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sys/kern/kern_lock.c
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1 /* $NetBSD: kern_lock.c,v 1.102.2.2 2007/08/01 14:45:46 liamjfoy Exp $ */ 2 3 /*- 4 * Copyright (c) 1999, 2000 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 9 * NASA Ames Research Center. 10 * 11 * This code is derived from software contributed to The NetBSD Foundation 12 * by Ross Harvey. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the NetBSD 25 * Foundation, Inc. and its contributors. 26 * 4. Neither the name of The NetBSD Foundation nor the names of its 27 * contributors may be used to endorse or promote products derived 28 * from this software without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 31 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 32 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 33 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 34 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 35 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 36 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 37 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 38 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 39 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 40 * POSSIBILITY OF SUCH DAMAGE. 41 */ 42 43 /* 44 * Copyright (c) 1995 45 * The Regents of the University of California. All rights reserved. 46 * 47 * This code contains ideas from software contributed to Berkeley by 48 * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating 49 * System project at Carnegie-Mellon University. 50 * 51 * Redistribution and use in source and binary forms, with or without 52 * modification, are permitted provided that the following conditions 53 * are met: 54 * 1. Redistributions of source code must retain the above copyright 55 * notice, this list of conditions and the following disclaimer. 56 * 2. Redistributions in binary form must reproduce the above copyright 57 * notice, this list of conditions and the following disclaimer in the 58 * documentation and/or other materials provided with the distribution. 59 * 3. Neither the name of the University nor the names of its contributors 60 * may be used to endorse or promote products derived from this software 61 * without specific prior written permission. 62 * 63 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 64 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 65 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 66 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 67 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 68 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 69 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 70 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 71 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 72 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 73 * SUCH DAMAGE. 74 * 75 * @(#)kern_lock.c 8.18 (Berkeley) 5/21/95 76 */ 77 78 #include <sys/cdefs.h> 79 __KERNEL_RCSID(0, "$NetBSD: kern_lock.c,v 1.102.2.2 2007/08/01 14:45:46 liamjfoy Exp $"); 80 81 #include "opt_multiprocessor.h" 82 #include "opt_lockdebug.h" 83 #include "opt_ddb.h" 84 85 #include <sys/param.h> 86 #include <sys/proc.h> 87 #include <sys/lock.h> 88 #include <sys/systm.h> 89 #include <machine/cpu.h> 90 91 #include <dev/lockstat.h> 92 93 #if defined(LOCKDEBUG) 94 #include <sys/syslog.h> 95 /* 96 * note that stdarg.h and the ansi style va_start macro is used for both 97 * ansi and traditional c compiles. 98 * XXX: this requires that stdarg.h define: va_alist and va_dcl 99 */ 100 #include <machine/stdarg.h> 101 102 void lock_printf(const char *fmt, ...) 103 __attribute__((__format__(__printf__,1,2))); 104 105 static int acquire(volatile struct lock **, int *, int, int, int, uintptr_t ra); 106 107 int lock_debug_syslog = 0; /* defaults to printf, but can be patched */ 108 109 #ifdef DDB 110 #include <ddb/ddbvar.h> 111 #include <machine/db_machdep.h> 112 #include <ddb/db_command.h> 113 #include <ddb/db_interface.h> 114 #endif 115 #endif /* defined(LOCKDEBUG) */ 116 117 #if defined(MULTIPROCESSOR) 118 struct simplelock kernel_lock; 119 #endif 120 121 /* 122 * Locking primitives implementation. 123 * Locks provide shared/exclusive synchronization. 124 */ 125 126 #if defined(LOCKDEBUG) || defined(DIAGNOSTIC) /* { */ 127 #if defined(MULTIPROCESSOR) /* { */ 128 #define COUNT_CPU(cpu_id, x) \ 129 curcpu()->ci_spin_locks += (x) 130 #else 131 u_long spin_locks; 132 #define COUNT_CPU(cpu_id, x) spin_locks += (x) 133 #endif /* MULTIPROCESSOR */ /* } */ 134 135 #define COUNT(lkp, l, cpu_id, x) \ 136 do { \ 137 if ((lkp)->lk_flags & LK_SPIN) \ 138 COUNT_CPU((cpu_id), (x)); \ 139 else \ 140 (l)->l_locks += (x); \ 141 } while (/*CONSTCOND*/0) 142 #else 143 #define COUNT(lkp, p, cpu_id, x) 144 #define COUNT_CPU(cpu_id, x) 145 #endif /* LOCKDEBUG || DIAGNOSTIC */ /* } */ 146 147 #define INTERLOCK_ACQUIRE(lkp, flags, s) \ 148 do { \ 149 if ((flags) & LK_SPIN) \ 150 s = spllock(); \ 151 simple_lock(&(lkp)->lk_interlock); \ 152 } while (/*CONSTCOND*/ 0) 153 154 #define INTERLOCK_RELEASE(lkp, flags, s) \ 155 do { \ 156 simple_unlock(&(lkp)->lk_interlock); \ 157 if ((flags) & LK_SPIN) \ 158 splx(s); \ 159 } while (/*CONSTCOND*/ 0) 160 161 #ifdef DDB /* { */ 162 #if defined(MULTIPROCESSOR) || defined(LOCKDEBUG) 163 int simple_lock_debugger = 1; /* more serious on MP */ 164 #else 165 int simple_lock_debugger = 0; 166 #endif 167 #define SLOCK_DEBUGGER() if (simple_lock_debugger && db_onpanic) Debugger() 168 #define SLOCK_TRACE() \ 169 db_stack_trace_print((db_expr_t)__builtin_frame_address(0), \ 170 TRUE, 65535, "", lock_printf); 171 #else 172 #define SLOCK_DEBUGGER() /* nothing */ 173 #define SLOCK_TRACE() /* nothing */ 174 #endif /* } */ 175 176 #if defined(LOCKDEBUG) 177 #if defined(DDB) 178 #define SPINLOCK_SPINCHECK_DEBUGGER if (db_onpanic) Debugger() 179 #else 180 #define SPINLOCK_SPINCHECK_DEBUGGER /* nothing */ 181 #endif 182 183 #define SPINLOCK_SPINCHECK_DECL \ 184 /* 32-bits of count -- wrap constitutes a "spinout" */ \ 185 uint32_t __spinc = 0 186 187 #define SPINLOCK_SPINCHECK \ 188 do { \ 189 if (++__spinc == 0) { \ 190 lock_printf("LK_SPIN spinout, excl %d, share %d\n", \ 191 lkp->lk_exclusivecount, lkp->lk_sharecount); \ 192 if (lkp->lk_exclusivecount) \ 193 lock_printf("held by CPU %lu\n", \ 194 (u_long) lkp->lk_cpu); \ 195 if (lkp->lk_lock_file) \ 196 lock_printf("last locked at %s:%d\n", \ 197 lkp->lk_lock_file, lkp->lk_lock_line); \ 198 if (lkp->lk_unlock_file) \ 199 lock_printf("last unlocked at %s:%d\n", \ 200 lkp->lk_unlock_file, lkp->lk_unlock_line); \ 201 SLOCK_TRACE(); \ 202 SPINLOCK_SPINCHECK_DEBUGGER; \ 203 } \ 204 } while (/*CONSTCOND*/ 0) 205 #else 206 #define SPINLOCK_SPINCHECK_DECL /* nothing */ 207 #define SPINLOCK_SPINCHECK /* nothing */ 208 #endif /* LOCKDEBUG && DDB */ 209 210 #define RETURN_ADDRESS ((uintptr_t)__builtin_return_address(0)) 211 212 /* 213 * Acquire a resource. 214 */ 215 static int 216 acquire(volatile struct lock **lkpp, int *s, int extflags, 217 int drain, int wanted, uintptr_t ra) 218 { 219 int error; 220 volatile struct lock *lkp = *lkpp; 221 LOCKSTAT_TIMER(slptime); 222 223 KASSERT(drain || (wanted & LK_WAIT_NONZERO) == 0); 224 225 if (extflags & LK_SPIN) { 226 int interlocked; 227 228 SPINLOCK_SPINCHECK_DECL; 229 230 if (!drain) { 231 lkp->lk_waitcount++; 232 lkp->lk_flags |= LK_WAIT_NONZERO; 233 } 234 for (interlocked = 1;;) { 235 SPINLOCK_SPINCHECK; 236 if ((lkp->lk_flags & wanted) != 0) { 237 if (interlocked) { 238 INTERLOCK_RELEASE(lkp, LK_SPIN, *s); 239 interlocked = 0; 240 } 241 SPINLOCK_SPIN_HOOK; 242 } else if (interlocked) { 243 break; 244 } else { 245 INTERLOCK_ACQUIRE(lkp, LK_SPIN, *s); 246 interlocked = 1; 247 } 248 } 249 if (!drain) { 250 lkp->lk_waitcount--; 251 if (lkp->lk_waitcount == 0) 252 lkp->lk_flags &= ~LK_WAIT_NONZERO; 253 } 254 KASSERT((lkp->lk_flags & wanted) == 0); 255 error = 0; /* sanity */ 256 } else { 257 for (error = 0; (lkp->lk_flags & wanted) != 0; ) { 258 if (drain) 259 lkp->lk_flags |= LK_WAITDRAIN; 260 else { 261 lkp->lk_waitcount++; 262 lkp->lk_flags |= LK_WAIT_NONZERO; 263 } 264 /* XXX Cast away volatile. */ 265 LOCKSTAT_START_TIMER(slptime); 266 error = ltsleep(drain ? 267 (volatile const void *)&lkp->lk_flags : 268 (volatile const void *)lkp, lkp->lk_prio, 269 lkp->lk_wmesg, lkp->lk_timo, &lkp->lk_interlock); 270 LOCKSTAT_STOP_TIMER(slptime); 271 LOCKSTAT_EVENT_RA((void *)(uintptr_t)lkp, 272 LB_LOCKMGR | LB_SLEEP, 1, slptime, ra); 273 if (!drain) { 274 lkp->lk_waitcount--; 275 if (lkp->lk_waitcount == 0) 276 lkp->lk_flags &= ~LK_WAIT_NONZERO; 277 } 278 if (error) 279 break; 280 if (extflags & LK_SLEEPFAIL) { 281 error = ENOLCK; 282 break; 283 } 284 if (lkp->lk_newlock != NULL) { 285 simple_lock(&lkp->lk_newlock->lk_interlock); 286 simple_unlock(&lkp->lk_interlock); 287 if (lkp->lk_waitcount == 0) 288 wakeup(&lkp->lk_newlock); 289 *lkpp = lkp = lkp->lk_newlock; 290 } 291 } 292 } 293 294 return error; 295 } 296 297 #define SETHOLDER(lkp, pid, lid, cpu_id) \ 298 do { \ 299 if ((lkp)->lk_flags & LK_SPIN) \ 300 (lkp)->lk_cpu = cpu_id; \ 301 else { \ 302 (lkp)->lk_lockholder = pid; \ 303 (lkp)->lk_locklwp = lid; \ 304 } \ 305 } while (/*CONSTCOND*/0) 306 307 #define WEHOLDIT(lkp, pid, lid, cpu_id) \ 308 (((lkp)->lk_flags & LK_SPIN) != 0 ? \ 309 ((lkp)->lk_cpu == (cpu_id)) : \ 310 ((lkp)->lk_lockholder == (pid) && (lkp)->lk_locklwp == (lid))) 311 312 #define WAKEUP_WAITER(lkp) \ 313 do { \ 314 if (((lkp)->lk_flags & (LK_SPIN | LK_WAIT_NONZERO)) == \ 315 LK_WAIT_NONZERO) { \ 316 wakeup((lkp)); \ 317 } \ 318 } while (/*CONSTCOND*/0) 319 320 #if defined(LOCKDEBUG) /* { */ 321 #if defined(MULTIPROCESSOR) /* { */ 322 struct simplelock spinlock_list_slock = SIMPLELOCK_INITIALIZER; 323 324 #define SPINLOCK_LIST_LOCK() \ 325 __cpu_simple_lock(&spinlock_list_slock.lock_data) 326 327 #define SPINLOCK_LIST_UNLOCK() \ 328 __cpu_simple_unlock(&spinlock_list_slock.lock_data) 329 #else 330 #define SPINLOCK_LIST_LOCK() /* nothing */ 331 332 #define SPINLOCK_LIST_UNLOCK() /* nothing */ 333 #endif /* MULTIPROCESSOR */ /* } */ 334 335 _TAILQ_HEAD(, struct lock, volatile) spinlock_list = 336 TAILQ_HEAD_INITIALIZER(spinlock_list); 337 338 #define HAVEIT(lkp) \ 339 do { \ 340 if ((lkp)->lk_flags & LK_SPIN) { \ 341 int sp = spllock(); \ 342 SPINLOCK_LIST_LOCK(); \ 343 TAILQ_INSERT_TAIL(&spinlock_list, (lkp), lk_list); \ 344 SPINLOCK_LIST_UNLOCK(); \ 345 splx(sp); \ 346 } \ 347 } while (/*CONSTCOND*/0) 348 349 #define DONTHAVEIT(lkp) \ 350 do { \ 351 if ((lkp)->lk_flags & LK_SPIN) { \ 352 int sp = spllock(); \ 353 SPINLOCK_LIST_LOCK(); \ 354 TAILQ_REMOVE(&spinlock_list, (lkp), lk_list); \ 355 SPINLOCK_LIST_UNLOCK(); \ 356 splx(sp); \ 357 } \ 358 } while (/*CONSTCOND*/0) 359 #else 360 #define HAVEIT(lkp) /* nothing */ 361 362 #define DONTHAVEIT(lkp) /* nothing */ 363 #endif /* LOCKDEBUG */ /* } */ 364 365 #if defined(LOCKDEBUG) 366 /* 367 * Lock debug printing routine; can be configured to print to console 368 * or log to syslog. 