1 /* $NetBSD: kern_lock.c,v 1.80 2004/05/31 09:05:10 yamt 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 1.80 2004/05/31 09:05:10 yamt 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 #if defined(LOCKDEBUG) 92 #include <sys/syslog.h> 93 /* 94 * note that stdarg.h and the ansi style va_start macro is used for both 95 * ansi and traditional c compiles. 96 * XXX: this requires that stdarg.h define: va_alist and va_dcl 97 */ 98 #include <machine/stdarg.h> 99 100 void lock_printf(const char *fmt, ...) 101 __attribute__((__format__(__printf__,1,2))); 102 103 static int acquire(__volatile struct lock **, int *, int, int, int); 104 105 int lock_debug_syslog = 0; /* defaults to printf, but can be patched */ 106 107 #ifdef DDB 108 #include <ddb/ddbvar.h> 109 #include <machine/db_machdep.h> 110 #include <ddb/db_command.h> 111 #include <ddb/db_interface.h> 112 #endif 113 #endif 114 115 /* 116 * Locking primitives implementation. 117 * Locks provide shared/exclusive synchronization. 118 */ 119 120 #if defined(LOCKDEBUG) || defined(DIAGNOSTIC) /* { */ 121 #if defined(MULTIPROCESSOR) /* { */ 122 #define COUNT_CPU(cpu_id, x) \ 123 curcpu()->ci_spin_locks += (x) 124 #else 125 u_long spin_locks; 126 #define COUNT_CPU(cpu_id, x) spin_locks += (x) 127 #endif /* MULTIPROCESSOR */ /* } */ 128 129 #define COUNT(lkp, l, cpu_id, x) \ 130 do { \ 131 if ((lkp)->lk_flags & LK_SPIN) \ 132 COUNT_CPU((cpu_id), (x)); \ 133 else \ 134 (l)->l_locks += (x); \ 135 } while (/*CONSTCOND*/0) 136 #else 137 #define COUNT(lkp, p, cpu_id, x) 138 #define COUNT_CPU(cpu_id, x) 139 #endif /* LOCKDEBUG || DIAGNOSTIC */ /* } */ 140 141 #ifndef SPINLOCK_SPIN_HOOK /* from <machine/lock.h> */ 142 #define SPINLOCK_SPIN_HOOK /* nothing */ 143 #endif 144 145 #define INTERLOCK_ACQUIRE(lkp, flags, s) \ 146 do { \ 147 if ((flags) & LK_SPIN) \ 148 s = spllock(); \ 149 simple_lock(&(lkp)->lk_interlock); \ 150 } while (/*CONSTCOND*/ 0) 151 152 #define INTERLOCK_RELEASE(lkp, flags, s) \ 153 do { \ 154 simple_unlock(&(lkp)->lk_interlock); \ 155 if ((flags) & LK_SPIN) \ 156 splx(s); \ 157 } while (/*CONSTCOND*/ 0) 158 159 #ifdef DDB /* { */ 160 #ifdef MULTIPROCESSOR 161 int simple_lock_debugger = 1; /* more serious on MP */ 162 #else 163 int simple_lock_debugger = 0; 164 #endif 165 #define SLOCK_DEBUGGER() if (simple_lock_debugger) Debugger() 166 #define SLOCK_TRACE() \ 167 db_stack_trace_print((db_expr_t)__builtin_frame_address(0), \ 168 TRUE, 65535, "", lock_printf); 169 #else 170 #define SLOCK_DEBUGGER() /* nothing */ 171 #define SLOCK_TRACE() /* nothing */ 172 #endif /* } */ 173 174 #if defined(LOCKDEBUG) 175 #if defined(DDB) 176 #define SPINLOCK_SPINCHECK_DEBUGGER Debugger() 177 #else 178 #define SPINLOCK_SPINCHECK_DEBUGGER /* nothing */ 179 #endif 180 181 #define SPINLOCK_SPINCHECK_DECL \ 182 /* 32-bits of count -- wrap constitutes a "spinout" */ \ 183 uint32_t __spinc = 0 184 185 #define SPINLOCK_SPINCHECK \ 186 do { \ 187 if (++__spinc == 0) { \ 188 lock_printf("LK_SPIN spinout, excl %d, share %d\n", \ 189 lkp->lk_exclusivecount, lkp->lk_sharecount); \ 190 if (lkp->lk_exclusivecount) \ 191 lock_printf("held by CPU %lu\n", \ 192 (u_long) lkp->lk_cpu); \ 193 if (lkp->lk_lock_file) \ 194 lock_printf("last locked at %s:%d\n", \ 195 lkp->lk_lock_file, lkp->lk_lock_line); \ 196 if (lkp->lk_unlock_file) \ 197 lock_printf("last unlocked at %s:%d\n", \ 198 lkp->lk_unlock_file, lkp->lk_unlock_line); \ 199 SLOCK_TRACE(); \ 200 SPINLOCK_SPINCHECK_DEBUGGER; \ 201 } \ 202 } while (/*CONSTCOND*/ 0) 203 #else 204 #define SPINLOCK_SPINCHECK_DECL /* nothing */ 205 #define SPINLOCK_SPINCHECK /* nothing */ 206 #endif /* LOCKDEBUG && DDB */ 207 208 /* 209 * Acquire a resource. 210 */ 211 static int 212 acquire(__volatile struct lock **lkpp, int *s, int extflags, 213 int drain, int wanted) 214 { 215 int error; 216 __volatile struct lock *lkp = *lkpp; 217 218 KASSERT(drain || (wanted & LK_WAIT_NONZERO) == 0); 219 220 if (extflags & LK_SPIN) { 221 int interlocked; 222 223 SPINLOCK_SPINCHECK_DECL; 224 225 if (!drain) { 226 lkp->lk_waitcount++; 227 lkp->lk_flags |= LK_WAIT_NONZERO; 228 } 229 for (interlocked = 1;;) { 230 SPINLOCK_SPINCHECK; 231 if ((lkp->lk_flags & wanted) != 0) { 232 if (interlocked) { 233 INTERLOCK_RELEASE(lkp, LK_SPIN, *s); 234 interlocked = 0; 235 } 236 SPINLOCK_SPIN_HOOK; 237 } else if (interlocked) { 238 break; 239 } else { 240 INTERLOCK_ACQUIRE(lkp, LK_SPIN, *s); 241 interlocked = 1; 242 } 243 } 244 if (!drain) { 245 lkp->lk_waitcount--; 246 if (lkp->lk_waitcount == 0) 247 lkp->lk_flags &= ~LK_WAIT_NONZERO; 248 } 249 KASSERT((lkp->lk_flags & wanted) == 0); 250 error = 0; /* sanity */ 251 } else { 252 for (error = 0; (lkp->lk_flags & wanted) != 0; ) { 253 if (drain) 254 lkp->lk_flags |= LK_WAITDRAIN; 255 else { 256 lkp->lk_waitcount++; 257 lkp->lk_flags |= LK_WAIT_NONZERO; 258 } 259 /* XXX Cast away volatile. */ 260 error = ltsleep(drain ? 