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  *      $FreeBSD$
  27  */
  28
  29 #include <sys/param.h>
  30 #include <sys/systm.h>
  31 #include <sys/bus.h>
  32 #include <sys/interrupt.h>
  33 #include <sys/kernel.h>
  34 #include <sys/lock.h>
  35 #include <sys/malloc.h>
  36 #include <sys/mutex.h>
  37 #include <sys/taskqueue.h>
  38
  39 static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
  40
  41 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
  42
  43 static void     *taskqueue_ih;
  44 static struct mtx taskqueue_queues_mutex;
  45
  46 struct taskqueue {
  47         STAILQ_ENTRY(taskqueue) tq_link;
  48         STAILQ_HEAD(, task)     tq_queue;
  49         const char              *tq_name;
  50         taskqueue_enqueue_fn    tq_enqueue;
  51         void                    *tq_context;
  52         int                     tq_draining;
  53         struct mtx              tq_mutex;
  54 };
  55
  56 static void     init_taskqueue_list(void *data);
  57
  58 static void
  59 init_taskqueue_list(void *data __unused)
  60 {
  61
  62         mtx_init(&taskqueue_queues_mutex, "taskqueue list", MTX_DEF);
  63         STAILQ_INIT(&taskqueue_queues);
  64 }
  65 SYSINIT(taskqueue_list, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_taskqueue_list,
  66     NULL);
  67
  68 struct taskqueue *
  69 taskqueue_create(const char *name, int mflags,
  70                  taskqueue_enqueue_fn enqueue, void *context)
  71 {
  72         struct taskqueue *queue;
  73
  74         queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
  75         if (!queue)
  76                 return 0;
  77
  78         STAILQ_INIT(&queue->tq_queue);
  79         queue->tq_name = name;
  80         queue->tq_enqueue = enqueue;
  81         queue->tq_context = context;
  82         queue->tq_draining = 0;
  83         mtx_init(&queue->tq_mutex, "taskqueue", MTX_DEF);
  84
  85         mtx_lock(&taskqueue_queues_mutex);
  86         STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
  87         mtx_unlock(&taskqueue_queues_mutex);
  88
  89         return queue;
  90 }
  91
  92 void
  93 taskqueue_free(struct taskqueue *queue)
  94 {
  95
  96         mtx_lock(&queue->tq_mutex);
  97         queue->tq_draining = 1;
  98         mtx_unlock(&queue->tq_mutex);
  99
 100         taskqueue_run(queue);
 101
 102         mtx_lock(&taskqueue_queues_mutex);
 103         STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
 104         mtx_unlock(&taskqueue_queues_mutex);
 105
 106         mtx_destroy(&queue->tq_mutex);
 107         free(queue, M_TASKQUEUE);
 108 }
 109
 110 /*
 111  * Returns with the taskqueue locked.
 112  */
 113 struct taskqueue *
 114 taskqueue_find(const char *name)
 115 {
 116         struct taskqueue *queue;
 117
 118         mtx_lock(&taskqueue_queues_mutex);
 119         STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
 120                 mtx_lock(&queue->tq_mutex);
 121                 if (!strcmp(queue->tq_name, name)) {
 122                         mtx_unlock(&taskqueue_queues_mutex);
 123                         return queue;
 124                 }
 125                 mtx_unlock(&queue->tq_mutex);
 126         }
 127         mtx_unlock(&taskqueue_queues_mutex);
 128         return 0;
 129 }
 130
 131 int
 132 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 133 {
 134         struct task *ins;
 135         struct task *prev;
 136
 137         mtx_lock(&queue->tq_mutex);
 138
 139         /*
 140          * Don't allow new tasks on a queue which is being freed.
 141          */
 142         if (queue->tq_draining) {
 143                 mtx_unlock(&queue->tq_mutex);
 144                 return EPIPE;
 145         }
 146
 147         /*
 148          * Count multiple enqueues.
 149          */
 150         if (task->ta_pending) {
 151                 task->ta_pending++;
 152                 mtx_unlock(&queue->tq_mutex);
 153                 return 0;
 154         }
 155
 156         /*
 157          * Optimise the case when all tasks have the same priority.
 158          */
 159         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 160         if (!prev || prev->ta_priority >= task->ta_priority) {
 161                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 162         } else {
 163                 prev = 0;
 164                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 165                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 166                         if (ins->ta_priority < task->ta_priority)
 167                                 break;
 168
 169                 if (prev)
 170                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 171                 else
 172                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 173         }
 174
 175         task->ta_pending = 1;
 176         if (queue->tq_enqueue)
 177                 queue->tq_enqueue(queue->tq_context);
 178
 179         mtx_unlock(&queue->tq_mutex);
 180
 181         return 0;
 182 }
 183
 184 void
 185 taskqueue_run(struct taskqueue *queue)
 186 {
 187         struct task *task;
 188         int pending;
 189
 190         mtx_lock(&queue->tq_mutex);
 191         while (STAILQ_FIRST(&queue->tq_queue)) {
 192                 /*
 193                  * Carefully remove the first task from the queue and
 194                  * zero its pending count.
 195                  */
 196                 task = STAILQ_FIRST(&queue->tq_queue);
 197                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 198                 pending = task->ta_pending;
 199                 task->ta_pending = 0;
 200                 mtx_unlock(&queue->tq_mutex);
 201
 202                 task->ta_func(task->ta_context, pending);
 203
 204                 mtx_lock(&queue->tq_mutex);
 205         }
 206         mtx_unlock(&queue->tq_mutex);
 207 }
 208
 209 static void
 210 taskqueue_swi_enqueue(void *context)
 211 {
 212         swi_sched(taskqueue_ih, 0);
 213 }
 214
 215 static void
 216 taskqueue_swi_run(void *dummy)
 217 {
 218         taskqueue_run(taskqueue_swi);
 219 }
 220
 221 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
 222                  swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ, 0,
 223                      &taskqueue_ih));