369 */ 370 void 371 lock_printf(const char *fmt, ...) 372 { 373 char b[150]; 374 va_list ap; 375 376 va_start(ap, fmt); 377 if (lock_debug_syslog) 378 vlog(LOG_DEBUG, fmt, ap); 379 else { 380 vsnprintf(b, sizeof(b), fmt, ap); 381 printf_nolog("%s", b); 382 } 383 va_end(ap); 384 } 385 #endif /* LOCKDEBUG */ 386 387 /* 388 * Transfer any waiting processes from one lock to another. 389 */ 390 void 391 transferlockers(struct lock *from, struct lock *to) 392 { 393 394 KASSERT(from != to); 395 KASSERT((from->lk_flags & LK_WAITDRAIN) == 0); 396 if (from->lk_waitcount == 0) 397 return; 398 from->lk_newlock = to; 399 wakeup((void *)from); 400 tsleep((void *)&from->lk_newlock, from->lk_prio, "lkxfer", 0); 401 from->lk_newlock = NULL; 402 from->lk_flags &= ~(LK_WANT_EXCL | LK_WANT_UPGRADE); 403 KASSERT(from->lk_waitcount == 0); 404 } 405 406 407 /* 408 * Initialize a lock; required before use. 409 */ 410 void 411 lockinit(struct lock *lkp, int prio, const char *wmesg, int timo, int flags) 412 { 413 414 memset(lkp, 0, sizeof(struct lock)); 415 simple_lock_init(&lkp->lk_interlock); 416 lkp->lk_flags = flags & LK_EXTFLG_MASK; 417 if (flags & LK_SPIN) 418 lkp->lk_cpu = LK_NOCPU; 419 else { 420 lkp->lk_lockholder = LK_NOPROC; 421 lkp->lk_newlock = NULL; 422 lkp->lk_prio = prio; 423 lkp->lk_timo = timo; 424 } 425 lkp->lk_wmesg = wmesg; /* just a name for spin locks */ 426 #if defined(LOCKDEBUG) 427 lkp->lk_lock_file = NULL; 428 lkp->lk_unlock_file = NULL; 429 #endif 430 } 431 432 /* 433 * Determine the status of a lock. 434 */ 435 int 436 lockstatus(struct lock *lkp) 437 { 438 int s = 0; /* XXX: gcc */ 439 int lock_type = 0; 440 struct lwp *l = curlwp; /* XXX */ 441 pid_t pid; 442 lwpid_t lid; 443 cpuid_t cpu_num; 444 445 if ((lkp->lk_flags & LK_SPIN) || l == NULL) { 446 cpu_num = cpu_number(); 447 pid = LK_KERNPROC; 448 lid = 0; 449 } else { 450 cpu_num = LK_NOCPU; 451 pid = l->l_proc->p_pid; 452 lid = l->l_lid; 453 } 454 455 INTERLOCK_ACQUIRE(lkp, lkp->lk_flags, s); 456 if (lkp->lk_exclusivecount != 0) { 457 if (WEHOLDIT(lkp, pid, lid, cpu_num)) 458 lock_type = LK_EXCLUSIVE; 459 else 460 lock_type = LK_EXCLOTHER; 461 } else if (lkp->lk_sharecount != 0) 462 lock_type = LK_SHARED; 463 else if (lkp->lk_flags & (LK_WANT_EXCL | LK_WANT_UPGRADE)) 464 lock_type = LK_EXCLOTHER; 465 INTERLOCK_RELEASE(lkp, lkp->lk_flags, s); 466 return (lock_type); 467 } 468 469 #if defined(LOCKDEBUG) 470 /* 471 * Make sure no spin locks are held by a CPU that is about 472 * to context switch. 473 */ 474 void 475 spinlock_switchcheck(void) 476 { 477 u_long cnt; 478 int s; 479 480 s = spllock(); 481 #if defined(MULTIPROCESSOR) 482 cnt = curcpu()->ci_spin_locks; 483 #else 484 cnt = spin_locks; 485 #endif 486 splx(s); 487 488 if (cnt != 0) 489 panic("spinlock_switchcheck: CPU %lu has %lu spin locks", 490 (u_long) cpu_number(), cnt); 491 } 492 #endif /* LOCKDEBUG */ 493 494 /* 495 * Locks and IPLs (interrupt priority levels): 496 * 497 * Locks which may be taken from interrupt context must be handled 498 * very carefully; you must spl to the highest IPL where the lock 499 * is needed before acquiring the lock. 500 * 501 * It is also important to avoid deadlock, since certain (very high 502 * priority) interrupts are often needed to keep the system as a whole 503 * from deadlocking, and must not be blocked while you are spinning 504 * waiting for a lower-priority lock. 505 * 506 * In addition, the lock-debugging hooks themselves need to use locks! 507 * 508 * A raw __cpu_simple_lock may be used from interrupts are long as it 509 * is acquired and held at a single IPL. 510 * 511 * A simple_lock (which is a __cpu_simple_lock wrapped with some 512 * debugging hooks) may be used at or below spllock(), which is 513 * typically at or just below splhigh() (i.e. blocks everything 514 * but certain machine-dependent extremely high priority interrupts). 515 * 516 * spinlockmgr spinlocks should be used at or below splsched(). 517 * 518 * Some platforms may have interrupts of higher priority than splsched(), 519 * including hard serial interrupts, inter-processor interrupts, and 520 * kernel debugger traps. 521 */ 522 523 /* 524 * XXX XXX kludge around another kludge.. 525 * 526 * vfs_shutdown() may be called from interrupt context, either as a result 527 * of a panic, or from the debugger. It proceeds to call 528 * sys_sync(&proc0, ...), pretending its running on behalf of proc0 529 * 530 * We would like to make an attempt to sync the filesystems in this case, so 531 * if this happens, we treat attempts to acquire locks specially. 532 * All locks are acquired on behalf of proc0. 533 * 534 * If we've already paniced, we don't block waiting for locks, but 535 * just barge right ahead since we're already going down in flames. 536 */ 537 538 /* 539 * Set, change, or release a lock. 540 * 541 * Shared requests increment the shared count. Exclusive requests set the 542 * LK_WANT_EXCL flag (preventing further shared locks), and wait for already 543 * accepted shared locks and shared-to-exclusive upgrades to go away. 544 */ 545 int 546 #if defined(LOCKDEBUG) 547 _lockmgr(volatile struct lock *lkp, u_int flags, 548 struct simplelock *interlkp, const char *file, int line) 549 #else 550 lockmgr(volatile struct lock *lkp, u_int flags, 551 struct simplelock *interlkp) 552 #endif 553 { 554 int error; 555 pid_t pid; 556 lwpid_t lid; 557 int extflags; 558 cpuid_t cpu_num; 559 struct lwp *l = curlwp; 560 int lock_shutdown_noblock = 0; 561 int s = 0; 562 563 error = 0; 564 565 /* LK_RETRY is for vn_lock, not for lockmgr. */ 566 KASSERT((flags & LK_RETRY) == 0); 567 568 INTERLOCK_ACQUIRE(lkp, lkp->lk_flags, s); 569 if (flags & LK_INTERLOCK) 570 simple_unlock(interlkp); 571 extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; 572 573 #ifdef DIAGNOSTIC /* { */ 574 /* 575 * Don't allow spins on sleep locks and don't allow sleeps 576 * on spin locks. 