261 (void *)&lkp->lk_flags : 262 (void *)lkp, lkp->lk_prio, 263 lkp->lk_wmesg, lkp->lk_timo, &lkp->lk_interlock); 264 if (!drain) { 265 lkp->lk_waitcount--; 266 if (lkp->lk_waitcount == 0) 267 lkp->lk_flags &= ~LK_WAIT_NONZERO; 268 } 269 if (error) 270 break; 271 if (extflags & LK_SLEEPFAIL) { 272 error = ENOLCK; 273 break; 274 } 275 if (lkp->lk_newlock != NULL) { 276 simple_lock(&lkp->lk_newlock->lk_interlock); 277 simple_unlock(&lkp->lk_interlock); 278 if (lkp->lk_waitcount == 0) 279 wakeup((void *)&lkp->lk_newlock); 280 *lkpp = lkp = lkp->lk_newlock; 281 } 282 } 283 } 284 285 return error; 286 } 287 288 #define SETHOLDER(lkp, pid, lid, cpu_id) \ 289 do { \ 290 if ((lkp)->lk_flags & LK_SPIN) \ 291 (lkp)->lk_cpu = cpu_id; \ 292 else { \ 293 (lkp)->lk_lockholder = pid; \ 294 (lkp)->lk_locklwp = lid; \ 295 } \ 296 } while (/*CONSTCOND*/0) 297 298 #define WEHOLDIT(lkp, pid, lid, cpu_id) \ 299 (((lkp)->lk_flags & LK_SPIN) != 0 ? \ 300 ((lkp)->lk_cpu == (cpu_id)) : \ 301 ((lkp)->lk_lockholder == (pid) && (lkp)->lk_locklwp == (lid))) 302 303 #define WAKEUP_WAITER(lkp) \ 304 do { \ 305 if (((lkp)->lk_flags & (LK_SPIN | LK_WAIT_NONZERO)) == \ 306 LK_WAIT_NONZERO) { \ 307 /* XXX Cast away volatile. */ \ 308 wakeup((void *)(lkp)); \ 309 } \ 310 } while (/*CONSTCOND*/0) 311 312 #if defined(LOCKDEBUG) /* { */ 313 #if defined(MULTIPROCESSOR) /* { */ 314 struct simplelock spinlock_list_slock = SIMPLELOCK_INITIALIZER; 315 316 #define SPINLOCK_LIST_LOCK() \ 317 __cpu_simple_lock(&spinlock_list_slock.lock_data) 318 319 #define SPINLOCK_LIST_UNLOCK() \ 320 __cpu_simple_unlock(&spinlock_list_slock.lock_data) 321 #else 322 #define SPINLOCK_LIST_LOCK() /* nothing */ 323 324 #define SPINLOCK_LIST_UNLOCK() /* nothing */ 325 #endif /* MULTIPROCESSOR */ /* } */ 326 327 TAILQ_HEAD(, lock) spinlock_list = 328 TAILQ_HEAD_INITIALIZER(spinlock_list); 329 330 #define HAVEIT(lkp) \ 331 do { \ 332 if ((lkp)->lk_flags & LK_SPIN) { \ 333 int s = spllock(); \ 334 SPINLOCK_LIST_LOCK(); \ 335 /* XXX Cast away volatile. */ \ 336 TAILQ_INSERT_TAIL(&spinlock_list, (struct lock *)(lkp), \ 337 lk_list); \ 338 SPINLOCK_LIST_UNLOCK(); \ 339 splx(s); \ 340 } \ 341 } while (/*CONSTCOND*/0) 342 343 #define DONTHAVEIT(lkp) \ 344 do { \ 345 if ((lkp)->lk_flags & LK_SPIN) { \ 346 int s = spllock(); \ 347 SPINLOCK_LIST_LOCK(); \ 348 /* XXX Cast away volatile. */ \ 349 TAILQ_REMOVE(&spinlock_list, (struct lock *)(lkp), \ 350 lk_list); \ 351 SPINLOCK_LIST_UNLOCK(); \ 352 splx(s); \ 353 } \ 354 } while (/*CONSTCOND*/0) 355 #else 356 #define HAVEIT(lkp) /* nothing */ 357 358 #define DONTHAVEIT(lkp) /* nothing */ 359 #endif /* LOCKDEBUG */ /* } */ 360 361 #if defined(LOCKDEBUG) 362 /* 363 * Lock debug printing routine; can be configured to print to console 364 * or log to syslog. 365 */ 366 void 367 lock_printf(const char *fmt, ...) 368 { 369 char b[150]; 370 va_list ap; 371 372 va_start(ap, fmt); 373 if (lock_debug_syslog) 374 vlog(LOG_DEBUG, fmt, ap); 375 else { 376 vsnprintf(b, sizeof(b), fmt, ap); 377 printf_nolog("%s", b); 378 } 379 va_end(ap); 380 } 381 #endif /* LOCKDEBUG */ 382 383 /* 384 * Transfer any waiting processes from one lock to another. 385 */ 386 void 387 transferlockers(struct lock *from, struct lock *to) 388 { 389 390 KASSERT(from != to); 391 KASSERT((from->lk_flags & LK_WAITDRAIN) == 0); 392 if (from->lk_waitcount == 0) 393 return; 394 from->lk_newlock = to; 395 wakeup((void *)from); 396 tsleep((void *)&from->lk_newlock, from->lk_prio, "lkxfer", 0); 397 from->lk_newlock = NULL; 398 from->lk_flags &= ~(LK_WANT_EXCL | LK_WANT_UPGRADE); 399 KASSERT(from->lk_waitcount == 0); 400 } 401 402 403 /* 404 * Initialize a lock; required before use. 405 */ 406 void 407 lockinit(struct lock *lkp, int prio, const char *wmesg, int timo, int flags) 408 { 409 410 memset(lkp, 0, sizeof(struct lock)); 411 simple_lock_init(&lkp->lk_interlock); 412 lkp->lk_flags = flags & LK_EXTFLG_MASK; 413 if (flags & LK_SPIN) 414 lkp->lk_cpu = LK_NOCPU; 415 else { 416 lkp->lk_lockholder = LK_NOPROC; 417 lkp->lk_newlock = NULL; 418 lkp->lk_prio = prio; 419 lkp->lk_timo = timo; 420 } 421 lkp->lk_wmesg = wmesg; /* just a name for spin locks */ 422 #if defined(LOCKDEBUG) 423 lkp->lk_lock_file = NULL; 424 lkp->lk_unlock_file = NULL; 425 #endif 426 } 427 428 /* 429 * Determine the status of a lock. 430 */ 431 int 432 lockstatus(struct