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/8.1/sys/kern/subr_taskqueue.c 202764 2010-01-21 19:11:18Z jhb $");
   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/kthread.h>
   36 #include <sys/lock.h>
   37 #include <sys/malloc.h>
   38 #include <sys/mutex.h>
   39 #include <sys/proc.h>
   40 #include <sys/sched.h>
   41 #include <sys/taskqueue.h>
   42 #include <sys/unistd.h>
   43 #include <machine/stdarg.h>
   44 
   45 static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
   46 static void     *taskqueue_giant_ih;
   47 static void     *taskqueue_ih;
   48 
   49 struct taskqueue {
   50         STAILQ_HEAD(, task)     tq_queue;
   51         const char              *tq_name;
   52         taskqueue_enqueue_fn    tq_enqueue;
   53         void                    *tq_context;
   54         struct task             *tq_running;
   55         struct mtx              tq_mutex;
   56         struct thread           **tq_threads;
   57         int                     tq_tcount;
   58         int                     tq_spin;
   59         int                     tq_flags;
   60 };
   61 
   62 #define TQ_FLAGS_ACTIVE         (1 << 0)
   63 #define TQ_FLAGS_BLOCKED        (1 << 1)
   64 #define TQ_FLAGS_PENDING        (1 << 2)
   65 
   66 static __inline void
   67 TQ_LOCK(struct taskqueue *tq)
   68 {
   69         if (tq->tq_spin)
   70                 mtx_lock_spin(&tq->tq_mutex);
   71         else
   72                 mtx_lock(&tq->tq_mutex);
   73 }
   74 
   75 static __inline void
   76 TQ_UNLOCK(struct taskqueue *tq)
   77 {
   78         if (tq->tq_spin)
   79                 mtx_unlock_spin(&tq->tq_mutex);
   80         else
   81                 mtx_unlock(&tq->tq_mutex);
   82 }
   83 
   84 static __inline int
   85 TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm,
   86     int t)
   87 {
   88         if (tq->tq_spin)
   89                 return (msleep_spin(p, m, wm, t));
   90         return (msleep(p, m, pri, wm, t));
   91 }
   92 
   93 static struct taskqueue *
   94 _taskqueue_create(const char *name, int mflags,
   95                  taskqueue_enqueue_fn enqueue, void *context,
   96                  int mtxflags, const char *mtxname)
   97 {
   98         struct taskqueue *queue;
   99 
  100         queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
  101         if (!queue)
  102                 return NULL;
  103 
  104         STAILQ_INIT(&queue->tq_queue);
  105         queue->tq_name = name;
  106         queue->tq_enqueue = enqueue;
  107         queue->tq_context = context;
  108         queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
  109         queue->tq_flags |= TQ_FLAGS_ACTIVE;
  110         mtx_init(&queue->tq_mutex, mtxname, NULL, mtxflags);
  111 
  112         return queue;
  113 }
  114 
  115 struct taskqueue *
  116 taskqueue_create(const char *name, int mflags,
  117                  taskqueue_enqueue_fn enqueue, void *context)
  118 {
  119         return _taskqueue_create(name, mflags, enqueue, context,
  120                         MTX_DEF, "taskqueue");
  121 }
  122 
  123 /*
  124  * Signal a taskqueue thread to terminate.
  125  */
  126 static void
  127 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
  128 {
  129 
  130         while (tq->tq_tcount > 0) {
  131                 wakeup(tq);
  132                 TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0);
  133         }
  134 }
  135 
  136 void
  137 taskqueue_free(struct taskqueue *queue)
  138 {
  139 
  140         TQ_LOCK(queue);
  141         queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
  142         taskqueue_run(queue);
  143         taskqueue_terminate(queue->tq_threads, queue);
  144         mtx_destroy(&queue->tq_mutex);
  145         free(queue->tq_threads, M_TASKQUEUE);
  146         free(queue, M_TASKQUEUE);
  147 }
  148 
  149 int
  150 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
  151 {
  152         struct task *ins;
  153         struct task *prev;
  154 
  155         TQ_LOCK(queue);
  156 
  157         /*
  158          * Count multiple enqueues.
  159          */
  160         if (task->ta_pending) {
  161                 task->ta_pending++;
  162                 TQ_UNLOCK(queue);
  163                 return 0;
  164         }
  165 
  166         /*
  167          * Optimise the case when all tasks have the same priority.
