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 https://opensource.org/licenses/CDDL-1.0.
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/types.h>
27 #include <sys/param.h>
28 #include <sys/time.h>
29 #include <sys/sysmacros.h>
30 #include <sys/systm.h>
31 #include <sys/proc.h>
32 #include <sys/mutex.h>
33 #include <sys/condvar.h>
34 #include <sys/callb.h>
35 #include <sys/kmem.h>
36 #include <sys/cmn_err.h>
37 #include <sys/debug.h>
38 #include <sys/kobj.h>
39 #include <sys/systm.h> /* for delay() */
40 #include <sys/taskq.h> /* For TASKQ_NAMELEN */
41 #include <sys/kernel.h>
42
43 #define CB_MAXNAME TASKQ_NAMELEN
44
45 /*
46 * The callb mechanism provides generic event scheduling/echoing.
47 * A callb function is registered and called on behalf of the event.
48 */
49 typedef struct callb {
50 struct callb *c_next; /* next in class or on freelist */
51 kthread_id_t c_thread; /* ptr to caller's thread struct */
52 char c_flag; /* info about the callb state */
53 uchar_t c_class; /* this callb's class */
54 kcondvar_t c_done_cv; /* signal callb completion */
55 boolean_t (*c_func)(void *, int);
56 /* cb function: returns true if ok */
57 void *c_arg; /* arg to c_func */
58 char c_name[CB_MAXNAME+1]; /* debug:max func name length */
59 } callb_t;
60
61 /*
62 * callb c_flag bitmap definitions
63 */
64 #define CALLB_FREE 0x0
65 #define CALLB_TAKEN 0x1
66 #define CALLB_EXECUTING 0x2
67
68 /*
69 * Basic structure for a callb table.
70 * All callbs are organized into different class groups described
71 * by ct_class array.
72 * The callbs within a class are single-linked and normally run by a
73 * serial execution.
74 */
75 typedef struct callb_table {
76 kmutex_t ct_lock; /* protect all callb states */
77 callb_t *ct_freelist; /* free callb structures */
78 boolean_t ct_busy; /* B_TRUE prevents additions */
79 kcondvar_t ct_busy_cv; /* to wait for not busy */
80 int ct_ncallb; /* num of callbs allocated */
81 callb_t *ct_first_cb[NCBCLASS]; /* ptr to 1st callb in a class */
82 } callb_table_t;
83
84 int callb_timeout_sec = CPR_KTHREAD_TIMEOUT_SEC;
85
86 static callb_id_t callb_add_common(boolean_t (*)(void *, int),
87 void *, int, char *, kthread_id_t);
88
89 static callb_table_t callb_table; /* system level callback table */
90 static callb_table_t *ct = &callb_table;
91 static kmutex_t callb_safe_mutex;
92 callb_cpr_t callb_cprinfo_safe = {
93 &callb_safe_mutex, CALLB_CPR_ALWAYS_SAFE, 0, {0, 0} };
94
95 /*
96 * Init all callb tables in the system.
97 */
98 static void
callb_init(void * dummy __unused)99 callb_init(void *dummy __unused)
100 {
101 callb_table.ct_busy = B_FALSE; /* mark table open for additions */
102 mutex_init(&callb_safe_mutex, NULL, MUTEX_DEFAULT, NULL);
103 mutex_init(&callb_table.ct_lock, NULL, MUTEX_DEFAULT, NULL);
104 }
105
106 static void
callb_fini(void * dummy __unused)107 callb_fini(void *dummy __unused)
108 {
109 callb_t *cp;
110 int i;
111
112 mutex_enter(&ct->ct_lock);
113 for (i = 0; i < 16; i++) {
114 while ((cp = ct->ct_freelist) != NULL) {
115 ct->ct_freelist = cp->c_next;
116 ct->ct_ncallb--;
117 kmem_free(cp, sizeof (callb_t));
118 }
119 if (ct->ct_ncallb == 0)
120 break;
121 /* Not all callbacks finished, waiting for the rest. */
122 mutex_exit(&ct->ct_lock);
123 tsleep(ct, 0, "callb", hz / 4);
124 mutex_enter(&ct->ct_lock);
125 }
126 if (ct->ct_ncallb > 0)
127 printf("%s: Leaked %d callbacks!\n", __func__, ct->ct_ncallb);
128 mutex_exit(&ct->ct_lock);
129 mutex_destroy(&callb_safe_mutex);
130 mutex_destroy(&callb_table.ct_lock);
131 }
132
133 /*
134 * callout_add() is called to register func() be called later.
