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