17c478bd9Sstevel@tonic-gate /* 27c478bd9Sstevel@tonic-gate * CDDL HEADER START 37c478bd9Sstevel@tonic-gate * 47c478bd9Sstevel@tonic-gate * The contents of this file are subject to the terms of the 541efec22Sraf * Common Development and Distribution License (the "License"). 641efec22Sraf * You may not use this file except in compliance with the License. 77c478bd9Sstevel@tonic-gate * 87c478bd9Sstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 97c478bd9Sstevel@tonic-gate * or http://www.opensolaris.org/os/licensing. 107c478bd9Sstevel@tonic-gate * See the License for the specific language governing permissions 117c478bd9Sstevel@tonic-gate * and limitations under the License. 127c478bd9Sstevel@tonic-gate * 137c478bd9Sstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each 147c478bd9Sstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 157c478bd9Sstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the 167c478bd9Sstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying 177c478bd9Sstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner] 187c478bd9Sstevel@tonic-gate * 197c478bd9Sstevel@tonic-gate * CDDL HEADER END 207c478bd9Sstevel@tonic-gate */ 2141efec22Sraf 227c478bd9Sstevel@tonic-gate /* 2341efec22Sraf * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 247c478bd9Sstevel@tonic-gate * Use is subject to license terms. 257c478bd9Sstevel@tonic-gate */ 267c478bd9Sstevel@tonic-gate 277c478bd9Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI" 287c478bd9Sstevel@tonic-gate 297c478bd9Sstevel@tonic-gate #include "lint.h" 307c478bd9Sstevel@tonic-gate #include "thr_uberdata.h" 317c478bd9Sstevel@tonic-gate #include <sys/sdt.h> 327c478bd9Sstevel@tonic-gate 337c478bd9Sstevel@tonic-gate #define TRY_FLAG 0x10 347c478bd9Sstevel@tonic-gate #define READ_LOCK 0 357c478bd9Sstevel@tonic-gate #define WRITE_LOCK 1 367c478bd9Sstevel@tonic-gate #define READ_LOCK_TRY (READ_LOCK | TRY_FLAG) 377c478bd9Sstevel@tonic-gate #define WRITE_LOCK_TRY (WRITE_LOCK | TRY_FLAG) 387c478bd9Sstevel@tonic-gate 397c478bd9Sstevel@tonic-gate #define NLOCKS 4 /* initial number of readlock_t structs allocated */ 407c478bd9Sstevel@tonic-gate 4141efec22Sraf #define ASSERT_CONSISTENT_STATE(readers) \ 4241efec22Sraf ASSERT(!((readers) & URW_WRITE_LOCKED) || \ 4341efec22Sraf ((readers) & ~URW_HAS_WAITERS) == URW_WRITE_LOCKED) 4441efec22Sraf 457c478bd9Sstevel@tonic-gate /* 467c478bd9Sstevel@tonic-gate * Find/allocate an entry for rwlp in our array of rwlocks held for reading. 4741efec22Sraf * We must be deferring signals for this to be safe. 48*883492d5Sraf * Else if we are returning an entry with ul_rdlockcnt == 0, 4941efec22Sraf * it could be reassigned behind our back in a signal handler. 