135 */
136 static callb_id_t
callb_add_common(boolean_t (* func)(void * arg,int code),void * arg,int class,char * name,kthread_id_t t)137 callb_add_common(boolean_t (*func)(void *arg, int code),
138 void *arg, int class, char *name, kthread_id_t t)
139 {
140 callb_t *cp;
141
142 ASSERT3S(class, <, NCBCLASS);
143
144 mutex_enter(&ct->ct_lock);
145 while (ct->ct_busy)
146 cv_wait(&ct->ct_busy_cv, &ct->ct_lock);
147 if ((cp = ct->ct_freelist) == NULL) {
148 ct->ct_ncallb++;
149 cp = kmem_zalloc(sizeof (callb_t), KM_SLEEP);
150 }
151 ct->ct_freelist = cp->c_next;
152 cp->c_thread = t;
153 cp->c_func = func;
154 cp->c_arg = arg;
155 cp->c_class = (uchar_t)class;
156 cp->c_flag |= CALLB_TAKEN;
157 #ifdef ZFS_DEBUG
158 if (strlen(name) > CB_MAXNAME)
159 cmn_err(CE_WARN, "callb_add: name of callback function '%s' "
160 "too long -- truncated to %d chars",
161 name, CB_MAXNAME);
162 #endif
163 (void) strlcpy(cp->c_name, name, sizeof (cp->c_name));
164
165 /*
166 * Insert the new callb at the head of its class list.
167 */
168 cp->c_next = ct->ct_first_cb[class];
169 ct->ct_first_cb[class] = cp;
170
171 mutex_exit(&ct->ct_lock);
172 return ((callb_id_t)cp);
173 }
174
175 /*
176 * The default function to add an entry to the callback table. Since
177 * it uses curthread as the thread identifier to store in the table,
178 * it should be used for the normal case of a thread which is calling
179 * to add ITSELF to the table.
180 */
181 callb_id_t
callb_add(boolean_t (* func)(void * arg,int code),void * arg,int class,char * name)182 callb_add(boolean_t (*func)(void *arg, int code),
183 void *arg, int class, char *name)
184 {
185 return (callb_add_common(func, arg, class, name, curthread));
186 }
187
188 /*
189 * A special version of callb_add() above for use by threads which
190 * might be adding an entry to the table on behalf of some other
191 * thread (for example, one which is constructed but not yet running).
192 * In this version the thread id is an argument.
193 */
194 callb_id_t
callb_add_thread(boolean_t (* func)(void * arg,int code),void * arg,int class,char * name,kthread_id_t t)195 callb_add_thread(boolean_t (*func)(void *arg, int code),
196 void *arg, int class, char *name, kthread_id_t t)
197 {
198 return (callb_add_common(func, arg, class, name, t));
199 }
200
201 /*
202 * callout_delete() is called to remove an entry identified by id
203 * that was originally placed there by a call to callout_add().
204 * return -1 if fail to delete a callb entry otherwise return 0.
205 */
206 int
callb_delete(callb_id_t id)207 callb_delete(callb_id_t id)
208 {
209 callb_t **pp;
210 callb_t *me = (callb_t *)id;
211
212 mutex_enter(&ct->ct_lock);
213
214 for (;;) {
215 pp = &ct->ct_first_cb[me->c_class];
216 while (*pp != NULL && *pp != me)
217 pp = &(*pp)->c_next;
218
219 #ifdef ZFS_DEBUG
220 if (*pp != me) {
221 cmn_err(CE_WARN, "callb delete bogus entry 0x%p",
222 (void *)me);
223 mutex_exit(&ct->ct_lock);
224 return (-1);
225 }
226 #endif /* DEBUG */
227
228 /*
229 * It is not allowed to delete a callb in the middle of
230 * executing otherwise, the callb_execute() will be confused.
231 */
232 if (!(me->c_flag & CALLB_EXECUTING))
233 break;
234
235 cv_wait(&me->c_done_cv, &ct->ct_lock);
236 }
237 /* relink the class list */
238 *pp = me->c_next;
239
240 /* clean up myself and return the free callb to the head of freelist */
241 me->c_flag = CALLB_FREE;
242 me->c_next = ct->ct_freelist;
243 ct->ct_freelist = me;
244
245 mutex_exit(&ct->ct_lock);
246 return (0);
247 }
248
249 /*
250 * class: indicates to execute all callbs in the same class;
251 * code: optional argument for the callb functions.
