| 1 | /* |
| 2 | * Copyright (c) 1995 |
| 3 | * The Regents of the University of California. All rights reserved. |
| 4 | * |
| 5 | * Copyright (C) 1997 |
| 6 | * John S. Dyson. All rights reserved. |
| 7 | * |
| 8 | * This code contains ideas from software contributed to Berkeley by |
| 9 | * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating |
| 10 | * System project at Carnegie-Mellon University. |
| 11 | * |
| 12 | * Redistribution and use in source and binary forms, with or without |
| 13 | * modification, are permitted provided that the following conditions |
| 14 | * are met: |
| 15 | * 1. Redistributions of source code must retain the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer. |
| 17 | * 2. Redistributions in binary form must reproduce the above copyright |
| 18 | * notice, this list of conditions and the following disclaimer in the |
| 19 | * documentation and/or other materials provided with the distribution. |
| 20 | * 3. All advertising materials mentioning features or use of this software |
| 21 | * must display the following acknowledgement: |
| 22 | * This product includes software developed by the University of |
| 23 | * California, Berkeley and its contributors. |
| 24 | * 4. Neither the name of the University nor the names of its contributors |
| 25 | * may be used to endorse or promote products derived from this software |
| 26 | * without specific prior written permission. |
| 27 | * |
| 28 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 29 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 30 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 31 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 32 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 33 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 34 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 35 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 36 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 37 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 38 | * SUCH DAMAGE. |
| 39 | * |
| 40 | * @(#)kern_lock.c 8.18 (Berkeley) 5/21/95 |
| 41 | * $FreeBSD: src/sys/kern/kern_lock.c,v 1.31.2.3 2001/12/25 01:44:44 dillon Exp $ |
| 42 | * $DragonFly: src/sys/kern/kern_lock.c,v 1.2 2003/06/17 04:28:41 dillon Exp $ |
| 43 | */ |
| 44 | |
| 45 | #include "opt_lint.h" |
| 46 | |
| 47 | #include <sys/param.h> |
| 48 | #include <sys/proc.h> |
| 49 | #include <sys/lock.h> |
| 50 | #include <sys/systm.h> |
| 51 | |
| 52 | /* |
| 53 | * Locking primitives implementation. |
| 54 | * Locks provide shared/exclusive sychronization. |
| 55 | */ |
| 56 | |
| 57 | #ifdef SIMPLELOCK_DEBUG |
| 58 | #define COUNT(p, x) if (p) (p)->p_locks += (x) |
| 59 | #else |
| 60 | #define COUNT(p, x) |
| 61 | #endif |
| 62 | |
| 63 | #define LOCK_WAIT_TIME 100 |
| 64 | #define LOCK_SAMPLE_WAIT 7 |
| 65 | |
| 66 | #if defined(DIAGNOSTIC) |
| 67 | #define LOCK_INLINE |
| 68 | #else |
| 69 | #define LOCK_INLINE __inline |
| 70 | #endif |
| 71 | |
| 72 | #define LK_ALL (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | \ |
| 73 | LK_SHARE_NONZERO | LK_WAIT_NONZERO) |
| 74 | |
| 75 | static int acquire(struct lock *lkp, int extflags, int wanted); |
| 76 | static int apause(struct lock *lkp, int flags); |
| 77 | static int acquiredrain(struct lock *lkp, int extflags) ; |
| 78 | |
| 79 | static LOCK_INLINE void |
| 80 | sharelock(struct lock *lkp, int incr) { |
| 81 | lkp->lk_flags |= LK_SHARE_NONZERO; |
| 82 | lkp->lk_sharecount += incr; |
| 83 | } |
| 84 | |
| 85 | static LOCK_INLINE void |
| 86 | shareunlock(struct lock *lkp, int decr) { |
| 87 | |
| 88 | KASSERT(lkp->lk_sharecount >= decr, ("shareunlock: count < decr")); |
| 89 | |
| 90 | if (lkp->lk_sharecount == decr) { |
| 91 | lkp->lk_flags &= ~LK_SHARE_NONZERO; |
| 92 | if (lkp->lk_flags & (LK_WANT_UPGRADE | LK_WANT_EXCL)) { |
| 93 | wakeup(lkp); |
| 94 | } |
| 95 | lkp->lk_sharecount = 0; |
| 96 | } else { |
| 97 | lkp->lk_sharecount -= decr; |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | /* |
| 102 | * This is the waitloop optimization, and note for this to work |
| 103 | * simple_lock and simple_unlock should be subroutines to avoid |
| 104 | * optimization troubles. |
| 105 | */ |
| 106 | static int |
| 107 | apause(struct lock *lkp, int flags) |
| 108 | { |
| 109 | #ifdef SMP |
| 110 | int i, lock_wait; |
| 111 | #endif |
| 112 | |
| 113 | if ((lkp->lk_flags & flags) == 0) |
| 114 | return 0; |
| 115 | #ifdef SMP |
| 116 | for (lock_wait = LOCK_WAIT_TIME; lock_wait > 0; lock_wait--) { |
| 117 | simple_unlock(&lkp->lk_interlock); |
| 118 | for (i = LOCK_SAMPLE_WAIT; i > 0; i--) |
| 119 | if ((lkp->lk_flags & flags) == 0) |
| 120 | break; |
| 121 | simple_lock(&lkp->lk_interlock); |
| 122 | if ((lkp->lk_flags & flags) == 0) |
| 123 | return 0; |
| 124 | } |
| 125 | #endif |
| 126 | return 1; |
| 127 | } |
| 128 | |
| 129 | static int |
| 130 | acquire(struct lock *lkp, int extflags, int wanted) { |
| 131 | int s, error; |
| 132 | |
| 133 | if ((extflags & LK_NOWAIT) && (lkp->lk_flags & wanted)) { |
| 134 | return EBUSY; |
| 135 | } |
| 136 | |
| 137 | if (((lkp->lk_flags | extflags) & LK_NOPAUSE) == 0) { |
| 138 | error = apause(lkp, wanted); |
| 139 | if (error == 0) |
| 140 | return 0; |
| 141 | } |
| 142 | |
| 143 | s = splhigh(); |
| 144 | while ((lkp->lk_flags & wanted) != 0) { |
| 145 | lkp->lk_flags |= LK_WAIT_NONZERO; |
| 146 | lkp->lk_waitcount++; |
| 147 | simple_unlock(&lkp->lk_interlock); |
| 148 | error = tsleep(lkp, lkp->lk_prio, lkp->lk_wmesg, |
| 149 | ((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0)); |
| 150 | simple_lock(&lkp->lk_interlock); |
| 151 | if (lkp->lk_waitcount == 1) { |
| 152 | lkp->lk_flags &= ~LK_WAIT_NONZERO; |
| 153 | lkp->lk_waitcount = 0; |
| 154 | } else { |
| 155 | lkp->lk_waitcount--; |
| 156 | } |
| 157 | if (error) { |
| 158 | splx(s); |
| 159 | return error; |
| 160 | } |
| 161 | if (extflags & LK_SLEEPFAIL) { |
| 162 | splx(s); |
| 163 | return ENOLCK; |
| 164 | } |
| 165 | } |
| 166 | splx(s); |
| 167 | return 0; |
| 168 | } |
| 169 | |
| 170 | /* |
| 171 | * Set, change, or release a lock. |
