| 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 1.27 2008/01/09 10:59:12 corecode Exp $ |
| 43 | */ |
| 44 | |
| 45 | #include "opt_lint.h" |
| 46 | |
| 47 | #include <sys/param.h> |
| 48 | #include <sys/systm.h> |
| 49 | #include <sys/kernel.h> |
| 50 | #include <sys/proc.h> |
| 51 | #include <sys/lock.h> |
| 52 | #include <sys/sysctl.h> |
| 53 | #include <sys/spinlock.h> |
| 54 | #include <sys/thread2.h> |
| 55 | #include <sys/spinlock2.h> |
| 56 | |
| 57 | /* |
| 58 | * Locking primitives implementation. |
| 59 | * Locks provide shared/exclusive sychronization. |
| 60 | */ |
| 61 | |
| 62 | #ifdef DEBUG_LOCKS |
| 63 | #define COUNT(td, x) (td)->td_locks += (x) |
| 64 | #else |
| 65 | #define COUNT(td, x) |
| 66 | #endif |
| 67 | |
| 68 | #define LOCK_WAIT_TIME 100 |
| 69 | #define LOCK_SAMPLE_WAIT 7 |
| 70 | |
| 71 | #if defined(DIAGNOSTIC) |
| 72 | #define LOCK_INLINE |
| 73 | #else |
| 74 | #define LOCK_INLINE __inline |
| 75 | #endif |
| 76 | |
| 77 | #define LK_ALL (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | \ |
| 78 | LK_SHARE_NONZERO | LK_WAIT_NONZERO) |
| 79 | |
| 80 | static int acquire(struct lock *lkp, int extflags, int wanted); |
| 81 | |
| 82 | static LOCK_INLINE void |
| 83 | sharelock(struct lock *lkp, int incr) |
| 84 | { |
| 85 | lkp->lk_flags |= LK_SHARE_NONZERO; |
| 86 | lkp->lk_sharecount += incr; |
| 87 | } |
| 88 | |
| 89 | static LOCK_INLINE int |
| 90 | shareunlock(struct lock *lkp, int decr) |
| 91 | { |
| 92 | int dowakeup = 0; |
| 93 | |
| 94 | KASSERT(lkp->lk_sharecount >= decr, ("shareunlock: count < decr")); |
| 95 | |
| 96 | if (lkp->lk_sharecount == decr) { |
| 97 | lkp->lk_flags &= ~LK_SHARE_NONZERO; |
| 98 | if (lkp->lk_flags & (LK_WANT_UPGRADE | LK_WANT_EXCL)) { |
| 99 | dowakeup = 1; |
| 100 | } |
| 101 | lkp->lk_sharecount = 0; |
| 102 | } else { |
| 103 | lkp->lk_sharecount -= decr; |
| 104 | } |
| 105 | return(dowakeup); |
| 106 | } |
| 107 | |
| 108 | /* |
| 109 | * lock acquisition helper routine. Called with the lock's spinlock held. |
| 110 | */ |
| 111 | static int |
| 112 | acquire(struct lock *lkp, int extflags, int wanted) |
| 113 | { |
| 114 | int error; |
| 115 | |
| 116 | if ((extflags & LK_NOWAIT) && (lkp->lk_flags & wanted)) { |
| 117 | return EBUSY; |
| 118 | } |
| 119 | |
| 120 | while ((lkp->lk_flags & wanted) != 0) { |
| 121 | lkp->lk_flags |= LK_WAIT_NONZERO; |
| 122 | lkp->lk_waitcount++; |
| 123 | |
| 124 | /* |
| 125 | * Atomic spinlock release/sleep/reacquire. |
| 126 | */ |
| 127 | error = ssleep(lkp, &lkp->lk_spinlock, |
| 128 | ((extflags & LK_PCATCH) ? PCATCH : 0), |
| 129 | lkp->lk_wmesg, |
| 130 | ((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0)); |
| 131 | if (lkp->lk_waitcount == 1) { |
| 132 | lkp->lk_flags &= ~LK_WAIT_NONZERO; |