577 */ 578 if ((flags ^ lkp->lk_flags) & LK_SPIN) 579 panic("lockmgr: sleep/spin mismatch"); 580 #endif /* } */ 581 582 if (extflags & LK_SPIN) { 583 pid = LK_KERNPROC; 584 lid = 0; 585 } else { 586 if (l == NULL) { 587 if (!doing_shutdown) { 588 panic("lockmgr: no context"); 589 } else { 590 l = &lwp0; 591 if (panicstr && (!(flags & LK_NOWAIT))) { 592 flags |= LK_NOWAIT; 593 lock_shutdown_noblock = 1; 594 } 595 } 596 } 597 lid = l->l_lid; 598 pid = l->l_proc->p_pid; 599 } 600 cpu_num = cpu_number(); 601 602 /* 603 * Once a lock has drained, the LK_DRAINING flag is set and an 604 * exclusive lock is returned. The only valid operation thereafter 605 * is a single release of that exclusive lock. This final release 606 * clears the LK_DRAINING flag and sets the LK_DRAINED flag. Any 607 * further requests of any sort will result in a panic. The bits 608 * selected for these two flags are chosen so that they will be set 609 * in memory that is freed (freed memory is filled with 0xdeadbeef). 610 * The final release is permitted to give a new lease on life to 611 * the lock by specifying LK_REENABLE. 612 */ 613 if (lkp->lk_flags & (LK_DRAINING|LK_DRAINED)) { 614 #ifdef DIAGNOSTIC /* { */ 615 if (lkp->lk_flags & LK_DRAINED) 616 panic("lockmgr: using decommissioned lock"); 617 if ((flags & LK_TYPE_MASK) != LK_RELEASE || 618 WEHOLDIT(lkp, pid, lid, cpu_num) == 0) 619 panic("lockmgr: non-release on draining lock: %d", 620 flags & LK_TYPE_MASK); 621 #endif /* DIAGNOSTIC */ /* } */ 622 lkp->lk_flags &= ~LK_DRAINING; 623 if ((flags & LK_REENABLE) == 0) 624 lkp->lk_flags |= LK_DRAINED; 625 } 626 627 switch (flags & LK_TYPE_MASK) { 628 629 case LK_SHARED: 630 if (WEHOLDIT(lkp, pid, lid, cpu_num) == 0) { 631 /* 632 * If just polling, check to see if we will block. 633 */ 634 if ((extflags & LK_NOWAIT) && (lkp->lk_flags & 635 (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE))) { 636 error = EBUSY; 637 break; 638 } 639 /* 640 * Wait for exclusive locks and upgrades to clear. 641 */ 642 error = acquire(&lkp, &s, extflags, 0, 643 LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE, 644 RETURN_ADDRESS); 645 if (error) 646 break; 647 lkp->lk_sharecount++; 648 lkp->lk_flags |= LK_SHARE_NONZERO; 649 COUNT(lkp, l, cpu_num, 1); 650 break; 651 } 652 /* 653 * We hold an exclusive lock, so downgrade it to shared. 654 * An alternative would be to fail with EDEADLK. 655 */ 656 lkp->lk_sharecount++; 657 lkp->lk_flags |= LK_SHARE_NONZERO; 658 COUNT(lkp, l, cpu_num, 1); 659 /* fall into downgrade */ 660 661 case LK_DOWNGRADE: 662 if (WEHOLDIT(lkp, pid, lid, cpu_num) == 0 || 663 lkp->lk_exclusivecount == 0) 664 panic("lockmgr: not holding exclusive lock"); 665 lkp->lk_sharecount += lkp->lk_exclusivecount; 666 lkp->lk_flags |= LK_SHARE_NONZERO; 667 lkp->lk_exclusivecount = 0; 668 lkp->lk_recurselevel = 0; 669 lkp->lk_flags &= ~LK_HAVE_EXCL; 670 SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU); 671 #if defined(LOCKDEBUG) 672 lkp->lk_unlock_file = file; 673 lkp->lk_unlock_line = line; 674 #endif 675 DONTHAVEIT(lkp); 676 WAKEUP_WAITER(lkp); 677 break; 678 679 case LK_EXCLUPGRADE: 680 /* 681 * If another process is ahead of us to get an upgrade, 682 * then we want to fail rather than have an intervening 683 * exclusive access. 684 */ 685 if (lkp->lk_flags & LK_WANT_UPGRADE) { 686 lkp->lk_sharecount--; 687 if (lkp->lk_sharecount == 0) 688 lkp->lk_flags &= ~LK_SHARE_NONZERO; 689 COUNT(lkp, l, cpu_num, -1); 690 error = EBUSY; 691 break; 692 } 693 /* fall into normal upgrade */ 694 695 case LK_UPGRADE: 696 /* 697 * Upgrade a shared lock to an exclusive one. If another 698 * shared lock has already requested an upgrade to an 699 * exclusive lock, our shared lock is released and an 700 * exclusive lock is requested (which will be granted 701 * after the upgrade). If we return an error, the file 702 * will always be unlocked. 703 */ 704 if (WEHOLDIT(lkp, pid, lid, cpu_num) || lkp->lk_sharecount <= 0) 705 panic("lockmgr: upgrade exclusive lock"); 706 lkp->lk_sharecount--; 707 if (lkp->lk_sharecount == 0) 708 lkp->lk_flags &= ~LK_SHARE_NONZERO; 709 COUNT(lkp, l, cpu_num, -1); 710 /* 711 * If we are just polling, check to see if we will block. 712 */ 713 if ((extflags & LK_NOWAIT) && 714 ((lkp->lk_flags & LK_WANT_UPGRADE) || 715 lkp->lk_sharecount > 1)) { 716 error = EBUSY; 717 break; 718 } 719 if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) { 720 /* 721 * We are first shared lock to request an upgrade, so 722 * request upgrade and wait for the shared count to 723 * drop to zero, then take exclusive lock. 724 */ 725 lkp->lk_flags |= LK_WANT_UPGRADE; 726 error = acquire(&lkp, &s, extflags, 0, LK_SHARE_NONZERO, 727 RETURN_ADDRESS); 728 lkp->lk_flags &= ~LK_WANT_UPGRADE; 729 if (error) { 730 WAKEUP_WAITER(lkp); 731 break; 732 } 733 lkp->lk_flags |= LK_HAVE_EXCL; 734 SETHOLDER(lkp, pid, lid, cpu_num); 735 #if defined(LOCKDEBUG) 736 lkp->lk_lock_file = file; 737 lkp->lk_lock_line = line; 738 #endif 739 HAVEIT(lkp); 740 if (lkp->lk_exclusivecount != 0) 741 panic("lockmgr: non-zero exclusive count"); 742 lkp->lk_exclusivecount = 1; 743 if (extflags & LK_SETRECURSE) 744 