File: /usr/src/linux/net/decnet/dn_timer.c
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
36 static void dn_slow_timer(unsigned long arg);
37
38 void 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
47 void dn_stop_slow_timer(struct sock *sk)
48 {
49 del_timer(&sk->timer);
50 }
51
52 static 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);
107 out:
108 bh_unlock_sock(sk);
109 sock_put(sk);
110 }
111
112 static 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);
128 out:
129 bh_unlock_sock(sk);
130 }
131
132 void 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
146 void 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