| 133 | lkp->lk_waitcount = 0; |
| 134 | } else { |
| 135 | lkp->lk_waitcount--; |
| 136 | } |
| 137 | if (error) |
| 138 | return error; |
| 139 | if (extflags & LK_SLEEPFAIL) |
| 140 | return ENOLCK; |
| 141 | } |
| 142 | return 0; |
| 143 | } |
| 144 | |
| 145 | /* |
| 146 | * Set, change, or release a lock. |
| 147 | * |
| 148 | * Shared requests increment the shared count. Exclusive requests set the |
| 149 | * LK_WANT_EXCL flag (preventing further shared locks), and wait for already |
| 150 | * accepted shared locks and shared-to-exclusive upgrades to go away. |
| 151 | * |
| 152 | * A spinlock is held for most of the procedure. We must not do anything |
| 153 | * fancy while holding the spinlock. |
| 154 | */ |
| 155 | int |
| 156 | #ifndef DEBUG_LOCKS |
| 157 | lockmgr(struct lock *lkp, u_int flags) |
| 158 | #else |
| 159 | debuglockmgr(struct lock *lkp, u_int flags, |
| 160 | const char *name, const char *file, int line) |
| 161 | #endif |
| 162 | { |
| 163 | thread_t td; |
| 164 | int error; |
| 165 | int extflags; |
| 166 | int dowakeup; |
| 167 | #ifdef DEBUG_LOCKS |
| 168 | int i; |
| 169 | #endif |
| 170 | |
| 171 | error = 0; |
| 172 | dowakeup = 0; |
| 173 | |
| 174 | if (mycpu->gd_intr_nesting_level && |
| 175 | (flags & LK_NOWAIT) == 0 && |
| 176 | (flags & LK_TYPE_MASK) != LK_RELEASE && |
| 177 | panic_cpu_gd != mycpu |
| 178 | ) { |
| 179 | |
| 180 | #ifndef DEBUG_LOCKS |
| 181 | panic("lockmgr %s from %p: called from interrupt, ipi, " |
| 182 | "or hard code section", |
| 183 | lkp->lk_wmesg, ((int **)&lkp)[-1]); |
| 184 | #else |
| 185 | panic("lockmgr %s from %s:%d: called from interrupt, ipi, " |
| 186 | "or hard code section", |
| 187 | lkp->lk_wmesg, file, line); |
| 188 | #endif |
| 189 | } |
| 190 | |
| 191 | #ifdef DEBUG_LOCKS |
| 192 | if (mycpu->gd_spinlocks_wr && |
| 193 | ((flags & LK_NOWAIT) == 0) |
| 194 | ) { |
| 195 | panic("lockmgr %s from %s:%d: called with %d spinlocks held", |
| 196 | lkp->lk_wmesg, file, line, mycpu->gd_spinlocks_wr); |
| 197 | } |
| 198 | #endif |
| 199 | |
| 200 | spin_lock(&lkp->lk_spinlock); |
| 201 | |
| 202 | extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; |
| 203 | td = curthread; |
| 204 | |
| 205 | switch (flags & LK_TYPE_MASK) { |
| 206 | case LK_SHARED: |
| 207 | /* |
| 208 | * If we are not the exclusive lock holder, we have to block |
| 209 | * while there is an exclusive lock holder or while an |
| 210 | * exclusive lock request or upgrade request is in progress. |
| 211 | * |
| 212 | * However, if TDF_DEADLKTREAT is set, we override exclusive |
| 213 | * lock requests or upgrade requests ( but not the exclusive |
| 214 | * lock itself ). |
| 215 | */ |
| 216 | if (lkp->lk_lockholder != td) { |
| 217 | if (td->td_flags & TDF_DEADLKTREAT) { |
