subr_taskqueue.c

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    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: releng/5.1/sys/kern/subr_taskqueue.c 111528 2003-02-26 03:15:42Z scottl $
   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 void     *taskqueue_giant_ih;
   45 static struct mtx taskqueue_queues_mutex;
   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         struct mtx              tq_mutex;
   55 };
   56 
   57 static void     init_taskqueue_list(void *data);
   58 
   59 static void
   60 init_taskqueue_list(void *data __unused)
   61 {
   62 
   63         mtx_init(&taskqueue_queues_mutex, "taskqueue list", NULL, MTX_DEF);
   64         STAILQ_INIT(&taskqueue_queues);
   65 }
   66 SYSINIT(taskqueue_list, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_taskqueue_list,
   67     NULL);
   68 
   69 struct taskqueue *
   70 taskqueue_create(const char *name, int mflags,
   71                  taskqueue_enqueue_fn enqueue, void *context)
   72 {
   73         struct taskqueue *queue;
   74 
   75         queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
   76         if (!queue)
   77                 return 0;
   78 
   79         STAILQ_INIT(&queue->tq_queue);
   80         queue->tq_name = name;
   81         queue->tq_enqueue = enqueue;
   82         queue->tq_context = context;
   83         queue->tq_draining = 0;
   84         mtx_init(&queue->tq_mutex, "taskqueue", NULL, MTX_DEF);
   85 
   86         mtx_lock(&taskqueue_queues_mutex);
   87         STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
   88         mtx_unlock(&taskqueue_queues_mutex);
   89 
   90         return queue;
   91 }
   92 
   93 void
   94 taskqueue_free(struct taskqueue *queue)
   95 {
   96 
   97         mtx_lock(&queue->tq_mutex);
   98         KASSERT(queue->tq_draining == 0, ("free'ing a draining taskqueue"));
   99         queue->tq_draining = 1;
  100         mtx_unlock(&queue->tq_mutex);
  101 
  102         taskqueue_run(queue);
  103 
  104         mtx_lock(&taskqueue_queues_mutex);
  105         STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
  106         mtx_unlock(&taskqueue_queues_mutex);
  107 
  108         mtx_destroy(&queue->tq_mutex);
  109         free(queue, M_TASKQUEUE);
  110 }
  111 
  112 /*
  113  * Returns with the taskqueue locked.
  114  */
  115 struct taskqueue *
  116 taskqueue_find(const char *name)
  117 {
  118         struct taskqueue *queue;
  119 
  120         mtx_lock(&taskqueue_queues_mutex);
  121         STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
  122                 mtx_lock(&queue->tq_mutex);
  123                 if (!strcmp(queue->tq_name, name)) {
  124                         mtx_unlock(&taskqueue_queues_mutex);
  125                         return queue;
  126                 }
  127                 mtx_unlock(&queue->tq_mutex);
  128         }
  129         mtx_unlock(&taskqueue_queues_mutex);
  130         return 0;
  131 }
  132 
  133 int
  134 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
  135 {
  136         struct task *ins;
  137         struct task *prev;
  138 
  139         mtx_lock(&queue->tq_mutex);
  140 
  141         /*
  142          * Don't allow new tasks on a queue which is being freed.
  143          */
  144         if (queue->tq_draining) {
  145                 mtx_unlock(&queue->tq_mutex);
  146                 return EPIPE;
  147         }
  148 
  149         /*
  150          * Count multiple enqueues.
  151          */
  152         if (task->ta_pending) {
  153                 task->ta_pending++;
  154                 mtx_unlock(&queue->tq_mutex);
  155                 return 0;
  156         }
  157 
  158         /*
  159          * Optimise the case when all tasks have the same priority.
  160          */
  161         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
  162         if (!prev || prev->ta_priority >= task->ta_priority) {
  163                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
  164         } else {
  165                 prev = 0;
  166                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
  167                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
  168                         if (ins->ta_priority < task->ta_priority)
  169                                 break;
  170 
  171                 if (prev)
  172                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
  173                 else
  174                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
  175         }
  176 
  177         task->ta_pending = 1;
  178         if (queue->tq_enqueue)
  179                 queue->tq_enqueue(queue->tq_context);
  180 
  181         mtx_unlock(&queue->tq_mutex);
  182 
  183         return 0;
  184 }
  185 
  186 void
  187 taskqueue_run(struct taskqueue *queue)
  188 {
  189         struct task *task;
  190         int pending;
  191 
  192         mtx_lock(&queue->tq_mutex);
  193         while (STAILQ_FIRST(&queue->tq_queue)) {
  194                 /*
  195                  * Carefully remove the first task from the queue and
  196                  * zero its pending count.
  197                  */
  198                 task = STAILQ_FIRST(&queue->tq_queue);
  199                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
  200                 pending = task->ta_pending;
  201                 task->ta_pending = 0;
  202                 mtx_unlock(&queue->tq_mutex);
  203 
  204                 task->ta_func(task->ta_context, pending);
  205 
  206                 mtx_lock(&queue->tq_mutex);
  207         }
  208         mtx_unlock(&queue->tq_mutex);
  209 }
  210 
  211 static void
  212 taskqueue_swi_enqueue(void *context)
  213 {
  214         swi_sched(taskqueue_ih, 0);
  215 }
  216 
  217 static void
  218 taskqueue_swi_run(void *dummy)
  219 {
  220         taskqueue_run(taskqueue_swi);
  221 }
  222 
  223 static void
  224 taskqueue_swi_giant_enqueue(void *context)
  225 {
  226         swi_sched(taskqueue_giant_ih, 0);
  227 }
  228 
  229 static void
  230 taskqueue_swi_giant_run(void *dummy)
  231 {
  232         taskqueue_run(taskqueue_swi_giant);
  233 }
  234 
  235 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
  236                  swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
  237                      INTR_MPSAFE, &taskqueue_ih)); 
  238 
  239 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, 0,
  240                  swi_add(NULL, "Giant task queue", taskqueue_swi_giant_run,
  241                      NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));

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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_taskqueue.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_taskqueue.c