linux-old/net/decnet/dn_timer.c
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   1/*
   2 * DECnet       An implementation of the DECnet protocol suite for the LINUX
   3 *              operating system.  DECnet is implemented using the  BSD Socket
   4 *              interface as the means of communication with the user level.
   5 *
   6 *              DECnet Socket Timer Functions
   7 *
   8 * Author:      Steve Whitehouse <SteveW@ACM.org>
   9 *
  10 *
  11 * Changes:
  12 *       Steve Whitehouse      : Made keepalive timer part of the same
  13 *                               timer idea.
  14 *       Steve Whitehouse      : Added checks for sk->sock_readers
  15 *       David S. Miller       : New socket locking
  16 *       Steve Whitehouse      : Timer grabs socket ref.
  17 */
  18#include <linux/net.h>
  19#include <linux/socket.h>
  20#include <linux/skbuff.h>
  21#include <linux/netdevice.h>
  22#include <linux/timer.h>
  23#include <linux/spinlock.h>
  24#include <net/sock.h>
  25#include <asm/atomic.h>
  26#include <net/dn.h>
  27
  28/*
  29 * Fast timer is for delayed acks (200mS max)
  30 * Slow timer is for everything else (n * 500mS)
  31 */
  32
  33#define FAST_INTERVAL (HZ/5)
  34#define SLOW_INTERVAL (HZ/2)
  35
  36static void dn_slow_timer(unsigned long arg);
  37
  38void dn_start_slow_timer(struct sock *sk)
  39{
  40        sk->timer.expires = jiffies + SLOW_INTERVAL;
  41        sk->timer.function = dn_slow_timer;
  42        sk->timer.data = (unsigned long)sk;
  43
  44        add_timer(&sk->timer);
  45}
  46
  47void dn_stop_slow_timer(struct sock *sk)
  48{
  49        del_timer(&sk->timer);
  50}
  51
  52static void dn_slow_timer(unsigned long arg)
  53{
  54        struct sock *sk = (struct sock *)arg;
  55        struct dn_scp *scp = DN_SK(sk);
  56
  57        sock_hold(sk);
  58        bh_lock_sock(sk);
  59
  60        if (sk->lock.users != 0) {
  61                sk->timer.expires = jiffies + HZ / 10;
  62                add_timer(&sk->timer);
  63                goto out;
  64        }
  65
  66        /*
  67         * The persist timer is the standard slow timer used for retransmits
  68         * in both connection establishment and disconnection as well as
  69         * in the RUN state. The different states are catered for by changing
  70         * the function pointer in the socket. Setting the timer to a value
  71         * of zero turns it off. We allow the persist_fxn to turn the
  72         * timer off in a permant way by returning non-zero, so that
  73         * timer based routines may remove sockets. This is why we have a
  74         * sock_hold()/sock_put() around the timer to prevent the socket
  75         * going away in the middle.
  76         */
  77        if (scp->persist && scp->persist_fxn) {
  78                if (scp->persist <= SLOW_INTERVAL) {
  79                        scp->persist = 0;
  80
  81                        if (scp->persist_fxn(sk))
  82                                goto out;
  83                } else {
  84                        scp->persist -= SLOW_INTERVAL;
  85                }
  86        }
  87
  88        /*
  89         * Check for keepalive timeout. After the other timer 'cos if
  90         * the previous timer caused a retransmit, we don't need to
  91         * do this. scp->stamp is the last time that we sent a packet.
  92         * The keepalive function sends a link service packet to the
  93         * other end. If it remains unacknowledged, the standard
  94         * socket timers will eventually shut the socket down. Each
  95         * time we do this, scp->stamp will be updated, thus
  96         * we won't try and send another until scp->keepalive has passed
  97         * since the last successful transmission.
  98         */
  99        if (scp->keepalive && scp->keepalive_fxn && (scp->state == DN_RUN)) {
 100                if ((jiffies - scp->stamp) >= scp->keepalive)
 101                        scp->keepalive_fxn(sk);
 102        }
 103
 104        sk->timer.expires = jiffies + SLOW_INTERVAL;
 105
 106        add_timer(&sk->timer);
 107out:
 108        bh_unlock_sock(sk);
 109        sock_put(sk);
 110}
 111
 112static void dn_fast_timer(unsigned long arg)
 113{
 114        struct sock *sk = (struct sock *)arg;
 115        struct dn_scp *scp = DN_SK(sk);
 116
 117        bh_lock_sock(sk);
 118        if (sk->lock.users != 0) {
 119                scp->delack_timer.expires = jiffies + HZ / 20;
 120                add_timer(&scp->delack_timer);
 121                goto out;
 122        }
 123
 124        scp->delack_pending = 0;
 125
 126        if (scp->delack_fxn)
 127                scp->delack_fxn(sk);
 128out:
 129        bh_unlock_sock(sk);
 130}
 131
 132void dn_start_fast_timer(struct sock *sk)
 133{
 134        struct dn_scp *scp = DN_SK(sk);
 135
 136        if (!scp->delack_pending) {
 137                scp->delack_pending = 1;
 138                init_timer(&scp->delack_timer);
 139                scp->delack_timer.expires = jiffies + FAST_INTERVAL;
 140                scp->delack_timer.data = (unsigned long)sk;
 141                scp->delack_timer.function = dn_fast_timer;
 142                add_timer(&scp->delack_timer);
 143        }
 144}
 145
 146void dn_stop_fast_timer(struct sock *sk)
 147{
 148        struct dn_scp *scp = DN_SK(sk);
 149
 150        if (scp->delack_pending) {
 151                scp->delack_pending = 0;
 152                del_timer(&scp->delack_timer);
 153        }
 154}
 155
 156
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