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