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 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 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 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 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 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 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 * 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 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 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 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 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