lock *lkp) 433 { 434 int s = 0; /* XXX: gcc */ 435 int lock_type = 0; 436 struct lwp *l = curlwp; /* XXX */ 437 pid_t pid; 438 lwpid_t lid; 439 cpuid_t cpu_id; 440 441 if ((lkp->lk_flags & LK_SPIN) || l == NULL) { 442 cpu_id = cpu_number(); 443 pid = LK_KERNPROC; 444 lid = 0; 445 } else { 446 cpu_id = LK_NOCPU; 447 pid = l->l_proc->p_pid; 448 lid = l->l_lid; 449 } 450 451 INTERLOCK_ACQUIRE(lkp, lkp->lk_flags, s); 452 if (lkp->lk_exclusivecount != 0) { 453 if (WEHOLDIT(lkp, pid, lid, cpu_id)) 454 lock_type = LK_EXCLUSIVE; 455 else 456 lock_type = LK_EXCLOTHER; 457 } else if (lkp->lk_sharecount != 0) 458 lock_type = LK_SHARED; 459 INTERLOCK_RELEASE(lkp, lkp->lk_flags, s); 460 return (lock_type); 461 } 462 463 #if defined(LOCKDEBUG) || defined(DIAGNOSTIC) 464 /* 465 * Make sure no spin locks are held by a CPU that is about 466 * to context switch. 467 */ 468 void 469 spinlock_switchcheck(void) 470 { 471 u_long cnt; 472 int s; 473 474 s = spllock(); 475 #if defined(MULTIPROCESSOR) 476 cnt = curcpu()->ci_spin_locks; 477 #else 478 cnt = spin_locks; 479 #endif 480 splx(s); 481 482 if (cnt != 0) 483 panic("spinlock_switchcheck: CPU %lu has %lu spin locks", 484 (u_long) cpu_number(), cnt); 485 } 486 #endif /* LOCKDEBUG || DIAGNOSTIC */ 487 488 /* 489 * Locks and IPLs (interrupt priority levels): 490 * 491 * Locks which may be taken from interrupt context must be handled 492 * very carefully; you must spl to the highest IPL where the lock 493 * is needed before acquiring the lock. 494 * 495 * It is also important to avoid deadlock, since certain (very high 496 * priority) interrupts are often needed to keep the system as a whole 497 * from deadlocking, and must not be blocked while you are spinning 498 * waiting for a lower-priority lock. 499 * 500 * In addition, the lock-debugging hooks themselves need to use locks! 501 * 502 * A raw __cpu_simple_lock may be used from interrupts are long as it 503 * is acquired and held at a single IPL. 504 * 505 * A simple_lock (which is a __cpu_simple_lock wrapped with some 506 * debugging hooks) may be used at or below spllock(), which is 507 * typically at or just below splhigh() (i.e. blocks everything 508 * but certain machine-dependent extremely high priority interrupts). 509 * 510 * spinlockmgr spinlocks should be used at or below splsched(). 511 * 512 * Some platforms may have interrupts of higher priority than splsched(), 513 * including hard serial interrupts, inter-processor interrupts, and 514 * kernel debugger traps. 515 */ 516 517 /* 518 * XXX XXX kludge around another kludge.. 519 * 520 * vfs_shutdown() may be called from interrupt context, either as a result 521 * of a panic, or from the debugger. It proceeds to call 522 * sys_sync(&proc0, ...), pretending its running on behalf of proc0 523 * 524 * We would like to make an attempt to sync the filesystems in this case, so 525 * if this happens, we treat attempts to acquire locks specially. 526 * All locks are acquired on behalf of proc0. 527 * 528 * If we've already paniced, we don't block waiting for locks, but 529 * just barge right ahead since we're already going down in flames. 530 */ 531 532 /* 533 * Set, change, or release a lock. 534 * 535 * Shared requests increment the shared count. Exclusive requests set the 536 * LK_WANT_EXCL flag (preventing further shared locks), and wait for already 537 * accepted shared locks and shared-to-exclusive upgrades to go away. 538 */ 539 int 540 #if defined(LOCKDEBUG) 541 _lockmgr(__volatile struct lock *lkp, u_int flags, 542 struct simplelock *interlkp, const char *file, int line) 543 #else 544 lockmgr(__volatile struct lock *lkp, u_int flags, 545 struct simplelock *interlkp) 546 #endif 547 { 548 int error; 549 pid_t pid; 550 lwpid_t lid; 551 int extflags; 552 cpuid_t cpu_id; 553 struct lwp *l = curlwp; 554 int lock_shutdown_noblock = 0; 555 int s = 0; 556 557 error = 0; 558 559 /* LK_RETRY is for vn_lock, not for lockmgr. */ 560 KASSERT((flags & LK_RETRY) == 0); 561 562 INTERLOCK_ACQUIRE(lkp, lkp->lk_flags, s); 563 if (flags & LK_INTERLOCK) 564 simple_unlock(interlkp); 565 extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; 566 567 #ifdef DIAGNOSTIC /* { */ 568 /* 569 * Don't allow spins on sleep locks and don't allow sleeps 570 * on spin locks. 571 */ 572 if ((flags ^ lkp->lk_flags) & LK_SPIN) 573 panic("lockmgr: sleep/spin mismatch"); 574 #endif /* } */ 575 576 if (extflags & LK_SPIN) { 577 pid = LK_KERNPROC; 578 lid = 0; 579 } else { 580 if (l == NULL) { 581 if (!doing_shutdown) { 582 panic("lockmgr: no context"); 583 } else { 584 l = &lwp0; 585 if (panicstr && (!