// 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(struct timer_list *t); void dn_start_slow_timer(struct sock *sk) { timer_setup(&sk->sk_timer, dn_slow_timer, 0); 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(struct timer_list *t) { struct sock *sk = from_timer(sk, t, sk_timer); 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); }