x25_timer.c

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/*
 *  X.25 Packet Layer release 002
 *
 *  This is ALPHA test software. This code may break your machine,
 *  randomly fail to work with new releases, misbehave and/or generally
 *  screw up. It might even work.
 *
 *  This code REQUIRES 2.1.15 or higher
 *
 *  This module:
 *      This module is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 *  History
 *  X.25 001    Jonathan Naylor Started coding.
 *  X.25 002    Jonathan Naylor New timer architecture.
 *                  Centralised disconnection processing.
 */

#include <linux/errno.h>
#include <linux/jiffies.h>
#include <linux/timer.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <net/x25.h>

static void x25_heartbeat_expiry(unsigned long);
static void x25_timer_expiry(unsigned long);

void x25_init_timers(struct sock *sk)
{
    struct x25_sock *x25 = x25_sk(sk);

    setup_timer(&x25->timer, x25_timer_expiry, (unsigned long)sk);

    /* initialized by sock_init_data */
    sk->sk_timer.data     = (unsigned long)sk;
    sk->sk_timer.function = &x25_heartbeat_expiry;
}

void x25_start_heartbeat(struct sock *sk)
{
    mod_timer(&sk->sk_timer, jiffies + 5 * HZ);
}

void x25_stop_heartbeat(struct sock *sk)
{
    del_timer(&sk->sk_timer);
}

void x25_start_t2timer(struct sock *sk)
{
    struct x25_sock *x25 = x25_sk(sk);

    mod_timer(&x25->timer, jiffies + x25->t2);
}

void x25_start_t21timer(struct sock *sk)
{
    struct x25_sock *x25 = x25_sk(sk);

    mod_timer(&x25->timer, jiffies + x25->t21);
}

void x25_start_t22timer(struct sock *sk)
{
    struct x25_sock *x25 = x25_sk(sk);

    mod_timer(&x25->timer, jiffies + x25->t22);
}

void x25_start_t23timer(struct sock *sk)
{
    struct x25_sock *x25 = x25_sk(sk);

    mod_timer(&x25->timer, jiffies + x25->t23);
}

void x25_stop_timer(struct sock *sk)
{
    del_timer(&x25_sk(sk)->timer);
}

unsigned long x25_display_timer(struct sock *sk)
{
    struct x25_sock *x25 = x25_sk(sk);

    if (!timer_pending(&x25->timer))
        return 0;

    return x25->timer.expires - jiffies;
}

static void x25_heartbeat_expiry(unsigned long param)
{
    struct sock *sk = (struct sock *)param;

    bh_lock_sock(sk);
    if (sock_owned_by_user(sk)) /* can currently only occur in state 3 */
        goto restart_heartbeat;

    switch (x25_sk(sk)->state) {

        case X25_STATE_0:
            /*
             * Magic here: If we listen() and a new link dies
             * before it is accepted() it isn't 'dead' so doesn't
             * get removed.
             */
            if (sock_flag(sk, SOCK_DESTROY) ||
                (sk->sk_state == TCP_LISTEN &&
                 sock_flag(sk, SOCK_DEAD))) {
                bh_unlock_sock(sk);
                x25_destroy_socket_from_timer(sk);
                return;
            }
            break;

        case X25_STATE_3:
            /*
             * Check for the state of the receive buffer.
             */
            x25_check_rbuf(sk);
            break;
    }
restart_heartbeat:
    x25_start_heartbeat(sk);
    bh_unlock_sock(sk);
}

/*
 *  Timer has expired, it may have been T2, T21, T22, or T23. We can tell
 *  by the state machine state.
 */
static inline void x25_do_timer_expiry(struct sock * sk)
{
    struct x25_sock *x25 = x25_sk(sk);

    switch (x25->state) {

        case X25_STATE_3:   /* T2 */
            if (x25->condition & X25_COND_ACK_PENDING) {
                x25->condition &= ~X25_COND_ACK_PENDING;
                x25_enquiry_response(sk);
            }
            break;

        case X25_STATE_1:   /* T21 */
        case X25_STATE_4:   /* T22 */
            x25_write_internal(sk, X25_CLEAR_REQUEST);
            x25->state = X25_STATE_2;
            x25_start_t23timer(sk);
            break;

        case X25_STATE_2:   /* T23 */
            x25_disconnect(sk, ETIMEDOUT, 0, 0);
            break;
    }
}

static void x25_timer_expiry(unsigned long param)
{
    struct sock *sk = (struct sock *)param;

    bh_lock_sock(sk);
    if (sock_owned_by_user(sk)) { /* can currently only occur in state 3 */
        if (x25_sk(sk)->state == X25_STATE_3)
            x25_start_t2timer(sk);
    } else
        x25_do_timer_expiry(sk);
    bh_unlock_sock(sk);
}