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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * DECnet An implementation of the DECnet protocol suite for the LINUX | |
4 | * operating system. DECnet is implemented using the BSD Socket | |
5 | * interface as the means of communication with the user level. | |
6 | * | |
7 | * DECnet Socket Timer Functions | |
8 | * | |
9 | * Author: Steve Whitehouse <SteveW@ACM.org> | |
10 | * | |
11 | * | |
12 | * Changes: | |
13 | * Steve Whitehouse : Made keepalive timer part of the same | |
14 | * timer idea. | |
15 | * Steve Whitehouse : Added checks for sk->sock_readers | |
16 | * David S. Miller : New socket locking | |
17 | * Steve Whitehouse : Timer grabs socket ref. | |
18 | */ | |
19 | #include <linux/net.h> | |
20 | #include <linux/socket.h> | |
21 | #include <linux/skbuff.h> | |
22 | #include <linux/netdevice.h> | |
23 | #include <linux/timer.h> | |
24 | #include <linux/spinlock.h> | |
25 | #include <net/sock.h> | |
60063497 | 26 | #include <linux/atomic.h> |
8b1b1eb5 | 27 | #include <linux/jiffies.h> |
1da177e4 LT |
28 | #include <net/flow.h> |
29 | #include <net/dn.h> | |
30 | ||
31 | /* | |
32 | * Slow timer is for everything else (n * 500mS) | |
33 | */ | |
34 | ||
35 | #define SLOW_INTERVAL (HZ/2) | |
36 | ||
e99e88a9 | 37 | static void dn_slow_timer(struct timer_list *t); |
1da177e4 LT |
38 | |
39 | void dn_start_slow_timer(struct sock *sk) | |
40 | { | |
e99e88a9 | 41 | timer_setup(&sk->sk_timer, dn_slow_timer, 0); |
8a6e77d5 | 42 | sk_reset_timer(sk, &sk->sk_timer, jiffies + SLOW_INTERVAL); |
1da177e4 LT |
43 | } |
44 | ||
45 | void dn_stop_slow_timer(struct sock *sk) | |
46 | { | |
8a6e77d5 | 47 | sk_stop_timer(sk, &sk->sk_timer); |
1da177e4 LT |
48 | } |
49 | ||
e99e88a9 | 50 | static void dn_slow_timer(struct timer_list *t) |
1da177e4 | 51 | { |
e99e88a9 | 52 | struct sock *sk = from_timer(sk, t, sk_timer); |
1da177e4 LT |
53 | struct dn_scp *scp = DN_SK(sk); |
54 | ||
1da177e4 LT |
55 | bh_lock_sock(sk); |
56 | ||
57 | if (sock_owned_by_user(sk)) { | |
8a6e77d5 | 58 | sk_reset_timer(sk, &sk->sk_timer, jiffies + HZ / 10); |
1da177e4 LT |
59 | goto out; |
60 | } | |
61 | ||
62 | /* | |
63 | * The persist timer is the standard slow timer used for retransmits | |
64 | * in both connection establishment and disconnection as well as | |
65 | * in the RUN state. The different states are catered for by changing | |
66 | * the function pointer in the socket. Setting the timer to a value | |
67 | * of zero turns it off. We allow the persist_fxn to turn the | |
68 | * timer off in a permant way by returning non-zero, so that | |
69 | * timer based routines may remove sockets. This is why we have a | |
70 | * sock_hold()/sock_put() around the timer to prevent the socket | |
71 | * going away in the middle. | |
72 | */ | |
73 | if (scp->persist && scp->persist_fxn) { | |
74 | if (scp->persist <= SLOW_INTERVAL) { | |
75 | scp->persist = 0; | |
76 | ||
77 | if (scp->persist_fxn(sk)) | |
78 | goto out; | |
79 | } else { | |
80 | scp->persist -= SLOW_INTERVAL; | |
81 | } | |
82 | } | |
83 | ||
84 | /* | |
85 | * Check for keepalive timeout. After the other timer 'cos if | |
86 | * the previous timer caused a retransmit, we don't need to | |
87 | * do this. scp->stamp is the last time that we sent a packet. | |
88 | * The keepalive function sends a link service packet to the | |
89 | * other end. If it remains unacknowledged, the standard | |
90 | * socket timers will eventually shut the socket down. Each | |
91 | * time we do this, scp->stamp will be updated, thus | |
92 | * we won't try and send another until scp->keepalive has passed | |
93 | * since the last successful transmission. | |
94 | */ | |
95 | if (scp->keepalive && scp->keepalive_fxn && (scp->state == DN_RUN)) { | |
8b1b1eb5 | 96 | if (time_after_eq(jiffies, scp->stamp + scp->keepalive)) |
1da177e4 LT |
97 | scp->keepalive_fxn(sk); |
98 | } | |
99 | ||
8a6e77d5 | 100 | sk_reset_timer(sk, &sk->sk_timer, jiffies + SLOW_INTERVAL); |
1da177e4 LT |
101 | out: |
102 | bh_unlock_sock(sk); | |
103 | sock_put(sk); | |
104 | } |