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