| 218 | error = acquire( |
| 219 | lkp, |
| 220 | extflags, |
| 221 | LK_HAVE_EXCL |
| 222 | ); |
| 223 | } else { |
| 224 | error = acquire( |
| 225 | lkp, |
| 226 | extflags, |
| 227 | LK_HAVE_EXCL | LK_WANT_EXCL | |
| 228 | LK_WANT_UPGRADE |
| 229 | ); |
| 230 | } |
| 231 | if (error) |
| 232 | break; |
| 233 | sharelock(lkp, 1); |
| 234 | COUNT(td, 1); |
| 235 | break; |
| 236 | } |
| 237 | |
| 238 | /* |
| 239 | * If we already hold an exclusive lock we bump the |
| 240 | * exclusive count instead of downgrading to a shared |
| 241 | * lock. |
| 242 | * |
| 243 | * WARNING! The old FreeBSD behavior was to downgrade, |
| 244 | * but this creates a problem when recursions |
| 245 | * return to the caller and the caller expects |
| 246 | * its original exclusive lock to remain exclusively |
| 247 | * locked. |
| 248 | */ |
| 249 | if (extflags & LK_CANRECURSE) { |
| 250 | lkp->lk_exclusivecount++; |
| 251 | COUNT(td, 1); |
| 252 | break; |
| 253 | } |
| 254 | if (extflags & LK_NOWAIT) { |
| 255 | error = EBUSY; |
| 256 | break; |
| 257 | } |
| 258 | spin_unlock(&lkp->lk_spinlock); |
| 259 | panic("lockmgr: locking against myself"); |
| 260 | #if 0 |
| 261 | /* |
| 262 | * old code queued a shared lock request fell into |
| 263 | * a downgrade. |
| 264 | */ |
| 265 | sharelock(lkp, 1); |
| 266 | COUNT(td, 1); |
| 267 | /* fall into downgrade */ |
| 268 | #endif |
| 269 | |
| 270 | case LK_DOWNGRADE: |
| 271 | if (lkp->lk_lockholder != td || lkp->lk_exclusivecount == 0) { |
| 272 | spin_unlock(&lkp->lk_spinlock); |
| 273 | panic("lockmgr: not holding exclusive lock"); |
| 274 | } |
| 275 | |
| 276 | #ifdef DEBUG_LOCKS |
| 277 | for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { |
| 278 | if (td->td_lockmgr_stack[i] == lkp && |
| 279 | td->td_lockmgr_stack_id[i] > 0 |
| 280 | ) { |
| 281 | td->td_lockmgr_stack_id[i]--; |
| 282 | break; |
| 283 | } |
| 284 | } |
| 285 | #endif |
| 286 | |
| 287 | sharelock(lkp, lkp->lk_exclusivecount); |
| 288 | lkp->lk_exclusivecount = 0; |
| 289 | lkp->lk_flags &= ~LK_HAVE_EXCL; |
| 290 | lkp->lk_lockholder = LK_NOTHREAD; |
| 291 | if (lkp->lk_waitcount) |
| 292 | dowakeup = 1; |
| 293 | break; |
| 294 | |
| 295 | case LK_EXCLUPGRADE: |
| 296 | /* |
| 297 | * If another process is ahead of us to get an upgrade, |
| 298 | * then we want to fail rather than have an intervening |
| 299 | * exclusive access. |
| 300 | */ |
| 301 | if (lkp->lk_flags & LK_WANT_UPGRADE) { |
| 302 | dowakeup = shareunlock(lkp, 1); |
| 303 | COUNT(td, -1); |
| 304 | error = EBUSY; |
| 305 | break; |
| 306 | } |
| 307 | /* fall into normal upgrade */ |
| 308 | |
| 309 | case LK_UPGRADE: |
| 310 | /* |
| 311 | * Upgrade a shared lock to an exclusive one. If another |
| 312 | * shared lock has already requested an upgrade to an |