507c478bd9Sstevel@tonic-gate */ 517c478bd9Sstevel@tonic-gate static readlock_t * 527c478bd9Sstevel@tonic-gate rwl_entry(rwlock_t *rwlp) 537c478bd9Sstevel@tonic-gate { 547c478bd9Sstevel@tonic-gate ulwp_t *self = curthread; 557c478bd9Sstevel@tonic-gate readlock_t *remembered = NULL; 567c478bd9Sstevel@tonic-gate readlock_t *readlockp; 577c478bd9Sstevel@tonic-gate uint_t nlocks; 587c478bd9Sstevel@tonic-gate 5941efec22Sraf /* we must be deferring signals */ 6041efec22Sraf ASSERT((self->ul_critical + self->ul_sigdefer) != 0); 6141efec22Sraf 62*883492d5Sraf if ((nlocks = self->ul_rdlockcnt) != 0) 637c478bd9Sstevel@tonic-gate readlockp = self->ul_readlock.array; 647c478bd9Sstevel@tonic-gate else { 657c478bd9Sstevel@tonic-gate nlocks = 1; 667c478bd9Sstevel@tonic-gate readlockp = &self->ul_readlock.single; 677c478bd9Sstevel@tonic-gate } 687c478bd9Sstevel@tonic-gate 697c478bd9Sstevel@tonic-gate for (; nlocks; nlocks--, readlockp++) { 707c478bd9Sstevel@tonic-gate if (readlockp->rd_rwlock == rwlp) 717c478bd9Sstevel@tonic-gate return (readlockp); 727c478bd9Sstevel@tonic-gate if (readlockp->rd_count == 0 && remembered == NULL) 737c478bd9Sstevel@tonic-gate remembered = readlockp; 747c478bd9Sstevel@tonic-gate } 757c478bd9Sstevel@tonic-gate if (remembered != NULL) { 767c478bd9Sstevel@tonic-gate remembered->rd_rwlock = rwlp; 777c478bd9Sstevel@tonic-gate return (remembered); 787c478bd9Sstevel@tonic-gate } 797c478bd9Sstevel@tonic-gate 807c478bd9Sstevel@tonic-gate /* 817c478bd9Sstevel@tonic-gate * No entry available. Allocate more space, converting the single 827c478bd9Sstevel@tonic-gate * readlock_t entry into an array of readlock_t entries if necessary. 837c478bd9Sstevel@tonic-gate */ 84*883492d5Sraf if ((nlocks = self->ul_rdlockcnt) == 0) { 857c478bd9Sstevel@tonic-gate /* 867c478bd9Sstevel@tonic-gate * Initial allocation of the readlock_t array. 877c478bd9Sstevel@tonic-gate * Convert the single entry into an array. 887c478bd9Sstevel@tonic-gate */ 89*883492d5Sraf self->ul_rdlockcnt = nlocks = NLOCKS; 907c478bd9Sstevel@tonic-gate readlockp = lmalloc(nlocks * sizeof (readlock_t)); 917c478bd9Sstevel@tonic-gate /* 927c478bd9Sstevel@tonic-gate * The single readlock_t becomes the first entry in the array. 937c478bd9Sstevel@tonic-gate */ 947c478bd9Sstevel@tonic-gate *readlockp = self->ul_readlock.single; 957c478bd9Sstevel@tonic-gate self->ul_readlock.single.rd_count = 0; 967c478bd9Sstevel@tonic-gate self->ul_readlock.array = readlockp; 977c478bd9Sstevel@tonic-gate /* 987c478bd9Sstevel@tonic-gate * Return the next available entry in the array. 997c478bd9Sstevel@tonic-gate */ 1007c478bd9Sstevel@tonic-gate (++readlockp)->rd_rwlock = rwlp; 1017c478bd9Sstevel@tonic-gate return (readlockp); 1027c478bd9Sstevel@tonic-gate } 1037c478bd9Sstevel@tonic-gate /* 1047c478bd9Sstevel@tonic-gate * Reallocate the array, double the size each time. 1057c478bd9Sstevel@tonic-gate */ 1067c478bd9Sstevel@tonic-gate readlockp = lmalloc(nlocks * 2 * sizeof (readlock_t)); 1077c478bd9Sstevel@tonic-gate (void) _memcpy(readlockp, self->ul_readlock.array, 1087c478bd9Sstevel@tonic-gate nlocks * sizeof (readlock_t)); 1097c478bd9Sstevel@tonic-gate lfree(self->ul_readlock.array, nlocks * sizeof (readlock_t)); 1107c478bd9Sstevel@tonic-gate self->ul_readlock.array = readlockp; 111*883492d5Sraf self->ul_rdlockcnt *= 2; 1127c478bd9Sstevel@tonic-gate /* 1137c478bd9Sstevel@tonic-gate * Return the next available entry in the newly allocated array. 