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 2009 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 #include <sys/param.h>
27 #include <sys/t_lock.h>
28 #include <sys/types.h>
29 #include <sys/time.h>
30 #include <sys/sysmacros.h>
31 #include <sys/systm.h>
32 #include <sys/cpuvar.h>
33 #include <sys/user.h>
34 #include <sys/proc.h>
35 #include <sys/callb.h>
36 #include <sys/kmem.h>
37 #include <sys/cmn_err.h>
38 #include <sys/swap.h>
39 #include <sys/vmsystm.h>
40 #include <sys/class.h>
41 #include <sys/debug.h>
42 #include <sys/thread.h>
43 #include <sys/kobj.h>
44 #include <sys/ddi.h> /* for delay() */
45 #include <sys/taskq.h> /* For TASKQ_NAMELEN */
46
47 #define CB_MAXNAME TASKQ_NAMELEN
48
49 /*
50 * The callb mechanism provides generic event scheduling/echoing.
51 * A callb function is registered and called on behalf of the event.
52 */
53 typedef struct callb {
54 struct callb *c_next; /* next in class or on freelist */
55 kthread_id_t c_thread; /* ptr to caller's thread struct */
56 char c_flag; /* info about the callb state */
57 uchar_t c_class; /* this callb's class */
58 kcondvar_t c_done_cv; /* signal callb completion */
59 boolean_t (*c_func)(); /* cb function: returns true if ok */
60 void *c_arg; /* arg to c_func */
61 char c_name[CB_MAXNAME+1]; /* debug:max func name length */
62 } callb_t;
63
64 /*
65 * callb c_flag bitmap definitions
66 */
67 #define CALLB_FREE 0x0
68 #define CALLB_TAKEN 0x1
69 #define CALLB_EXECUTING 0x2
70
71 /*
72 * Basic structure for a callb table.
73 * All callbs are organized into different class groups described
74 * by ct_class array.
75 * The callbs within a class are single-linked and normally run by a
76 * serial execution.
77 */
78 typedef struct callb_table {
79 kmutex_t ct_lock; /* protect all callb states */
80 callb_t *ct_freelist; /* free callb structures */
81 int ct_busy; /* != 0 prevents additions */
82 kcondvar_t ct_busy_cv; /* to wait for not busy */
83 int ct_ncallb; /* num of callbs allocated */
84 callb_t *ct_first_cb[NCBCLASS]; /* ptr to 1st callb in a class */
85 } callb_table_t;
86
87 int callb_timeout_sec = CPR_KTHREAD_TIMEOUT_SEC;
88
89 static callb_id_t callb_add_common(boolean_t (*)(void *, int),
90 void *, int, char *, kthread_id_t);
91
92 static callb_table_t callb_table; /* system level callback table */
93 static callb_table_t *ct = &callb_table;
94 static kmutex_t callb_safe_mutex;
95 callb_cpr_t callb_cprinfo_safe = {
96 &callb_safe_mutex, CALLB_CPR_ALWAYS_SAFE, NULL, {0}, {0} };
97
98 /*
99 * Init all callb tables in the system.
100 */
101 void
102 callb_init()
103 {
104 callb_table.ct_busy = 0; /* mark table open for additions */
105 mutex_init(&callb_safe_mutex, NULL, MUTEX_DEFAULT, NULL);
106 mutex_init(&callb_table.ct_lock, NULL, MUTEX_DEFAULT, NULL);
107 }
108
109 /*
110 * callout_add() is called to register func() be called later.
111 */
112 static callb_id_t
113 callb_add_common(boolean_t (*func)(void *arg, int code),
114 void *arg, int class, char *name, kthread_id_t t)
115 {
116 callb_t *cp;
117
118 ASSERT(class < NCBCLASS);
119
120 mutex_enter(&ct->ct_lock);
121 while (ct->ct_busy)
122 cv_wait(&ct->ct_busy_cv, &ct->ct_lock);
123 if ((cp = ct->ct_freelist) == NULL) {
124 ct->ct_ncallb++;
125 cp = (callb_t *)kmem_zalloc(sizeof (callb_t), KM_SLEEP);
126 }
127 ct->ct_freelist = cp->c_next;
128 cp->c_thread = t;
129 cp->c_func = func;
130 cp->c_arg = arg;
131 cp->c_class = (uchar_t)class;
132 cp->c_flag |= CALLB_TAKEN;
133 #ifdef DEBUG
134 if (strlen(name) > CB_MAXNAME)
135 cmn_err(CE_WARN, "callb_add: name of callback function '%s' "
136 "too long -- truncated to %d chars",
137 name, CB_MAXNAME);
138 #endif
139 (void) strncpy(cp->c_name, name, CB_MAXNAME);
140 cp->c_name[CB_MAXNAME] = '\0';
141
142 /*
143 * Insert the new callb at the head of its class list.