| 313 | * exclusive lock, our shared lock is released and an |
| 314 | * exclusive lock is requested (which will be granted |
| 315 | * after the upgrade). If we return an error, the file |
| 316 | * will always be unlocked. |
| 317 | */ |
| 318 | if ((lkp->lk_lockholder == td) || (lkp->lk_sharecount <= 0)) { |
| 319 | spin_unlock(&lkp->lk_spinlock); |
| 320 | panic("lockmgr: upgrade exclusive lock"); |
| 321 | } |
| 322 | dowakeup += shareunlock(lkp, 1); |
| 323 | COUNT(td, -1); |
| 324 | /* |
| 325 | * If we are just polling, check to see if we will block. |
| 326 | */ |
| 327 | if ((extflags & LK_NOWAIT) && |
| 328 | ((lkp->lk_flags & LK_WANT_UPGRADE) || |
| 329 | lkp->lk_sharecount > 1)) { |
| 330 | error = EBUSY; |
| 331 | break; |
| 332 | } |
| 333 | if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) { |
| 334 | /* |
| 335 | * We are first shared lock to request an upgrade, so |
| 336 | * request upgrade and wait for the shared count to |
| 337 | * drop to zero, then take exclusive lock. |
| 338 | * |
| 339 | * Although I don't think this can occur for |
| 340 | * robustness we also wait for any exclusive locks |
| 341 | * to be released. LK_WANT_UPGRADE is supposed to |
| 342 | * prevent new exclusive locks but might not in the |
| 343 | * future. |
| 344 | */ |
| 345 | lkp->lk_flags |= LK_WANT_UPGRADE; |
| 346 | error = acquire(lkp, extflags, |
| 347 | LK_HAVE_EXCL | LK_SHARE_NONZERO); |
| 348 | lkp->lk_flags &= ~LK_WANT_UPGRADE; |
| 349 | |
| 350 | if (error) |
| 351 | break; |
| 352 | lkp->lk_flags |= LK_HAVE_EXCL; |
| 353 | lkp->lk_lockholder = td; |
| 354 | if (lkp->lk_exclusivecount != 0) { |
| 355 | spin_unlock(&lkp->lk_spinlock); |
| 356 | panic("lockmgr(1): non-zero exclusive count"); |
| 357 | } |
| 358 | lkp->lk_exclusivecount = 1; |
| 359 | #if defined(DEBUG_LOCKS) |
| 360 | lkp->lk_filename = file; |
| 361 | lkp->lk_lineno = line; |
| 362 | lkp->lk_lockername = name; |
| 363 | |
| 364 | for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { |
| 365 | /* |
| 366 | * Recursive lockmgr path |
| 367 | */ |
| 368 | if (td->td_lockmgr_stack[i] == lkp && |
| 369 | td->td_lockmgr_stack_id[i] != 0 |
| 370 | ) { |
| 371 | td->td_lockmgr_stack_id[i]++; |
| 372 | goto lkmatch2; |
| 373 | } |
| 374 | } |
| 375 | |
| 376 | for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { |
| 377 | /* |
| 378 | * Use new lockmgr tracking slot |
| 379 | */ |
| 380 | if (td->td_lockmgr_stack_id[i] == 0) { |
| 381 | td->td_lockmgr_stack_id[i]++; |
| 382 | td->td_lockmgr_stack[i] = lkp; |
| 383 | break; |
| 384 | } |
| 385 | } |
| 386 | lkmatch2: |
| 387 | ; |
| 388 | #endif |
| 389 | COUNT(td, 1); |
| 390 | break; |
| 391 | } |
| 392 | /* |
| 393 | * Someone else has requested upgrade. Release our shared |
