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 <linux/jiffies.h>
27 #include <net/flow.h>
28 #include <net/dn.h>
29
30 /*
31 * Slow timer is for everything else (n * 500mS)
32 */
33
34 #define SLOW_INTERVAL (HZ/2)
35
36 static void dn_slow_timer(unsigned long arg);
37
dn_start_slow_timer(struct sock * sk)38 void dn_start_slow_timer(struct sock *sk)
39 {
40 setup_timer(&sk->sk_timer, dn_slow_timer, (unsigned long)sk);
41 sk_reset_timer(sk, &sk->sk_timer, jiffies + SLOW_INTERVAL);
42 }
43
dn_stop_slow_timer(struct sock * sk)44 void dn_stop_slow_timer(struct sock *sk)
45 {
46 sk_stop_timer(sk, &sk->sk_timer);
47 }
48
dn_slow_timer(unsigned long arg)49 static void dn_slow_timer(unsigned long arg)
50 {
51 struct sock *sk = (struct sock *)arg;
52 struct dn_scp *scp = DN_SK(sk);
53
54 bh_lock_sock(sk);
55
56 if (sock_owned_by_user(sk)) {
57 sk_reset_timer(sk, &sk->sk_timer, jiffies + HZ / 10);
58 goto out;
59 }
60
61 /*
62 * The persist timer is the standard slow timer used for retransmits
63 * in both connection establishment and disconnection as well as
64 * in the RUN state. The different states are catered for by changing
65 * the function pointer in the socket. Setting the timer to a value
66 * of zero turns it off. We allow the persist_fxn to turn the
67 * timer off in a permant way by returning non-zero, so that
68 * timer based routines may remove sockets. This is why we have a
69 * sock_hold()/sock_put() around the timer to prevent the socket
70 * going away in the middle.
71 */
72 if (scp->persist && scp->persist_fxn) {
73 if (scp->persist <= SLOW_INTERVAL) {
74 scp->persist = 0;
75
76 if (scp->persist_fxn(sk))
77 goto out;
78 } else {
79 scp->persist -= SLOW_INTERVAL;
80 }
81 }
82
83 /*
84 * Check for keepalive timeout. After the other timer 'cos if
85 * the previous timer caused a retransmit, we don't need to
86 * do this. scp->stamp is the last time that we sent a packet.
87 * The keepalive function sends a link service packet to the
88 * other end. If it remains unacknowledged, the standard
89 * socket timers will eventually shut the socket down. Each
90 * time we do this, scp->stamp will be updated, thus
91 * we won't try and send another until scp->keepalive has passed
92 * since the last successful transmission.
93 */
94 if (scp->keepalive && scp->keepalive_fxn && (scp->state == DN_RUN)) {
95 if (time_after_eq(jiffies, scp->stamp + scp->keepalive))
96 scp->keepalive_fxn(sk);
97 }
98
99 sk_reset_timer(sk, &sk->sk_timer, jiffies + SLOW_INTERVAL);
100 out:
101 bh_unlock_sock(sk);
102 sock_put(sk);
103 }
104