root/net/decnet/dn_timer.c

DEFINITIONS

1. dn_start_slow_timer
2. dn_stop_slow_timer
3. dn_slow_timer

/*
 * DECnet       An implementation of the DECnet protocol suite for the LINUX
 *              operating system.  DECnet is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              DECnet Socket Timer Functions
 *
 * Author:      Steve Whitehouse <SteveW@ACM.org>
 *
 *
 * Changes:
 *       Steve Whitehouse      : Made keepalive timer part of the same
 *                               timer idea.
 *       Steve Whitehouse      : Added checks for sk->sock_readers
 *       David S. Miller       : New socket locking
 *       Steve Whitehouse      : Timer grabs socket ref.
 */
#include <linux/net.h>
#include <linux/socket.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/timer.h>
#include <linux/spinlock.h>
#include <net/sock.h>
#include <asm/atomic.h>
#include <net/flow.h>
#include <net/dn.h>

/*
 * Slow timer is for everything else (n * 500mS)
 */

#define SLOW_INTERVAL (HZ/2)

static void dn_slow_timer(unsigned long arg);

void dn_start_slow_timer(struct sock *sk)
{
        sk->sk_timer.expires    = jiffies + SLOW_INTERVAL;
        sk->sk_timer.function   = dn_slow_timer;
        sk->sk_timer.data       = (unsigned long)sk;

        add_timer(&sk->sk_timer);
}

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

static void dn_slow_timer(unsigned long arg)
{
        struct sock *sk = (struct sock *)arg;
        struct dn_scp *scp = DN_SK(sk);

        sock_hold(sk);
        bh_lock_sock(sk);

        if (sock_owned_by_user(sk)) {
                sk->sk_timer.expires = jiffies + HZ / 10;
                add_timer(&sk->sk_timer);
                goto out;
        }

        /*
         * The persist timer is the standard slow timer used for retransmits
         * in both connection establishment and disconnection as well as
         * in the RUN state. The different states are catered for by changing
         * the function pointer in the socket. Setting the timer to a value
         * of zero turns it off. We allow the persist_fxn to turn the
         * timer off in a permant way by returning non-zero, so that
         * timer based routines may remove sockets. This is why we have a
         * sock_hold()/sock_put() around the timer to prevent the socket
         * going away in the middle.
         */
        if (scp->persist && scp->persist_fxn) {
                if (scp->persist <= SLOW_INTERVAL) {
                        scp->persist = 0;

                        if (scp->persist_fxn(sk))
                                goto out;
                } else {
                        scp->persist -= SLOW_INTERVAL;
                }
        }

        /*
         * Check for keepalive timeout. After the other timer 'cos if
         * the previous timer caused a retransmit, we don't need to
         * do this. scp->stamp is the last time that we sent a packet.
         * The keepalive function sends a link service packet to the
         * other end. If it remains unacknowledged, the standard
         * socket timers will eventually shut the socket down. Each
         * time we do this, scp->stamp will be updated, thus
         * we won't try and send another until scp->keepalive has passed
         * since the last successful transmission.
         */
        if (scp->keepalive && scp->keepalive_fxn && (scp->state == DN_RUN)) {
                if ((jiffies - scp->stamp) >= scp->keepalive)
                        scp->keepalive_fxn(sk);
        }

        sk->sk_timer.expires = jiffies + SLOW_INTERVAL;

        add_timer(&sk->sk_timer);
out:
        bh_unlock_sock(sk);
        sock_put(sk);
}