| 394 | * lock, awaken upgrade requestor if we are the last shared |
| 395 | * lock, then request an exclusive lock. |
| 396 | */ |
| 397 | if ((lkp->lk_flags & (LK_SHARE_NONZERO|LK_WAIT_NONZERO)) == |
| 398 | LK_WAIT_NONZERO) { |
| 399 | ++dowakeup; |
| 400 | } |
| 401 | /* fall into exclusive request */ |
| 402 | |
| 403 | case LK_EXCLUSIVE: |
| 404 | if (lkp->lk_lockholder == td && td != LK_KERNTHREAD) { |
| 405 | /* |
| 406 | * Recursive lock. |
| 407 | */ |
| 408 | if ((extflags & (LK_NOWAIT | LK_CANRECURSE)) == 0) { |
| 409 | spin_unlock(&lkp->lk_spinlock); |
| 410 | panic("lockmgr: locking against myself"); |
| 411 | } |
| 412 | if ((extflags & LK_CANRECURSE) != 0) { |
| 413 | lkp->lk_exclusivecount++; |
| 414 | COUNT(td, 1); |
| 415 | break; |
| 416 | } |
| 417 | } |
| 418 | /* |
| 419 | * If we are just polling, check to see if we will sleep. |
| 420 | */ |
| 421 | if ((extflags & LK_NOWAIT) && |
| 422 | (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | |
| 423 | LK_WANT_UPGRADE | LK_SHARE_NONZERO))) { |
| 424 | error = EBUSY; |
| 425 | break; |
| 426 | } |
| 427 | /* |
| 428 | * Wait for exclusive lock holders to release and try to |
| 429 | * acquire the want_exclusive flag. |
| 430 | */ |
| 431 | error = acquire(lkp, extflags, (LK_HAVE_EXCL | LK_WANT_EXCL)); |
| 432 | if (error) |
| 433 | break; |
| 434 | lkp->lk_flags |= LK_WANT_EXCL; |
| 435 | |
| 436 | /* |
| 437 | * Wait for shared locks and upgrades to finish. We can lose |
| 438 | * the race against a successful shared lock upgrade in which |
| 439 | * case LK_HAVE_EXCL will get set regardless of our |
| 440 | * acquisition of LK_WANT_EXCL, so we have to acquire |
| 441 | * LK_HAVE_EXCL here as well. |
| 442 | */ |
| 443 | error = acquire(lkp, extflags, LK_HAVE_EXCL | |
| 444 | LK_WANT_UPGRADE | |
| 445 | LK_SHARE_NONZERO); |
| 446 | lkp->lk_flags &= ~LK_WANT_EXCL; |
| 447 | if (error) |
| 448 | break; |
| 449 | lkp->lk_flags |= LK_HAVE_EXCL; |
| 450 | lkp->lk_lockholder = td; |
| 451 | if (lkp->lk_exclusivecount != 0) { |
| 452 | spin_unlock(&lkp->lk_spinlock); |
| 453 | panic("lockmgr(2): non-zero exclusive count"); |
| 454 | } |
| 455 | lkp->lk_exclusivecount = 1; |
| 456 | #if defined(DEBUG_LOCKS) |
| 457 | lkp->lk_filename = file; |
| 458 | lkp->lk_lineno = line; |
| 459 | lkp->lk_lockername = name; |
| 460 | |
| 461 | for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { |
| 462 | /* |
| 463 | * Recursive lockmgr path |
| 464 | */ |
| 465 | if (td->td_lockmgr_stack[i] == lkp && |
| 466 | td->td_lockmgr_stack_id[i] != 0 |
| 467 | ) { |
| 468 | td->td_lockmgr_stack_id[i]++; |
| 469 | goto lkmatch1; |
| 470 | } |
| 471 | } |
| 472 | |
| 473 | for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { |
| 474 | /* |
| 475 | * Use new lockmgr tracking slot |