1147c478bd9Sstevel@tonic-gate */ 1157c478bd9Sstevel@tonic-gate (readlockp += nlocks)->rd_rwlock = rwlp; 1167c478bd9Sstevel@tonic-gate return (readlockp); 1177c478bd9Sstevel@tonic-gate } 1187c478bd9Sstevel@tonic-gate 1197c478bd9Sstevel@tonic-gate /* 1207c478bd9Sstevel@tonic-gate * Free the array of rwlocks held for reading. 1217c478bd9Sstevel@tonic-gate */ 1227c478bd9Sstevel@tonic-gate void 1237c478bd9Sstevel@tonic-gate rwl_free(ulwp_t *ulwp) 1247c478bd9Sstevel@tonic-gate { 1257c478bd9Sstevel@tonic-gate uint_t nlocks; 1267c478bd9Sstevel@tonic-gate 127*883492d5Sraf if ((nlocks = ulwp->ul_rdlockcnt) != 0) 1287c478bd9Sstevel@tonic-gate lfree(ulwp->ul_readlock.array, nlocks * sizeof (readlock_t)); 129*883492d5Sraf ulwp->ul_rdlockcnt = 0; 1307c478bd9Sstevel@tonic-gate ulwp->ul_readlock.single.rd_rwlock = NULL; 1317c478bd9Sstevel@tonic-gate ulwp->ul_readlock.single.rd_count = 0; 1327c478bd9Sstevel@tonic-gate } 1337c478bd9Sstevel@tonic-gate 1347c478bd9Sstevel@tonic-gate /* 1357c478bd9Sstevel@tonic-gate * Check if a reader version of the lock is held by the current thread. 1367c478bd9Sstevel@tonic-gate * rw_read_is_held() is private to libc. 1377c478bd9Sstevel@tonic-gate */ 1387c478bd9Sstevel@tonic-gate #pragma weak rw_read_is_held = _rw_read_held 1397c478bd9Sstevel@tonic-gate #pragma weak rw_read_held = _rw_read_held 1407c478bd9Sstevel@tonic-gate int 1417c478bd9Sstevel@tonic-gate _rw_read_held(rwlock_t *rwlp) 1427c478bd9Sstevel@tonic-gate { 14341efec22Sraf volatile uint32_t *rwstate = (volatile uint32_t *)&rwlp->rwlock_readers; 14441efec22Sraf uint32_t readers; 14541efec22Sraf ulwp_t *self = curthread; 1467c478bd9Sstevel@tonic-gate readlock_t *readlockp; 1477c478bd9Sstevel@tonic-gate uint_t nlocks; 14841efec22Sraf int rval = 0; 1497c478bd9Sstevel@tonic-gate 15041efec22Sraf no_preempt(self); 1517c478bd9Sstevel@tonic-gate 15241efec22Sraf readers = *rwstate; 15341efec22Sraf ASSERT_CONSISTENT_STATE(readers); 15441efec22Sraf if (!(readers & URW_WRITE_LOCKED) && 15541efec22Sraf (readers & URW_READERS_MASK) != 0) { 1567c478bd9Sstevel@tonic-gate /* 1577c478bd9Sstevel@tonic-gate * The lock is held for reading by some thread. 1587c478bd9Sstevel@tonic-gate * Search our array of rwlocks held for reading for a match. 1597c478bd9Sstevel@tonic-gate */ 160*883492d5Sraf if ((nlocks = self->ul_rdlockcnt) != 0) 1617c478bd9Sstevel@tonic-gate readlockp = self->ul_readlock.array; 1627c478bd9Sstevel@tonic-gate else { 1637c478bd9Sstevel@tonic-gate nlocks = 1; 1647c478bd9Sstevel@tonic-gate readlockp = &self->ul_readlock.single; 1657c478bd9Sstevel@tonic-gate } 16641efec22Sraf for (; nlocks; nlocks--, readlockp++) { 16741efec22Sraf if (readlockp->rd_rwlock == rwlp) { 16841efec22Sraf if (readlockp->rd_count) 16941efec22Sraf rval = 1; 17041efec22Sraf break; 17141efec22Sraf } 17241efec22Sraf } 17341efec22Sraf } 1747c478bd9Sstevel@tonic-gate 17541efec22Sraf preempt(self); 17641efec22Sraf return (rval); 1777c478bd9Sstevel@tonic-gate } 1787c478bd9Sstevel@tonic-gate 1797c478bd9Sstevel@tonic-gate /* 1807c478bd9Sstevel@tonic-gate * Check if a writer version of the lock is held by the current thread. 