| 172 | * |
| 173 | * Shared requests increment the shared count. Exclusive requests set the |
| 174 | * LK_WANT_EXCL flag (preventing further shared locks), and wait for already |
| 175 | * accepted shared locks and shared-to-exclusive upgrades to go away. |
| 176 | */ |
| 177 | int |
| 178 | #ifndef DEBUG_LOCKS |
| 179 | lockmgr(lkp, flags, interlkp, p) |
| 180 | #else |
| 181 | debuglockmgr(lkp, flags, interlkp, p, name, file, line) |
| 182 | #endif |
| 183 | struct lock *lkp; |
| 184 | u_int flags; |
| 185 | struct simplelock *interlkp; |
| 186 | struct proc *p; |
| 187 | #ifdef DEBUG_LOCKS |
| 188 | const char *name; /* Name of lock function */ |
| 189 | const char *file; /* Name of file call is from */ |
| 190 | int line; /* Line number in file */ |
| 191 | #endif |
| 192 | { |
| 193 | int error; |
| 194 | pid_t pid; |
| 195 | int extflags; |
| 196 | |
| 197 | error = 0; |
| 198 | if (p == NULL) |
| 199 | pid = LK_KERNPROC; |
| 200 | else |
| 201 | pid = p->p_pid; |
| 202 | |
| 203 | simple_lock(&lkp->lk_interlock); |
| 204 | if (flags & LK_INTERLOCK) |
| 205 | simple_unlock(interlkp); |
| 206 | |
| 207 | extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; |
| 208 | |
| 209 | switch (flags & LK_TYPE_MASK) { |
| 210 | |
| 211 | case LK_SHARED: |
| 212 | /* |
| 213 | * If we are not the exclusive lock holder, we have to block |
| 214 | * while there is an exclusive lock holder or while an |
| 215 | * exclusive lock request or upgrade request is in progress. |
| 216 | * |
| 217 | * However, if P_DEADLKTREAT is set, we override exclusive |
| 218 | * lock requests or upgrade requests ( but not the exclusive |
| 219 | * lock itself ). |
| 220 | */ |
| 221 | if (lkp->lk_lockholder != pid) { |
| 222 | if (p && (p->p_flag & P_DEADLKTREAT)) { |
| 223 | error = acquire( |
| 224 | lkp, |
| 225 | extflags, |
| 226 | LK_HAVE_EXCL |
| 227 | ); |
| 228 | } else { |
| 229 | error = acquire( |
| 230 | lkp, |
| 231 | extflags, |
| 232 | LK_HAVE_EXCL | LK_WANT_EXCL | |
| 233 | LK_WANT_UPGRADE |
| 234 | ); |
| 235 | } |
| 236 | if (error) |
| 237 | break; |
| 238 | sharelock(lkp, 1); |
| 239 | COUNT(p, 1); |
| 240 | break; |
| 241 | } |
| 242 | /* |
| 243 | * We hold an exclusive lock, so downgrade it to shared. |
| 244 | * An alternative would be to fail with EDEADLK. |
| 245 | */ |
| 246 | sharelock(lkp, 1); |
| 247 | COUNT(p, 1); |
| 248 | /* fall into downgrade */ |
| 249 | |
| 250 | case LK_DOWNGRADE: |
| 251 | if (lkp->lk_lockholder != pid || lkp->lk_exclusivecount == 0) |
| 252 | panic("lockmgr: not holding exclusive lock"); |
| 253 | sharelock(lkp, lkp->lk_exclusivecount); |
| 254 | lkp->lk_exclusivecount = 0; |
| 255 | lkp->lk_flags &= ~LK_HAVE_EXCL; |
| 256 | lkp->lk_lockholder = LK_NOPROC; |
| 257 | if (lkp->lk_waitcount) |
| 258 | wakeup((void *)lkp); |
| 259 | break; |
| 260 | |
| 261 | case LK_EXCLUPGRADE: |
| 262 | /* |
| 263 | * If another process is ahead of us to get an upgrade, |
| 264 | * then we want to fail rather than have an intervening |
| 265 | * exclusive access. |
| 266 | */ |