| 476 | */ |
| 477 | if (td->td_lockmgr_stack_id[i] == 0) { |
| 478 | td->td_lockmgr_stack_id[i]++; |
| 479 | td->td_lockmgr_stack[i] = lkp; |
| 480 | break; |
| 481 | } |
| 482 | } |
| 483 | lkmatch1: |
| 484 | ; |
| 485 | #endif |
| 486 | COUNT(td, 1); |
| 487 | break; |
| 488 | |
| 489 | case LK_RELEASE: |
| 490 | if (lkp->lk_exclusivecount != 0) { |
| 491 | if (lkp->lk_lockholder != td && |
| 492 | lkp->lk_lockholder != LK_KERNTHREAD) { |
| 493 | spin_unlock(&lkp->lk_spinlock); |
| 494 | panic("lockmgr: pid %d, not %s thr %p/%p unlocking", |
| 495 | (td->td_proc ? td->td_proc->p_pid : -1), |
| 496 | "exclusive lock holder", |
| 497 | td, lkp->lk_lockholder); |
| 498 | } |
| 499 | if (lkp->lk_lockholder != LK_KERNTHREAD) { |
| 500 | COUNT(td, -1); |
| 501 | } |
| 502 | if (lkp->lk_exclusivecount == 1) { |
| 503 | lkp->lk_flags &= ~LK_HAVE_EXCL; |
| 504 | lkp->lk_lockholder = LK_NOTHREAD; |
| 505 | lkp->lk_exclusivecount = 0; |
| 506 | } else { |
| 507 | lkp->lk_exclusivecount--; |
| 508 | } |
| 509 | #ifdef DEBUG_LOCKS |
| 510 | for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { |
| 511 | if (td->td_lockmgr_stack[i] == lkp && |
| 512 | td->td_lockmgr_stack_id[i] > 0 |
| 513 | ) { |
| 514 | td->td_lockmgr_stack_id[i]--; |
| 515 | lkp->lk_filename = file; |
| 516 | lkp->lk_lineno = line; |
| 517 | break; |
| 518 | } |
| 519 | } |
| 520 | #endif |
| 521 | } else if (lkp->lk_flags & LK_SHARE_NONZERO) { |
| 522 | dowakeup += shareunlock(lkp, 1); |
| 523 | COUNT(td, -1); |
| 524 | } else { |
| 525 | panic("lockmgr: LK_RELEASE: no lock held"); |
| 526 | } |
| 527 | if (lkp->lk_flags & LK_WAIT_NONZERO) |
| 528 | ++dowakeup; |
| 529 | break; |
| 530 | |
| 531 | default: |
| 532 | spin_unlock(&lkp->lk_spinlock); |
| 533 | panic("lockmgr: unknown locktype request %d", |
| 534 | flags & LK_TYPE_MASK); |
| 535 | /* NOTREACHED */ |
| 536 | } |
| 537 | spin_unlock(&lkp->lk_spinlock); |
| 538 | if (dowakeup) |
| 539 | wakeup(lkp); |
| 540 | return (error); |
| 541 | } |
| 542 | |
| 543 | void |
| 544 | lockmgr_kernproc(struct lock *lp) |
| 545 | { |
| 546 | struct thread *td __debugvar = curthread; |
| 547 | |
| 548 | if (lp->lk_lockholder != LK_KERNTHREAD) { |
| 549 | KASSERT(lp->lk_lockholder == td, |
| 550 | ("lockmgr_kernproc: lock not owned by curthread %p", td)); |
| 551 | COUNT(td, -1); |
| 552 | lp->lk_lockholder = LK_KERNTHREAD; |
| 553 | } |
| 554 | } |
| 555 | |
| 556 | #if 0 |
| 557 | /* |
| 558 | * Set the lock to be exclusively held. The caller is holding the lock's |
| 559 | * spinlock and the spinlock remains held on return. A panic will occur |
| 560 | * if the lock cannot be set to exclusive. |
| 561 | * |
| 562 | * XXX not only unused but these functions also break EXCLUPGRADE's |
| 563 | * atomicy. |
| 564 | */ |