252 * return: = 0: success
253 * != 0: ptr to string supplied when callback was registered
254 */
255 void *
callb_execute_class(int class,int code)256 callb_execute_class(int class, int code)
257 {
258 callb_t *cp;
259 void *ret = NULL;
260
261 ASSERT3S(class, <, NCBCLASS);
262
263 mutex_enter(&ct->ct_lock);
264
265 for (cp = ct->ct_first_cb[class];
266 cp != NULL && ret == NULL; cp = cp->c_next) {
267 while (cp->c_flag & CALLB_EXECUTING)
268 cv_wait(&cp->c_done_cv, &ct->ct_lock);
269 /*
270 * cont if the callb is deleted while we're sleeping
271 */
272 if (cp->c_flag == CALLB_FREE)
273 continue;
274 cp->c_flag |= CALLB_EXECUTING;
275
276 #ifdef CALLB_DEBUG
277 printf("callb_execute: name=%s func=%p arg=%p\n",
278 cp->c_name, (void *)cp->c_func, (void *)cp->c_arg);
279 #endif /* CALLB_DEBUG */
280
281 mutex_exit(&ct->ct_lock);
282 /* If callback function fails, pass back client's name */
283 if (!(*cp->c_func)(cp->c_arg, code))
284 ret = cp->c_name;
285 mutex_enter(&ct->ct_lock);
286
287 cp->c_flag &= ~CALLB_EXECUTING;
288 cv_broadcast(&cp->c_done_cv);
289 }
290 mutex_exit(&ct->ct_lock);
291 return (ret);
292 }
293
294 /*
295 * callers make sure no recursive entries to this func.
296 * dp->cc_lockp is registered by callb_add to protect callb_cpr_t structure.
297 *
298 * When calling to stop a kernel thread (code == CB_CODE_CPR_CHKPT) we
299 * use a cv_timedwait() in case the kernel thread is blocked.
300 *
301 * Note that this is a generic callback handler for daemon CPR and
302 * should NOT be changed to accommodate any specific requirement in a daemon.
303 * Individual daemons that require changes to the handler shall write
304 * callback routines in their own daemon modules.
305 */
306 boolean_t
callb_generic_cpr(void * arg,int code)307 callb_generic_cpr(void *arg, int code)
308 {
309 callb_cpr_t *cp = (callb_cpr_t *)arg;
310 clock_t ret = 0; /* assume success */
311
312 mutex_enter(cp->cc_lockp);
313
314 switch (code) {
315 case CB_CODE_CPR_CHKPT:
316 cp->cc_events |= CALLB_CPR_START;
317 #ifdef CPR_NOT_THREAD_SAFE
318 while (!(cp->cc_events & CALLB_CPR_SAFE))
319 /* cv_timedwait() returns -1 if it times out. */
320 if ((ret = cv_reltimedwait(&cp->cc_callb_cv,
321 cp->cc_lockp, (callb_timeout_sec * hz),
322 TR_CLOCK_TICK)) == -1)
323 break;
324 #endif
325 break;
326
327 case CB_CODE_CPR_RESUME:
328 cp->cc_events &= ~CALLB_CPR_START;
329 cv_signal(&cp->cc_stop_cv);
330 break;
331 }
332 mutex_exit(cp->cc_lockp);
333 return (ret != -1);
334 }
335
336 /*
337 * The generic callback function associated with kernel threads which
338 * are always considered safe.
339 */
340 boolean_t
callb_generic_cpr_safe(void * arg,int code)341 callb_generic_cpr_safe(void *arg, int code)
342 {
343 (void) arg, (void) code;
344 return (B_TRUE);
345 }
346 /*
347 * Prevent additions to callback table.
348 */
349 void
callb_lock_table(void)350 callb_lock_table(void)
351 {
352 mutex_enter(&ct->ct_lock);
353 ASSERT(!ct->ct_busy);
354 ct->ct_busy = B_TRUE;
355 mutex_exit(&ct->ct_lock);
356 }
357
358 /*
359 * Allow additions to callback table.
360 */
361 void
callb_unlock_table(void)362 callb_unlock_table(void)
363 {
364 mutex_enter(&ct->ct_lock);
365 ASSERT(ct->ct_busy);
366 ct->ct_busy = B_FALSE;
367 cv_broadcast(&ct->ct_busy_cv);
368 mutex_exit(&ct->ct_lock);
369 }
370
371 SYSINIT(sol_callb, SI_SUB_DRIVERS, SI_ORDER_FIRST, callb_init, NULL);
372 SYSUNINIT(sol_callb, SI_SUB_DRIVERS, SI_ORDER_FIRST, callb_fini, NULL);
373