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 <linux/atomic.h>
26 #include <linux/jiffies.h>
31 * Slow timer is for everything else (n * 500mS)
34 #define SLOW_INTERVAL (HZ/2)
36 static void dn_slow_timer(unsigned long arg
);
38 void dn_start_slow_timer(struct sock
*sk
)
40 setup_timer(&sk
->sk_timer
, dn_slow_timer
, (unsigned long)sk
);
41 sk_reset_timer(sk
, &sk
->sk_timer
, jiffies
+ SLOW_INTERVAL
);
44 void dn_stop_slow_timer(struct sock
*sk
)
46 sk_stop_timer(sk
, &sk
->sk_timer
);
49 static void dn_slow_timer(unsigned long arg
)
51 struct sock
*sk
= (struct sock
*)arg
;
52 struct dn_scp
*scp
= DN_SK(sk
);
56 if (sock_owned_by_user(sk
)) {
57 sk_reset_timer(sk
, &sk
->sk_timer
, jiffies
+ HZ
/ 10);
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.
72 if (scp
->persist
&& scp
->persist_fxn
) {
73 if (scp
->persist
<= SLOW_INTERVAL
) {
76 if (scp
->persist_fxn(sk
))
79 scp
->persist
-= SLOW_INTERVAL
;
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.
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
);
99 sk_reset_timer(sk
, &sk
->sk_timer
, jiffies
+ SLOW_INTERVAL
);
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