(flags & LK_NOWAIT))) { 586 flags |= LK_NOWAIT; 587 lock_shutdown_noblock = 1; 588 } 589 } 590 } 591 lid = l->l_lid; 592 pid = l->l_proc->p_pid; 593 } 594 cpu_id = cpu_number(); 595 596 /* 597 * Once a lock has drained, the LK_DRAINING flag is set and an 598 * exclusive lock is returned. The only valid operation thereafter 599 * is a single release of that exclusive lock. This final release 600 * clears the LK_DRAINING flag and sets the LK_DRAINED flag. Any 601 * further requests of any sort will result in a panic. The bits 602 * selected for these two flags are chosen so that they will be set 603 * in memory that is freed (freed memory is filled with 0xdeadbeef). 604 * The final release is permitted to give a new lease on life to 605 * the lock by specifying LK_REENABLE. 606 */ 607 if (lkp->lk_flags & (LK_DRAINING|LK_DRAINED)) { 608 #ifdef DIAGNOSTIC /* { */ 609 if (lkp->lk_flags & LK_DRAINED) 610 panic("lockmgr: using decommissioned lock"); 611 if ((flags & LK_TYPE_MASK) != LK_RELEASE || 612 WEHOLDIT(lkp, pid, lid, cpu_id) == 0) 613 panic("lockmgr: non-release on draining lock: %d", 614 flags & LK_TYPE_MASK); 615 #endif /* DIAGNOSTIC */ /* } */ 616 lkp->lk_flags &= ~LK_DRAINING; 617 if ((flags & LK_REENABLE) == 0) 618 lkp->lk_flags |= LK_DRAINED; 619 } 620 621 switch (flags & LK_TYPE_MASK) { 622 623 case LK_SHARED: 624 if (WEHOLDIT(lkp, pid, lid, cpu_id) == 0) { 625 /* 626 * If just polling, check to see if we will block. 627 */ 628 if ((extflags & LK_NOWAIT) && (lkp->lk_flags & 629 (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE))) { 630 error = EBUSY; 631 break; 632 } 633 /* 634 * Wait for exclusive locks and upgrades to clear. 635 */ 636 error = acquire(&lkp, &s, extflags, 0, 637 LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE); 638 if (error) 639 break; 640 lkp->lk_sharecount++; 641 lkp->lk_flags |= LK_SHARE_NONZERO; 642 COUNT(lkp, l, cpu_id, 1); 643 break; 644 } 645 /* 646 * We hold an exclusive lock, so downgrade it to shared. 647 * An alternative would be to fail with EDEADLK. 648 */ 649 lkp->lk_sharecount++; 650 lkp->lk_flags |= LK_SHARE_NONZERO; 651 COUNT(lkp, l, cpu_id, 1); 652 /* fall into downgrade */ 653 654 case LK_DOWNGRADE: 655 if (WEHOLDIT(lkp, pid, lid, cpu_id) == 0 || 656 lkp->lk_exclusivecount == 0) 657 panic("lockmgr: not holding exclusive lock"); 658 lkp->lk_sharecount += lkp->lk_exclusivecount; 659 lkp->lk_flags |= LK_SHARE_NONZERO; 660 lkp->lk_exclusivecount = 0; 661 lkp->lk_recurselevel = 0; 662 lkp->lk_flags &= ~LK_HAVE_EXCL; 663 SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU); 664 #if defined(LOCKDEBUG) 665 lkp->lk_unlock_file = file; 666 lkp->lk_unlock_line = line; 667 #endif 668 DONTHAVEIT(lkp); 669 WAKEUP_WAITER(lkp); 670 break; 671 672 case LK_EXCLUPGRADE: 673 /* 674 * If another process is ahead of us to get an upgrade, 675 * then we want to fail rather than have an intervening 676 * exclusive access. 677 */ 678 if (lkp->lk_flags & LK_WANT_UPGRADE) { 679 lkp->lk_sharecount--; 680 if (lkp->lk_sharecount == 0) 681 lkp->lk_flags &= ~LK_SHARE_NONZERO; 682 COUNT(lkp, l, cpu_id, -1); 683 error = EBUSY; 684 break; 685 } 686 /* fall into normal upgrade */ 687 688 case LK_UPGRADE: 689 /* 690 * Upgrade a shared lock to an exclusive one. If another 691 * shared lock has already requested an upgrade to an 692 * exclusive lock, our shared lock is released and an 693 * exclusive lock is requested (which will be granted 694 * after the upgrade). If we return an error, the file 695 * will always be unlocked. 696 */ 697 if (WEHOLDIT(lkp, pid, lid, cpu_id) || lkp->lk_sharecount <= 0) 698 panic("lockmgr: upgrade exclusive lock"); 699 lkp->lk_sharecount--; 700 if (lkp->lk_sharecount == 0) 701 lkp->lk_flags &= ~LK_SHARE_NONZERO; 702 COUNT(lkp, l, cpu_id, -1); 703 /* 704 * If we are just polling, check to see if we will block. 705 */ 706 if ((extflags & LK_NOWAIT) && 707 ((lkp->lk_flags & LK_WANT_UPGRADE) || 708 lkp->lk_sharecount > 1)) { 709 error = EBUSY; 710 break; 711 } 712 if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) { 713 /* 714 * We are first shared lock to request an upgrade, so 715 * request upgrade and wait for the shared count to 716 * drop to zero, then take exclusive lock. 717 */ 718 lkp->lk_flags |= LK_WANT_UPGRADE; 719 error = acquire(&lkp, &s, extflags, 0, LK_SHARE_NONZERO); 720 lkp->lk_flags &= ~LK_WANT_UPGRADE; 721 if (error) 722 break; 723 lkp->lk_flags |= LK_HAVE_EXCL; 724 SETHOLDER(lkp, pid, lid, cpu_id); 725 #if defined(LOCKDEBUG) 726 lkp->lk_lock_file = file; 727 lkp->lk_lock_line = line; 728 #endif 729 HAVEIT(lkp); 730 if (lkp->lk_exclusivecount != 0) 731 panic("lockmgr: non-zero exclusive count"); 732 lkp->lk_exclusivecount = 1; 733 if (extflags & LK_SETRECURSE) 734 lkp->lk_recurselevel = 1; 735 COUNT(lkp, l, cpu_id, 1); 736 break; 737 } 738 /* 739 * Someone else has requested upgrade. Release our shared 740 * lock, awaken upgrade requestor if we are the last shared 741 * lock, then request an exclusive lock. 742 */ 743 if (lkp->lk_sharecount == 0) 744 WAKEUP_WAITER(lkp); 745 /* fall into exclusive request */ 746 747 case LK_EXCLUSIVE: 748 if (WEHOLDIT(lkp, pid, lid, cpu_id)) { 749 /* 750 * Recursive lock. 751 */ 752 if ((extflags & LK_CANRECURSE) == 0 && 753 lkp->lk_recurselevel == 0) { 754 if (extflags & LK_RECURSEFAIL) { 755 error = EDEADLK; 756 break; 757 } else 758 panic("lockmgr: locking against myself"); 759 } 760 lkp->lk_exclusivecount++; 761 if (extflags & LK_SETRECURSE && 762 lkp->lk_recurselevel == 0) 763 lkp->lk_recurselevel = lkp->lk_exclusivecount; 764 COUNT(lkp, l, cpu_id, 1); 765 break; 766 } 767 /* 768 * If we are just polling, check to see if we will sleep. 769 */ 770 if ((extflags & LK_NOWAIT) && (lkp->lk_flags & 771 (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | 772 LK_SHARE_NONZERO))) { 773 error = EBUSY; 774 break; 775 } 776 /* 777 * Try to acquire the want_exclusive flag. 778 */ 779 error = acquire(&lkp, &s, extflags, 0, 780 LK_HAVE_EXCL | LK_WANT_EXCL); 781 if (error) 782 break; 783 lkp->lk_flags |= LK_WANT_EXCL; 784 /* 785 * Wait for shared locks and upgrades to finish. 786 */ 787 error = acquire(&lkp, &s, extflags, 0, 788 LK_WANT_UPGRADE | LK_SHARE_NONZERO); 789 lkp->lk_flags &= ~LK_WANT_EXCL; 790 if (error) 791 break; 792 lkp->lk_flags |= LK_HAVE_EXCL; 793 SETHOLDER(lkp, pid, lid, cpu_id); 794 #if defined(LOCKDEBUG) 795 lkp->lk_lock_file = file; 796 lkp->lk_lock_line = line; 797 #endif 798 HAVEIT(lkp); 799 if (lkp->lk_exclusivecount != 0) 800 panic("lockmgr: non-zero exclusive count"); 801 lkp->lk_exclusivecount = 1; 802 if (extflags & LK_SETRECURSE) 803 lkp->lk_recurselevel = 1; 804 COUNT(lkp, l, cpu_id, 1); 805 break; 806 807 case LK_RELEASE: 808 if (lkp->lk_exclusivecount != 0) { 809 if (WEHOLDIT(lkp, pid, lid, cpu_id) == 0) { 810 if (lkp->lk_flags & LK_SPIN) { 811 panic("lockmgr: processor %lu, not " 812 "exclusive lock holder %lu " 813 "unlocking", cpu_id, lkp->lk_cpu); 814 } else { 815 panic("lockmgr: pid %d, not " 816 "exclusive lock holder %d " 817 "unlocking", pid, 818 lkp->lk_lockholder); 819 } 820 } 821 if (lkp->lk_exclusivecount == lkp->lk_recurselevel) 822 lkp->lk_recurselevel = 0; 823 lkp->lk_exclusivecount--; 824 COUNT(lkp, l, cpu_id, -1); 825 if (lkp->lk_exclusivecount == 0) { 826 lkp->lk_flags &= ~LK_HAVE_EXCL; 827 SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU); 828 #if defined(LOCKDEBUG) 829 lkp->lk_unlock_file = file; 830 lkp->lk_unlock_line = line; 831 #endif 832 DONTHAVEIT(lkp); 833 } 834 } else if (lkp->lk_sharecount != 0) { 835 lkp->lk_sharecount--; 836 if (lkp->lk_sharecount == 0) 837 lkp->lk_flags &= ~LK_SHARE_NONZERO; 838 COUNT(lkp, l, cpu_id, -1); 839 } 840 #ifdef DIAGNOSTIC 841 else 842 panic("lockmgr: release of unlocked lock!"); 843 #endif 844 WAKEUP_WAITER(lkp); 845 break; 846 847 case LK_DRAIN: 848 /* 849 * Check that we do not already hold the lock, as it can 850 * never drain if we do. Unfortunately, we have no way to 851 * check for holding a shared lock, but at least we can 852 * check for an exclusive one. 853 */ 854 if (WEHOLDIT(lkp, pid, lid, cpu_id)) 855 panic("lockmgr: draining against myself"); 856 /* 857 * If we are just polling, check to see if we will sleep. 858 */ 859 if ((extflags & LK_NOWAIT) && (lkp->lk_flags & 860 (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | 861 LK_SHARE_NONZERO | LK_WAIT_NONZERO))) { 862 error = EBUSY; 863 break; 864 } 865 error = acquire(&lkp, &s, extflags, 1, 866 LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | 867 LK_SHARE_NONZERO | LK_WAIT_NONZERO); 868 if (error) 869 break; 870 lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL; 871 SETHOLDER(lkp, pid, lid, cpu_id); 872 #if defined(LOCKDEBUG) 873 lkp->lk_lock_file = file; 874 lkp->lk_lock_line = line; 875 #endif 876 HAVEIT(lkp); 877 lkp->lk_exclusivecount = 1; 878 /* XXX unlikely that we'd want this */ 879 if (extflags & LK_SETRECURSE) 880 lkp->lk_recurselevel = 1; 881 COUNT(lkp, l, cpu_id, 1); 882 break; 883 884 default: 885 INTERLOCK_RELEASE(lkp, lkp->lk_flags, s); 886 panic("lockmgr: unknown locktype request %d", 887 flags & LK_TYPE_MASK); 888 /* NOTREACHED */ 889 } 890 if ((lkp->lk_flags & (LK_WAITDRAIN|LK_SPIN)) == LK_WAITDRAIN && 891 ((lkp->lk_flags & 892 (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | 893 LK_SHARE_NONZERO | LK_WAIT_NONZERO)) == 0)) { 894 lkp->lk_flags &= ~LK_WAITDRAIN; 895 wakeup((void *)&lkp->lk_flags); 896 } 897 /* 898 * Note that this panic will be a recursive panic, since 899 * we only set lock_shutdown_noblock above if panicstr != NULL. 900 */ 901 if (error && lock_shutdown_noblock) 902 panic("lockmgr: deadlock (see previous panic)"); 903 904 INTERLOCK_RELEASE(lkp, lkp->lk_flags, s); 905 return (error); 906 } 907 908 /* 909 * For a recursive spinlock held one or more times by the current CPU, 910 * release all N locks, and return N. 911 * Intended for use in mi_switch() shortly before context switching. 