lkp->lk_recurselevel = 1; 745 COUNT(lkp, l, cpu_num, 1); 746 break; 747 } 748 /* 749 * Someone else has requested upgrade. Release our shared 750 * lock, awaken upgrade requestor if we are the last shared 751 * lock, then request an exclusive lock. 752 */ 753 if (lkp->lk_sharecount == 0) 754 WAKEUP_WAITER(lkp); 755 /* fall into exclusive request */ 756 757 case LK_EXCLUSIVE: 758 if (WEHOLDIT(lkp, pid, lid, cpu_num)) { 759 /* 760 * Recursive lock. 761 */ 762 if ((extflags & LK_CANRECURSE) == 0 && 763 lkp->lk_recurselevel == 0) { 764 if (extflags & LK_RECURSEFAIL) { 765 error = EDEADLK; 766 break; 767 } else 768 panic("lockmgr: locking against myself"); 769 } 770 lkp->lk_exclusivecount++; 771 if (extflags & LK_SETRECURSE && 772 lkp->lk_recurselevel == 0) 773 lkp->lk_recurselevel = lkp->lk_exclusivecount; 774 COUNT(lkp, l, cpu_num, 1); 775 break; 776 } 777 /* 778 * If we are just polling, check to see if we will sleep. 779 */ 780 if ((extflags & LK_NOWAIT) && (lkp->lk_flags & 781 (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | 782 LK_SHARE_NONZERO))) { 783 error = EBUSY; 784 break; 785 } 786 /* 787 * Try to acquire the want_exclusive flag. 788 */ 789 error = acquire(&lkp, &s, extflags, 0, 790 LK_HAVE_EXCL | LK_WANT_EXCL, RETURN_ADDRESS); 791 if (error) 792 break; 793 lkp->lk_flags |= LK_WANT_EXCL; 794 /* 795 * Wait for shared locks and upgrades to finish. 796 */ 797 error = acquire(&lkp, &s, extflags, 0, 798 LK_HAVE_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO, 799 RETURN_ADDRESS); 800 lkp->lk_flags &= ~LK_WANT_EXCL; 801 if (error) { 802 WAKEUP_WAITER(lkp); 803 break; 804 } 805 lkp->lk_flags |= LK_HAVE_EXCL; 806 SETHOLDER(lkp, pid, lid, cpu_num); 807 #if defined(LOCKDEBUG) 808 lkp->lk_lock_file = file; 809 lkp->lk_lock_line = line; 810 #endif 811 HAVEIT(lkp); 812 if (lkp->lk_exclusivecount != 0) 813 panic("lockmgr: non-zero exclusive count"); 814 lkp->lk_exclusivecount = 1; 815 if (extflags & LK_SETRECURSE) 816 lkp->lk_recurselevel = 1; 817 COUNT(lkp, l, cpu_num, 1); 818 break; 819 820 case LK_RELEASE: 821 if (lkp->lk_exclusivecount != 0) { 822 if (WEHOLDIT(lkp, pid, lid, cpu_num) == 0) { 823 if (lkp->lk_flags & LK_SPIN) { 824 panic("lockmgr: processor %lu, not " 825 "exclusive lock holder %lu " 826 "unlocking", cpu_num, lkp->lk_cpu); 827 } else { 828 panic("lockmgr: pid %d, not " 829 "exclusive lock holder %d " 830 "unlocking", pid, 831 lkp->lk_lockholder); 832 } 833 } 834 if (lkp->lk_exclusivecount == lkp->lk_recurselevel) 835 lkp->lk_recurselevel = 0; 836 lkp->lk_exclusivecount--; 837 COUNT(lkp, l, cpu_num, -1); 838 if (lkp->lk_exclusivecount == 0) { 839 lkp->lk_flags &= ~LK_HAVE_EXCL; 840 SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU); 841 #if defined(LOCKDEBUG) 842 lkp->lk_unlock_file = file; 843 lkp->lk_unlock_line = line; 844 #endif 845 DONTHAVEIT(lkp); 846 } 847 } else if (lkp->lk_sharecount != 0) { 848 lkp->lk_sharecount--; 849 if (lkp->lk_sharecount == 0) 850 lkp->lk_flags &= ~LK_SHARE_NONZERO; 851 COUNT(lkp, l, cpu_num, -1); 852 } 853 #ifdef DIAGNOSTIC 854 else 855 panic("lockmgr: release of unlocked lock!"); 856 #endif 857 WAKEUP_WAITER(lkp); 858 break; 859 860 case LK_DRAIN: 861 /* 862 * Check that we do not already hold the lock, as it can 863 * never drain if we do. Unfortunately, we have no way to 864 * check for holding a shared lock, but at least we can 865 * check for an exclusive one. 866 */ 867 if (WEHOLDIT(lkp, pid, lid, cpu_num)) 868 panic("lockmgr: draining against myself"); 869 /* 870 * If we are just polling, check to see if we will sleep. 871 */ 872 if ((extflags & LK_NOWAIT) && (lkp->lk_flags & 873 (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | 874 LK_SHARE_NONZERO | LK_WAIT_NONZERO))) { 875 error = EBUSY; 876 break; 877 } 878 error = acquire(&lkp, &s, extflags, 1, 879 LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | 880 LK_SHARE_NONZERO | LK_WAIT_NONZERO, 881 RETURN_ADDRESS); 882 if (error) 883 break; 884 lkp->lk_flags |= LK_HAVE_EXCL; 885 if ((extflags & LK_RESURRECT) == 0) 886 lkp->lk_flags |= LK_DRAINING; 887 SETHOLDER(lkp, pid, lid, cpu_num); 888 #if defined(LOCKDEBUG) 889 lkp->lk_lock_file = file; 890 lkp->lk_lock_line = line; 891 #endif 892 HAVEIT(lkp); 893 lkp->lk_exclusivecount = 1; 894 /* XXX unlikely that we'd want this */ 895 if (extflags & LK_SETRECURSE) 896 lkp->lk_recurselevel = 1; 897 COUNT(lkp, l, cpu_num, 1); 898 break; 899 900 default: 901 INTERLOCK_RELEASE(lkp, lkp->lk_flags, s); 902 panic("lockmgr: unknown locktype request %d", 903 flags & LK_TYPE_MASK); 904 /* NOTREACHED */ 905 } 906 if ((lkp->lk_flags & (LK_WAITDRAIN|LK_SPIN)) == LK_WAITDRAIN && 907 ((lkp->lk_flags & 908 (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | 909 LK_SHARE_NONZERO | LK_WAIT_NONZERO)) == 0)) { 910 lkp->lk_flags &= ~LK_WAITDRAIN; 911 wakeup(&lkp->lk_flags); 912 } 913 /* 914 * Note that this panic will be a recursive panic, since 915 * we only set lock_shutdown_noblock above if panicstr != NULL. 916 */ 917 if (error && lock_shutdown_noblock) 918 panic("lockmgr: deadlock (see previous panic)"); 919 920 INTERLOCK_RELEASE(lkp, lkp->lk_flags, s); 921 return (error); 922 } 923 924 /* 925 * For a recursive spinlock held one or more times by the current CPU, 926 * release all N locks, and return N. 927 * Intended for use in mi_switch() shortly before context switching. 