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 1.13 2008/06/07 11:44:04 mneumann 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 NULL; 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 NULL; 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); 248