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 /*
23 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26 /*
27 * Copyright (c) 2013, Joyent, Inc. All rights reserved.
28 */
29
30 #include <sys/cmn_err.h>
31 #include <sys/ddi_timer.h>
32 #include <sys/id_space.h>
33 #include <sys/kobj.h>
34 #include <sys/sysmacros.h>
35 #include <sys/systm.h>
36 #include <sys/taskq.h>
37 #include <sys/taskq_impl.h>
38 #include <sys/time.h>
39 #include <sys/types.h>
40 #include <sys/sdt.h>
41
42 /*
43 * The ddi_periodic_add(9F) Implementation
44 *
45 * This file contains the implementation of the ddi_periodic_add(9F) interface.
46 * It is a thin wrapper around the cyclic subsystem (see documentation in
47 * uts/common/os/cyclic.c), providing a DDI interface for registering
48 * (and unregistering) callbacks for periodic invocation at arbitrary
49 * interrupt levels, or in kernel context.
50 *
51 * Each call to ddi_periodic_add will result in a new opaque handle, as
52 * allocated from an id_space, a new "periodic" object (ddi_periodic_impl_t)
53 * and a registered cyclic.
54 *
55 * Operation
56 *
57 * Whenever the cyclic fires, our cyclic handler checks that the particular
58 * periodic is not dispatched already (we do not support overlapping execution
59 * of the consumer's handler function), and not yet cancelled. If both of
60 * these conditions hold, we mark the periodic as DPF_DISPATCHED and enqueue it
61 * to either the taskq (for DDI_IPL_0) or to one of the soft interrupt queues
62 * (DDI_IPL_1 to DDI_IPL_10).
63 *
64 * While the taskq (or soft interrupt handler) is handling a particular
65 * periodic, we mark it as DPF_EXECUTING. When complete, we reset both
66 * DPF_DISPATCHED and DPF_EXECUTING.
67 *
68 * Cancellation
69 *
70 * ddi_periodic_delete(9F) historically had spectacularly loose semantics with
71 * respect to cancellation concurrent with handler execution. These semantics
72 * are now tighter:
73 *
74 * 1. At most one invocation of ddi_periodic_delete(9F) will actually
75 * perform the deletion, all others will return immediately.
76 * 2. The invocation that performs the deletion will _block_ until
77 * the handler is no longer running, and all resources have been
78 * released.
79 *
80 * We affect this model by removing the cancelling periodic from the
81 * global list and marking it DPF_CANCELLED. This will prevent further
82 * execution of the handler. We then wait on a CV until the DPF_EXECUTING
83 * and DPF_DISPATCHED flags are clear, which means the periodic is removed
84 * from all request queues, is no longer executing, and may be freed. At this
85 * point we return the opaque ID to the id_space and free the memory.
86 *
87 * NOTE:
88 * The ddi_periodic_add(9F) interface is presently limited to a minimum period
89 * of 10ms between firings.
90 */
91
92 /*
93 * Tuneables:
94 */
95 int ddi_periodic_max_id = 1024;
96 int ddi_periodic_taskq_threadcount = 4;
97 hrtime_t ddi_periodic_resolution = 10000000;
98
99 /*
100 * Globals:
101 */
102 static kmem_cache_t *periodic_cache;
103 static id_space_t *periodic_id_space;
104 static taskq_t *periodic_taskq;
105
106 /*
107 * periodics_lock protects the list of all periodics (periodics), and
108 * each of the soft interrupt request queues (periodic_softint_queue).
109 *
110 * Do not hold an individual periodic's lock while obtaining periodics_lock.
111 * While in the periodic_softint_queue list, the periodic will be marked
112 * DPF_DISPATCHED, and thus safe from frees. Only the invocation of
113 * i_untimeout() that removes the periodic from the global list is allowed
114 * to free it.
115 */
116 static kmutex_t periodics_lock;
117 static list_t periodics;
118 static list_t periodic_softint_queue[10]; /* for IPL1 up to IPL10 */
119
120 typedef enum periodic_ipl {
121 PERI_IPL_0 = 0,
122 PERI_IPL_1,
123 PERI_IPL_2,
124 PERI_IPL_3,
125 PERI_IPL_4,
126 PERI_IPL_5,
127 PERI_IPL_6,
128 PERI_IPL_7,
129 PERI_IPL_8,
130 PERI_IPL_9,
131 PERI_IPL_10,
132 } periodic_ipl_t;
133
134 /*
135 * This function may be called either from a soft interrupt handler
136 * (ddi_periodic_softintr), or as a taskq worker function.
