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 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/5.2/sys/kern/subr_taskqueue.c 122436 2003-11-10 20:39:44Z alfred $");
   29 
   30 #include <sys/param.h>
   31 #include <sys/systm.h>
   32 #include <sys/bus.h>
   33 #include <sys/interrupt.h>
   34 #include <sys/kernel.h>
   35 #include <sys/lock.h>
   36 #include <sys/malloc.h>
   37 #include <sys/mutex.h>
   38 #include <sys/taskqueue.h>
   39 #include <sys/kthread.h>
   40 #include <sys/unistd.h>
   41 
   42 static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
   43 
   44 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
   45 
   46 static void     *taskqueue_ih;
   47 static void     *taskqueue_giant_ih;
   48 static struct mtx taskqueue_queues_mutex;
   49 static struct proc *taskqueue_thread_proc;
   50 
   51 struct taskqueue {
   52         STAILQ_ENTRY(taskqueue) tq_link;
   53         STAILQ_HEAD(, task)     tq_queue;
   54         const char              *tq_name;
   55         taskqueue_enqueue_fn    tq_enqueue;
   56         void                    *tq_context;
   57         int                     tq_draining;
   58         struct mtx              tq_mutex;
   59 };
   60 
   61 static void     init_taskqueue_list(void *data);
   62 
   63 static void
   64 init_taskqueue_list(void *data __unused)
   65 {
   66 
   67         mtx_init(&taskqueue_queues_mutex, "taskqueue list", NULL, MTX_DEF);
   68         STAILQ_INIT(&taskqueue_queues);
   69 }
   70 SYSINIT(taskqueue_list, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_taskqueue_list,
   71     NULL);
   72 
   73 struct taskqueue *
   74 taskqueue_create(const char *name, int mflags,
   75                  taskqueue_enqueue_fn enqueue, void *context)
   76 {
   77         struct taskqueue *queue;
   78 
   79         queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
   80         if (!queue)
   81                 return 0;
   82 
   83         STAILQ_INIT(&queue->tq_queue);
   84         queue->tq_name = name;
   85         queue->tq_enqueue = enqueue;
   86         queue->tq_context = context;
   87         queue->tq_draining = 0;
   88         mtx_init(&queue->tq_mutex, "taskqueue", NULL, MTX_DEF);
   89 
   90         mtx_lock(&taskqueue_queues_mutex);
   91         STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
   92         mtx_unlock(&taskqueue_queues_mutex);
   93 
   94         return queue;
   95 }
   96 
   97 void
   98 taskqueue_free(struct taskqueue *queue)
   99 {
  100 
  101         mtx_lock(&queue->tq_mutex);
  102         KASSERT(queue->tq_draining == 0, ("free'ing a draining taskqueue"));
  103         queue->tq_draining = 1;
  104         mtx_unlock(&queue->tq_mutex);
  105 
  106         taskqueue_run(queue);
  107 
  108         mtx_lock(&taskqueue_queues_mutex);
  109         STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
  110         mtx_unlock(&taskqueue_queues_mutex);
  111 
  112         mtx_destroy(&queue->tq_mutex);
  113         free(queue, M_TASKQUEUE);
  114 }
  115 
  116 /*
  117  * Returns with the taskqueue locked.
  118  */
  119 struct taskqueue *
  120 taskqueue_find(const char *name)
  121 {
  122         struct taskqueue *queue;
  123 
  124         mtx_lock(&taskqueue_queues_mutex);
  125         STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
  126                 mtx_lock(&queue->tq_mutex);
  127                 if (!strcmp(queue->tq_name, name)) {
  128                         mtx_unlock(&taskqueue_queues_mutex);
  129                         return queue;
  130                 }
  131                 mtx_unlock(&queue->tq_mutex);
  132         }
  133         mtx_unlock(&taskqueue_queues_mutex);
  134         return 0;
  135 }
  136 
  137 int
  138 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
  139 {
  140         struct task *ins;
  141         struct task *prev;
  142 
  143         mtx_lock(&queue->tq_mutex);
  144 
  145         /*
  146          * Don't allow new tasks on a queue which is being freed.