  168          */
  169         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
  170         if (!prev || prev->ta_priority >= task->ta_priority) {
  171                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
  172         } else {
  173                 prev = NULL;
  174                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
  175                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
  176                         if (ins->ta_priority < task->ta_priority)
  177                                 break;
  178 
  179                 if (prev)
  180                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
  181                 else
  182                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
  183         }
  184 
  185         task->ta_pending = 1;
  186         if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0)
  187                 queue->tq_enqueue(queue->tq_context);
  188         else
  189                 queue->tq_flags |= TQ_FLAGS_PENDING;
  190 
  191         TQ_UNLOCK(queue);
  192 
  193         return 0;
  194 }
  195 
  196 void
  197 taskqueue_block(struct taskqueue *queue)
  198 {
  199 
  200         TQ_LOCK(queue);
  201         queue->tq_flags |= TQ_FLAGS_BLOCKED;
  202         TQ_UNLOCK(queue);
  203 }
  204 
  205 void
  206 taskqueue_unblock(struct taskqueue *queue)
  207 {
  208 
  209         TQ_LOCK(queue);
  210         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
  211         if (queue->tq_flags & TQ_FLAGS_PENDING) {
  212                 queue->tq_flags &= ~TQ_FLAGS_PENDING;
  213                 queue->tq_enqueue(queue->tq_context);
  214         }
  215         TQ_UNLOCK(queue);
  216 }
  217 
  218 void
  219 taskqueue_run(struct taskqueue *queue)
  220 {
  221         struct task *task;
  222         int owned, pending;
  223 
  224         owned = mtx_owned(&queue->tq_mutex);
  225         if (!owned)
  226                 TQ_LOCK(queue);
  227         while (STAILQ_FIRST(&queue->tq_queue)) {
  228                 /*
  229                  * Carefully remove the first task from the queue and
  230                  * zero its pending count.
  231                  */
  232                 task = STAILQ_FIRST(&queue->tq_queue);
  233                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
  234                 pending = task->ta_pending;
  235                 task->ta_pending = 0;
  236                 queue->tq_running = task;
  237                 TQ_UNLOCK(queue);
  238 
  239                 task->ta_func(task->ta_context, pending);
  240 
  241                 TQ_LOCK(queue);
  242                 queue->tq_running = NULL;
  243                 wakeup(task);
  244         }
  245 
  246         /*
  247          * For compatibility, unlock on return if the queue was not locked
  248          * on entry, although this opens a race window.
  249          */
  250         if (!owned)
  251                 TQ_UNLOCK(queue);
  252 }
  253 
  254 void
  255 taskqueue_drain(struct taskqueue *queue, struct task *task)
  256 {
  257         if (queue->tq_spin) {           /* XXX */
  258                 mtx_lock_spin(&queue->tq_mutex);
  259                 while (task->ta_pending != 0 || task == queue->tq_running)
  260                         msleep_spin(task, &queue->tq_mutex, "-", 0);
  261                 mtx_unlock_spin(&queue->tq_mutex);
  262         } else {
  263                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
  264 
  265                 mtx_lock(&queue->tq_mutex);
  266                 while (task->ta_pending != 0 || task == queue->tq_running)
  267                         msleep(task, &queue->tq_mutex, PWAIT, "-", 0);
  268                 mtx_unlock(&queue->tq_mutex);
  269         }
  270 }
  271 
  272 static void
  273 taskqueue_swi_enqueue(void *context)
  274 {
  275         swi_sched(taskqueue_ih, 0);
  276 }
  277 
  278 static void
  279 taskqueue_swi_run(void *dummy)
  280 {
  281         taskqueue_run(taskqueue_swi);
  282 }
  283 
  284 static void
  285 taskqueue_swi_giant_enqueue(void *context)
  286 {
  287         swi_sched(taskqueue_giant_ih, 0);
  288 }
  289 
  290 static void
  291 taskqueue_swi_giant_run(void *dummy)
  292 {
  293         taskqueue_run(taskqueue_swi_giant);
  294 }
  295 
  296 int
  297 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
  298                         const char *name, ...)