137 */
138 static void
139 periodic_execute(void *arg)
140 {
141 ddi_periodic_impl_t *dpr = arg;
142 mutex_enter(&dpr->dpr_lock);
143
144 /*
145 * We must be DISPATCHED, but not yet EXECUTING:
146 */
147 VERIFY((dpr->dpr_flags & (DPF_DISPATCHED | DPF_EXECUTING)) ==
148 DPF_DISPATCHED);
149
150 if (!(dpr->dpr_flags & DPF_CANCELLED)) {
151 int level = dpr->dpr_level;
152 uint64_t count = dpr->dpr_fire_count;
153 /*
154 * If we have not yet been cancelled, then
155 * mark us executing:
156 */
157 dpr->dpr_flags |= DPF_EXECUTING;
158 mutex_exit(&dpr->dpr_lock);
159
160 /*
161 * Execute the handler, without holding locks:
162 */
163 DTRACE_PROBE4(ddi__periodic__execute, void *, dpr->dpr_handler,
164 void *, dpr->dpr_arg, int, level, uint64_t, count);
165 (*dpr->dpr_handler)(dpr->dpr_arg);
166 DTRACE_PROBE4(ddi__periodic__done, void *, dpr->dpr_handler,
167 void *, dpr->dpr_arg, int, level, uint64_t, count);
168
169 mutex_enter(&dpr->dpr_lock);
170 dpr->dpr_fire_count++;
171 }
172
173 /*
174 * We're done with this periodic for now, so release it and
175 * wake anybody that was waiting for us to be finished:
176 */
177 dpr->dpr_flags &= ~(DPF_DISPATCHED | DPF_EXECUTING);
178 cv_broadcast(&dpr->dpr_cv);
179 mutex_exit(&dpr->dpr_lock);
180 }
181
182 void
183 ddi_periodic_softintr(int level)
184 {
185 ddi_periodic_impl_t *dpr;
186 VERIFY(level >= PERI_IPL_1 && level <= PERI_IPL_10);
187
188 mutex_enter(&periodics_lock);
189 /*
190 * Pull the first scheduled periodic off the queue for this priority
191 * level:
192 */
193 while ((dpr = list_remove_head(&periodic_softint_queue[level - 1]))
194 != NULL) {
195 mutex_exit(&periodics_lock);
196 /*
197 * And execute it:
198 */
199 periodic_execute(dpr);
200 mutex_enter(&periodics_lock);
201 }
202 mutex_exit(&periodics_lock);
203 }
204
205 void
206 ddi_periodic_init(void)
207 {
208 int i;
209
210 /*
211 * Create a kmem_cache for request tracking objects, and a list
212 * to store them in so we can later delete based on opaque handles:
213 */
214 periodic_cache = kmem_cache_create("ddi_periodic",
215 sizeof (ddi_periodic_impl_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
216 list_create(&periodics, sizeof (ddi_periodic_impl_t),
217 offsetof(ddi_periodic_impl_t, dpr_link));
218
219 /*
220 * Initialise the identifier space for ddi_periodic_add(9F):
221 */
222 periodic_id_space = id_space_create("ddi_periodic", 1,
223 ddi_periodic_max_id);
224
225 /*
226 * Initialise the request queue for each soft interrupt level:
227 */
228 for (i = PERI_IPL_1; i <= PERI_IPL_10; i++) {
229 list_create(&periodic_softint_queue[i - 1],
230 sizeof (ddi_periodic_impl_t), offsetof(ddi_periodic_impl_t,
231 dpr_softint_link));
232 }
233
234 /*
235 * Create the taskq for running PERI_IPL_0 handlers. This taskq will
236 * _only_ be used with taskq_dispatch_ent(), and a taskq_ent_t
237 * pre-allocated with the ddi_periodic_impl_t.
