1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 /*
26  * Copyright 2012 Garrett D'Amore <garrett@damore.org>.  All rights reserved.
27  * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
28  * Copyright 2017 RackTop Systems.
29  * Copyright 2018, Joyent, Inc.
30  */
31 
32 #include <sys/taskq_impl.h>
33 
34 #include <sys/class.h>
35 #include <sys/debug.h>
36 #include <sys/ksynch.h>
37 #include <sys/kmem.h>
38 #include <sys/time.h>
39 #include <sys/systm.h>
40 #include <sys/sysmacros.h>
41 #include <sys/unistd.h>
42 
43 /* avoid <sys/disp.h> */
44 #define	maxclsyspri	99
45 
46 /* avoid <unistd.h> */
47 extern long sysconf(int);
48 
49 /* avoiding <thread.h> */
50 typedef unsigned int thread_t;
51 typedef unsigned int thread_key_t;
52 
53 extern int thr_create(void *, size_t, void *(*)(void *), void *, long,
54 			thread_t *);
55 extern int thr_join(thread_t, thread_t *, void **);
56 
57 /*
58  * POSIX.1c Note:
59  * THR_BOUND is defined same as PTHREAD_SCOPE_SYSTEM in <pthread.h>
60  * THR_DETACHED is defined same as PTHREAD_CREATE_DETACHED in <pthread.h>
61  * Any changes in these definitions should be reflected in <pthread.h>
62  */
63 #define	THR_BOUND		0x00000001	/* = PTHREAD_SCOPE_SYSTEM */
64 #define	THR_NEW_LWP		0x00000002
65 #define	THR_DETACHED		0x00000040	/* = PTHREAD_CREATE_DETACHED */
66 #define	THR_SUSPENDED		0x00000080
67 #define	THR_DAEMON		0x00000100
68 
69 
70 int taskq_now;
71 taskq_t *system_taskq;
72 
73 #define	TASKQ_ACTIVE	0x00010000
74 
75 struct taskq {
76 	kmutex_t	tq_lock;
77 	krwlock_t	tq_threadlock;
78 	kcondvar_t	tq_dispatch_cv;
79 	kcondvar_t	tq_wait_cv;
80 	thread_t	*tq_threadlist;
81 	int		tq_flags;
82 	int		tq_active;
83 	int		tq_nthreads;
84 	int		tq_nalloc;
85 	int		tq_minalloc;
86 	int		tq_maxalloc;
87 	kcondvar_t	tq_maxalloc_cv;
88 	int		tq_maxalloc_wait;
89 	taskq_ent_t	*tq_freelist;
90 	taskq_ent_t	tq_task;
91 };
92 
93 static taskq_ent_t *
94 task_alloc(taskq_t *tq, int tqflags)
95 {
96 	taskq_ent_t *t;
97 	int rv;
98 
99 again:	if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
100 		tq->tq_freelist = t->tqent_next;
101 	} else {
102 		if (tq->tq_nalloc >= tq->tq_maxalloc) {
103 			if (!(tqflags & KM_SLEEP))
104 				return (NULL);
105 
106 			/*
107 			 * We don't want to exceed tq_maxalloc, but we can't
108 			 * wait for other tasks to complete (and thus free up
109 			 * task structures) without risking deadlock with
110 			 * the caller.  So, we just delay for one second
111 			 * to throttle the allocation rate. If we have tasks
112 			 * complete before one second timeout expires then
113 			 * taskq_ent_free will signal us and we will
114 			 * immediately retry the allocation.
