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.
6 * DECnet Socket Timer Functions
8 * Author: Steve Whitehouse <SteveW@ACM.org>
12 * Steve Whitehouse : Made keepalive timer part of the same
14 * Steve Whitehouse : Added checks for sk->sock_readers
15 * David S. Miller : New socket locking
16 * Steve Whitehouse : Timer grabs socket ref.
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>
25 #include <asm/atomic.h>
30 * Fast timer is for delayed acks (200mS max)
31 * Slow timer is for everything else (n * 500mS)
34 #define FAST_INTERVAL (HZ/5)
35 #define SLOW_INTERVAL (HZ/2)
37 static void dn_slow_timer(unsigned long arg);
39 void dn_start_slow_timer(struct sock *sk)
41 sk->sk_timer.expires = jiffies + SLOW_INTERVAL;
42 sk->sk_timer.function = dn_slow_timer;
43 sk->sk_timer.data = (unsigned long)sk;
45 add_timer(&sk->sk_timer);
48 void dn_stop_slow_timer(struct sock *sk)
50 del_timer(&sk->sk_timer);
53 static void dn_slow_timer(unsigned long arg)
55 struct sock *sk = (struct sock *)arg;
56 struct dn_scp *scp = DN_SK(sk);
61 if (sock_owned_by_user(sk)) {
62 sk->sk_timer.expires = jiffies + HZ / 10;
63 add_timer(&sk->sk_timer);
68 * The persist timer is the standard slow timer used for retransmits
69 * in both connection establishment and disconnection as well as
70 * in the RUN state. The different states are catered for by changing
71 * the function pointer in the socket. Setting the timer to a value
72 * of zero turns it off. We allow the persist_fxn to turn the
73 * timer off in a permant way by returning non-zero, so that
74 * timer based routines may remove sockets. This is why we have a
75 * sock_hold()/sock_put() around the timer to prevent the socket
76 * going away in the middle.
78 if (scp->persist && scp->persist_fxn) {
79 if (scp->persist <= SLOW_INTERVAL) {
82 if (scp->persist_fxn(sk))
85 scp->persist -= SLOW_INTERVAL;
90 * Check for keepalive timeout. After the other timer 'cos if
91 * the previous timer caused a retransmit, we don't need to
92 * do this. scp->stamp is the last time that we sent a packet.
93 * The keepalive function sends a link service packet to the
94 * other end. If it remains unacknowledged, the standard
95 * socket timers will eventually shut the socket down. Each
96 * time we do this, scp->stamp will be updated, thus
97 * we won't try and send another until scp->keepalive has passed
98 * since the last successful transmission.
100 if (scp->keepalive && scp->keepalive_fxn && (scp->state == DN_RUN)) {
101 if ((jiffies - scp->stamp) >= scp->keepalive)
102 scp->keepalive_fxn(sk);
105 sk->sk_timer.expires = jiffies + SLOW_INTERVAL;
107 add_timer(&sk->sk_timer);
113 static void dn_fast_timer(unsigned long arg)
115 struct sock *sk = (struct sock *)arg;
116 struct dn_scp *scp = DN_SK(sk);
119 if (sock_owned_by_user(sk)) {
120 scp->delack_timer.expires = jiffies + HZ / 20;
121 add_timer(&scp->delack_timer);
125 scp->delack_pending = 0;
133 void dn_start_fast_timer(struct sock *sk)
135 struct dn_scp *scp = DN_SK(sk);
137 if (!scp->delack_pending) {
138 scp->delack_pending = 1;
139 init_timer(&scp->delack_timer);
140 scp->delack_timer.expires = jiffies + FAST_INTERVAL;
141 scp->delack_timer.data = (unsigned long)sk;
142 scp->delack_timer.function = dn_fast_timer;
143 add_timer(&scp->delack_timer);
147 void dn_stop_fast_timer(struct sock *sk)
149 struct dn_scp *scp = DN_SK(sk);
151 if (scp->delack_pending) {
152 scp->delack_pending = 0;
153 del_timer(&scp->delack_timer);