  299 {
  300         va_list ap;
  301         struct thread *td;
  302         struct taskqueue *tq;
  303         int i, error;
  304         char ktname[MAXCOMLEN + 1];
  305 
  306         if (count <= 0)
  307                 return (EINVAL);
  308 
  309         tq = *tqp;
  310 
  311         va_start(ap, name);
  312         vsnprintf(ktname, sizeof(ktname), name, ap);
  313         va_end(ap);
  314 
  315         tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
  316             M_NOWAIT | M_ZERO);
  317         if (tq->tq_threads == NULL) {
  318                 printf("%s: no memory for %s threads\n", __func__, ktname);
  319                 return (ENOMEM);
  320         }
  321 
  322         for (i = 0; i < count; i++) {
  323                 if (count == 1)
  324                         error = kthread_add(taskqueue_thread_loop, tqp, NULL,
  325                             &tq->tq_threads[i], RFSTOPPED, 0, ktname);
  326                 else
  327                         error = kthread_add(taskqueue_thread_loop, tqp, NULL,
  328                             &tq->tq_threads[i], RFSTOPPED, 0,
  329                             "%s_%d", ktname, i);
  330                 if (error) {
  331                         /* should be ok to continue, taskqueue_free will dtrt */
  332                         printf("%s: kthread_add(%s): error %d", __func__,
  333                             ktname, error);
  334                         tq->tq_threads[i] = NULL;               /* paranoid */
  335                 } else
  336                         tq->tq_tcount++;
  337         }
  338         for (i = 0; i < count; i++) {
  339                 if (tq->tq_threads[i] == NULL)
  340                         continue;
  341                 td = tq->tq_threads[i];
  342                 thread_lock(td);
  343                 sched_prio(td, pri);
  344                 sched_add(td, SRQ_BORING);
  345                 thread_unlock(td);
  346         }
  347 
  348         return (0);
  349 }
  350 
  351 void
  352 taskqueue_thread_loop(void *arg)
  353 {
  354         struct taskqueue **tqp, *tq;
  355 
  356         tqp = arg;
  357         tq = *tqp;
  358         TQ_LOCK(tq);
  359         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
  360                 taskqueue_run(tq);
  361                 /*
  362                  * Because taskqueue_run() can drop tq_mutex, we need to
  363                  * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
  364                  * meantime, which means we missed a wakeup.
  365                  */
  366                 if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
  367                         break;
  368                 TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
  369         }
  370 
  371         /* rendezvous with thread that asked us to terminate */
  372         tq->tq_tcount--;
  373         wakeup_one(tq->tq_threads);
  374         TQ_UNLOCK(tq);
  375         kthread_exit();
  376 }
  377 
  378 void
  379 taskqueue_thread_enqueue(void *context)
  380 {
  381         struct taskqueue **tqp, *tq;
  382 
  383         tqp = context;
  384         tq = *tqp;
  385 
  386         mtx_assert(&tq->tq_mutex, MA_OWNED);
  387         wakeup_one(tq);
  388 }
  389 
  390 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
  391                  swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
  392                      INTR_MPSAFE, &taskqueue_ih)); 
  393 
  394 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
  395                  swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
  396                      NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih)); 
  397 
  398 TASKQUEUE_DEFINE_THREAD(thread);
  399 
  400 struct taskqueue *
  401 taskqueue_create_fast(const char *name, int mflags,
  402                  taskqueue_enqueue_fn enqueue, void *context)
  403 {
  404         return _taskqueue_create(name, mflags, enqueue, context,
  405                         MTX_SPIN, "fast_taskqueue");
  406 }
  407 
  408 /* NB: for backwards compatibility */
  409 int
  410 taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
  411 {
  412         return taskqueue_enqueue(queue, task);
  413 }
  414 
  415 static void     *taskqueue_fast_ih;
  416 
  417 static void
  418 taskqueue_fast_enqueue(void *context)
  419 {
  420         swi_sched(taskqueue_fast_ih, 0);
  421 }
  422 
  423 static void
  424 taskqueue_fast_run(void *dummy)
  425 {
  426         taskqueue_run(taskqueue_fast);
  427 }
  428 
  429 TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
  430         swi_add(NULL, "Fast task queue", taskqueue_fast_run, NULL,
  431         SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
  432 
  433 int
  434 taskqueue_member(struct taskqueue *queue, struct thread *td)
  435 {
  436         int i, j, ret = 0;
  437 
  438         TQ_LOCK(queue);
  439         for (i = 0, j = 0; ; i++) {
  440                 if (queue->tq_threads[i] == NULL)
  441                         continue;
  442                 if (queue->tq_threads[i] == td) {
  443                         ret = 1;
  444                         break;
  445                 }
  446                 if (++j >= queue->tq_tcount)
  447                         break;
  448         }
  449         TQ_UNLOCK(queue);
  450         return (ret);
  451 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_taskqueue.c

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