144 */
145 cp->c_next = ct->ct_first_cb[class];
146 ct->ct_first_cb[class] = cp;
147
148 mutex_exit(&ct->ct_lock);
149 return ((callb_id_t)cp);
150 }
151
152 /*
153 * The default function to add an entry to the callback table. Since
154 * it uses curthread as the thread identifier to store in the table,
155 * it should be used for the normal case of a thread which is calling
156 * to add ITSELF to the table.
157 */
158 callb_id_t
159 callb_add(boolean_t (*func)(void *arg, int code),
160 void *arg, int class, char *name)
161 {
162 return (callb_add_common(func, arg, class, name, curthread));
163 }
164
165 /*
166 * A special version of callb_add() above for use by threads which
167 * might be adding an entry to the table on behalf of some other
168 * thread (for example, one which is constructed but not yet running).
169 * In this version the thread id is an argument.
170 */
171 callb_id_t
172 callb_add_thread(boolean_t (*func)(void *arg, int code),
173 void *arg, int class, char *name, kthread_id_t t)
174 {
175 return (callb_add_common(func, arg, class, name, t));
176 }
177
178 /*
179 * callout_delete() is called to remove an entry identified by id
180 * that was originally placed there by a call to callout_add().
181 * return -1 if fail to delete a callb entry otherwise return 0.
182 */
183 int
184 callb_delete(callb_id_t id)
185 {
186 callb_t **pp;
187 callb_t *me = (callb_t *)id;
188
189 mutex_enter(&ct->ct_lock);
190
191 for (;;) {
192 pp = &ct->ct_first_cb[me->c_class];
193 while (*pp != NULL && *pp != me)
194 pp = &(*pp)->c_next;
195
196 #ifdef DEBUG
197 if (*pp != me) {
198 cmn_err(CE_WARN, "callb delete bogus entry 0x%p",
199 (void *)me);
200 mutex_exit(&ct->ct_lock);
201 return (-1);
202 }
203 #endif /* DEBUG */
204
205 /*
206 * It is not allowed to delete a callb in the middle of
207 * executing otherwise, the callb_execute() will be confused.
208 */
209 if (!(me->c_flag & CALLB_EXECUTING))
210 break;
211
212 cv_wait(&me->c_done_cv, &ct->ct_lock);
213 }
214 /* relink the class list */
215 *pp = me->c_next;
216
217 /* clean up myself and return the free callb to the head of freelist */
218 me->c_flag = CALLB_FREE;
219 me->c_next = ct->ct_freelist;
220 ct->ct_freelist = me;
221
222 mutex_exit(&ct->ct_lock);
223 return (0);
224 }
225
226 /*
227 * class: indicates to execute all callbs in the same class;
228 * code: optional argument for the callb functions.
229 * return: = 0: success
230 * != 0: ptr to string supplied when callback was registered
231 */
232 void *
233 callb_execute_class(int class, int code)
234 {
235 callb_t *cp;
236 void *ret = NULL;
237
238 ASSERT(class < NCBCLASS);
239
240 mutex_enter(&ct->ct_lock);
241
242 for (cp = ct->ct_first_cb[class];
243 cp != NULL && ret == 0; cp = cp->c_next) {
244 while (cp->c_flag & CALLB_EXECUTING)
245 cv_wait(&cp->c_done_cv, &ct->ct_lock);
246 /*
247 * cont if the callb is deleted while we're sleeping
248 */
249 if (cp->c_flag == CALLB_FREE)
250 continue;
251 cp->c_flag |= CALLB_EXECUTING;
252
253 #ifdef CALLB_DEBUG
254 printf("callb_execute: name=%s func=%p arg=%p\n",
255 cp->c_name, (void *)cp->c_func, (void *)cp->c_arg);
256 #endif /* CALLB_DEBUG */
257
258 mutex_exit(&ct->ct_lock);
259 /* If callback function fails, pass back client's name */
260 if (!(*cp->c_func)(cp->c_arg, code))
261 ret = cp->c_name;
262 mutex_enter(&ct->ct_lock);
263
264 cp->c_flag &= ~CALLB_EXECUTING;
265 cv_broadcast(&cp->c_done_cv);
266 }
267 mutex_exit(&ct->ct_lock);
268 return (ret);
269 }
270
271 /*
272 * callers make sure no recursive entries to this func.
273 * dp->cc_lockp is registered by callb_add to protect callb_cpr_t structure.