238 */
239 periodic_taskq = taskq_create_instance("ddi_periodic_taskq", -1,
240 ddi_periodic_taskq_threadcount, maxclsyspri, 0, 0, 0);
241
242 /*
243 * Initialize the mutex lock used for the soft interrupt request
244 * queues.
245 */
246 mutex_init(&periodics_lock, NULL, MUTEX_ADAPTIVE, NULL);
247 }
248
249 static void
250 periodic_cyclic_handler(void *arg)
251 {
252 extern void sir_on(int);
253 ddi_periodic_impl_t *dpr = arg;
254
255 mutex_enter(&dpr->dpr_lock);
256 /*
257 * If we've been cancelled, or we're already dispatched, then exit
258 * immediately:
259 */
260 if (dpr->dpr_flags & (DPF_CANCELLED | DPF_DISPATCHED)) {
261 mutex_exit(&dpr->dpr_lock);
262 return;
263 }
264 VERIFY(!(dpr->dpr_flags & DPF_EXECUTING));
265
266 /*
267 * This periodic is not presently dispatched, so dispatch it now:
268 */
269 dpr->dpr_flags |= DPF_DISPATCHED;
270 mutex_exit(&dpr->dpr_lock);
271
272 if (dpr->dpr_level == PERI_IPL_0) {
273 /*
274 * DDI_IPL_0 periodics are dispatched onto the taskq:
275 */
276 taskq_dispatch_ent(periodic_taskq, periodic_execute,
277 dpr, 0, &dpr->dpr_taskq_ent);
278 } else {
279 /*
280 * Higher priority periodics are handled by a soft
281 * interrupt handler. Enqueue us for processing and
282 * fire the soft interrupt:
283 */
284 mutex_enter(&periodics_lock);
285 list_insert_tail(&periodic_softint_queue[dpr->dpr_level - 1],
286 dpr);
287 mutex_exit(&periodics_lock);
288
289 /*
290 * Raise the soft interrupt level for this periodic:
291 */
292 sir_on(dpr->dpr_level);
293 }
294 }
295
296 static void
297 periodic_destroy(ddi_periodic_impl_t *dpr)
298 {
299 if (dpr == NULL)
300 return;
301
302 /*
303 * By now, we should have a periodic that is not busy, and has been
304 * cancelled:
305 */
306 VERIFY(dpr->dpr_flags == DPF_CANCELLED);
307
308 id_free(periodic_id_space, dpr->dpr_id);
309 kmem_cache_free(periodic_cache, dpr);
310 }
311
312 static ddi_periodic_impl_t *
313 periodic_create(void)
314 {
315 ddi_periodic_impl_t *dpr;
316
317 dpr = kmem_cache_alloc(periodic_cache, KM_SLEEP);
318 bzero(dpr, sizeof (*dpr));
319 dpr->dpr_id = id_alloc(periodic_id_space);
320 mutex_init(&dpr->dpr_lock, NULL, MUTEX_ADAPTIVE, NULL);
321 cv_init(&dpr->dpr_cv, NULL, CV_DEFAULT, NULL);
322
323 return (dpr);
324 }
325
326 timeout_t
327 i_timeout(void (*func)(void *), void *arg, hrtime_t interval, int level)
328 {
329 cyc_handler_t cyh;
330 cyc_time_t cyt;
331 ddi_periodic_impl_t *dpr;
332
333 VERIFY(func != NULL);
334 VERIFY(level >= 0 && level <= 10);
335
336 /*
337 * Allocate object to track this periodic:
338 */
339 dpr = periodic_create();
340 dpr->dpr_level = level;
341 dpr->dpr_handler = func;
342 dpr->dpr_arg = arg;
343
344 /*
345 * The resolution must be finer than or equal to
346 * the requested interval. If it's not, set the resolution
347 * to the interval.
348 * Note. There is a restriction currently. Regardless of the
349 * clock resolution used here, 10ms is set as the timer resolution.
350 * Even on the 1ms resolution timer, the minimum interval is 10ms.