| 565 | void |
| 566 | lockmgr_setexclusive_interlocked(struct lock *lkp) |
| 567 | { |
| 568 | thread_t td = curthread; |
| 569 | |
| 570 | KKASSERT((lkp->lk_flags & (LK_HAVE_EXCL|LK_SHARE_NONZERO)) == 0); |
| 571 | KKASSERT(lkp->lk_exclusivecount == 0); |
| 572 | lkp->lk_flags |= LK_HAVE_EXCL; |
| 573 | lkp->lk_lockholder = td; |
| 574 | lkp->lk_exclusivecount = 1; |
| 575 | COUNT(td, 1); |
| 576 | } |
| 577 | |
| 578 | /* |
| 579 | * Clear the caller's exclusive lock. The caller is holding the lock's |
| 580 | * spinlock. THIS FUNCTION WILL UNLOCK THE SPINLOCK. |
| 581 | * |
| 582 | * A panic will occur if the caller does not hold the lock. |
| 583 | */ |
| 584 | void |
| 585 | lockmgr_clrexclusive_interlocked(struct lock *lkp) |
| 586 | { |
| 587 | thread_t td __debugvar = curthread; |
| 588 | int dowakeup = 0; |
| 589 | |
| 590 | KKASSERT((lkp->lk_flags & LK_HAVE_EXCL) && lkp->lk_exclusivecount == 1 |
| 591 | && lkp->lk_lockholder == td); |
| 592 | lkp->lk_lockholder = LK_NOTHREAD; |
| 593 | lkp->lk_flags &= ~LK_HAVE_EXCL; |
| 594 | lkp->lk_exclusivecount = 0; |
| 595 | if (lkp->lk_flags & LK_WAIT_NONZERO) |
| 596 | dowakeup = 1; |
| 597 | COUNT(td, -1); |
| 598 | spin_unlock(&lkp->lk_spinlock); |
| 599 | if (dowakeup) |
| 600 | wakeup((void *)lkp); |
| 601 | } |
| 602 | |
| 603 | #endif |
| 604 | |
| 605 | /* |
| 606 | * Initialize a lock; required before use. |
| 607 | */ |
| 608 | void |
| 609 | lockinit(struct lock *lkp, const char *wmesg, int timo, int flags) |
| 610 | { |
| 611 | spin_init(&lkp->lk_spinlock); |
| 612 | lkp->lk_flags = (flags & LK_EXTFLG_MASK); |
| 613 | lkp->lk_sharecount = 0; |
| 614 | lkp->lk_waitcount = 0; |
| 615 | lkp->lk_exclusivecount = 0; |
| 616 | lkp->lk_wmesg = wmesg; |
| 617 | lkp->lk_timo = timo; |
| 618 | lkp->lk_lockholder = LK_NOTHREAD; |
| 619 | } |
| 620 | |
| 621 | /* |
| 622 | * Reinitialize a lock that is being reused for a different purpose, but |
| 623 | * which may have pending (blocked) threads sitting on it. The caller |
| 624 | * must already hold the interlock. |
| 625 | */ |
| 626 | void |
| 627 | lockreinit(struct lock *lkp, const char *wmesg, int timo, int flags) |
| 628 | { |
| 629 | spin_lock(&lkp->lk_spinlock); |
| 630 | lkp->lk_flags = (lkp->lk_flags & ~LK_EXTFLG_MASK) | |
| 631 | (flags & LK_EXTFLG_MASK); |
| 632 | lkp->lk_wmesg = wmesg; |
| 633 | lkp->lk_timo = timo; |
| 634 | spin_unlock(&lkp->lk_spinlock); |
| 635 | } |
| 636 | |
| 637 | /* |
| 638 | * Requires that the caller is the exclusive owner of this lock. |
| 639 | */ |
| 640 | void |
| 641 | lockuninit(struct lock *l) |
| 642 | { |
| 643 | /* |
| 644 | * At this point we should have removed all the references to this lock |
| 645 | * so there can't be anyone waiting on it. |
| 646 | */ |