  147          */
  148         if (queue->tq_draining) {
  149                 mtx_unlock(&queue->tq_mutex);
  150                 return EPIPE;
  151         }
  152 
  153         /*
  154          * Count multiple enqueues.
  155          */
  156         if (task->ta_pending) {
  157                 task->ta_pending++;
  158                 mtx_unlock(&queue->tq_mutex);
  159                 return 0;
  160         }
  161 
  162         /*
  163          * Optimise the case when all tasks have the same priority.
  164          */
  165         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
  166         if (!prev || prev->ta_priority >= task->ta_priority) {
  167                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
  168         } else {
  169                 prev = 0;
  170                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
  171                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
  172                         if (ins->ta_priority < task->ta_priority)
  173                                 break;
  174 
  175                 if (prev)
  176                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
  177                 else
  178                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
  179         }
  180 
  181         task->ta_pending = 1;
  182         if (queue->tq_enqueue)
  183                 queue->tq_enqueue(queue->tq_context);
  184 
  185         mtx_unlock(&queue->tq_mutex);
  186 
  187         return 0;
  188 }
  189 
  190 void
  191 taskqueue_run(struct taskqueue *queue)
  192 {
  193         struct task *task;
  194         int pending;
  195 
  196         mtx_lock(&queue->tq_mutex);
  197         while (STAILQ_FIRST(&queue->tq_queue)) {
  198                 /*
  199                  * Carefully remove the first task from the queue and
  200                  * zero its pending count.
  201                  */
  202                 task = STAILQ_FIRST(&queue->tq_queue);
  203                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
  204                 pending = task->ta_pending;
  205                 task->ta_pending = 0;
  206                 mtx_unlock(&queue->tq_mutex);
  207 
  208                 task->ta_func(task->ta_context, pending);
  209 
  210                 mtx_lock(&queue->tq_mutex);
  211         }
  212         mtx_unlock(&queue->tq_mutex);
  213 }
  214 
  215 static void
  216 taskqueue_swi_enqueue(void *context)
  217 {
  218         swi_sched(taskqueue_ih, 0);
  219 }
  220 
  221 static void
  222 taskqueue_swi_run(void *dummy)
  223 {
  224         taskqueue_run(taskqueue_swi);
  225 }
  226 
  227 static void
  228 taskqueue_swi_giant_enqueue(void *context)
  229 {
  230         swi_sched(taskqueue_giant_ih, 0);
  231 }
  232 
  233 static void
  234 taskqueue_swi_giant_run(void *dummy)
  235 {
  236         taskqueue_run(taskqueue_swi_giant);
  237 }
  238 
  239 static void
  240 taskqueue_kthread(void *arg)
  241 {
  242         struct mtx kthread_mutex;
  243 
  244         bzero(&kthread_mutex, sizeof(kthread_mutex));
  245 
  246         mtx_init(&kthread_mutex, "taskqueue kthread", NULL, MTX_DEF);
  247 
  248         mtx_lock(&kthread_mutex);
  249 
  250         for (;;) {
  251                 mtx_unlock(&kthread_mutex);
  252                 taskqueue_run(taskqueue_thread);
  253                 mtx_lock(&kthread_mutex);
  254                 msleep(&taskqueue_thread, &kthread_mutex, PWAIT, "tqthr", 0); 
  255         }
  256 }
  257 
  258 static void
  259 taskqueue_thread_enqueue(void *context)
  260 {
  261         wakeup(&taskqueue_thread);
  262 }
  263 
  264 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
  265                  swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
  266                      INTR_MPSAFE, &taskqueue_ih)); 
  267 
  268 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, 0,
  269                  swi_add(NULL, "Giant task queue", taskqueue_swi_giant_run,
  270                      NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih)); 
  271 
  272 TASKQUEUE_DEFINE(thread, taskqueue_thread_enqueue, 0,
  273                  kthread_create(taskqueue_kthread, NULL,
  274                  &taskqueue_thread_proc, 0, 0, "taskqueue"));
  275 
  276 int
  277 taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
  278 {
  279         struct task *ins;
  280         struct task *prev;
  281 
  282         mtx_lock_spin(&queue->tq_mutex);
  283 
  284         /*
  285          * Don't allow new tasks on a queue which is being freed.