115 			 */
116 			tq->tq_maxalloc_wait++;
117 			rv = cv_timedwait(&tq->tq_maxalloc_cv,
118 			    &tq->tq_lock, ddi_get_lbolt() + hz);
119 			tq->tq_maxalloc_wait--;
120 			if (rv > 0)
121 				goto again;		/* signaled */
122 		}
123 		mutex_exit(&tq->tq_lock);
124 
125 		t = kmem_alloc(sizeof (taskq_ent_t), tqflags);
126 
127 		mutex_enter(&tq->tq_lock);
128 		if (t != NULL)
129 			tq->tq_nalloc++;
130 	}
131 	return (t);
132 }
133 
134 static void
135 task_free(taskq_t *tq, taskq_ent_t *t)
136 {
137 	if (tq->tq_nalloc <= tq->tq_minalloc) {
138 		t->tqent_next = tq->tq_freelist;
139 		tq->tq_freelist = t;
140 	} else {
141 		tq->tq_nalloc--;
142 		mutex_exit(&tq->tq_lock);
143 		kmem_free(t, sizeof (taskq_ent_t));
144 		mutex_enter(&tq->tq_lock);
145 	}
146 
147 	if (tq->tq_maxalloc_wait)
148 		cv_signal(&tq->tq_maxalloc_cv);
149 }
150 
151 taskqid_t
152 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
153 {
154 	taskq_ent_t *t;
155 
156 	if (taskq_now) {
157 		func(arg);
158 		return (1);
159 	}
160 
161 	mutex_enter(&tq->tq_lock);
162 	ASSERT(tq->tq_flags & TASKQ_ACTIVE);
163 	if ((t = task_alloc(tq, tqflags)) == NULL) {
164 		mutex_exit(&tq->tq_lock);
165 		return (0);
166 	}
167 	if (tqflags & TQ_FRONT) {
168 		t->tqent_next = tq->tq_task.tqent_next;
169 		t->tqent_prev = &tq->tq_task;
170 	} else {
171 		t->tqent_next = &tq->tq_task;
172 		t->tqent_prev = tq->tq_task.tqent_prev;
173 	}
174 	t->tqent_next->tqent_prev = t;
175 	t->tqent_prev->tqent_next = t;
176 	t->tqent_func = func;
177 	t->tqent_arg = arg;
178 	t->tqent_flags = 0;
179 	cv_signal(&tq->tq_dispatch_cv);
180 	mutex_exit(&tq->tq_lock);
181 	return (1);
182 }
183 
184 void
185 taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
186     taskq_ent_t *t)
187 {
188 	ASSERT(func != NULL);
189 	ASSERT(!(tq->tq_flags & TASKQ_DYNAMIC));
190 
191 	/*
192 	 * Mark it as a prealloc'd task.  This is important
193 	 * to ensure that we don't free it later.
194 	 */
195 	t->tqent_flags |= TQENT_FLAG_PREALLOC;
196 	/*
197 	 * Enqueue the task to the underlying queue.
198 	 */
199 	mutex_enter(&tq->tq_lock);
200 
201 	if (flags & TQ_FRONT) {
202 		t->tqent_next = tq->tq_task.tqent_next;
203 		t->tqent_prev = &tq->tq_task;
204 	} else {
205 		t->tqent_next = &tq->tq_task;
206 		t->tqent_prev = tq->tq_task.tqent_prev;
207 	}
208 	t->tqent_next->tqent_prev = t;
209 	t->tqent_prev->tqent_next = t;
210 	t->tqent_func = func;
211 	t->tqent_arg = arg;
212 	cv_signal(&tq->tq_dispatch_cv);
213 	mutex_exit(&tq->tq_lock);
214 }
215 
216 boolean_t
217 taskq_empty(taskq_t *tq)
218 {
219 	boolean_t rv;
220 
221 	mutex_enter(&tq->tq_lock);
222 	rv = (tq->tq_task.tqent_next == &tq->tq_task) && (tq->tq_active == 0);
223 	mutex_exit(&tq->tq_lock);
224 
225 	return (rv);
226 }
227 
228 void
229 taskq_wait(taskq_t *tq)
230 {
231 	mutex_enter(&tq->tq_lock);
232 	while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0)
233 		cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
234 	mutex_exit(&tq->tq_lock);
235 }
236 
237 static void *
238 taskq_thread(void *arg)
239 {
240 	taskq_t *tq = arg;
241 	taskq_ent_t *t;
242 	boolean_t prealloc;
243 
244 	mutex_enter(&tq->tq_lock);
245 	while (tq->tq_flags & TASKQ_ACTIVE) {
246 		if ((t = tq->tq_task.tqent_next) == &tq->tq_task) {
247 			if (--tq->tq_active == 0)
248 				cv_broadcast(&tq->tq_wait_cv);
249 			cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
250 			tq->tq_active++;
251 			continue;
252 		}
253 		t->tqent_prev->tqent_next = t->tqent_next;
254 		t->tqent_next->tqent_prev = t->tqent_prev;
255 		t->tqent_next = NULL;
256 		t->tqent_prev = NULL;
257 		prealloc = t->tqent_flags & TQENT_FLAG_PREALLOC;
258 		mutex_exit(&tq->tq_lock);
259 
260 		rw_enter(&tq->tq_threadlock, RW_READER);
261 		t->tqent_func(t->tqent_arg);
262 		rw_exit(&tq->tq_threadlock);
263 
264 		mutex_enter(&tq->tq_lock);
