sk);
 705
 706        if (!newsk)
 707                goto out;
 708        newllc = llc_sk(newsk);
 709        memcpy(&newllc->laddr, daddr, sizeof(newllc->laddr));
 710        memcpy(&newllc->daddr, saddr, sizeof(newllc->daddr));
 711        newllc->dev = dev;
 712        dev_hold(dev);
 713        llc_sap_add_socket(llc->sap, newsk);
 714        llc_sap_hold(llc->sap);
 715out:
 716        return newsk;
 717}
 718
 719void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
 720{
 721        struct llc_addr saddr, daddr;
 722        struct sock *sk;
 723
 724        llc_pdu_decode_sa(skb, saddr.mac);
 725        llc_pdu_decode_ssap(skb, &saddr.lsap);
 726        llc_pdu_decode_da(skb, daddr.mac);
 727        llc_pdu_decode_dsap(skb, &daddr.lsap);
 728
 729        sk = __llc_lookup(sap, &saddr, &daddr);
 730        if (!sk)
 731                goto drop;
 732
 733        bh_lock_sock(sk);
 734        /*
 735         * This has to be done here and not at the upper layer ->accept
 736         * method because of the way the PROCOM state machine works:
 737         * it needs to set several state variables (see, for instance,
 738         * llc_adm_actions_2 in net/llc/llc_c_st.c) and send a packet to
 739         * the originator of the new connection, and this state has to be
 740         * in the newly created struct sock private area. -acme
 741         */
 742        if (unlikely(sk->sk_state == TCP_LISTEN)) {
 743                struct sock *newsk = llc_create_incoming_sock(sk, skb->dev,
 744                                                              &saddr, &daddr);
 745                if (!newsk)
 746                        goto drop_unlock;
 747                skb_set_owner_r(skb, newsk);
 748        } else {
 749                /*
 750                 * Can't be skb_set_owner_r, this will be done at the
 751                 * llc_conn_state_process function, later on, when we will use
 752                 * skb_queue_rcv_skb to send it to upper layers, this is
 753                 * another trick required to cope with how the PROCOM state
 754                 * machine works. -acme
 755                 */
 756                skb->sk = sk;
 757        }
 758        if (!sock_owned_by_user(sk))
 759                llc_conn_rcv(sk, skb);
 760        else {
 761                dprintk("%s: adding to backlog...\n", __func__);
 762                llc_set_backlog_type(skb, LLC_PACKET);
 763                sk_add_backlog(sk, skb);
 764        }
 765out:
 766        bh_unlock_sock(sk);
 767        sock_put(sk);
 768        return;
 769drop:
 770        kfree_skb(skb);
 771        return;
 772drop_unlock:
 773        kfree_skb(skb);
 774        goto out;
 775}
 776
 777#undef LLC_REFCNT_DEBUG
 778#ifdef LLC_REFCNT_DEBUG
 779static atomic_t llc_sock_nr;
 780#endif
 781
 782/**
 783 *      llc_backlog_rcv - Processes rx frames and expired timers.
 784 *      @sk: LLC sock (p8022 connection)
 785 *      @skb: queued rx frame or event
 786 *
 787 *      This function processes frames that has received and timers that has
 788 *      expired during sending an I pdu (refer to data_req_handler).  frames
 789 *      queue by llc_rcv function (llc_mac.c) and timers queue by timer
 790 *      callback functions(llc_c_ac.c).
 791 */
 792static int llc_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 793{
 794        int rc = 0;
 795        struct llc_sock *llc = llc_sk(sk);
 796
 797        if (likely(llc_backlog_type(skb) == LLC_PACKET)) {
 798                if (likely(llc->state > 1)) /* not closed */
 799                        rc = llc_conn_rcv(sk, skb);
 800                else
 801                        goto out_kfree_skb;
 802        } else if (llc_backlog_type(skb) == LLC_EVENT) {
 803                /* timer expiration event */
 804                if (likely(llc->state > 1))  /* not closed */
 805                        rc = llc_conn_state_process(sk, skb);
 806                else
 807                        goto out_kfree_skb;
 808        } else {
 809                printk(KERN_ERR "%s: invalid skb in backlog\n", __func__);
 810                goto out_kfree_skb;
 811        }
 812out:
 813        return rc;
 814out_kfree_skb:
 815        kfree_skb(skb);
 816        goto out;
 817}
 818
 819/**
 820 *     llc_sk_init - Initializes a socket with default llc values.
 821 *     @sk: socket to initialize.
 822 *
 823 *     Initializes a socket with default llc values.