1817c478bd9Sstevel@tonic-gate * rw_write_is_held() is private to libc. 1827c478bd9Sstevel@tonic-gate */ 1837c478bd9Sstevel@tonic-gate #pragma weak rw_write_is_held = _rw_write_held 1847c478bd9Sstevel@tonic-gate #pragma weak rw_write_held = _rw_write_held 1857c478bd9Sstevel@tonic-gate int 1867c478bd9Sstevel@tonic-gate _rw_write_held(rwlock_t *rwlp) 1877c478bd9Sstevel@tonic-gate { 18841efec22Sraf volatile uint32_t *rwstate = (volatile uint32_t *)&rwlp->rwlock_readers; 18941efec22Sraf uint32_t readers; 1907c478bd9Sstevel@tonic-gate ulwp_t *self = curthread; 19141efec22Sraf int rval; 1927c478bd9Sstevel@tonic-gate 19341efec22Sraf no_preempt(self); 1947c478bd9Sstevel@tonic-gate 19541efec22Sraf readers = *rwstate; 19641efec22Sraf ASSERT_CONSISTENT_STATE(readers); 19741efec22Sraf rval = ((readers & URW_WRITE_LOCKED) && 19841efec22Sraf rwlp->rwlock_owner == (uintptr_t)self && 19941efec22Sraf (rwlp->rwlock_type == USYNC_THREAD || 20041efec22Sraf rwlp->rwlock_ownerpid == self->ul_uberdata->pid)); 20141efec22Sraf 20241efec22Sraf preempt(self); 20341efec22Sraf return (rval); 2047c478bd9Sstevel@tonic-gate } 2057c478bd9Sstevel@tonic-gate 2067c478bd9Sstevel@tonic-gate #pragma weak rwlock_init = __rwlock_init 2077c478bd9Sstevel@tonic-gate #pragma weak _rwlock_init = __rwlock_init 2087c478bd9Sstevel@tonic-gate /* ARGSUSED2 */ 2097c478bd9Sstevel@tonic-gate int 2107c478bd9Sstevel@tonic-gate __rwlock_init(rwlock_t *rwlp, int type, void *arg) 2117c478bd9Sstevel@tonic-gate { 2127c478bd9Sstevel@tonic-gate if (type != USYNC_THREAD && type != USYNC_PROCESS) 2137c478bd9Sstevel@tonic-gate return (EINVAL); 2147c478bd9Sstevel@tonic-gate /* 2157c478bd9Sstevel@tonic-gate * Once reinitialized, we can no longer be holding a read or write lock. 2167c478bd9Sstevel@tonic-gate * We can do nothing about other threads that are holding read locks. 2177c478bd9Sstevel@tonic-gate */ 21841efec22Sraf sigoff(curthread); 2197c478bd9Sstevel@tonic-gate rwl_entry(rwlp)->rd_count = 0; 22041efec22Sraf sigon(curthread); 2217c478bd9Sstevel@tonic-gate (void) _memset(rwlp, 0, sizeof (*rwlp)); 2227c478bd9Sstevel@tonic-gate rwlp->rwlock_type = (uint16_t)type; 2237c478bd9Sstevel@tonic-gate rwlp->rwlock_magic = RWL_MAGIC; 2247c478bd9Sstevel@tonic-gate rwlp->mutex.mutex_type = (uint8_t)type; 2257c478bd9Sstevel@tonic-gate rwlp->mutex.mutex_flag = LOCK_INITED; 2267c478bd9Sstevel@tonic-gate rwlp->mutex.mutex_magic = MUTEX_MAGIC; 2277c478bd9Sstevel@tonic-gate return (0); 2287c478bd9Sstevel@tonic-gate } 2297c478bd9Sstevel@tonic-gate 2307c478bd9Sstevel@tonic-gate #pragma weak rwlock_destroy = __rwlock_destroy 2317c478bd9Sstevel@tonic-gate #pragma weak _rwlock_destroy = __rwlock_destroy 