linux/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 <linux/atomic.h>
  26#include <net/flow.h>
  27#include <net/dn.h>
  28
  29/*
  30 * Slow timer is for everything else (n * 500mS)
  31 */
  32
  33#define SLOW_INTERVAL (HZ/2)
  34
  35static void dn_slow_timer(unsigned long arg);
  36
  37void dn_start_slow_timer(struct sock *sk)
  38{
  39        setup_timer(&sk->sk_timer, dn_slow_timer, (unsigned long)sk);
  40        sk_reset_timer(sk, &sk->sk_timer, jiffies + SLOW_INTERVAL);
  41}
  42
  43void dn_stop_slow_timer(struct sock *sk)
  44{
  45        sk_stop_timer(sk, &sk->sk_timer);
  46}
  47
  48static void dn_slow_timer(unsigned long arg)
  49{
  50        struct sock *sk = (struct sock *)arg;
  51        struct dn_scp *scp = DN_SK(sk);
  52
  53        bh_lock_sock(sk);
  54
  55        if (sock_owned_by_user(sk)) {
  56                sk_reset_timer(sk, &sk->sk_timer, jiffies + HZ / 10);
  57                goto out;
  58        }
  59
  60        /*
  61         * The persist timer is the standard slow timer used for retransmits
  62         * in both connection establishment and disconnection as well as
  63         * in the RUN state. The different states are catered for by changing
  64         * the function pointer in the socket. Setting the timer to a value
  65         * of zero turns it off. We allow the persist_fxn to turn the
  66         * timer off in a permant way by returning non-zero, so that
  67         * timer based routines may remove sockets. This is why we have a
  68         * sock_hold()/sock_put() around the timer to prevent the socket
  69         * going away in the middle.
  70         */
  71        if (scp->persist && scp->persist_fxn) {
  72                if (scp->persist <= SLOW_INTERVAL) {
  73                        scp->persist = 0;
  74
  75                        if (scp->persist_fxn(sk))
  76                                goto out;
  77                } else {
  78                        scp->persist -= SLOW_INTERVAL;
  79                }
  80        }
  81
  82        /*
  83         * Check for keepalive timeout. After the other timer 'cos if
  84         * the previous timer caused a retransmit, we don't need to
  85         * do this. scp->stamp is the last time that we sent a packet.
  86         * The keepalive function sends a link service packet to the
  87         * other end. If it remains unacknowledged, the standard
  88         * socket timers will eventually shut the socket down. Each
  89         * time we do this, scp->stamp will be updated, thus
  90         * we won't try and send another until scp->keepalive has passed
  91         * since the last successful transmission.
  92         */
  93        if (scp->keepalive && scp->keepalive_fxn && (scp->state == DN_RUN)) {
  94                if ((jiffies - scp->stamp) >= scp->keepalive)
  95                        scp->keepalive_fxn(sk);
  96        }
  97
  98        sk_reset_timer(sk, &sk->sk_timer, jiffies + SLOW_INTERVAL);
  99out:
 100        bh_unlock_sock(sk);
 101        sock_put(sk);
 102}
 103
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