928 */ 929 930 int 931 #if defined(LOCKDEBUG) 932 _spinlock_release_all(volatile struct lock *lkp, const char *file, int line) 933 #else 934 spinlock_release_all(volatile struct lock *lkp) 935 #endif 936 { 937 int s, count; 938 cpuid_t cpu_num; 939 940 KASSERT(lkp->lk_flags & LK_SPIN); 941 942 INTERLOCK_ACQUIRE(lkp, LK_SPIN, s); 943 944 cpu_num = cpu_number(); 945 count = lkp->lk_exclusivecount; 946 947 if (count != 0) { 948 #ifdef DIAGNOSTIC 949 if (WEHOLDIT(lkp, 0, 0, cpu_num) == 0) { 950 panic("spinlock_release_all: processor %lu, not " 951 "exclusive lock holder %lu " 952 "unlocking", (long)cpu_num, lkp->lk_cpu); 953 } 954 #endif 955 lkp->lk_recurselevel = 0; 956 lkp->lk_exclusivecount = 0; 957 COUNT_CPU(cpu_num, -count); 958 lkp->lk_flags &= ~LK_HAVE_EXCL; 959 SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU); 960 #if defined(LOCKDEBUG) 961 lkp->lk_unlock_file = file; 962 lkp->lk_unlock_line = line; 963 #endif 964 DONTHAVEIT(lkp); 965 } 966 #ifdef DIAGNOSTIC 967 else if (lkp->lk_sharecount != 0) 968 panic("spinlock_release_all: release of shared lock!"); 969 else 970 panic("spinlock_release_all: release of unlocked lock!"); 971 #endif 972 INTERLOCK_RELEASE(lkp, LK_SPIN, s); 973 974 return (count); 975 } 976 977 /* 978 * For a recursive spinlock held one or more times by the current CPU, 979 * release all N locks, and return N. 980 * Intended for use in mi_switch() right after resuming execution. 981 */ 982 983 void 984 #if defined(LOCKDEBUG) 985 _spinlock_acquire_count(volatile struct lock *lkp, int count, 986 const char *file, int line) 987 #else 988 spinlock_acquire_count(volatile struct lock *lkp, int count) 989 #endif 990 { 991 int s, error; 992 cpuid_t cpu_num; 993 994 KASSERT(lkp->lk_flags & LK_SPIN); 995 996 INTERLOCK_ACQUIRE(lkp, LK_SPIN, s); 997 998 cpu_num = cpu_number(); 999 1000 #ifdef DIAGNOSTIC 1001 if (WEHOLDIT(lkp, LK_NOPROC, 0, cpu_num)) 1002 panic("spinlock_acquire_count: processor %lu already holds lock", (long)cpu_num); 1003 #endif 1004 /* 1005 * Try to acquire the want_exclusive flag. 1006 */ 1007 error = acquire(&lkp, &s, LK_SPIN, 0, LK_HAVE_EXCL | LK_WANT_EXCL, 1008 RETURN_ADDRESS); 1009 lkp->lk_flags |= LK_WANT_EXCL; 1010 /* 1011 * Wait for shared locks and upgrades to finish. 1012 */ 1013 error = acquire(&lkp, &s, LK_SPIN, 0, 1014 LK_HAVE_EXCL | LK_SHARE_NONZERO | LK_WANT_UPGRADE, 1015 RETURN_ADDRESS); 1016 lkp->lk_flags &= ~LK_WANT_EXCL; 1017 lkp->lk_flags |= LK_HAVE_EXCL; 1018 SETHOLDER(lkp, LK_NOPROC, 0, cpu_num); 1019 #if defined(LOCKDEBUG) 1020 lkp->lk_lock_file = file; 1021 lkp->lk_lock_line = line; 1022 #endif 1023 HAVEIT(lkp); 1024 if (lkp->lk_exclusivecount != 0) 1025 panic("lockmgr: non-zero exclusive count"); 1026 lkp->lk_exclusivecount = count; 1027 lkp->lk_recurselevel = 1; 1028 COUNT_CPU(cpu_num, count); 1029 1030 INTERLOCK_RELEASE(lkp, lkp->lk_flags, s); 1031 } 1032 1033 1034 1035 /* 1036 * Print out information about state of a lock. Used by VOP_PRINT 1037 * routines to display ststus about contained locks. 1038 */ 1039 void 1040 lockmgr_printinfo(volatile struct lock *lkp) 1041 { 1042 1043 if (lkp->lk_sharecount) 1044 printf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg, 1045 lkp->lk_sharecount); 1046 else if (lkp->lk_flags & LK_HAVE_EXCL) { 1047 printf(" lock type %s: EXCL (count %d) by ", 1048 lkp->lk_wmesg, lkp->lk_exclusivecount); 1049 if (lkp->lk_flags & LK_SPIN) 1050 printf("processor %lu", lkp->lk_cpu); 1051 else 1052 printf("pid %d.%d", lkp->lk_lockholder, 1053 lkp->lk_locklwp); 1054 } else 1055 printf(" not locked"); 1056 if ((lkp->lk_flags & LK_SPIN) == 0 && lkp->lk_waitcount > 0) 1057 printf(" with %d pending", lkp->lk_waitcount); 1058 } 1059 1060 #if defined(LOCKDEBUG) /* { */ 1061 _TAILQ_HEAD(, struct simplelock, volatile) simplelock_list = 1062 TAILQ_HEAD_INITIALIZER(simplelock_list); 1063 1064 #if defined(MULTIPROCESSOR) /* { */ 1065 struct simplelock simplelock_list_slock = SIMPLELOCK_INITIALIZER; 1066 1067 #define SLOCK_LIST_LOCK() \ 1068 __cpu_simple_lock(&simplelock_list_slock.lock_data) 1069 1070 #define SLOCK_LIST_UNLOCK() \ 1071 __cpu_simple_unlock(&simplelock_list_slock.lock_data) 1072 1073 #define SLOCK_COUNT(x) \ 1074 curcpu()->ci_simple_locks += (x) 1075 #else 1076 u_long simple_locks; 1077 1078 #define SLOCK_LIST_LOCK() /* nothing */ 1079 1080 #define SLOCK_LIST_UNLOCK() /* nothing */ 1081 1082 #define SLOCK_COUNT(x) simple_locks += (x) 1083 #endif /* MULTIPROCESSOR */ /* } */ 1084 1085 #ifdef MULTIPROCESSOR 1086 #define SLOCK_MP() lock_printf("on CPU %ld\n", \ 1087 (u_long) cpu_number()) 1088 #else 1089 #define SLOCK_MP() /* nothing */ 1090 #endif 1091 1092 #define SLOCK_WHERE(str, alp, id, l) \ 1093 do { \ 1094 lock_printf("\n"); \ 1095 lock_printf(str); \ 1096 lock_printf("lock: %p, currently at: %s:%d\n", (alp), (id), (l)); \ 1097 SLOCK_MP(); \ 1098 if ((alp)->lock_file != NULL) \ 1099 lock_printf("last locked: %s:%d\n", (alp)->lock_file, \ 1100 (alp)->lock_line); \ 1101 if ((alp)->unlock_file != NULL) \ 1102 lock_printf("last unlocked: %s:%d\n", (alp)->unlock_file, \ 1103 (alp)->unlock_line); \ 1104 SLOCK_TRACE() \ 1105 SLOCK_DEBUGGER(); \ 1106 } while (/*CONSTCOND*/0) 1107 1108 /* 1109 * Simple lock functions so that the debugger can see from whence 1110 * they are being called. 