| 267 | if (lkp->lk_flags & LK_WANT_UPGRADE) { |
| 268 | shareunlock(lkp, 1); |
| 269 | COUNT(p, -1); |
| 270 | error = EBUSY; |
| 271 | break; |
| 272 | } |
| 273 | /* fall into normal upgrade */ |
| 274 | |
| 275 | case LK_UPGRADE: |
| 276 | /* |
| 277 | * Upgrade a shared lock to an exclusive one. If another |
| 278 | * shared lock has already requested an upgrade to an |
| 279 | * exclusive lock, our shared lock is released and an |
| 280 | * exclusive lock is requested (which will be granted |
| 281 | * after the upgrade). If we return an error, the file |
| 282 | * will always be unlocked. |
| 283 | */ |
| 284 | if ((lkp->lk_lockholder == pid) || (lkp->lk_sharecount <= 0)) |
| 285 | panic("lockmgr: upgrade exclusive lock"); |
| 286 | shareunlock(lkp, 1); |
| 287 | COUNT(p, -1); |
| 288 | /* |
| 289 | * If we are just polling, check to see if we will block. |
| 290 | */ |
| 291 | if ((extflags & LK_NOWAIT) && |
| 292 | ((lkp->lk_flags & LK_WANT_UPGRADE) || |
| 293 | lkp->lk_sharecount > 1)) { |
| 294 | error = EBUSY; |
| 295 | break; |
| 296 | } |
| 297 | if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) { |
| 298 | /* |
| 299 | * We are first shared lock to request an upgrade, so |
| 300 | * request upgrade and wait for the shared count to |
| 301 | * drop to zero, then take exclusive lock. |
| 302 | */ |
| 303 | lkp->lk_flags |= LK_WANT_UPGRADE; |
| 304 | error = acquire(lkp, extflags, LK_SHARE_NONZERO); |
| 305 | lkp->lk_flags &= ~LK_WANT_UPGRADE; |
| 306 | |
| 307 | if (error) |
| 308 | break; |
| 309 | lkp->lk_flags |= LK_HAVE_EXCL; |
| 310 | lkp->lk_lockholder = pid; |
| 311 | if (lkp->lk_exclusivecount != 0) |
| 312 | panic("lockmgr: non-zero exclusive count"); |
| 313 | lkp->lk_exclusivecount = 1; |
| 314 | #if defined(DEBUG_LOCKS) |
| 315 | lkp->lk_filename = file; |
| 316 | lkp->lk_lineno = line; |
| 317 | lkp->lk_lockername = name; |
| 318 | #endif |
| 319 | COUNT(p, 1); |
| 320 | break; |
| 321 | } |
| 322 | /* |
| 323 | * Someone else has requested upgrade. Release our shared |
| 324 | * lock, awaken upgrade requestor if we are the last shared |
| 325 | * lock, then request an exclusive lock. |
| 326 | */ |
| 327 | if ( (lkp->lk_flags & (LK_SHARE_NONZERO|LK_WAIT_NONZERO)) == |
| 328 | LK_WAIT_NONZERO) |
| 329 | wakeup((void *)lkp); |
| 330 | /* fall into exclusive request */ |
| 331 | |
| 332 | case LK_EXCLUSIVE: |
| 333 | if (lkp->lk_lockholder == pid && pid != LK_KERNPROC) { |
| 334 | /* |
| 335 | * Recursive lock. |
| 336 | */ |
| 337 | if ((extflags & (LK_NOWAIT | LK_CANRECURSE)) == 0) |
| 338 | panic("lockmgr: locking against myself"); |
| 339 | if ((extflags & LK_CANRECURSE) != 0) { |
| 340 | lkp->lk_exclusivecount++; |
| 341 | COUNT(p, 1); |
| 342 | break; |
| 343 | } |
| 344 | } |
| 345 | /* |
| 346 | * If we are just polling, check to see if we will sleep. |
| 347 | */ |
| 348 | if ((extflags & LK_NOWAIT) && |
| 349 | (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO))) { |
| 350 | error = EBUSY; |
| 351 | break; |
| 352 | } |
| 353 | /* |
