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: src/sys/kern/subr_taskqueue.c,v 1.1.2.3 2003/09/10 00:40:39 ken Exp $
  27  *      $DragonFly: src/sys/kern/subr_taskqueue.c,v 1.12 2007/02/24 04:36:21 corecode Exp $
  28  */
  29
  30 #include <sys/param.h>
  31 #include <sys/queue.h>
  32 #include <sys/systm.h>
  33 #include <sys/kernel.h>
  34 #include <sys/taskqueue.h>
  35 #include <sys/interrupt.h>
  36 #include <sys/lock.h>
  37 #include <sys/malloc.h>
  38 #include <sys/kthread.h>
  39 #include <sys/thread2.h>
  40
  41 MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
  42
  43 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
  44
  45 struct taskqueue {
  46         STAILQ_ENTRY(taskqueue) tq_link;
  47         STAILQ_HEAD(, task)     tq_queue;
  48         const char              *tq_name;
  49         taskqueue_enqueue_fn    tq_enqueue;
  50         void                    *tq_context;
  51         int                     tq_draining;
  52 };
  53
  54 struct taskqueue *
  55 taskqueue_create(const char *name, int mflags,
  56                  taskqueue_enqueue_fn enqueue, void *context)
  57 {
  58         struct taskqueue *queue;
  59         static int once = 1;
  60
  61         queue = kmalloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags);
  62         if (!queue)
  63                 return 0;
  64         STAILQ_INIT(&queue->tq_queue);
  65         queue->tq_name = name;
  66         queue->tq_enqueue = enqueue;
  67         queue->tq_context = context;
  68         queue->tq_draining = 0;
  69
  70         crit_enter();
  71         if (once) {
  72                 STAILQ_INIT(&taskqueue_queues);
  73                 once = 0;
  74         }
  75         STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
  76         crit_exit();
  77
  78         return queue;
  79 }
  80
  81 void
  82 taskqueue_free(struct taskqueue *queue)
  83 {
  84         crit_enter();
  85         queue->tq_draining = 1;
  86         crit_exit();
  87
  88         taskqueue_run(queue);
  89
  90         crit_enter();
  91         STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
  92         crit_exit();
  93
  94         kfree(queue, M_TASKQUEUE);
  95 }
  96
  97 struct taskqueue *
  98 taskqueue_find(const char *name)
  99 {
 100         struct taskqueue *queue;
 101
 102         crit_enter();
 103         STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
 104                 if (!strcmp(queue->tq_name, name)) {
 105                         crit_exit();
 106                         return queue;
 107                 }
 108         }
 109         crit_exit();
 110         return 0;
 111 }
 112
 113 /*
 114  * NOTE!  If using the per-cpu taskqueues ``taskqueue_thread[mycpuid]'',
 115  * be sure NOT TO SHARE the ``task'' between CPUs.  TASKS ARE NOT LOCKED.
 116  * So either use a throwaway task which will only be enqueued once, or
 117  * use one task per CPU!
 118  */
 119 int
 120 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 121 {
 122         struct task *ins;
 123         struct task *prev;
 124
 125         crit_enter();
 126
 127         /*
 128          * Don't allow new tasks on a queue which is being freed.
 129          */
 130         if (queue->tq_draining) {
 131                 crit_exit();
 132                 return EPIPE;
 133         }
 134
 135         /*
 136          * Count multiple enqueues.
 137          */
 138         if (task->ta_pending) {
 139                 task->ta_pending++;
 140                 crit_exit();
 141                 return 0;
 142         }
 143
 144         /*
 145          * Optimise the case when all tasks have the same priority.
 146          */
 147         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 148         if (!prev || prev->ta_priority >= task->ta_priority) {
 149                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 150         } else {
 151                 prev = 0;
 152                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 153                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 154                         if (ins->ta_priority < task->ta_priority)
 155                                 break;
 156
 157                 if (prev)
 158                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 159                 else
 160                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 161         }
 162
 163         task->ta_pending = 1;
 164         if (queue->tq_enqueue)
 165                 queue->tq_enqueue(queue->tq_context);
 166
 167         crit_exit();
 168
 169         return 0;
 170 }
 171
 172 void
 173 taskqueue_run(struct taskqueue *queue)
 174 {
 175         struct task *task;
 176         int pending;
 177
 178         crit_enter();
 179         while (STAILQ_FIRST(&queue->tq_queue)) {
 180                 /*
 181                  * Carefully remove the first task from the queue and
 182                  * zero its pending count.
 183                  */
 184                 task = STAILQ_FIRST(&queue->tq_queue);
 185                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 186                 pending = task->ta_pending;
 187                 task->ta_pending = 0;
 188                 crit_exit();
 189
 190                 task->ta_func(task->ta_context, pending);
 191
 192                 crit_enter();
 193         }
 194         crit_exit();
 195 }
 196
 197 static void
 198 taskqueue_swi_enqueue(void *context)
 199 {
 200         setsofttq();
 201 }
 202
 203 static void
 204 taskqueue_swi_run(void *arg, void *frame)
 205 {
 206         taskqueue_run(taskqueue_swi);
 207 }
 208
 209 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
 210          register_swi(SWI_TQ, taskqueue_swi_run, NULL, "swi_taskq", NULL));
 211
 212 static void
 213 taskqueue_kthread(void *arg)
 214 {
 215         for (;;) {
 216                 taskqueue_run(taskqueue_thread[mycpuid]);
 217                 crit_enter();
 218                 if (STAILQ_EMPTY(&taskqueue_thread[mycpuid]->tq_queue))
 219                         tsleep(taskqueue_thread[mycpuid], 0, "tqthr", 0);
 220                 crit_exit();
 221         }
 222 }
 223
 224 static void
 225 taskqueue_thread_enqueue(void *context)
 226 {
 227         wakeup(taskqueue_thread[mycpuid]);
 228 }
 229
 230 struct taskqueue *taskqueue_thread[MAXCPU];
 231 static struct thread *taskqueue_thread_td[MAXCPU];
 232
 233 static void
 234 taskqueue_init(void)
 235 {
 236         int cpu;
 237
 238         for (cpu = 0; cpu < ncpus; cpu++) {
 239                 taskqueue_thread[cpu] = taskqueue_create("thread", M_INTWAIT,
 240                     taskqueue_thread_enqueue, NULL);
 241                 lwkt_create(taskqueue_kthread, NULL,
 242                     &taskqueue_thread_td[cpu], NULL,
 243                     0, cpu, "taskqueue %d", cpu);
 244         }
 245 }
 246
 247 SYSINIT(taskqueueinit, SI_SUB_CONFIGURE, SI_ORDER_SECOND, taskqueue_init, NULL);