2327c478bd9Sstevel@tonic-gate #pragma weak pthread_rwlock_destroy = __rwlock_destroy 2337c478bd9Sstevel@tonic-gate #pragma weak _pthread_rwlock_destroy = __rwlock_destroy 2347c478bd9Sstevel@tonic-gate int 2357c478bd9Sstevel@tonic-gate __rwlock_destroy(rwlock_t *rwlp) 2367c478bd9Sstevel@tonic-gate { 2377c478bd9Sstevel@tonic-gate /* 2387c478bd9Sstevel@tonic-gate * Once destroyed, we can no longer be holding a read or write lock. 2397c478bd9Sstevel@tonic-gate * We can do nothing about other threads that are holding read locks. 2407c478bd9Sstevel@tonic-gate */ 24141efec22Sraf sigoff(curthread); 2427c478bd9Sstevel@tonic-gate rwl_entry(rwlp)->rd_count = 0; 24341efec22Sraf sigon(curthread); 2447c478bd9Sstevel@tonic-gate rwlp->rwlock_magic = 0; 2457c478bd9Sstevel@tonic-gate tdb_sync_obj_deregister(rwlp); 2467c478bd9Sstevel@tonic-gate return (0); 2477c478bd9Sstevel@tonic-gate } 2487c478bd9Sstevel@tonic-gate 2497c478bd9Sstevel@tonic-gate /* 25041efec22Sraf * Attempt to acquire a readers lock. Return true on success. 2517c478bd9Sstevel@tonic-gate */ 2527c478bd9Sstevel@tonic-gate static int 25341efec22Sraf read_lock_try(rwlock_t *rwlp, int ignore_waiters_flag) 2547c478bd9Sstevel@tonic-gate { 25541efec22Sraf volatile uint32_t *rwstate = (volatile uint32_t *)&rwlp->rwlock_readers; 25641efec22Sraf uint32_t mask = ignore_waiters_flag? 25741efec22Sraf URW_WRITE_LOCKED : (URW_HAS_WAITERS | URW_WRITE_LOCKED); 25841efec22Sraf uint32_t readers; 2597c478bd9Sstevel@tonic-gate ulwp_t *self = curthread; 2607c478bd9Sstevel@tonic-gate 2617c478bd9Sstevel@tonic-gate no_preempt(self); 26241efec22Sraf while (((readers = *rwstate) & mask) == 0) { 26341efec22Sraf if (atomic_cas_32(rwstate, readers, readers + 1) == readers) { 2647c478bd9Sstevel@tonic-gate preempt(self); 2657c478bd9Sstevel@tonic-gate return (1); 2667c478bd9Sstevel@tonic-gate } 2677c478bd9Sstevel@tonic-gate } 26841efec22Sraf preempt(self); 26941efec22Sraf return (0); 2707c478bd9Sstevel@tonic-gate } 27141efec22Sraf 27241efec22Sraf /* 27341efec22Sraf * Attempt to release a reader lock. Return true on success. 27441efec22Sraf */ 27541efec22Sraf static int 27641efec22Sraf read_unlock_try(rwlock_t *rwlp) 27741efec22Sraf { 27841efec22Sraf volatile uint32_t *rwstate = (volatile uint32_t *)&rwlp->rwlock_readers; 27941efec22Sraf uint32_t readers; 28041efec22Sraf ulwp_t *self = curthread; 28141efec22Sraf 28241efec22Sraf no_preempt(self); 28341efec22Sraf while (((readers = *rwstate) & URW_HAS_WAITERS) == 0) { 28441efec22Sraf if (atomic_cas_32(rwstate, readers, readers - 1) == readers) { 28541efec22Sraf preempt(self); 28641efec22Sraf return (1); 28741efec22Sraf } 28841efec22Sraf } 28941efec22Sraf preempt(self); 29041efec22Sraf return (0); 29141efec22Sraf } 29241efec22Sraf 29341efec22Sraf /* 29441efec22Sraf * Attempt to acquire a writer lock. Return true on success. 