1111 */ 1112 void 1113 simple_lock_init(volatile struct simplelock *alp) 1114 { 1115 1116 #if defined(MULTIPROCESSOR) /* { */ 1117 __cpu_simple_lock_init(&alp->lock_data); 1118 #else 1119 alp->lock_data = __SIMPLELOCK_UNLOCKED; 1120 #endif /* } */ 1121 alp->lock_file = NULL; 1122 alp->lock_line = 0; 1123 alp->unlock_file = NULL; 1124 alp->unlock_line = 0; 1125 alp->lock_holder = LK_NOCPU; 1126 } 1127 1128 void 1129 _simple_lock(volatile struct simplelock *alp, const char *id, int l) 1130 { 1131 cpuid_t cpu_num = cpu_number(); 1132 int s; 1133 1134 s = spllock(); 1135 1136 /* 1137 * MULTIPROCESSOR case: This is `safe' since if it's not us, we 1138 * don't take any action, and just fall into the normal spin case. 1139 */ 1140 if (alp->lock_data == __SIMPLELOCK_LOCKED) { 1141 #if defined(MULTIPROCESSOR) /* { */ 1142 if (alp->lock_holder == cpu_num) { 1143 SLOCK_WHERE("simple_lock: locking against myself\n", 1144 alp, id, l); 1145 goto out; 1146 } 1147 #else 1148 SLOCK_WHERE("simple_lock: lock held\n", alp, id, l); 1149 goto out; 1150 #endif /* MULTIPROCESSOR */ /* } */ 1151 } 1152 1153 #if defined(MULTIPROCESSOR) /* { */ 1154 /* Acquire the lock before modifying any fields. */ 1155 splx(s); 1156 __cpu_simple_lock(&alp->lock_data); 1157 s = spllock(); 1158 #else 1159 alp->lock_data = __SIMPLELOCK_LOCKED; 1160 #endif /* } */ 1161 1162 if (alp->lock_holder != LK_NOCPU) { 1163 SLOCK_WHERE("simple_lock: uninitialized lock\n", 1164 alp, id, l); 1165 } 1166 alp->lock_file = id; 1167 alp->lock_line = l; 1168 alp->lock_holder = cpu_num; 1169 1170 SLOCK_LIST_LOCK(); 1171 TAILQ_INSERT_TAIL(&simplelock_list, alp, list); 1172 SLOCK_LIST_UNLOCK(); 1173 1174 SLOCK_COUNT(1); 1175 1176 out: 1177 splx(s); 1178 } 1179 1180 int 1181 _simple_lock_held(volatile struct simplelock *alp) 1182 { 1183 #if defined(MULTIPROCESSOR) || defined(DIAGNOSTIC) 1184 cpuid_t cpu_num = cpu_number(); 1185 #endif 1186 int s, locked = 0; 1187 1188 s = spllock(); 1189 1190 #if defined(MULTIPROCESSOR) 1191 if (__cpu_simple_lock_try(&alp->lock_data) == 0) 1192 locked = (alp->lock_holder == cpu_num); 1193 else 1194 __cpu_simple_unlock(&alp->lock_data); 1195 #else 1196 if (alp->lock_data == __SIMPLELOCK_LOCKED) { 1197 locked = 1; 1198 KASSERT(alp->lock_holder == cpu_num); 1199 } 1200 #endif 1201 1202 splx(s); 1203 1204 return (locked); 1205 } 1206 1207 int 1208 _simple_lock_try(volatile struct simplelock *alp, const char *id, int l) 1209 { 1210 cpuid_t cpu_num = cpu_number(); 1211 int s, rv = 0; 1212 1213 s = spllock(); 1214 1215 /* 1216 * MULTIPROCESSOR case: This is `safe' since if it's not us, we 1217 * don't take any action. 1218 */ 1219 #if defined(MULTIPROCESSOR) /* { */ 1220 if ((rv = __cpu_simple_lock_try(&alp->lock_data)) == 0) { 1221 if (alp->lock_holder == cpu_num) 1222 SLOCK_WHERE("simple_lock_try: locking against myself\n", 1223 alp, id, l); 1224 goto out; 1225 } 1226 #else 1227 if (alp->lock_data == __SIMPLELOCK_LOCKED) { 1228 SLOCK_WHERE("simple_lock_try: lock held\n", alp, id, l); 1229 goto out; 1230 } 1231 alp->lock_data = __SIMPLELOCK_LOCKED; 1232 #endif /* MULTIPROCESSOR */ /* } */ 1233 1234 /* 1235 * At this point, we have acquired the lock. 1236 */ 1237 1238 rv = 1; 1239 1240 alp->lock_file = id; 1241 alp->lock_line = l; 1242 alp->lock_holder = cpu_num; 1243 1244 SLOCK_LIST_LOCK(); 1245 TAILQ_INSERT_TAIL(&simplelock_list, alp, list); 1246 SLOCK_LIST_UNLOCK(); 1247 1248 SLOCK_COUNT(1); 1249 1250 out: 1251 splx(s); 1252 return (rv); 1253 } 1254 1255 void 1256 _simple_unlock(volatile struct simplelock *alp, const char *id, int l) 1257 { 1258 int s; 1259 1260 s = spllock(); 1261 1262 /* 1263 * MULTIPROCESSOR case: This is `safe' because we think we hold 1264 * the lock, and if we don't, we don't take any action. 1265 */ 1266 if (alp->lock_data == __SIMPLELOCK_UNLOCKED) { 1267 SLOCK_WHERE("simple_unlock: lock not held\n", 1268 alp, id, l); 1269 goto out; 1270 } 1271 1272 SLOCK_LIST_LOCK(); 1273 TAILQ_REMOVE(&simplelock_list, alp, list); 1274 SLOCK_LIST_UNLOCK(); 1275 1276 SLOCK_COUNT(-1); 1277 1278 alp->list.tqe_next = NULL; /* sanity */ 1279 alp->list.tqe_prev = NULL; /* sanity */ 1280 1281 alp->unlock_file = id; 1282 alp->unlock_line = l; 1283 1284 #if defined(MULTIPROCESSOR) /* { */ 1285 alp->lock_holder = LK_NOCPU; 1286 /* Now that we've modified all fields, release the lock. */ 1287 __cpu_simple_unlock(&alp->lock_data); 1288 #else 1289 alp->lock_data = __SIMPLELOCK_UNLOCKED; 1290 KASSERT(alp->lock_holder == cpu_number()); 1291 alp->lock_holder = LK_NOCPU; 1292 #endif /* } */ 1293 1294 out: 1295 splx(s); 1296 } 1297 1298 void 1299 simple_lock_dump(void) 1300 { 1301 volatile struct simplelock *alp; 1302 int s; 1303 1304 s = spllock(); 1305 SLOCK_LIST_LOCK(); 1306 lock_printf("all simple locks:\n"); 1307 TAILQ_FOREACH(alp, &simplelock_list, list) { 1308 lock_printf("%p CPU %lu %s:%d\n", alp, alp->lock_holder, 1309 alp->lock_file, alp->lock_line); 1310 } 1311 SLOCK_LIST_UNLOCK(); 1312 splx(s); 1313 } 1314 1315 void 1316 simple_lock_freecheck(void *start, void *end) 1317 { 1318 volatile struct simplelock *alp; 1319 int s; 1320 1321 s = spllock(); 1322 SLOCK_LIST_LOCK(); 1323 TAILQ_FOREACH(alp, &simplelock_list, list) { 1324 if ((volatile void *)alp >= start && 1325 (volatile void *)alp < end) { 1326 lock_printf("freeing simple_lock %p CPU %lu %s:%d\n", 1327 alp, alp->lock_holder, alp->lock_file, 1328 alp->lock_line); 1329 SLOCK_DEBUGGER(); 1330 } 1331 } 1332 SLOCK_LIST_UNLOCK(); 1333 splx(s); 1334 } 1335 1336 /* 1337 * We must be holding exactly one lock: the sched_lock. 1338 */ 1339 1340 void 1341 simple_lock_switchcheck(void) 1342 { 1343 1344 simple_lock_only_held(&sched_lock, "switching"); 1345 } 1346 1347 /* 1348 * Drop into the debugger if lp isn't the only lock held. 1349 * lp may be NULL. 1350 */ 1351 void 1352 simple_lock_only_held(volatile struct simplelock *lp, const char *where) 1353 { 1354 volatile struct simplelock *alp; 1355 cpuid_t cpu_num = cpu_number(); 1356 int s; 1357 1358 if (lp) { 1359 LOCK_ASSERT(simple_lock_held(lp)); 1360 } 1361 s = spllock(); 1362 SLOCK_LIST_LOCK(); 1363 TAILQ_FOREACH(alp, &simplelock_list, list) { 1364 if (alp == lp) 1365 continue; 1366 #if defined(MULTIPROCESSOR) 1367 if (alp == &kernel_lock) 1368 continue; 1369 #endif /* defined(MULTIPROCESSOR) */ 1370 if (alp->lock_holder == cpu_num) 1371 break; 1372 } 1373 SLOCK_LIST_UNLOCK(); 1374 splx(s); 1375 1376 if (alp != NULL) { 1377 lock_printf("\n%s with held simple_lock %p " 1378 "CPU %lu %s:%d\n", 1379 where, alp, alp->lock_holder, alp->lock_file, 1380 alp->lock_line); 1381 SLOCK_TRACE(); 1382 SLOCK_DEBUGGER(); 1383 } 1384 } 1385 1386 /* 1387 * Set to 1 by simple_lock_assert_*(). 