 824 */
 825static void llc_sk_init(struct sock* sk)
 826{
 827        struct llc_sock *llc = llc_sk(sk);
 828
 829        llc->state    = LLC_CONN_STATE_ADM;
 830        llc->inc_cntr = llc->dec_cntr = 2;
 831        llc->dec_step = llc->connect_step = 1;
 832
 833        setup_timer(&llc->ack_timer.timer, llc_conn_ack_tmr_cb,
 834                        (unsigned long)sk);
 835        llc->ack_timer.expire         = sysctl_llc2_ack_timeout;
 836
 837        setup_timer(&llc->pf_cycle_timer.timer, llc_conn_pf_cycle_tmr_cb,
 838                        (unsigned long)sk);
 839        llc->pf_cycle_timer.expire         = sysctl_llc2_p_timeout;
 840
 841        setup_timer(&llc->rej_sent_timer.timer, llc_conn_rej_tmr_cb,
 842                        (unsigned long)sk);
 843        llc->rej_sent_timer.expire         = sysctl_llc2_rej_timeout;
 844
 845        setup_timer(&llc->busy_state_timer.timer, llc_conn_busy_tmr_cb,
 846                        (unsigned long)sk);
 847        llc->busy_state_timer.expire         = sysctl_llc2_busy_timeout;
 848
 849        llc->n2 = 2;   /* max retransmit */
 850        llc->k  = 2;   /* tx win size, will adjust dynam */
 851        llc->rw = 128; /* rx win size (opt and equal to
 852                        * tx_win of remote LLC) */
 853        skb_queue_head_init(&llc->pdu_unack_q);
 854        sk->sk_backlog_rcv = llc_backlog_rcv;
 855}
 856
 857/**
 858 *      llc_sk_alloc - Allocates LLC sock
 859 *      @family: upper layer protocol family
 860 *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 861 *
 862 *      Allocates a LLC sock and initializes it. Returns the new LLC sock
 863 *      or %NULL if there's no memory available for one
 864 */
 865struct sock *llc_sk_alloc(struct net *net, int family, gfp_t priority, struct proto *prot)
 866{
 867        struct sock *sk = sk_alloc(net, family, priority, prot);
 868
 869        if (!sk)
 870                goto out;
 871        llc_sk_init(sk);
 872        sock_init_data(NULL, sk);
 873#ifdef LLC_REFCNT_DEBUG
 874        atomic_inc(&llc_sock_nr);
 875        printk(KERN_DEBUG "LLC socket %p created in %s, now we have %d alive\n", sk,
 876                __func__, atomic_read(&llc_sock_nr));
 877#endif
 878out:
 879        return sk;
 880}
 881
 882/**
 883 *      llc_sk_free - Frees a LLC socket
 884 *      @sk - socket to free
 885 *
 886 *      Frees a LLC socket
 887 */
 888void llc_sk_free(struct sock *sk)
 889{
 890        struct llc_sock *llc = llc_sk(sk);
 891
 892        llc->state = LLC_CONN_OUT_OF_SVC;
 893        /* Stop all (possibly) running timers */
 894        llc_conn_ac_stop_all_timers(sk, NULL);
 895#ifdef DEBUG_LLC_CONN_ALLOC
 896        printk(KERN_INFO "%s: unackq=%d, txq=%d\n", __func__,
 897                skb_queue_len(&llc->pdu_unack_q),
 898                skb_queue_len(&sk->sk_write_queue));
 899#endif
 900        skb_queue_purge(&sk->sk_receive_queue);
 901        skb_queue_purge(&sk->sk_write_queue);
 902        skb_queue_purge(&llc->pdu_unack_q);
 903#ifdef LLC_REFCNT_DEBUG
 904        if (atomic_read(&sk->sk_refcnt) != 1) {
 905                printk(KERN_DEBUG "Destruction of LLC sock %p delayed in %s, cnt=%d\n",
 906                        sk, __func__, atomic_read(&sk->sk_refcnt));
 907                printk(KERN_DEBUG "%d LLC sockets are still alive\n",
 908                        atomic_read(&llc_sock_nr));
 909        } else {
 910                atomic_dec(&llc_sock_nr);
 911                printk(KERN_DEBUG "LLC socket %p released in %s, %d are still alive\n", sk,
 912                        __func__, atomic_read(&llc_sock_nr));
 913        }
 914#endif
 915        sock_put(sk);
 916}
 917
 918/**
 919 *      llc_sk_reset - resets a connection
 920 *      @sk: LLC socket to reset
 921 *
 922 *      Resets a connection to the out of service state. Stops its timers
 923 *      and frees any frames in the queues of the connection.
 924 */
 925void llc_sk_reset(struct sock *sk)
 926{
 927        struct llc_sock *llc = llc_sk(sk);
 928
 929        llc_conn_ac_stop_all_timers(sk, NULL);
 930        skb_queue_purge(&sk->sk_write_queue);
 931        skb_queue_purge(&llc->pdu_unack_q);
 932        llc->remote_busy_flag   = 0;
 933        llc->cause_flag         = 0;
 934        llc->retry_count        = 0;
 935        llc_conn_set_p_flag(sk, 0);
 936        llc->f_flag             = 0;
 937        llc->s_flag             = 0;
 938        llc->ack_pf             = 0;
 939        llc->first_pdu_Ns       = 0;
 940        llc->ack_must_be_send   = 0;
 941        llc->dec_step           = 1;
 942        llc->inc_cntr           = 2;
 943        llc->dec_cntr           = 2;
 944        llc->X                  = 0;
 945        llc->failed_data_req    = 0 ;
 946        llc->last_nr            = 0;
 947}
 948