net/rxrpc/krxtimod.c

   1 /* krxtimod.c: RXRPC timeout daemon
   2  *
   3  * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/sched.h>
  15 #include <linux/completion.h>
  16 #include <rxrpc/rxrpc.h>
  17 #include <rxrpc/krxtimod.h>
  18 #include <asm/errno.h>
  19 #include "internal.h"
  20
  21 static DECLARE_COMPLETION(krxtimod_alive);
  22 static DECLARE_COMPLETION(krxtimod_dead);
  23 static DECLARE_WAIT_QUEUE_HEAD(krxtimod_sleepq);
  24 static int krxtimod_die;
  25
  26 static LIST_HEAD(krxtimod_list);
  27 static DEFINE_SPINLOCK(krxtimod_lock);
  28
  29 static int krxtimod(void *arg);
  30
  31 /*****************************************************************************/
  32 /*
  33  * start the timeout daemon
  34  */
  35 int rxrpc_krxtimod_start(void)
  36 {
  37         int ret;
  38
  39         ret = kernel_thread(krxtimod, NULL, 0);
  40         if (ret < 0)
  41                 return ret;
  42
  43         wait_for_completion(&krxtimod_alive);
  44
  45         return ret;
  46 } /* end rxrpc_krxtimod_start() */
  47
  48 /*****************************************************************************/
  49 /*
  50  * stop the timeout daemon
  51  */
  52 void rxrpc_krxtimod_kill(void)
  53 {
  54         /* get rid of my daemon */
  55         krxtimod_die = 1;
  56         wake_up(&krxtimod_sleepq);
  57         wait_for_completion(&krxtimod_dead);
  58
  59 } /* end rxrpc_krxtimod_kill() */
  60
  61 /*****************************************************************************/
  62 /*
  63  * timeout processing daemon
  64  */
  65 static int krxtimod(void *arg)
  66 {
  67         DECLARE_WAITQUEUE(myself, current);
  68
  69         rxrpc_timer_t *timer;
  70
  71         printk("Started krxtimod %d\n", current->pid);
  72
  73         daemonize("krxtimod");
  74
  75         complete(&krxtimod_alive);
  76
  77         /* loop around looking for things to attend to */
  78  loop:
  79         set_current_state(TASK_INTERRUPTIBLE);
  80         add_wait_queue(&krxtimod_sleepq, &myself);
  81
  82         for (;;) {
  83                 unsigned long jif;
  84                 signed long timeout;
  85
  86                 /* deal with the server being asked to die */
  87                 if (krxtimod_die) {
  88                         remove_wait_queue(&krxtimod_sleepq, &myself);
  89                         _leave("");
  90                         complete_and_exit(&krxtimod_dead, 0);
  91                 }
  92
  93                 try_to_freeze(PF_FREEZE);
  94
  95                 /* discard pending signals */
  96                 rxrpc_discard_my_signals();
  97
  98                 /* work out the time to elapse before the next event */
  99                 spin_lock(&krxtimod_lock);
 100                 if (list_empty(&krxtimod_list)) {
 101                         timeout = MAX_SCHEDULE_TIMEOUT;
 102                 }
 103                 else {
 104                         timer = list_entry(krxtimod_list.next,
 105                                            rxrpc_timer_t, link);
 106                         timeout = timer->timo_jif;
 107                         jif = jiffies;
 108
 109                         if (time_before_eq((unsigned long) timeout, jif))
 110                                 goto immediate;
 111
 112                         else {
 113                                 timeout = (long) timeout - (long) jiffies;
 114                         }
 115                 }
 116                 spin_unlock(&krxtimod_lock);
 117
 118                 schedule_timeout(timeout);
 119
 120                 set_current_state(TASK_INTERRUPTIBLE);
 121         }
 122
 123         /* the thing on the front of the queue needs processing
 124          * - we come here with the lock held and timer pointing to the expired
 125          *   entry
 126          */
 127  immediate:
 128         remove_wait_queue(&krxtimod_sleepq, &myself);
 129         set_current_state(TASK_RUNNING);
 130
 131         _debug("@@@ Begin Timeout of %p", timer);
 132
 133         /* dequeue the timer */
 134         list_del_init(&timer->link);
 135         spin_unlock(&krxtimod_lock);
 136
 137         /* call the timeout function */
 138         timer->ops->timed_out(timer);
 139
 140         _debug("@@@ End Timeout");
 141         goto loop;
 142
 143 } /* end krxtimod() */
 144
 145 /*****************************************************************************/
 146 /*
 147  * (re-)queue a timer
 148  */
 149 void rxrpc_krxtimod_add_timer(rxrpc_timer_t *timer, unsigned long timeout)
 150 {
 151         struct list_head *_p;
 152         rxrpc_timer_t *ptimer;
 153
 154         _enter("%p,%lu", timer, timeout);
 155
 156         spin_lock(&krxtimod_lock);
 157
 158         list_del(&timer->link);
 159
 160         /* the timer was deferred or reset - put it back in the queue at the
 161          * right place */
 162         timer->timo_jif = jiffies + timeout;
 163
 164         list_for_each(_p, &krxtimod_list) {
 165                 ptimer = list_entry(_p, rxrpc_timer_t, link);
 166                 if (time_before(timer->timo_jif, ptimer->timo_jif))
 167                         break;
 168         }
 169
 170         list_add_tail(&timer->link, _p); /* insert before stopping point */
 171
 172         spin_unlock(&krxtimod_lock);
 173
 174         wake_up(&krxtimod_sleepq);
 175
 176         _leave("");
 177 } /* end rxrpc_krxtimod_add_timer() */
 178
 179 /*****************************************************************************/
 180 /*
 181  * dequeue a timer
 182  * - returns 0 if the timer was deleted or -ENOENT if it wasn't queued
 183  */
 184 int rxrpc_krxtimod_del_timer(rxrpc_timer_t *timer)
 185 {
 186         int ret = 0;
 187
 188         _enter("%p", timer);
 189
 190         spin_lock(&krxtimod_lock);
 191
 192         if (list_empty(&timer->link))
 193                 ret = -ENOENT;
 194         else
 195                 list_del_init(&timer->link);
 196
 197         spin_unlock(&krxtimod_lock);
 198
 199         wake_up(&krxtimod_sleepq);
 200
 201         _leave(" = %d", ret);
 202         return ret;
 203 } /* end rxrpc_krxtimod_del_timer() */