1 /* $NetBSD: locks.c,v 1.88 2023/11/02 10:31:55 martin Exp $ */ 2 3 /* 4 * Copyright (c) 2007-2011 Antti Kantee. All Rights Reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 18 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #include <sys/cdefs.h> 29 __KERNEL_RCSID(0, "$NetBSD: locks.c,v 1.88 2023/11/02 10:31:55 martin Exp $"); 30 31 #include <sys/param.h> 32 #include <sys/kmem.h> 33 #include <sys/mutex.h> 34 #include <sys/rwlock.h> 35 36 #include <rump-sys/kern.h> 37 38 #include <rump/rumpuser.h> 39 40 #ifdef LOCKDEBUG 41 const int rump_lockdebug = 1; 42 #else 43 const int rump_lockdebug = 0; 44 #endif 45 46 /* 47 * Simple lockdebug. If it's compiled in, it's always active. 48 * Currently available only for mtx/rwlock. 49 */ 50 #ifdef LOCKDEBUG 51 #include <sys/lockdebug.h> 52 53 static lockops_t mutex_spin_lockops = { 54 .lo_name = "mutex", 55 .lo_type = LOCKOPS_SPIN, 56 .lo_dump = NULL, 57 }; 58 static lockops_t mutex_adaptive_lockops = { 59 .lo_name = "mutex", 60 .lo_type = LOCKOPS_SLEEP, 61 .lo_dump = NULL, 62 }; 63 static lockops_t rw_lockops = { 64 .lo_name = "rwlock", 65 .lo_type = LOCKOPS_SLEEP, 66 .lo_dump = NULL, 67 }; 68 69 #define ALLOCK(lock, ops, return_address) \ 70 lockdebug_alloc(__func__, __LINE__, lock, ops, \ 71 return_address) 72 #define FREELOCK(lock) \ 73 lockdebug_free(__func__, __LINE__, lock) 74 #define WANTLOCK(lock, shar) \ 75 lockdebug_wantlock(__func__, __LINE__, lock, \ 76 (uintptr_t)__builtin_return_address(0), shar) 77 #define LOCKED(lock, shar) \ 78 lockdebug_locked(__func__, __LINE__, lock, NULL,\ 79 (uintptr_t)__builtin_return_address(0), shar) 80 #define UNLOCKED(lock, shar) \ 81 lockdebug_unlocked(__func__, __LINE__, lock, \ 82 (uintptr_t)__builtin_return_address(0), shar) 83 #define BARRIER(lock, slp) \ 84 lockdebug_barrier(__func__, __LINE__, lock, slp) 85 #else 86 #define ALLOCK(a, b, c) do {} while (0) 87 #define FREELOCK(a) do {} while (0) 88 #define WANTLOCK(a, b) do {} while (0) 89 #define LOCKED(a, b) do {} while (0) 90 #define UNLOCKED(a, b) do {} while (0) 91 #define BARRIER(a, b) do {} while (0) 92 #endif 93 94 /* 95 * We map locks to pthread routines. The difference between kernel 96 * and rumpuser routines is that while the kernel uses static 97 * storage, rumpuser allocates the object from the heap. This 98 * indirection is necessary because we don't know the size of 99 * pthread objects here. It is also beneficial, since we can 100 * be easily compatible with the kernel ABI because all kernel 101 * objects regardless of machine architecture are always at least 102 * the size of a pointer. The downside, of course, is a performance 103 * penalty. 