| 354 | * Try to acquire the want_exclusive flag. |
| 355 | */ |
| 356 | error = acquire(lkp, extflags, (LK_HAVE_EXCL | LK_WANT_EXCL)); |
| 357 | if (error) |
| 358 | break; |
| 359 | lkp->lk_flags |= LK_WANT_EXCL; |
| 360 | /* |
| 361 | * Wait for shared locks and upgrades to finish. |
| 362 | */ |
| 363 | error = acquire(lkp, extflags, LK_WANT_UPGRADE | LK_SHARE_NONZERO); |
| 364 | lkp->lk_flags &= ~LK_WANT_EXCL; |
| 365 | if (error) |
| 366 | break; |
| 367 | lkp->lk_flags |= LK_HAVE_EXCL; |
| 368 | lkp->lk_lockholder = pid; |
| 369 | if (lkp->lk_exclusivecount != 0) |
| 370 | panic("lockmgr: non-zero exclusive count"); |
| 371 | lkp->lk_exclusivecount = 1; |
| 372 | #if defined(DEBUG_LOCKS) |
| 373 | lkp->lk_filename = file; |
| 374 | lkp->lk_lineno = line; |
| 375 | lkp->lk_lockername = name; |
| 376 | #endif |
| 377 | COUNT(p, 1); |
| 378 | break; |
| 379 | |
| 380 | case LK_RELEASE: |
| 381 | if (lkp->lk_exclusivecount != 0) { |
| 382 | if (lkp->lk_lockholder != pid && |
| 383 | lkp->lk_lockholder != LK_KERNPROC) { |
| 384 | panic("lockmgr: pid %d, not %s %d unlocking", |
| 385 | pid, "exclusive lock holder", |
| 386 | lkp->lk_lockholder); |
| 387 | } |
| 388 | if (lkp->lk_lockholder != LK_KERNPROC) { |
| 389 | COUNT(p, -1); |
| 390 | } |
| 391 | if (lkp->lk_exclusivecount == 1) { |
| 392 | lkp->lk_flags &= ~LK_HAVE_EXCL; |
| 393 | lkp->lk_lockholder = LK_NOPROC; |
| 394 | lkp->lk_exclusivecount = 0; |
| 395 | } else { |
| 396 | lkp->lk_exclusivecount--; |
| 397 | } |
| 398 | } else if (lkp->lk_flags & LK_SHARE_NONZERO) { |
| 399 | shareunlock(lkp, 1); |
| 400 | COUNT(p, -1); |
| 401 | } |
| 402 | if (lkp->lk_flags & LK_WAIT_NONZERO) |
| 403 | wakeup((void *)lkp); |
| 404 | break; |
| 405 | |
| 406 | case LK_DRAIN: |
| 407 | /* |
| 408 | * Check that we do not already hold the lock, as it can |
| 409 | * never drain if we do. Unfortunately, we have no way to |
| 410 | * check for holding a shared lock, but at least we can |
| 411 | * check for an exclusive one. |
| 412 | */ |
| 413 | if (lkp->lk_lockholder == pid) |
| 414 | panic("lockmgr: draining against myself"); |
| 415 | |
| 416 | error = acquiredrain(lkp, extflags); |
| 417 | if (error) |
| 418 | break; |
| 419 | lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL; |
| 420 | lkp->lk_lockholder = pid; |
| 421 | lkp->lk_exclusivecount = 1; |
| 422 | #if defined(DEBUG_LOCKS) |
| 423 | lkp->lk_filename = file; |
| 424 | lkp->lk_lineno = line; |
| 425 | lkp->lk_lockername = name; |
| 426 | #endif |
| 427 | COUNT(p, 1); |
| 428 | break; |
| 429 | |
| 430 | default: |
| 431 | simple_unlock(&lkp->lk_interlock); |
| 432 | panic("lockmgr: unknown locktype request %d", |
| 433 | flags & LK_TYPE_MASK); |
| 434 | /* NOTREACHED */ |
| 435 | } |
| 436 | if ((lkp->lk_flags & LK_WAITDRAIN) && |
| 437 | (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | |
| 438 | LK_SHARE_NONZERO | LK_WAIT_NONZERO)) == 0) { |
| 439 | lkp->lk_flags &= ~LK_WAITDRAIN; |
| 440 | wakeup((void *)&lkp->lk_flags); |
| 441 | } |
| 442 | simple_unlock(&lkp->lk_interlock); |
| 443 | return (error); |
