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