sys/kern/subr_taskqueue.c

   1 /*-
   2  * Copyright (c) 2000 Doug Rabson
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  *       $FreeBSD: src/sys/kern/subr_taskqueue.c,v 1.1.2.3 2003/09/10 00:40:39 ken Exp $
  27  *      $DragonFly: src/sys/kern/subr_taskqueue.c,v 1.9 2005/10/13 00:02:22 dillon Exp $
  28  */
  29
  30 #include <sys/param.h>
  31 #include <sys/queue.h>
  32 #include <sys/systm.h>
  33 #include <sys/kernel.h>
  34 #include <sys/taskqueue.h>
  35 #include <sys/interrupt.h>
  36 #include <sys/lock.h>
  37 #include <sys/malloc.h>
  38 #include <sys/kthread.h>
  39 #include <sys/thread2.h>
  40
  41 #include <machine/ipl.h>
  42
  43 MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
  44
  45 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
  46
  47 struct taskqueue {
  48         STAILQ_ENTRY(taskqueue) tq_link;
  49         STAILQ_HEAD(, task)     tq_queue;
  50         const char              *tq_name;
  51         taskqueue_enqueue_fn    tq_enqueue;
  52         void                    *tq_context;
  53         int                     tq_draining;
  54 };
  55
  56 struct taskqueue *
  57 taskqueue_create(const char *name, int mflags,
  58                  taskqueue_enqueue_fn enqueue, void *context)
  59 {
  60         struct taskqueue *queue;
  61         static int once = 1;
  62
  63         queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags);
  64         if (!queue)
  65                 return 0;
  66         STAILQ_INIT(&queue->tq_queue);
  67         queue->tq_name = name;
  68         queue->tq_enqueue = enqueue;
  69         queue->tq_context = context;
  70         queue->tq_draining = 0;
  71
  72         crit_enter();
  73         if (once) {
  74                 STAILQ_INIT(&taskqueue_queues);
  75                 once = 0;
  76         }
  77         STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
  78         crit_exit();
  79
  80         return queue;
  81 }
  82
  83 void
  84 taskqueue_free(struct taskqueue *queue)
  85 {
  86         crit_enter();
  87         queue->tq_draining = 1;
  88         crit_exit();
  89
  90         taskqueue_run(queue);
  91
  92         crit_enter();
  93         STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
  94         crit_exit();
  95
  96         free(queue, M_TASKQUEUE);
  97 }
  98
  99 struct taskqueue *
 100 taskqueue_find(const char *name)
 101 {
 102         struct taskqueue *queue;
 103
 104         crit_enter();
 105         STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
 106                 if (!strcmp(queue->tq_name, name)) {
 107                         crit_exit();
 108                         return queue;
 109                 }
 110         }
 111         crit_exit();
 112         return 0;
 113 }
 114
 115 int
 116 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 117 {
 118         struct task *ins;
 119         struct task *prev;
 120
 121         crit_enter();
 122
 123         /*
 124          * Don't allow new tasks on a queue which is being freed.
 125          */
 126         if (queue->tq_draining) {
 127                 crit_exit();
 128                 return EPIPE;
 129         }
 130
 131         /*
 132          * Count multiple enqueues.
 133          */
 134         if (task->ta_pending) {
 135                 task->ta_pending++;
 136                 crit_exit();
 137                 return 0;
 138         }
 139
 140         /*
 141          * Optimise the case when all tasks have the same priority.
 142          */
 143         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 144         if (!prev || prev->ta_priority >= task->ta_priority) {
 145                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 146         } else {
 147                 prev = 0;
 148                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 149                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 150                         if (ins->ta_priority < task->ta_priority)
 151                                 break;
 152
 153                 if (prev)
 154                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 155                 else
 156                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 157         }
 158
 159         task->ta_pending = 1;
 160         if (queue->tq_enqueue)
 161                 queue->tq_enqueue(queue->tq_context);
 162
 163         crit_exit();
 164
 165         return 0;
 166 }
 167
 168 void
 169 taskqueue_run(struct taskqueue *queue)
 170 {
 171         struct task *task;
 172         int pending;
 173
 174         crit_enter();
 175         while (STAILQ_FIRST(&queue->tq_queue)) {
 176                 /*
 177                  * Carefully remove the first task from the queue and
 178                  * zero its pending count.
 179                  */
 180                 task = STAILQ_FIRST(&queue->tq_queue);
 181                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 182                 pending = task->ta_pending;
 183                 task->ta_pending = 0;
 184                 crit_exit();
 185
 186                 task->ta_func(task->ta_context, pending);
 187
 188                 crit_enter();
 189         }
 190         crit_exit();
 191 }
 192
 193 static void
 194 taskqueue_swi_enqueue(void *context)
 195 {
 196         setsofttq();
 197 }
 198
 199 static void
 200 taskqueue_swi_run(void *arg, void *frame)
 201 {
 202         taskqueue_run(taskqueue_swi);
 203 }
 204
 205 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
 206          register_swi(SWI_TQ, taskqueue_swi_run, NULL, "swi_taskq", NULL));
 207
 208 static void
 209 taskqueue_kthread(void *arg)
 210 {
 211         for (;;) {
 212                 taskqueue_run(taskqueue_thread[mycpuid]);
 213                 crit_enter();
 214                 if (STAILQ_EMPTY(&taskqueue_thread[mycpuid]->tq_queue))
 215                         tsleep(taskqueue_thread[mycpuid], 0, "tqthr", 0);
 216                 crit_exit();
 217         }
 218 }
 219
 220 static void
 221 taskqueue_thread_enqueue(void *context)
 222 {
 223         wakeup(taskqueue_thread[mycpuid]);
 224 }
 225
 226 struct taskqueue *taskqueue_thread[MAXCPU];
 227 static struct thread *taskqueue_thread_td[MAXCPU];
 228
 229 static void
 230 taskqueue_init(void)
 231 {
 232         int cpu;
 233
 234         for (cpu = 0; cpu < ncpus; cpu++) {
 235                 taskqueue_thread[cpu] = taskqueue_create("thread", M_INTWAIT,
 236                     taskqueue_thread_enqueue, NULL);
 237                 kthread_create(taskqueue_kthread, NULL,
 238                     &taskqueue_thread_td[cpu], "taskqueue");
 239         }
 240 }
 241
 242 SYSINIT(taskqueueinit, SI_SUB_CONFIGURE, SI_ORDER_SECOND, taskqueue_init, NULL);