| 444 | } |
| 445 | |
| 446 | static int |
| 447 | acquiredrain(struct lock *lkp, int extflags) { |
| 448 | int error; |
| 449 | |
| 450 | if ((extflags & LK_NOWAIT) && (lkp->lk_flags & LK_ALL)) { |
| 451 | return EBUSY; |
| 452 | } |
| 453 | |
| 454 | error = apause(lkp, LK_ALL); |
| 455 | if (error == 0) |
| 456 | return 0; |
| 457 | |
| 458 | while (lkp->lk_flags & LK_ALL) { |
| 459 | lkp->lk_flags |= LK_WAITDRAIN; |
| 460 | simple_unlock(&lkp->lk_interlock); |
| 461 | error = tsleep(&lkp->lk_flags, lkp->lk_prio, |
| 462 | lkp->lk_wmesg, |
| 463 | ((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0)); |
| 464 | simple_lock(&lkp->lk_interlock); |
| 465 | if (error) |
| 466 | return error; |
| 467 | if (extflags & LK_SLEEPFAIL) { |
| 468 | return ENOLCK; |
| 469 | } |
| 470 | } |
| 471 | return 0; |
| 472 | } |
| 473 | |
| 474 | /* |
| 475 | * Initialize a lock; required before use. |
| 476 | */ |
| 477 | void |
| 478 | lockinit(lkp, prio, wmesg, timo, flags) |
| 479 | struct lock *lkp; |
| 480 | int prio; |
| 481 | char *wmesg; |
| 482 | int timo; |
| 483 | int flags; |
| 484 | { |
| 485 | |
| 486 | simple_lock_init(&lkp->lk_interlock); |
| 487 | lkp->lk_flags = (flags & LK_EXTFLG_MASK); |
| 488 | lkp->lk_sharecount = 0; |
| 489 | lkp->lk_waitcount = 0; |
| 490 | lkp->lk_exclusivecount = 0; |
| 491 | lkp->lk_prio = prio; |
| 492 | lkp->lk_wmesg = wmesg; |
| 493 | lkp->lk_timo = timo; |
| 494 | lkp->lk_lockholder = LK_NOPROC; |
| 495 | } |
| 496 | |
| 497 | /* |
| 498 | * Determine the status of a lock. |
| 499 | */ |
| 500 | int |
| 501 | lockstatus(lkp, p) |
| 502 | struct lock *lkp; |
| 503 | struct proc *p; |
| 504 | { |
| 505 | int lock_type = 0; |
| 506 | |
| 507 | simple_lock(&lkp->lk_interlock); |
| 508 | if (lkp->lk_exclusivecount != 0) { |
| 509 | if (p == NULL || lkp->lk_lockholder == p->p_pid) |
| 510 | lock_type = LK_EXCLUSIVE; |
| 511 | else |
| 512 | lock_type = LK_EXCLOTHER; |
| 513 | } else if (lkp->lk_sharecount != 0) |
| 514 | lock_type = LK_SHARED; |
| 515 | simple_unlock(&lkp->lk_interlock); |
| 516 | return (lock_type); |
| 517 | } |
| 518 | |
| 519 | /* |
| 520 | * Determine the number of holders of a lock. |
| 521 | */ |
| 522 | int |
| 523 | lockcount(lkp) |
| 524 | struct lock *lkp; |
| 525 | { |
| 526 | int count; |
| 527 | |
| 528 | simple_lock(&lkp->lk_interlock); |
| 529 | count = lkp->lk_exclusivecount + lkp->lk_sharecount; |
| 530 | simple_unlock(&lkp->lk_interlock); |
| 531 | return (count); |
| 532 | } |
| 533 | |
| 534 | /* |
| 535 | * Print out information about state of a lock. Used by VOP_PRINT |
| 536 | * routines to display status about contained locks. |
| 537 | */ |
| 538 | void |
| 539 | lockmgr_printinfo(lkp) |
| 540 | struct lock *lkp; |
| 541 | { |
| 542 | |
| 543 | if (lkp->lk_sharecount) |
| 544 | printf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg, |
| 545 | lkp->lk_sharecount); |
| 546 | else if (lkp->lk_flags & LK_HAVE_EXCL) |
| 547 | printf(" lock type %s: EXCL (count %d) by pid %d", |
| 548 | lkp->lk_wmesg, lkp->lk_exclusivecount, lkp->lk_lockholder); |