29541efec22Sraf */ 29641efec22Sraf static int 29741efec22Sraf write_lock_try(rwlock_t *rwlp, int ignore_waiters_flag) 29841efec22Sraf { 29941efec22Sraf volatile uint32_t *rwstate = (volatile uint32_t *)&rwlp->rwlock_readers; 30041efec22Sraf uint32_t mask = ignore_waiters_flag? 30141efec22Sraf (URW_WRITE_LOCKED | URW_READERS_MASK) : 30241efec22Sraf (URW_HAS_WAITERS | URW_WRITE_LOCKED | URW_READERS_MASK); 30341efec22Sraf ulwp_t *self = curthread; 30441efec22Sraf uint32_t readers; 30541efec22Sraf 30641efec22Sraf no_preempt(self); 30741efec22Sraf while (((readers = *rwstate) & mask) == 0) { 30841efec22Sraf if (atomic_cas_32(rwstate, readers, readers | URW_WRITE_LOCKED) 30941efec22Sraf == readers) { 31041efec22Sraf preempt(self); 31141efec22Sraf return (1); 31241efec22Sraf } 31341efec22Sraf } 31441efec22Sraf preempt(self); 31541efec22Sraf return (0); 31641efec22Sraf } 31741efec22Sraf 31841efec22Sraf /* 31941efec22Sraf * Attempt to release a writer lock. Return true on success. 32041efec22Sraf */ 32141efec22Sraf static int 32241efec22Sraf write_unlock_try(rwlock_t *rwlp) 32341efec22Sraf { 32441efec22Sraf volatile uint32_t *rwstate = (volatile uint32_t *)&rwlp->rwlock_readers; 32541efec22Sraf uint32_t readers; 32641efec22Sraf ulwp_t *self = curthread; 32741efec22Sraf 32841efec22Sraf no_preempt(self); 32941efec22Sraf while (((readers = *rwstate) & URW_HAS_WAITERS) == 0) { 33041efec22Sraf if (atomic_cas_32(rwstate, readers, 0) == readers) { 33141efec22Sraf preempt(self); 33241efec22Sraf return (1); 33341efec22Sraf } 33441efec22Sraf } 33541efec22Sraf preempt(self); 33641efec22Sraf return (0); 33741efec22Sraf } 33841efec22Sraf 33941efec22Sraf /* 34041efec22Sraf * Wake up thread(s) sleeping on the rwlock queue and then 34141efec22Sraf * drop the queue lock. Return non-zero if we wake up someone. 34241efec22Sraf * This is called when a thread releases a lock that appears to have waiters. 34341efec22Sraf */ 34441efec22Sraf static int 34541efec22Sraf rw_queue_release(queue_head_t *qp, rwlock_t *rwlp) 34641efec22Sraf { 34741efec22Sraf volatile uint32_t *rwstate = (volatile uint32_t *)&rwlp->rwlock_readers; 34841efec22Sraf uint32_t readers; 34941efec22Sraf uint32_t writers; 35041efec22Sraf int nlwpid = 0; 35141efec22Sraf int maxlwps = MAXLWPS; 35241efec22Sraf ulwp_t *self; 35341efec22Sraf ulwp_t **ulwpp; 35441efec22Sraf ulwp_t *ulwp; 35541efec22Sraf ulwp_t *prev = NULL; 35641efec22Sraf lwpid_t buffer[MAXLWPS]; 35741efec22Sraf lwpid_t *lwpid = buffer; 35841efec22Sraf 35941efec22Sraf readers = *rwstate; 36041efec22Sraf ASSERT_CONSISTENT_STATE(readers); 36141efec22Sraf if (!(readers & URW_HAS_WAITERS)) { 3627c478bd9Sstevel@tonic-gate queue_unlock(qp); 3637c478bd9Sstevel@tonic-gate return (0); 3647c478bd9Sstevel@tonic-gate } 36541efec22Sraf readers &= URW_READERS_MASK; 36641efec22Sraf writers = 0; 36741efec22Sraf 36841efec22Sraf /* 36941efec22Sraf * Walk the list of waiters and prepare to wake up as 37041efec22Sraf * many readers as we encounter before encountering 37141efec22Sraf * a writer. If the first thread on the list is a 37241efec22Sraf * writer, stop there and wake it up. 37341efec22Sraf * 37441efec22Sraf * We keep track of lwpids that are to be unparked in lwpid[]. 