351 */
352 if (ddi_periodic_resolution > interval) {
353 uintptr_t pc = (uintptr_t)dpr->dpr_handler;
354 ulong_t off;
355 cmn_err(CE_WARN,
356 "The periodic timeout (handler=%s, interval=%lld) "
357 "requests a finer interval than the supported resolution. "
358 "It rounds up to %lld\n", kobj_getsymname(pc, &off),
359 interval, ddi_periodic_resolution);
360 interval = ddi_periodic_resolution;
361 }
362
363 /*
364 * If the specified interval is already multiples of
365 * the resolution, use it as is. Otherwise, it rounds
366 * up to multiples of the timer resolution.
367 */
368 dpr->dpr_interval = roundup(interval, ddi_periodic_resolution);
369
370 /*
371 * Create the underlying cyclic:
372 */
373 cyh.cyh_func = periodic_cyclic_handler;
374 cyh.cyh_arg = dpr;
375 cyh.cyh_level = CY_LOCK_LEVEL;
376
377 cyt.cyt_when = roundup(gethrtime() + dpr->dpr_interval,
378 ddi_periodic_resolution);
379 cyt.cyt_interval = dpr->dpr_interval;
380
381 mutex_enter(&cpu_lock);
382 dpr->dpr_cyclic_id = cyclic_add(&cyh, &cyt);
383 mutex_exit(&cpu_lock);
384
385 /*
386 * Make the id visible to ddi_periodic_delete(9F) before we
387 * return it:
388 */
389 mutex_enter(&periodics_lock);
390 list_insert_tail(&periodics, dpr);
391 mutex_exit(&periodics_lock);
392
393 return ((timeout_t)(uintptr_t)dpr->dpr_id);
394 }
395
396 /*
397 * void
398 * i_untimeout(timeout_t req)
399 *
400 * Overview
401 * i_untimeout() is an internal function canceling the i_timeout()
402 * request previously issued.
403 * This function is used for ddi_periodic_delete(9F).
404 *
405 * Argument
406 * req: timeout_t opaque value i_timeout() returned previously.
407 *
408 * Return value
409 * Nothing.
410 *
411 * Caller's context
412 * i_untimeout() can be called in user, kernel or interrupt context.
413 * It cannot be called in high interrupt context.
414 *
415 * Note. This function is used by ddi_periodic_delete(), which cannot
416 * be called in interrupt context. As a result, this function is called
417 * in user or kernel context only in practice.
418 */
419 void
420 i_untimeout(timeout_t id)
421 {
422 ddi_periodic_impl_t *dpr;
423
424 /*
425 * Find the periodic in the list of all periodics and remove it.
426 * If we find in (and remove it from) the global list, we have
427 * license to free it once it is no longer busy.
428 */
429 mutex_enter(&periodics_lock);
430 for (dpr = list_head(&periodics); dpr != NULL; dpr =
431 list_next(&periodics, dpr)) {
432 if (dpr->dpr_id == (id_t)(uintptr_t)id) {
433 list_remove(&periodics, dpr);
434 break;
435 }
436 }
437 mutex_exit(&periodics_lock);
438
439 /*
440 * We could not find a periodic for this id, so bail out:
441 */
442 if (dpr == NULL)
443 return;
444
445 mutex_enter(&dpr->dpr_lock);
446 /*
447 * We should be the only one trying to cancel this periodic:
448 */
449 VERIFY(!(dpr->dpr_flags & DPF_CANCELLED));
450 /*
451 * Mark the periodic as cancelled:
452 */
453 dpr->dpr_flags |= DPF_CANCELLED;
454 mutex_exit(&dpr->dpr_lock);
455
456 /*
457 * Cancel our cyclic. cyclic_remove() guarantees that the cyclic
458 * handler will not run again after it returns. Note that the cyclic
459 * handler merely _dispatches_ the periodic, so this does _not_ mean
460 * the periodic handler is also finished running.
461 */
462 mutex_enter(&cpu_lock);
463 cyclic_remove(dpr->dpr_cyclic_id);
464 mutex_exit(&cpu_lock);
465
466 /*
467 * Wait until the periodic handler is no longer running:
468 */
469 mutex_enter(&dpr->dpr_lock);
470 while (dpr->dpr_flags & (DPF_DISPATCHED | DPF_EXECUTING)) {
471 cv_wait(&dpr->dpr_cv, &dpr->dpr_lock);
472 }
473 mutex_exit(&dpr->dpr_lock);
474
475 periodic_destroy(dpr);
476 }