| 549 | if (lkp->lk_waitcount > 0) |
| 550 | printf(" with %d pending", lkp->lk_waitcount); |
| 551 | } |
| 552 | |
| 553 | #if defined(SIMPLELOCK_DEBUG) && (MAXCPU == 1 || defined(COMPILING_LINT)) |
| 554 | #include <sys/kernel.h> |
| 555 | #include <sys/sysctl.h> |
| 556 | |
| 557 | static int lockpausetime = 0; |
| 558 | SYSCTL_INT(_debug, OID_AUTO, lockpausetime, CTLFLAG_RW, &lockpausetime, 0, ""); |
| 559 | |
| 560 | static int simplelockrecurse; |
| 561 | |
| 562 | /* |
| 563 | * Simple lock functions so that the debugger can see from whence |
| 564 | * they are being called. |
| 565 | */ |
| 566 | void |
| 567 | simple_lock_init(alp) |
| 568 | struct simplelock *alp; |
| 569 | { |
| 570 | |
| 571 | alp->lock_data = 0; |
| 572 | } |
| 573 | |
| 574 | void |
| 575 | _simple_lock(alp, id, l) |
| 576 | struct simplelock *alp; |
| 577 | const char *id; |
| 578 | int l; |
| 579 | { |
| 580 | |
| 581 | if (simplelockrecurse) |
| 582 | return; |
| 583 | if (alp->lock_data == 1) { |
| 584 | if (lockpausetime == -1) |
| 585 | panic("%s:%d: simple_lock: lock held", id, l); |
| 586 | printf("%s:%d: simple_lock: lock held\n", id, l); |
| 587 | if (lockpausetime == 1) { |
| 588 | Debugger("simple_lock"); |
| 589 | /*BACKTRACE(curproc); */ |
| 590 | } else if (lockpausetime > 1) { |
| 591 | printf("%s:%d: simple_lock: lock held...", id, l); |
| 592 | tsleep(&lockpausetime, PCATCH | PPAUSE, "slock", |
| 593 | lockpausetime * hz); |
| 594 | printf(" continuing\n"); |
| 595 | } |
| 596 | } |
| 597 | alp->lock_data = 1; |
| 598 | if (curproc) |
| 599 | curproc->p_simple_locks++; |
| 600 | } |
| 601 | |
| 602 | int |
| 603 | _simple_lock_try(alp, id, l) |
| 604 | struct simplelock *alp; |
| 605 | const char *id; |
| 606 | int l; |
| 607 | { |
| 608 | |
| 609 | if (alp->lock_data) |
| 610 | return (0); |
| 611 | if (simplelockrecurse) |
| 612 | return (1); |
| 613 | alp->lock_data = 1; |
| 614 | if (curproc) |
| 615 | curproc->p_simple_locks++; |
| 616 | return (1); |
| 617 | } |
| 618 | |
| 619 | void |
| 620 | _simple_unlock(alp, id, l) |
| 621 | struct simplelock *alp; |
| 622 | const char *id; |
| 623 | int l; |
| 624 | { |
| 625 | |
| 626 | if (simplelockrecurse) |
| 627 | return; |
| 628 | if (alp->lock_data == 0) { |
| 629 | if (lockpausetime == -1) |
| 630 | panic("%s:%d: simple_unlock: lock not held", id, l); |
| 631 | printf("%s:%d: simple_unlock: lock not held\n", id, l); |
| 632 | if (lockpausetime == 1) { |
| 633 | Debugger("simple_unlock"); |
| 634 | /* BACKTRACE(curproc); */ |
| 635 | } else if (lockpausetime > 1) { |
| 636 | printf("%s:%d: simple_unlock: lock not held...", id, l); |
| 637 | tsleep(&lockpausetime, PCATCH | PPAUSE, "sunlock", |
| 638 | lockpausetime * hz); |
| 639 | printf(" continuing\n"); |
| 640 | } |
| 641 | } |
| 642 | alp->lock_data = 0; |
| 643 | if (curproc) |
| 644 | curproc->p_simple_locks--; |
| 645 | } |
| 646 | #elif defined(SIMPLELOCK_DEBUG) |
| 647 | #error "SIMPLELOCK_DEBUG is not compatible with SMP!" |
| 648 | #endif /* SIMPLELOCK_DEBUG && MAXCPU == 1 */ |