104 */ 105 106 #define RUMPMTX(mtx) (*(struct rumpuser_mtx *const *)(mtx)) 107 108 void 109 _mutex_init(kmutex_t *mtx, kmutex_type_t type, int ipl, 110 uintptr_t return_address) 111 { 112 int ruflags = RUMPUSER_MTX_KMUTEX; 113 int isspin; 114 115 CTASSERT(sizeof(kmutex_t) >= sizeof(void *)); 116 117 /* 118 * Try to figure out if the caller wanted a spin mutex or 119 * not with this easy set of conditionals. The difference 120 * between a spin mutex and an adaptive mutex for a rump 121 * kernel is that the hypervisor does not relinquish the 122 * rump kernel CPU context for a spin mutex. The 123 * hypervisor itself may block even when "spinning". 124 */ 125 if (type == MUTEX_SPIN) { 126 isspin = 1; 127 } else if (ipl == IPL_NONE || ipl == IPL_SOFTCLOCK || 128 ipl == IPL_SOFTBIO || ipl == IPL_SOFTNET || 129 ipl == IPL_SOFTSERIAL) { 130 isspin = 0; 131 } else { 132 isspin = 1; 133 } 134 135 if (isspin) 136 ruflags |= RUMPUSER_MTX_SPIN; 137 rumpuser_mutex_init((struct rumpuser_mtx **)mtx, ruflags); 138 if (isspin) 139 ALLOCK(mtx, &mutex_spin_lockops, return_address); 140 else 141 ALLOCK(mtx, &mutex_adaptive_lockops, return_address); 142 } 143 144 void 145 mutex_init(kmutex_t *mtx, kmutex_type_t type, int ipl) 146 { 147 148 _mutex_init(mtx, type, ipl, (uintptr_t)__builtin_return_address(0)); 149 } 150 151 void 152 mutex_destroy(kmutex_t *mtx) 153 { 154 155 FREELOCK(mtx); 156 rumpuser_mutex_destroy(RUMPMTX(mtx)); 157 } 158 159 void 160 mutex_enter(kmutex_t *mtx) 161 { 162 163 WANTLOCK(mtx, 0); 164 if (!rumpuser_mutex_spin_p(RUMPMTX(mtx))) 165 BARRIER(mtx, 1); 166 rumpuser_mutex_enter(RUMPMTX(mtx)); 167 LOCKED(mtx, false); 168 } 169 170 void 171 mutex_spin_enter(kmutex_t *mtx) 172 { 173 174 KASSERT(rumpuser_mutex_spin_p(RUMPMTX(mtx))); 175 WANTLOCK(mtx, 0); 176 rumpuser_mutex_enter_nowrap(RUMPMTX(mtx)); 177 LOCKED(mtx, false); 178 } 179 180 int 181 mutex_tryenter(kmutex_t *mtx) 182 { 183 int error; 184 185 error = rumpuser_mutex_tryenter(RUMPMTX(mtx)); 186 if (error == 0) { 187 WANTLOCK(mtx, 0); 188 LOCKED(mtx, false); 189 } 190 return error == 0; 191 } 192 193 void 194 mutex_exit(kmutex_t *mtx) 195 { 196 197 #ifndef LOCKDEBUG 198 KASSERT(mutex_owned(mtx)); 199 #endif 200 UNLOCKED(mtx, false); 201 rumpuser_mutex_exit(RUMPMTX(mtx)); 202 } 203 __strong_alias(mutex_spin_exit,mutex_exit); 204 205 int 206 mutex_ownable(const kmutex_t *mtx) 207 { 208 209 #ifdef LOCKDEBUG 210 WANTLOCK(mtx, -1); 211 #endif 212 return 1; 213 } 214 215 int 216 mutex_owned(const kmutex_t *mtx) 217 { 218 struct lwp *l; 219 220 rumpuser_mutex_owner(RUMPMTX(mtx), &l); 221 return l == curlwp; 222 } 223 224 #define RUMPRW(rw) (*(struct rumpuser_rw **)(rw)) 225 226 /* reader/writer locks */ 227 228 static enum rumprwlock 229 krw2rumprw(const krw_t op) 230 { 231 232 switch (op) { 233 case RW_READER: 234 return RUMPUSER_RW_READER; 235 case RW_WRITER: 236 return RUMPUSER_RW_WRITER; 237 default: 238 panic("unknown rwlock type"); 239 } 240 } 241 242 void 243 _rw_init(krwlock_t *rw, uintptr_t return_address) 244 { 245 246 CTASSERT(sizeof(krwlock_t) >= sizeof(void *)); 247 248 rumpuser_rw_init((struct rumpuser_rw **)rw); 249 ALLOCK(rw, &rw_lockops, return_address); 250 } 251 252 void 253 rw_init(krwlock_t *rw) 254 { 255 256 _rw_init(rw, (uintptr_t)__builtin_return_address(0)); 257 } 258 259 void 260 rw_destroy(krwlock_t *rw) 261 { 262 263 FREELOCK(rw); 264 rumpuser_rw_destroy(RUMPRW(rw)); 265 } 266 267 void 268 rw_enter(krwlock_t *rw, const krw_t op) 269 { 270 271 WANTLOCK(rw, op == RW_READER); 272 BARRIER(rw, 1); 273 rumpuser_rw_enter(krw2rumprw(op), RUMPRW(rw)); 274 LOCKED(rw, op == RW_READER); 275 } 276 277 int 278 rw_tryenter(krwlock_t *rw, const krw_t op) 279 { 280 int error; 281 282 error = rumpuser_rw_tryenter(krw2rumprw(op), RUMPRW(rw)); 283 if (error == 0) { 284 WANTLOCK(rw, op == RW_READER); 285 LOCKED(rw, op == RW_READER); 286 } 287 return error == 0; 288 } 289 290 void 291 rw_exit(krwlock_t *rw) 292 { 293 294 #ifdef LOCKDEBUG 295 bool shared = !rw_write_held(rw); 296 297 if (shared) 298 KASSERT(rw_read_held(rw)); 299 UNLOCKED(rw, shared); 300 #endif 301 rumpuser_rw_exit(RUMPRW(rw)); 302 } 303 304 int 305 rw_tryupgrade(krwlock_t *rw) 306 { 307 int rv; 308 309 rv = rumpuser_rw_tryupgrade(RUMPRW(rw)); 310 if (rv == 0) { 311 UNLOCKED(rw, 1); 312 WANTLOCK(rw, 0); 313 LOCKED(rw, 0); 314 } 315 return rv == 0; 316 } 317 318 void 319 rw_downgrade(krwlock_t *rw) 320 { 321 322 rumpuser_rw_downgrade(RUMPRW(rw)); 323 UNLOCKED(rw, 0); 324 WANTLOCK(rw, 1); 325 LOCKED(rw, 1); 326 } 327 328 int 329 rw_read_held(krwlock_t *rw) 330 { 331 int rv; 332 333 rumpuser_rw_held(RUMPUSER_RW_READER, RUMPRW(rw), &rv); 334 return rv; 335 } 336 337 int 338 rw_write_held(krwlock_t *rw) 339 { 340 int rv; 341 342 rumpuser_rw_held(RUMPUSER_RW_WRITER, RUMPRW(rw), &rv); 343 return rv; 344 } 345 346 int 347 rw_lock_held(krwlock_t *rw) 348 { 349 350 return rw_read_held(rw) || rw_write_held(rw); 351 } 352 353 krw_t 354 rw_lock_op(krwlock_t *rw) 355 { 356 357 return rw_write_held(rw) ? RW_WRITER : RW_READER; 358 } 359 360 /* curriculum vitaes */ 361 362 #define RUMPCV(cv) (*(struct rumpuser_cv **)(cv)) 363 364 void 365 cv_init(kcondvar_t *cv, const char *msg) 366 { 367 368 CTASSERT(sizeof(kcondvar_t) >= sizeof(void *)); 369 370 rumpuser_cv_init((struct rumpuser_cv **)cv); 371 } 372 373 void 374 cv_destroy(kcondvar_t *cv) 375 { 376 377 rumpuser_cv_destroy(RUMPCV(cv)); 378 } 379 380 static int 381 docvwait(kcondvar_t *cv, kmutex_t *mtx, struct timespec *ts) 382 { 383 struct lwp *l = curlwp; 384 int rv; 385 386 if (__predict_false(l->l_flag & LW_RUMP_QEXIT)) { 387 /* 388 * yield() here, someone might want the cpu 389 * to set a condition. otherwise we'll just 390 * loop forever. 