fs/afs/kafstimod.c

   1 /* kafstimod.c: AFS 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 <linux/freezer.h>
  17 #include "cell.h"
  18 #include "volume.h"
  19 #include "kafstimod.h"
  20 #include <asm/errno.h>
  21 #include "internal.h"
  22
  23 static DECLARE_COMPLETION(kafstimod_alive);
  24 static DECLARE_COMPLETION(kafstimod_dead);
  25 static DECLARE_WAIT_QUEUE_HEAD(kafstimod_sleepq);
  26 static int kafstimod_die;
  27
  28 static LIST_HEAD(kafstimod_list);
  29 static DEFINE_SPINLOCK(kafstimod_lock);
  30
  31 static int kafstimod(void *arg);
  32
  33 /*****************************************************************************/
  34 /*
  35  * start the timeout daemon
  36  */
  37 int afs_kafstimod_start(void)
  38 {
  39         int ret;
  40
  41         ret = kernel_thread(kafstimod, NULL, 0);
  42         if (ret < 0)
  43                 return ret;
  44
  45         wait_for_completion(&kafstimod_alive);
  46
  47         return ret;
  48 } /* end afs_kafstimod_start() */
  49
  50 /*****************************************************************************/
  51 /*
  52  * stop the timeout daemon
  53  */
  54 void afs_kafstimod_stop(void)
  55 {
  56         /* get rid of my daemon */
  57         kafstimod_die = 1;
  58         wake_up(&kafstimod_sleepq);
  59         wait_for_completion(&kafstimod_dead);
  60
  61 } /* end afs_kafstimod_stop() */
  62
  63 /*****************************************************************************/
  64 /*
  65  * timeout processing daemon
  66  */
  67 static int kafstimod(void *arg)
  68 {
  69         struct afs_timer *timer;
  70
  71         DECLARE_WAITQUEUE(myself, current);
  72
  73         printk("kAFS: Started kafstimod %d\n", current->pid);
  74
  75         daemonize("kafstimod");
  76
  77         complete(&kafstimod_alive);
  78
  79         /* loop around looking for things to attend to */
  80  loop:
  81         set_current_state(TASK_INTERRUPTIBLE);
  82         add_wait_queue(&kafstimod_sleepq, &myself);
  83
  84         for (;;) {
  85                 unsigned long jif;
  86                 signed long timeout;
  87
  88                 /* deal with the server being asked to die */
  89                 if (kafstimod_die) {
  90                         remove_wait_queue(&kafstimod_sleepq, &myself);
  91                         _leave("");
  92                         complete_and_exit(&kafstimod_dead, 0);
  93                 }
  94
  95                 try_to_freeze();
  96
  97                 /* discard pending signals */
  98                 afs_discard_my_signals();
  99
 100                 /* work out the time to elapse before the next event */
 101                 spin_lock(&kafstimod_lock);
 102                 if (list_empty(&kafstimod_list)) {
 103                         timeout = MAX_SCHEDULE_TIMEOUT;
 104                 }
 105                 else {
 106                         timer = list_entry(kafstimod_list.next,
 107                                            struct afs_timer, link);
 108                         timeout = timer->timo_jif;
 109                         jif = jiffies;
 110
 111                         if (time_before_eq((unsigned long) timeout, jif))
 112                                 goto immediate;
 113
 114                         else {
 115                                 timeout = (long) timeout - (long) jiffies;
 116                         }
 117                 }
 118                 spin_unlock(&kafstimod_lock);
 119
 120                 schedule_timeout(timeout);
 121
 122                 set_current_state(TASK_INTERRUPTIBLE);
 123         }
 124
 125         /* the thing on the front of the queue needs processing
 126          * - we come here with the lock held and timer pointing to the expired
 127          *   entry
 128          */
 129  immediate:
 130         remove_wait_queue(&kafstimod_sleepq, &myself);
 131         set_current_state(TASK_RUNNING);
 132
 133         _debug("@@@ Begin Timeout of %p", timer);
 134
 135         /* dequeue the timer */
 136         list_del_init(&timer->link);
 137         spin_unlock(&kafstimod_lock);
 138
 139         /* call the timeout function */
 140         timer->ops->timed_out(timer);
 141
 142         _debug("@@@ End Timeout");
 143         goto loop;
 144
 145 } /* end kafstimod() */
 146
 147 /*****************************************************************************/
 148 /*
 149  * (re-)queue a timer
 150  */
 151 void afs_kafstimod_add_timer(struct afs_timer *timer, unsigned long timeout)
 152 {
 153         struct afs_timer *ptimer;
 154         struct list_head *_p;
 155
 156         _enter("%p,%lu", timer, timeout);
 157
 158         spin_lock(&kafstimod_lock);
 159
 160         list_del(&timer->link);
 161
 162         /* the timer was deferred or reset - put it back in the queue at the
 163          * right place */
 164         timer->timo_jif = jiffies + timeout;
 165
 166         list_for_each(_p, &kafstimod_list) {
 167                 ptimer = list_entry(_p, struct afs_timer, link);
 168                 if (time_before(timer->timo_jif, ptimer->timo_jif))
 169                         break;
 170         }
 171
 172         list_add_tail(&timer->link, _p); /* insert before stopping point */
 173
 174         spin_unlock(&kafstimod_lock);
 175
 176         wake_up(&kafstimod_sleepq);
 177
 178         _leave("");
 179 } /* end afs_kafstimod_add_timer() */
 180
 181 /*****************************************************************************/
 182 /*
 183  * dequeue a timer
 184  * - returns 0 if the timer was deleted or -ENOENT if it wasn't queued
 185  */
 186 int afs_kafstimod_del_timer(struct afs_timer *timer)
 187 {
 188         int ret = 0;
 189
 190         _enter("%p", timer);
 191
 192         spin_lock(&kafstimod_lock);
 193
 194         if (list_empty(&timer->link))
 195                 ret = -ENOENT;
 196         else
 197                 list_del_init(&timer->link);
 198
 199         spin_unlock(&kafstimod_lock);
 200
 201         wake_up(&kafstimod_sleepq);
 202
 203         _leave(" = %d", ret);
 204         return ret;
 205 } /* end afs_kafstimod_del_timer() */