1388 * Can be cleared from ddb to avoid a panic. 1389 */ 1390 int slock_assert_will_panic; 1391 1392 /* 1393 * If the lock isn't held, print a traceback, optionally drop into the 1394 * debugger, then panic. 1395 * The panic can be avoided by clearing slock_assert_with_panic from the 1396 * debugger. 1397 */ 1398 void 1399 _simple_lock_assert_locked(volatile struct simplelock *alp, 1400 const char *lockname, const char *id, int l) 1401 { 1402 if (simple_lock_held(alp) == 0) { 1403 slock_assert_will_panic = 1; 1404 lock_printf("%s lock not held\n", lockname); 1405 SLOCK_WHERE("lock not held", alp, id, l); 1406 if (slock_assert_will_panic) 1407 panic("%s: not locked", lockname); 1408 } 1409 } 1410 1411 void 1412 _simple_lock_assert_unlocked(volatile struct simplelock *alp, 1413 const char *lockname, const char *id, int l) 1414 { 1415 if (simple_lock_held(alp)) { 1416 slock_assert_will_panic = 1; 1417 lock_printf("%s lock held\n", lockname); 1418 SLOCK_WHERE("lock held", alp, id, l); 1419 if (slock_assert_will_panic) 1420 panic("%s: locked", lockname); 1421 } 1422 } 1423 1424 void 1425 assert_sleepable(struct simplelock *interlock, const char *msg) 1426 { 1427 1428 if (curlwp == NULL) { 1429 panic("assert_sleepable: NULL curlwp"); 1430 } 1431 spinlock_switchcheck(); 1432 simple_lock_only_held(interlock, msg); 1433 } 1434 1435 #endif /* LOCKDEBUG */ /* } */ 1436 1437 #if defined(MULTIPROCESSOR) 1438 /* 1439 * Functions for manipulating the kernel_lock. We put them here 1440 * so that they show up in profiles. 1441 */ 1442 1443 /* 1444 * splbiglock: block IPLs which need to grab kernel_lock. 1445 * XXX splvm or splaudio should be enough. 1446 */ 1447 #if !defined(__HAVE_SPLBIGLOCK) 1448 #define splbiglock() splclock() 1449 #endif 1450 1451 void 1452 _kernel_lock_init(void) 1453 { 1454 1455 simple_lock_init(&kernel_lock); 1456 } 1457 1458 /* 1459 * Acquire/release the kernel lock. Intended for use in the scheduler 1460 * and the lower half of the kernel. 1461 */ 1462 void 1463 _kernel_lock(int flag) 1464 { 1465 struct cpu_info *ci = curcpu(); 1466 1467 SCHED_ASSERT_UNLOCKED(); 1468 1469 if (ci->ci_data.cpu_biglock_count > 0) { 1470 LOCK_ASSERT(simple_lock_held(&kernel_lock)); 1471 ci->ci_data.cpu_biglock_count++; 1472 } else { 1473 int s; 1474 1475 s = splbiglock(); 1476 while (!simple_lock_try(&kernel_lock)) { 1477 splx(s); 1478 SPINLOCK_SPIN_HOOK; 1479 s = splbiglock(); 1480 } 1481 ci->ci_data.cpu_biglock_count++; 1482 splx(s); 1483 } 1484 } 1485 1486 void 1487 _kernel_unlock(void) 1488 { 1489 struct cpu_info *ci = curcpu(); 1490 int s; 1491 1492 KASSERT(ci->ci_data.cpu_biglock_count > 0); 1493 1494 s = splbiglock(); 1495 if ((--ci->ci_data.cpu_biglock_count) == 0) 1496 simple_unlock(&kernel_lock); 1497 splx(s); 1498 } 1499 1500 /* 1501 * Acquire/release the kernel_lock on behalf of a process. Intended for 1502 * use in the top half of the kernel. 1503 */ 1504 void 1505 _kernel_proc_lock(struct lwp *l) 1506 { 1507 1508 SCHED_ASSERT_UNLOCKED(); 1509 _kernel_lock(0); 1510 } 1511 1512 void 1513 _kernel_proc_unlock(struct lwp *l) 1514 { 1515 1516 _kernel_unlock(); 1517 } 1518 1519 int 1520 _kernel_lock_release_all() 1521 { 1522 struct cpu_info *ci = curcpu(); 1523 int hold_count; 1524 1525 hold_count = ci->ci_data.cpu_biglock_count; 1526 1527 if (hold_count) { 1528 int s; 1529 1530 s = splbiglock(); 1531 ci->ci_data.cpu_biglock_count = 0; 1532 simple_unlock(&kernel_lock); 1533 splx(s); 1534 } 1535 1536 return hold_count; 1537 } 1538 1539 void 1540 _kernel_lock_acquire_count(int hold_count) 1541 { 1542 1543 KASSERT(curcpu()->ci_data.cpu_biglock_count == 0); 1544 1545 if (hold_count != 0) { 1546 struct cpu_info *ci = curcpu(); 1547 int s; 1548 1549 s = splbiglock(); 1550 while (!simple_lock_try(&kernel_lock)) { 1551 splx(s); 1552 SPINLOCK_SPIN_HOOK; 1553 s = splbiglock(); 1554 } 1555 ci->ci_data.cpu_biglock_count = hold_count; 1556 splx(s); 1557 } 1558 } 1559 #if defined(DEBUG) 1560 void 1561 _kernel_lock_assert_locked() 1562 { 1563 1564 KDASSERT(curcpu()->ci_data.cpu_biglock_count > 0); 1565 simple_lock_assert_locked(&kernel_lock, "kernel_lock"); 1566 } 1567 1568 void 1569 _kernel_lock_assert_unlocked() 1570 { 1571 1572 KDASSERT(curcpu()->ci_data.cpu_biglock_count == 0); 1573 simple_lock_assert_unlocked(&kernel_lock, "kernel_lock"); 1574 } 1575 #endif 1576 1577 int 1578 lock_owner_onproc(uintptr_t owner) 1579 { 1580 CPU_INFO_ITERATOR cii; 1581 struct cpu_info *ci; 1582 1583 for (CPU_INFO_FOREACH(cii, ci)) 1584 if (owner == (uintptr_t)ci || owner == (uintptr_t)ci->ci_curlwp) 1585 return (1); 1586 1587 return (0); 1588 } 1589 1590 #else /* MULTIPROCESSOR */ 1591 1592 int 1593 lock_owner_onproc(uintptr_t owner) 1594 { 1595 1596 return 0; 1597 } 1598 1599 #endif /* MULTIPROCESSOR */
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