912 */ 913 914 int 915 #if defined(LOCKDEBUG) 916 _spinlock_release_all(__volatile struct lock *lkp, const char *file, int line) 917 #else 918 spinlock_release_all(__volatile struct lock *lkp) 919 #endif 920 { 921 int s, count; 922 cpuid_t cpu_id; 923 924 KASSERT(lkp->lk_flags & LK_SPIN); 925 926 INTERLOCK_ACQUIRE(lkp, LK_SPIN, s); 927 928 cpu_id = cpu_number(); 929 count = lkp->lk_exclusivecount; 930 931 if (count != 0) { 932 #ifdef DIAGNOSTIC 933 if (WEHOLDIT(lkp, 0, 0, cpu_id) == 0) { 934 panic("spinlock_release_all: processor %lu, not " 935 "exclusive lock holder %lu " 936 "unlocking", (long)cpu_id, lkp->lk_cpu); 937 } 938 #endif 939 lkp->lk_recurselevel = 0; 940 lkp->lk_exclusivecount = 0; 941 COUNT_CPU(cpu_id, -count); 942 lkp->lk_flags &= ~LK_HAVE_EXCL; 943 SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU); 944 #if defined(LOCKDEBUG) 945 lkp->lk_unlock_file = file; 946 lkp->lk_unlock_line = line; 947 #endif 948 DONTHAVEIT(lkp); 949 } 950 #ifdef DIAGNOSTIC 951 else if (lkp->lk_sharecount != 0) 952 panic("spinlock_release_all: release of shared lock!"); 953 else 954 panic("spinlock_release_all: release of unlocked lock!"); 955 #endif 956 INTERLOCK_RELEASE(lkp, LK_SPIN, s); 957 958 return (count); 959 } 960 961 /* 962 * For a recursive spinlock held one or more times by the current CPU, 963 * release all N locks, and return N. 964 * Intended for use in mi_switch() right after resuming execution. 965 */ 966 967 void 968 #if defined(LOCKDEBUG) 969 _spinlock_acquire_count(__volatile struct lock *lkp, int count, 970 const char *file, int line) 971 #else 972 spinlock_acquire_count(__volatile struct lock *lkp, int count) 973 #endif 974 { 975 int s, error; 976 cpuid_t cpu_id; 977 978 KASSERT(lkp->lk_flags & LK_SPIN); 979 980 INTERLOCK_ACQUIRE(lkp, LK_SPIN, s); 981 982 cpu_id = cpu_number(); 983 984 #ifdef DIAGNOSTIC 985 if (WEHOLDIT(lkp, LK_NOPROC, 0, cpu_id)) 986 panic("spinlock_acquire_count: processor %lu already holds lock", (long)cpu_id); 987 #endif 988 /* 989 * Try to acquire the want_exclusive flag. 990 */ 991 error = acquire(&lkp, &s, LK_SPIN, 0, LK_HAVE_EXCL | LK_WANT_EXCL); 992 lkp->lk_flags |= LK_WANT_EXCL; 993 /* 994 * Wait for shared locks and upgrades to finish. 995 */ 996 error = acquire(&lkp, &s, LK_SPIN, 0, 997 LK_SHARE_NONZERO | LK_WANT_UPGRADE); 998 lkp->lk_flags &= ~LK_WANT_EXCL; 999 lkp->lk_flags |= LK_HAVE_EXCL; 1000 SETHOLDER(lkp, LK_NOPROC, 0, cpu_id); 1001 #if defined(LOCKDEBUG) 1002 lkp->lk_lock_file = file; 1003 lkp->lk_lock_line = line; 1004 #endif 1005 HAVEIT(lkp); 1006 if (lkp->lk_exclusivecount != 0) 1007 panic("lockmgr: non-zero exclusive count"); 1008 lkp->lk_exclusivecount = count; 1009 lkp->lk_recurselevel = 1; 1010 COUNT_CPU(cpu_id, count); 1011 1012 INTERLOCK_RELEASE(lkp, lkp->lk_flags, s); 1013 } 1014 1015 1016 1017 /* 1018 * Print out information about state of a lock. Used by VOP_PRINT 1019 * routines to display ststus about contained locks. 1020 */ 1021 void 1022 lockmgr_printinfo(__volatile struct lock *lkp) 1023 { 1024 1025 if (lkp->lk_sharecount) 1026 printf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg, 1027 lkp->lk_sharecount); 1028 else if (lkp->lk_flags & LK_HAVE_EXCL) { 1029 printf(" lock type %s: EXCL (count %d) by ", 1030 lkp->lk_wmesg, lkp->lk_exclusivecount); 1031 if (lkp->lk_flags & LK_SPIN) 1032 printf("processor %lu", lkp->lk_cpu); 1033 else 1034 printf("pid %d.