37541efec22Sraf * __lwp_unpark_all() is called to unpark all of them after 37641efec22Sraf * they have been removed from the sleep queue and the sleep 37741efec22Sraf * queue lock has been dropped. If we run out of space in our 37841efec22Sraf * on-stack buffer, we need to allocate more but we can't call 37941efec22Sraf * lmalloc() because we are holding a queue lock when the overflow 38041efec22Sraf * occurs and lmalloc() acquires a lock. We can't use alloca() 38141efec22Sraf * either because the application may have allocated a small 38241efec22Sraf * stack and we don't want to overrun the stack. So we call 38341efec22Sraf * alloc_lwpids() to allocate a bigger buffer using the mmap() 38441efec22Sraf * system call directly since that path acquires no locks. 38541efec22Sraf */ 38641efec22Sraf ulwpp = &qp->qh_head; 38741efec22Sraf while ((ulwp = *ulwpp) != NULL) { 38841efec22Sraf if (ulwp->ul_wchan != rwlp) { 38941efec22Sraf prev = ulwp; 39041efec22Sraf ulwpp = &ulwp->ul_link; 39141efec22Sraf continue; 39241efec22Sraf } 39341efec22Sraf if (ulwp->ul_writer) { 39441efec22Sraf if (writers != 0 || readers != 0) 39541efec22Sraf break; 39641efec22Sraf /* one writer to wake */ 39741efec22Sraf writers++; 39841efec22Sraf } else { 39941efec22Sraf if (writers != 0) 40041efec22Sraf break; 40141efec22Sraf /* at least one reader to wake */ 40241efec22Sraf readers++; 40341efec22Sraf if (nlwpid == maxlwps) 40441efec22Sraf lwpid = alloc_lwpids(lwpid, &nlwpid, &maxlwps); 40541efec22Sraf } 40641efec22Sraf (void) queue_unlink(qp, ulwpp, prev); 40741efec22Sraf lwpid[nlwpid++] = ulwp->ul_lwpid; 40841efec22Sraf } 40941efec22Sraf if (ulwp == NULL) 41041efec22Sraf atomic_and_32(rwstate, ~URW_HAS_WAITERS); 41141efec22Sraf if (nlwpid == 0) { 41241efec22Sraf queue_unlock(qp); 41341efec22Sraf } else { 41441efec22Sraf self = curthread; 41541efec22Sraf no_preempt(self); 41641efec22Sraf queue_unlock(qp); 41741efec22Sraf if (nlwpid == 1) 41841efec22Sraf (void) __lwp_unpark(lwpid[0]); 41941efec22Sraf else 42041efec22Sraf (void) __lwp_unpark_all(lwpid, nlwpid); 42141efec22Sraf preempt(self); 42241efec22Sraf } 42341efec22Sraf if (lwpid != buffer) 42441efec22Sraf (void) _private_munmap(lwpid, maxlwps * sizeof (lwpid_t)); 42541efec22Sraf return (nlwpid != 0); 42641efec22Sraf } 4277c478bd9Sstevel@tonic-gate 4287c478bd9Sstevel@tonic-gate /* 4297c478bd9Sstevel@tonic-gate * Common code for rdlock, timedrdlock, wrlock, timedwrlock, tryrdlock, 4307c478bd9Sstevel@tonic-gate * and trywrlock for process-shared (USYNC_PROCESS) rwlocks. 4317c478bd9Sstevel@tonic-gate * 4327c478bd9Sstevel@tonic-gate * Note: if the lock appears to be contended we call __lwp_rwlock_rdlock() 4337c478bd9Sstevel@tonic-gate * or __lwp_rwlock_wrlock() holding the mutex. These return with the mutex 4347c478bd9Sstevel@tonic-gate * released, and if they need to sleep will release the mutex first. In the 4357c478bd9Sstevel@tonic-gate * event of a spurious wakeup, these will return EAGAIN (because it is much 4367c478bd9Sstevel@tonic-gate * easier for us to re-acquire the mutex here). 