| 647 | KKASSERT(l->lk_waitcount == 0); |
| 648 | |
| 649 | spin_uninit(&l->lk_spinlock); |
| 650 | } |
| 651 | |
| 652 | /* |
| 653 | * Determine the status of a lock. |
| 654 | */ |
| 655 | int |
| 656 | lockstatus(struct lock *lkp, struct thread *td) |
| 657 | { |
| 658 | int lock_type = 0; |
| 659 | |
| 660 | spin_lock(&lkp->lk_spinlock); |
| 661 | if (lkp->lk_exclusivecount != 0) { |
| 662 | if (td == NULL || lkp->lk_lockholder == td) |
| 663 | lock_type = LK_EXCLUSIVE; |
| 664 | else |
| 665 | lock_type = LK_EXCLOTHER; |
| 666 | } else if (lkp->lk_sharecount != 0) { |
| 667 | lock_type = LK_SHARED; |
| 668 | } |
| 669 | spin_unlock(&lkp->lk_spinlock); |
| 670 | return (lock_type); |
| 671 | } |
| 672 | |
| 673 | /* |
| 674 | * Return non-zero if the caller owns the lock shared or exclusive. |
| 675 | * We can only guess re: shared locks. |
| 676 | */ |
| 677 | int |
| 678 | lockowned(struct lock *lkp) |
| 679 | { |
| 680 | thread_t td = curthread; |
| 681 | |
| 682 | if (lkp->lk_exclusivecount) |
| 683 | return(lkp->lk_lockholder == td); |
| 684 | return(lkp->lk_sharecount != 0); |
| 685 | } |
| 686 | |
| 687 | /* |
| 688 | * Determine the number of holders of a lock. |
| 689 | * |
| 690 | * The non-blocking version can usually be used for assertions. |
| 691 | */ |
| 692 | int |
| 693 | lockcount(struct lock *lkp) |
| 694 | { |
| 695 | int count; |
| 696 | |
| 697 | spin_lock(&lkp->lk_spinlock); |
| 698 | count = lkp->lk_exclusivecount + lkp->lk_sharecount; |
| 699 | spin_unlock(&lkp->lk_spinlock); |
| 700 | return (count); |
| 701 | } |
| 702 | |
| 703 | int |
| 704 | lockcountnb(struct lock *lkp) |
| 705 | { |
| 706 | return (lkp->lk_exclusivecount + lkp->lk_sharecount); |
| 707 | } |
| 708 | |
| 709 | /* |
| 710 | * Print out information about state of a lock. Used by VOP_PRINT |
| 711 | * routines to display status about contained locks. |
| 712 | */ |
| 713 | void |
| 714 | lockmgr_printinfo(struct lock *lkp) |
| 715 | { |
| 716 | struct thread *td = lkp->lk_lockholder; |
| 717 | struct proc *p; |
| 718 | |
| 719 | if (td && td != LK_KERNTHREAD && td != LK_NOTHREAD) |
| 720 | p = td->td_proc; |
| 721 | else |
| 722 | p = NULL; |
| 723 | |
| 724 | if (lkp->lk_sharecount) |
| 725 | kprintf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg, |
| 726 | lkp->lk_sharecount); |
| 727 | else if (lkp->lk_flags & LK_HAVE_EXCL) |
| 728 | kprintf(" lock type %s: EXCL (count %d) by td %p pid %d", |
| 729 | lkp->lk_wmesg, lkp->lk_exclusivecount, td, |
| 730 | p ? p->p_pid : -99); |
| 731 | if (lkp->lk_waitcount > 0) |
| 732 | kprintf(" with %d pending", lkp->lk_waitcount); |
| 733 | } |
| 734 | |
| 735 | void |
| 736 | lock_sysinit(struct lock_args *arg) |
| 737 | { |
| 738 | lockinit(arg->la_lock, arg->la_desc, 0, arg->la_flags); |
| 739 | } |