265 		if (!prealloc)
266 			task_free(tq, t);
267 	}
268 	tq->tq_nthreads--;
269 	cv_broadcast(&tq->tq_wait_cv);
270 	mutex_exit(&tq->tq_lock);
271 	return (NULL);
272 }
273 
274 /*ARGSUSED*/
275 taskq_t *
276 taskq_create(const char *name, int nthr, pri_t pri, int minalloc,
277     int maxalloc, uint_t flags)
278 {
279 	return (taskq_create_proc(name, nthr, pri,
280 	    minalloc, maxalloc, NULL, flags));
281 }
282 
283 /*ARGSUSED*/
284 taskq_t *
285 taskq_create_sysdc(const char *name, int nthr, int minalloc,
286     int maxalloc, proc_t *proc, uint_t dc, uint_t flags)
287 {
288 	return (taskq_create_proc(name, nthr, maxclsyspri,
289 	    minalloc, maxalloc, proc, flags));
290 }
291 
292 /*ARGSUSED*/
293 taskq_t *
294 taskq_create_proc(const char *name, int nthreads, pri_t pri,
295     int minalloc, int maxalloc, proc_t *proc, uint_t flags)
296 {
297 	taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
298 	int t;
299 
300 	if (flags & TASKQ_THREADS_CPU_PCT) {
301 		int pct;
302 		ASSERT3S(nthreads, >=, 0);
303 		ASSERT3S(nthreads, <=, 100);
304 		pct = MIN(nthreads, 100);
305 		pct = MAX(pct, 0);
306 
307 		nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100;
308 		nthreads = MAX(nthreads, 1);	/* need at least 1 thread */
309 	} else {
310 		ASSERT3S(nthreads, >=, 1);
311 	}
312 
313 	rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
314 	mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL);
315 	cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL);
316 	cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL);
317 	cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL);
318 	tq->tq_flags = flags | TASKQ_ACTIVE;
319 	tq->tq_active = nthreads;
320 	tq->tq_nthreads = nthreads;
321 	tq->tq_minalloc = minalloc;
322 	tq->tq_maxalloc = maxalloc;
323 	tq->tq_task.tqent_next = &tq->tq_task;
324 	tq->tq_task.tqent_prev = &tq->tq_task;
325 	tq->tq_threadlist = kmem_alloc(nthreads * sizeof (thread_t), KM_SLEEP);
326 
327 	if (flags & TASKQ_PREPOPULATE) {
328 		mutex_enter(&tq->tq_lock);
329 		while (minalloc-- > 0)
330 			task_free(tq, task_alloc(tq, KM_SLEEP));
331 		mutex_exit(&tq->tq_lock);
332 	}
333 
334 	for (t = 0; t < nthreads; t++)
335 		(void) thr_create(0, 0, taskq_thread,
336 		    tq, THR_BOUND, &tq->tq_threadlist[t]);
337 
338 	return (tq);
339 }
340 
341 void
342 taskq_destroy(taskq_t *tq)
343 {
344 	int t;
345 	int nthreads = tq->tq_nthreads;
346 
347 	taskq_wait(tq);
348 
349 	mutex_enter(&tq->tq_lock);
350 
351 	tq->tq_flags &= ~TASKQ_ACTIVE;
352 	cv_broadcast(&tq->tq_dispatch_cv);
353 
354 	while (tq->tq_nthreads != 0)
355 		cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
356 
357 	tq->tq_minalloc = 0;
358 	while (tq->tq_nalloc != 0) {
359 		ASSERT(tq->tq_freelist != NULL);
360 		task_free(tq, task_alloc(tq, KM_SLEEP));
361 	}
362 
363 	mutex_exit(&tq->tq_lock);
364 
365 	for (t = 0; t < nthreads; t++)
366 		(void) thr_join(tq->tq_threadlist[t], NULL, NULL);
367 
368 	kmem_free(tq->tq_threadlist, nthreads * sizeof (thread_t));
369 
370 	rw_destroy(&tq->tq_threadlock);
371 	mutex_destroy(&tq->tq_lock);
372 	cv_destroy(&tq->tq_dispatch_cv);
373 	cv_destroy(&tq->tq_wait_cv);
374 	cv_destroy(&tq->tq_maxalloc_cv);
375 
376 	kmem_free(tq, sizeof (taskq_t));
377 }
378 
379 int
380 taskq_member(taskq_t *tq, struct _kthread *t)
381 {
382 	int i;
383 
384 	if (taskq_now)
385 		return (1);
386 
387 	for (i = 0; i < tq->tq_nthreads; i++)
388 		if (tq->tq_threadlist[i] == (thread_t)(uintptr_t)t)
389 			return (1);
390 
391 	return (0);
392 }
393 
394 void
395 system_taskq_init(void)
396 {
397 	system_taskq = taskq_create("system_taskq", 64, minclsyspri, 4, 512,
398 	    TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
399 }
400 
401 void
402 system_taskq_fini(void)
403 {
404 	taskq_destroy(system_taskq);
405 	system_taskq = NULL; /* defensive */
406 }
407