%d", lkp->lk_lockholder, 1035 lkp->lk_locklwp); 1036 } else 1037 printf(" not locked"); 1038 if ((lkp->lk_flags & LK_SPIN) == 0 && lkp->lk_waitcount > 0) 1039 printf(" with %d pending", lkp->lk_waitcount); 1040 } 1041 1042 #if defined(LOCKDEBUG) /* { */ 1043 TAILQ_HEAD(, simplelock) simplelock_list = 1044 TAILQ_HEAD_INITIALIZER(simplelock_list); 1045 1046 #if defined(MULTIPROCESSOR) /* { */ 1047 struct simplelock simplelock_list_slock = SIMPLELOCK_INITIALIZER; 1048 1049 #define SLOCK_LIST_LOCK() \ 1050 __cpu_simple_lock(&simplelock_list_slock.lock_data) 1051 1052 #define SLOCK_LIST_UNLOCK() \ 1053 __cpu_simple_unlock(&simplelock_list_slock.lock_data) 1054 1055 #define SLOCK_COUNT(x) \ 1056 curcpu()->ci_simple_locks += (x) 1057 #else 1058 u_long simple_locks; 1059 1060 #define SLOCK_LIST_LOCK() /* nothing */ 1061 1062 #define SLOCK_LIST_UNLOCK() /* nothing */ 1063 1064 #define SLOCK_COUNT(x) simple_locks += (x) 1065 #endif /* MULTIPROCESSOR */ /* } */ 1066 1067 #ifdef MULTIPROCESSOR 1068 #define SLOCK_MP() lock_printf("on CPU %ld\n", \ 1069 (u_long) cpu_number()) 1070 #else 1071 #define SLOCK_MP() /* nothing */ 1072 #endif 1073 1074 #define SLOCK_WHERE(str, alp, id, l) \ 1075 do { \ 1076 lock_printf("\n"); \ 1077 lock_printf(str); \ 1078 lock_printf("lock: %p, currently at: %s:%d\n", (alp), (id), (l)); \ 1079 SLOCK_MP(); \ 1080 if ((alp)->lock_file != NULL) \ 1081 lock_printf("last locked: %s:%d\n", (alp)->lock_file, \ 1082 (alp)->lock_line); \ 1083 if ((alp)->unlock_file != NULL) \ 1084 lock_printf("last unlocked: %s:%d\n", (alp)->unlock_file, \ 1085 (alp)->unlock_line); \ 1086 SLOCK_TRACE() \ 1087 SLOCK_DEBUGGER(); \ 1088 } while (/*CONSTCOND*/0) 1089 1090 /* 1091 * Simple lock functions so that the debugger can see from whence 1092 * they are being called. 1093 */ 1094 void 1095 simple_lock_init(struct simplelock *alp) 1096 { 1097 1098 #if defined(MULTIPROCESSOR) /* { */ 1099 __cpu_simple_lock_init(&alp->lock_data); 1100 #else 1101 alp->lock_data = __SIMPLELOCK_UNLOCKED; 1102 #endif /* } */ 1103 alp->lock_file = NULL; 1104 alp->lock_line = 0; 1105 alp->unlock_file = NULL; 1106 alp->unlock_line = 0; 1107 alp->lock_holder = LK_NOCPU; 1108 } 1109 1110 void 1111 _simple_lock(__volatile struct simplelock *alp, const char *id, int l) 1112 { 1113 cpuid_t cpu_id = cpu_number(); 1114 int s; 1115 1116 s = spllock(); 1117 1118 /* 1119 * MULTIPROCESSOR case: This is `safe' since if it's not us, we 1120 * don't take any action, and just fall into the normal spin case. 1121 */ 1122 if (alp->lock_data == __SIMPLELOCK_LOCKED) { 1123 #if defined(MULTIPROCESSOR) /* { */ 1124 if (alp->lock_holder == cpu_id) { 1125 SLOCK_WHERE("simple_lock: locking against myself\n", 1126 alp, id, l); 1127 goto out; 1128 } 1129 #else 1130 SLOCK_WHERE("simple_lock: lock held\n", alp, id, l); 1131 goto out; 1132 #endif /* MULTIPROCESSOR */ /* } */ 1133 } 1134 1135 #if defined(MULTIPROCESSOR) /* { */ 1136 /* Acquire the lock before modifying any fields. */ 1137 splx(s); 1138 __cpu_simple_lock(&alp->lock_data); 1139 s = spllock(); 1140 #else 1141 alp->lock_data = __SIMPLELOCK_LOCKED; 1142 #endif /* } */ 1143 1144 if (alp->lock_holder != LK_NOCPU) { 1145 SLOCK_WHERE("simple_lock: uninitialized lock\n", 1146 alp, id, l); 1147 } 1148 alp->lock_file = id; 1149 alp->lock_line = l; 1150 alp->lock_holder = cpu_id; 1151 1152 SLOCK_LIST_LOCK(); 1153 /* XXX Cast away volatile */ 1154 TAILQ_INSERT_TAIL(&simplelock_list, (struct simplelock *)alp, list); 1155 SLOCK_LIST_UNLOCK(); 1156 1157 SLOCK_COUNT(1); 1158 1159 out: 1160 splx(s); 1161 } 1162 1163 int 1164 _simple_lock_held(__volatile struct simplelock *alp) 1165 { 1166 #if defined(MULTIPROCESSOR) || defined(DIAGNOSTIC) 1167 cpuid_t cpu_id = cpu_number(); 1168 #endif 1169 int s, locked = 0; 1170 1171 s = spllock(); 1172 1173 #if defined(MULTIPROCESSOR) 1174 if (__cpu_simple_lock_try(&alp->lock_data) == 0) 1175 locked = (alp->lock_holder == cpu_id); 1176 else 1177 __cpu_simple_unlock(&alp->lock_data); 1178 #else 1179 if (alp->lock_data == __SIMPLELOCK_LOCKED) { 1180 locked = 1; 1181 KASSERT(alp->lock_holder == cpu_id); 1182 } 1183 #endif 1184 1185 splx(s); 1186 1187 return (locked); 1188 } 1189 1190 int 1191 _simple_lock_try(__volatile struct simplelock *alp, const char *id, int l) 1192 { 1193 cpuid_t cpu_id = cpu_number(); 1194 int s, rv = 0; 1195 1196 s = spllock(); 1197 1198 /* 1199 * MULTIPROCESSOR case: This is `safe' since if it's not us, we 1200 * don't take any action. 1201 */ 1202 #if defined(MULTIPROCESSOR) /* { */ 1203 if ((rv = __cpu_simple_lock_try(&alp->lock_data)) == 0) { 1204 if (alp->lock_holder == cpu_id) 1205 SLOCK_WHERE("simple_lock_try: locking against myself\n", 1206 alp, id, l); 1207 goto out; 1208 } 1209 #else 1210 if (alp->lock_data == __SIMPLELOCK_LOCKED) { 1211 SLOCK_WHERE("simple_lock_try: lock held\n", alp, id, l); 1212 goto out; 1213 } 1214 alp->lock_data = __SIMPLELOCK_LOCKED; 1215 #endif /* MULTIPROCESSOR */ /* } */ 1216 1217 /* 1218 * At this point, we have acquired the lock. 1219 */ 1220 1221 rv = 1; 1222 1223 alp->lock_file = id; 1224 alp->lock_line = l; 1225 alp->lock_holder = cpu_id; 1226 1227 SLOCK_LIST_LOCK(); 1228 /* XXX Cast away volatile. */ 1229 TAILQ_INSERT_TAIL(&simplelock_list, (struct simplelock *)alp, list); 1230 SLOCK_LIST_UNLOCK(); 1231 1232 SLOCK_COUNT(1); 1233 1234 out: 1235 splx(s); 1236 return (rv); 1237 } 1238 1239 void 1240 _simple_unlock(__volatile struct simplelock *alp, const char *id, int l) 1241 { 1242 int s; 1243 1244 s = spllock(); 1245 1246 /* 1247 * MULTIPROCESSOR case: This is `safe' because we think we hold 1248 * the lock, and if we don't, we don't take any action. 