  286          */
  287         if (queue->tq_draining) {
  288                 mtx_unlock_spin(&queue->tq_mutex);
  289                 return EPIPE;
  290         }
  291 
  292         /*
  293          * Count multiple enqueues.
  294          */
  295         if (task->ta_pending) {
  296                 task->ta_pending++;
  297                 mtx_unlock_spin(&queue->tq_mutex);
  298                 return 0;
  299         }
  300 
  301         /*
  302          * Optimise the case when all tasks have the same priority.
  303          */
  304         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
  305         if (!prev || prev->ta_priority >= task->ta_priority) {
  306                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
  307         } else {
  308                 prev = 0;
  309                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
  310                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
  311                         if (ins->ta_priority < task->ta_priority)
  312                                 break;
  313 
  314                 if (prev)
  315                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
  316                 else
  317                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
  318         }
  319 
  320         task->ta_pending = 1;
  321         if (queue->tq_enqueue)
  322                 queue->tq_enqueue(queue->tq_context);
  323 
  324         mtx_unlock_spin(&queue->tq_mutex);
  325 
  326         return 0;
  327 }
  328 
  329 static void
  330 taskqueue_run_fast(struct taskqueue *queue)
  331 {
  332         struct task *task;
  333         int pending;
  334 
  335         mtx_lock_spin(&queue->tq_mutex);
  336         while (STAILQ_FIRST(&queue->tq_queue)) {
  337                 /*
  338                  * Carefully remove the first task from the queue and
  339                  * zero its pending count.
  340                  */
  341                 task = STAILQ_FIRST(&queue->tq_queue);
  342                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
  343                 pending = task->ta_pending;
  344                 task->ta_pending = 0;
  345                 mtx_unlock_spin(&queue->tq_mutex);
  346 
  347                 task->ta_func(task->ta_context, pending);
  348 
  349                 mtx_lock_spin(&queue->tq_mutex);
  350         }
  351         mtx_unlock_spin(&queue->tq_mutex);
  352 }
  353 
  354 struct taskqueue *taskqueue_fast;
  355 static void     *taskqueue_fast_ih;
  356 
  357 static void
  358 taskqueue_fast_schedule(void *context)
  359 {
  360         swi_sched(taskqueue_fast_ih, 0);
  361 }
  362 
  363 static void
  364 taskqueue_fast_run(void *dummy)
  365 {
  366         taskqueue_run_fast(taskqueue_fast);
  367 }
  368 
  369 static void
  370 taskqueue_define_fast(void *arg)
  371 {
  372         taskqueue_fast = malloc(sizeof(struct taskqueue),
  373                 M_TASKQUEUE, M_NOWAIT | M_ZERO);
  374         if (!taskqueue_fast) {
  375                 printf("%s: Unable to allocate fast task queue!\n", __func__);
  376                 return;
  377         }
  378 
  379         STAILQ_INIT(&taskqueue_fast->tq_queue);
  380         taskqueue_fast->tq_name = "fast";
  381         taskqueue_fast->tq_enqueue = taskqueue_fast_schedule;
  382         mtx_init(&taskqueue_fast->tq_mutex, "taskqueue_fast", NULL, MTX_SPIN);
  383 
  384         mtx_lock(&taskqueue_queues_mutex);
  385         STAILQ_INSERT_TAIL(&taskqueue_queues, taskqueue_fast, tq_link);
  386         mtx_unlock(&taskqueue_queues_mutex);
  387 
  388         swi_add(NULL, "Fast task queue", taskqueue_fast_run,
  389                 NULL, SWI_TQ_FAST, 0, &taskqueue_fast_ih);
  390 }
  391 SYSINIT(taskqueue_fast, SI_SUB_CONFIGURE, SI_ORDER_SECOND,
  392         taskqueue_define_fast, NULL);
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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_taskqueue.c

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