cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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dn_timer.c (3169B)

      1// SPDX-License-Identifier: GPL-2.0
      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>
     26#include <linux/atomic.h>
     27#include <linux/jiffies.h>
     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
     37static void dn_slow_timer(struct timer_list *t);
     38
     39void dn_start_slow_timer(struct sock *sk)
     40{
     41	timer_setup(&sk->sk_timer, dn_slow_timer, 0);
     42	sk_reset_timer(sk, &sk->sk_timer, jiffies + SLOW_INTERVAL);
     43}
     44
     45void dn_stop_slow_timer(struct sock *sk)
     46{
     47	sk_stop_timer(sk, &sk->sk_timer);
     48}
     49
     50static void dn_slow_timer(struct timer_list *t)
     51{
     52	struct sock *sk = from_timer(sk, t, sk_timer);
     53	struct dn_scp *scp = DN_SK(sk);
     54
     55	bh_lock_sock(sk);
     56
     57	if (sock_owned_by_user(sk)) {
     58		sk_reset_timer(sk, &sk->sk_timer, jiffies + HZ / 10);
     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)) {
     96		if (time_after_eq(jiffies, scp->stamp + scp->keepalive))
     97			scp->keepalive_fxn(sk);
     98	}
     99
    100	sk_reset_timer(sk, &sk->sk_timer, jiffies + SLOW_INTERVAL);
    101out:
    102	bh_unlock_sock(sk);
    103	sock_put(sk);
    104}