274 *
275 * When calling to stop a kernel thread (code == CB_CODE_CPR_CHKPT) we
276 * use a cv_timedwait() in case the kernel thread is blocked.
277 *
278 * Note that this is a generic callback handler for daemon CPR and
279 * should NOT be changed to accommodate any specific requirement in a daemon.
280 * Individual daemons that require changes to the handler shall write
281 * callback routines in their own daemon modules.
282 */
283 boolean_t
284 callb_generic_cpr(void *arg, int code)
285 {
286 callb_cpr_t *cp = (callb_cpr_t *)arg;
287 clock_t ret = 0; /* assume success */
288
289 mutex_enter(cp->cc_lockp);
290
291 switch (code) {
292 case CB_CODE_CPR_CHKPT:
293 cp->cc_events |= CALLB_CPR_START;
294 #ifdef CPR_NOT_THREAD_SAFE
295 while (!(cp->cc_events & CALLB_CPR_SAFE))
296 /* cv_timedwait() returns -1 if it times out. */
297 if ((ret = cv_reltimedwait(&cp->cc_callb_cv,
298 cp->cc_lockp, (callb_timeout_sec * hz),
299 TR_CLOCK_TICK)) == -1)
300 break;
301 #endif
302 break;
303
304 case CB_CODE_CPR_RESUME:
305 cp->cc_events &= ~CALLB_CPR_START;
306 cv_signal(&cp->cc_stop_cv);
307 break;
308 }
309 mutex_exit(cp->cc_lockp);
310 return (ret != -1);
311 }
312
313 /*
314 * The generic callback function associated with kernel threads which
315 * are always considered safe.
316 */
317 /* ARGSUSED */
318 boolean_t
319 callb_generic_cpr_safe(void *arg, int code)
320 {
321 return (B_TRUE);
322 }
323 /*
324 * Prevent additions to callback table.
325 */
326 void
327 callb_lock_table(void)
328 {
329 mutex_enter(&ct->ct_lock);
330 ASSERT(ct->ct_busy == 0);
331 ct->ct_busy = 1;
332 mutex_exit(&ct->ct_lock);
333 }
334
335 /*
336 * Allow additions to callback table.
337 */
338 void
339 callb_unlock_table(void)
340 {
341 mutex_enter(&ct->ct_lock);
342 ASSERT(ct->ct_busy != 0);
343 ct->ct_busy = 0;
344 cv_broadcast(&ct->ct_busy_cv);
345 mutex_exit(&ct->ct_lock);
346 }
347
348 /*
349 * Return a boolean value indicating whether a particular kernel thread is
350 * stopped in accordance with the cpr callback protocol. If returning
351 * false, also return a pointer to the thread name via the 2nd argument.
352 */
353 boolean_t
354 callb_is_stopped(kthread_id_t tp, caddr_t *thread_name)
355 {
356 callb_t *cp;
357 boolean_t ret_val;
358
359 mutex_enter(&ct->ct_lock);
360
361 for (cp = ct->ct_first_cb[CB_CL_CPR_DAEMON];
362 cp != NULL && tp != cp->c_thread; cp = cp->c_next)
363 ;
364
365 ret_val = (cp != NULL);
366 if (ret_val) {
367 /*
368 * We found the thread in the callback table and have
369 * provisionally set the return value to true. Now
370 * see if it is marked "safe" and is sleeping or stopped.
371 */
372 callb_cpr_t *ccp = (callb_cpr_t *)cp->c_arg;
373
374 *thread_name = cp->c_name; /* in case not stopped */
375 mutex_enter(ccp->cc_lockp);
376
377 if (ccp->cc_events & CALLB_CPR_SAFE) {
378 int retry;
379
380 mutex_exit(ccp->cc_lockp);
381 for (retry = 0; retry < CALLB_MAX_RETRY; retry++) {
382 thread_lock(tp);
383 if (tp->t_state & (TS_SLEEP | TS_STOPPED)) {
384 thread_unlock(tp);
385 break;
386 }
387 thread_unlock(tp);
388 delay(CALLB_THREAD_DELAY);
389 }
390 ret_val = retry < CALLB_MAX_RETRY;
391 } else {
392 ret_val =
393 (ccp->cc_events & CALLB_CPR_ALWAYS_SAFE) != 0;
394 mutex_exit(ccp->cc_lockp);
395 }
396 } else {
397 /*
398 * Thread not found in callback table. Make the best
399 * attempt to identify the thread in the error message.
400 */
401 ulong_t offset;
402 char *sym = kobj_getsymname((uintptr_t)tp->t_startpc,
403 &offset);
404
405 *thread_name = sym ? sym : "*unknown*";
406 }
407
408 mutex_exit(&ct->ct_lock);
409 return (ret_val);
410 }