// SPDX-License-Identifier: GPL-2.0
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/*
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* DECnet An implementation of the DECnet protocol suite for the LINUX
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* operating system. DECnet is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* DECnet Socket Timer Functions
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*
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* Author: Steve Whitehouse <SteveW@ACM.org>
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*
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*
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* Changes:
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* Steve Whitehouse : Made keepalive timer part of the same
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* timer idea.
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* Steve Whitehouse : Added checks for sk->sock_readers
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* David S. Miller : New socket locking
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* Steve Whitehouse : Timer grabs socket ref.
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*/
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#include <linux/net.h>
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#include <linux/socket.h>
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#include <linux/skbuff.h>
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#include <linux/netdevice.h>
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#include <linux/timer.h>
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#include <linux/spinlock.h>
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#include <net/sock.h>
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#include <linux/atomic.h>
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#include <linux/jiffies.h>
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#include <net/flow.h>
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#include <net/dn.h>
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/*
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* Slow timer is for everything else (n * 500mS)
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*/
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#define SLOW_INTERVAL (HZ/2)
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static void dn_slow_timer(struct timer_list *t);
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void dn_start_slow_timer(struct sock *sk)
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{
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timer_setup(&sk->sk_timer, dn_slow_timer, 0);
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sk_reset_timer(sk, &sk->sk_timer, jiffies + SLOW_INTERVAL);
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}
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void dn_stop_slow_timer(struct sock *sk)
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{
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sk_stop_timer(sk, &sk->sk_timer);
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}
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static void dn_slow_timer(struct timer_list *t)
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{
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struct sock *sk = from_timer(sk, t, sk_timer);
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struct dn_scp *scp = DN_SK(sk);
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bh_lock_sock(sk);
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if (sock_owned_by_user(sk)) {
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sk_reset_timer(sk, &sk->sk_timer, jiffies + HZ / 10);
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goto out;
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}
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/*
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* The persist timer is the standard slow timer used for retransmits
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* in both connection establishment and disconnection as well as
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* in the RUN state. The different states are catered for by changing
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* the function pointer in the socket. Setting the timer to a value
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* of zero turns it off. We allow the persist_fxn to turn the
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* timer off in a permant way by returning non-zero, so that
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* timer based routines may remove sockets. This is why we have a
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* sock_hold()/sock_put() around the timer to prevent the socket
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* going away in the middle.
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*/
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if (scp->persist && scp->persist_fxn) {
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if (scp->persist <= SLOW_INTERVAL) {
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scp->persist = 0;
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if (scp->persist_fxn(sk))
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goto out;
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} else {
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scp->persist -= SLOW_INTERVAL;
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}
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}
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/*
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* Check for keepalive timeout. After the other timer 'cos if
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* the previous timer caused a retransmit, we don't need to
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* do this. scp->stamp is the last time that we sent a packet.
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* The keepalive function sends a link service packet to the
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* other end. If it remains unacknowledged, the standard
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* socket timers will eventually shut the socket down. Each
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* time we do this, scp->stamp will be updated, thus
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* we won't try and send another until scp->keepalive has passed
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* since the last successful transmission.
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*/
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if (scp->keepalive && scp->keepalive_fxn && (scp->state == DN_RUN)) {
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if (time_after_eq(jiffies, scp->stamp + scp->keepalive))
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scp->keepalive_fxn(sk);
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}
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sk_reset_timer(sk, &sk->sk_timer, jiffies + SLOW_INTERVAL);
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out:
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bh_unlock_sock(sk);
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sock_put(sk);
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}
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