1249 */ 1250 if (alp->lock_data == __SIMPLELOCK_UNLOCKED) { 1251 SLOCK_WHERE("simple_unlock: lock not held\n", 1252 alp, id, l); 1253 goto out; 1254 } 1255 1256 SLOCK_LIST_LOCK(); 1257 TAILQ_REMOVE(&simplelock_list, alp, list); 1258 SLOCK_LIST_UNLOCK(); 1259 1260 SLOCK_COUNT(-1); 1261 1262 alp->list.tqe_next = NULL; /* sanity */ 1263 alp->list.tqe_prev = NULL; /* sanity */ 1264 1265 alp->unlock_file = id; 1266 alp->unlock_line = l; 1267 1268 #if defined(MULTIPROCESSOR) /* { */ 1269 alp->lock_holder = LK_NOCPU; 1270 /* Now that we've modified all fields, release the lock. */ 1271 __cpu_simple_unlock(&alp->lock_data); 1272 #else 1273 alp->lock_data = __SIMPLELOCK_UNLOCKED; 1274 KASSERT(alp->lock_holder == cpu_number()); 1275 alp->lock_holder = LK_NOCPU; 1276 #endif /* } */ 1277 1278 out: 1279 splx(s); 1280 } 1281 1282 void 1283 simple_lock_dump(void) 1284 { 1285 struct simplelock *alp; 1286 int s; 1287 1288 s = spllock(); 1289 SLOCK_LIST_LOCK(); 1290 lock_printf("all simple locks:\n"); 1291 TAILQ_FOREACH(alp, &simplelock_list, list) { 1292 lock_printf("%p CPU %lu %s:%d\n", alp, alp->lock_holder, 1293 alp->lock_file, alp->lock_line); 1294 } 1295 SLOCK_LIST_UNLOCK(); 1296 splx(s); 1297 } 1298 1299 void 1300 simple_lock_freecheck(void *start, void *end) 1301 { 1302 struct simplelock *alp; 1303 int s; 1304 1305 s = spllock(); 1306 SLOCK_LIST_LOCK(); 1307 TAILQ_FOREACH(alp, &simplelock_list, list) { 1308 if ((void *)alp >= start && (void *)alp < end) { 1309 lock_printf("freeing simple_lock %p CPU %lu %s:%d\n", 1310 alp, alp->lock_holder, alp->lock_file, 1311 alp->lock_line); 1312 SLOCK_DEBUGGER(); 1313 } 1314 } 1315 SLOCK_LIST_UNLOCK(); 1316 splx(s); 1317 } 1318 1319 /* 1320 * We must be holding exactly one lock: the sched_lock. 1321 */ 1322 1323 void 1324 simple_lock_switchcheck(void) 1325 { 1326 1327 simple_lock_only_held(&sched_lock, "switching"); 1328 } 1329 1330 void 1331 simple_lock_only_held(volatile struct simplelock *lp, const char *where) 1332 { 1333 struct simplelock *alp; 1334 cpuid_t cpu_id = cpu_number(); 1335 int s; 1336 1337 if (lp) { 1338 LOCK_ASSERT(simple_lock_held(lp)); 1339 } 1340 s = spllock(); 1341 SLOCK_LIST_LOCK(); 1342 TAILQ_FOREACH(alp, &simplelock_list, list) { 1343 if (alp == lp) 1344 continue; 1345 if (alp->lock_holder == cpu_id) 1346 break; 1347 } 1348 SLOCK_LIST_UNLOCK(); 1349 splx(s); 1350 1351 if (alp != NULL) { 1352 lock_printf("\n%s with held simple_lock %p " 1353 "CPU %lu %s:%d\n", 1354 where, alp, alp->lock_holder, alp->lock_file, 1355 alp->lock_line); 1356 SLOCK_TRACE(); 1357 SLOCK_DEBUGGER(); 1358 } 1359 } 1360 #endif /* LOCKDEBUG */ /* } */ 1361 1362 #if defined(MULTIPROCESSOR) 1363 /* 1364 * Functions for manipulating the kernel_lock. We put them here 1365 * so that they show up in profiles. 1366 */ 1367 1368 struct lock kernel_lock; 1369 1370 void 1371 _kernel_lock_init(void) 1372 { 1373 1374 spinlockinit(&kernel_lock, "klock", 0); 1375 } 1376 1377 /* 1378 * Acquire/release the kernel lock. Intended for use in the scheduler 1379 * and the lower half of the kernel. 1380 */ 1381 void 1382 _kernel_lock(int flag) 1383 { 1384 1385 SCHED_ASSERT_UNLOCKED(); 1386 spinlockmgr(&kernel_lock, flag, 0); 1387 } 1388 1389 void 1390 _kernel_unlock(void) 1391 { 1392 1393 spinlockmgr(&kernel_lock, LK_RELEASE, 0); 1394 } 1395 1396 /* 1397 * Acquire/release the kernel_lock on behalf of a process. Intended for 1398 * use in the top half of the kernel. 1399 */ 1400 void 1401 _kernel_proc_lock(struct lwp *l) 1402 { 1403 1404 SCHED_ASSERT_UNLOCKED(); 1405 spinlockmgr(&kernel_lock, LK_EXCLUSIVE, 0); 1406 } 1407 1408 void 1409 _kernel_proc_unlock(struct lwp *l) 1410 { 1411 1412 spinlockmgr(&kernel_lock, LK_RELEASE, 0); 1413 } 1414 1415 int 1416 _kernel_lock_release_all() 1417 { 1418 int hold_count; 1419 1420 if (lockstatus(&kernel_lock) == LK_EXCLUSIVE) 1421 hold_count = spinlock_release_all(&kernel_lock); 1422 else 1423 hold_count = 0; 1424 1425 return hold_count; 1426 } 1427 1428 void 1429 _kernel_lock_acquire_count(int hold_count) 1430 { 1431 1432 if (hold_count != 0) 1433 spinlock_acquire_count(&kernel_lock, hold_count); 1434 } 1435 #endif /* MULTIPROCESSOR */ 1436