391 */ 392 yield(); 393 return EINTR; 394 } 395 396 UNLOCKED(mtx, false); 397 398 l->l_sched.info = cv; 399 rv = 0; 400 if (ts) { 401 if (rumpuser_cv_timedwait(RUMPCV(cv), RUMPMTX(mtx), 402 ts->tv_sec, ts->tv_nsec)) 403 rv = EWOULDBLOCK; 404 } else { 405 rumpuser_cv_wait(RUMPCV(cv), RUMPMTX(mtx)); 406 } 407 408 LOCKED(mtx, false); 409 410 /* 411 * Check for QEXIT. if so, we need to wait here until we 412 * are allowed to exit. 413 */ 414 if (__predict_false(l->l_flag & LW_RUMP_QEXIT)) { 415 struct proc *p = l->l_proc; 416 417 mutex_exit(mtx); /* drop and retake later */ 418 419 mutex_enter(p->p_lock); 420 while ((p->p_sflag & PS_RUMP_LWPEXIT) == 0) { 421 /* avoid recursion */ 422 rumpuser_cv_wait(RUMPCV(&p->p_waitcv), 423 RUMPMTX(p->p_lock)); 424 } 425 KASSERT(p->p_sflag & PS_RUMP_LWPEXIT); 426 mutex_exit(p->p_lock); 427 428 /* ok, we can exit and remove "reference" to l->l_sched.info */ 429 430 mutex_enter(mtx); 431 rv = EINTR; 432 } 433 l->l_sched.info = NULL; 434 435 return rv; 436 } 437 438 void 439 cv_wait(kcondvar_t *cv, kmutex_t *mtx) 440 { 441 442 if (__predict_false(rump_threads == 0)) 443 panic("cv_wait without threads"); 444 (void) docvwait(cv, mtx, NULL); 445 } 446 447 int 448 cv_wait_sig(kcondvar_t *cv, kmutex_t *mtx) 449 { 450 451 if (__predict_false(rump_threads == 0)) 452 panic("cv_wait without threads"); 453 return docvwait(cv, mtx, NULL); 454 } 455 456 int 457 cv_timedwait(kcondvar_t *cv, kmutex_t *mtx, int ticks) 458 { 459 struct timespec ts; 460 extern int hz; 461 int rv; 462 463 if (ticks == 0) { 464 rv = cv_wait_sig(cv, mtx); 465 } else { 466 ts.tv_sec = ticks / hz; 467 ts.tv_nsec = (ticks % hz) * (1000000000/hz); 468 rv = docvwait(cv, mtx, &ts); 469 } 470 471 return rv; 472 } 473 __strong_alias(cv_timedwait_sig,cv_timedwait); 474 475 void 476 cv_signal(kcondvar_t *cv) 477 { 478 479 rumpuser_cv_signal(RUMPCV(cv)); 480 } 481 482 void 483 cv_broadcast(kcondvar_t *cv) 484 { 485 486 rumpuser_cv_broadcast(RUMPCV(cv)); 487 } 488 489 bool 490 cv_has_waiters(kcondvar_t *cv) 491 { 492 int rv; 493 494 rumpuser_cv_has_waiters(RUMPCV(cv), &rv); 495 return rv != 0; 496 } 497 498 /* this is not much of an attempt, but ... */ 499 bool 500 cv_is_valid(kcondvar_t *cv) 501 { 502 503 return RUMPCV(cv) != NULL; 504 } 505
Indexes created Sun Sep 21 16:09:51 GMT 2025