4377c478bd9Sstevel@tonic-gate */ 4387c478bd9Sstevel@tonic-gate int 4397c478bd9Sstevel@tonic-gate shared_rwlock_lock(rwlock_t *rwlp, timespec_t *tsp, int rd_wr) 4407c478bd9Sstevel@tonic-gate { 44141efec22Sraf volatile uint32_t *rwstate = (volatile uint32_t *)&rwlp->rwlock_readers; 44241efec22Sraf mutex_t *mp = &rwlp->mutex; 44341efec22Sraf /* LINTED set but not used */ 44441efec22Sraf uint32_t readers; 4457c478bd9Sstevel@tonic-gate int try_flag; 44641efec22Sraf int error; 4477c478bd9Sstevel@tonic-gate 4487c478bd9Sstevel@tonic-gate try_flag = (rd_wr & TRY_FLAG); 4497c478bd9Sstevel@tonic-gate rd_wr &= ~TRY_FLAG; 4507c478bd9Sstevel@tonic-gate ASSERT(rd_wr == READ_LOCK || rd_wr == WRITE_LOCK); 4517c478bd9Sstevel@tonic-gate 4527c478bd9Sstevel@tonic-gate if (!try_flag) { 4537c478bd9Sstevel@tonic-gate DTRACE_PROBE2(plockstat, rw__block, rwlp, rd_wr); 4547c478bd9Sstevel@tonic-gate } 4557c478bd9Sstevel@tonic-gate 4567c478bd9Sstevel@tonic-gate do { 45741efec22Sraf if (try_flag && (*rwstate & URW_WRITE_LOCKED)) { 45841efec22Sraf error = EBUSY; 4597c478bd9Sstevel@tonic-gate break; 46041efec22Sraf } 46141efec22Sraf if ((error = _private_mutex_lock(mp)) != 0) 46241efec22Sraf break; 4637c478bd9Sstevel@tonic-gate if (rd_wr == READ_LOCK) { 46441efec22Sraf if (read_lock_try(rwlp, 0)) { 46541efec22Sraf (void) _private_mutex_unlock(mp); 46641efec22Sraf break; 4677c478bd9Sstevel@tonic-gate } 4687c478bd9Sstevel@tonic-gate } else { 46941efec22Sraf if (write_lock_try(rwlp, 0)) { 47041efec22Sraf (void) _private_mutex_unlock(mp); 47141efec22Sraf break; 4727c478bd9Sstevel@tonic-gate } 47341efec22Sraf } 47441efec22Sraf atomic_or_32(rwstate, URW_HAS_WAITERS); 47541efec22Sraf readers = *rwstate; 47641efec22Sraf ASSERT_CONSISTENT_STATE(readers); 4777c478bd9Sstevel@tonic-gate /* 47841efec22Sraf * The calls to __lwp_rwlock_*() below will release the mutex, 47941efec22Sraf * so we need a dtrace probe here. 4807c478bd9Sstevel@tonic-gate */ 48141efec22Sraf mp->mutex_owner = 0; 48241efec22Sraf DTRACE_PROBE2(plockstat, mutex__release, mp, 0); 4837c478bd9Sstevel@tonic-gate /* 4847c478bd9Sstevel@tonic-gate * The waiters bit may be inaccurate. 4857c478bd9Sstevel@tonic-gate * Only the kernel knows for sure. 4867c478bd9Sstevel@tonic-gate */ 48741efec22Sraf if (rd_wr == READ_LOCK) { 48841efec22Sraf if (try_flag) 48941efec22Sraf error = __lwp_rwlock_tryrdlock(rwlp); 49041efec22Sraf else 49141efec22Sraf error = __lwp_rwlock_rdlock(rwlp, tsp); 4927c478bd9Sstevel@tonic-gate } else { 49341efec22Sraf if (try_flag) 49441efec22Sraf error = __lwp_rwlock_trywrlock(rwlp); 49541efec22Sraf else 4967c478bd9Sstevel@tonic-gate error = __lwp_rwlock_wrlock(rwlp, tsp); 4977c478bd9Sstevel@tonic-gate } 49841efec22Sraf } while (error == EAGAIN || error == EINTR); 4997c478bd9Sstevel@tonic-gate 5007c478bd9Sstevel@tonic-gate if (!try_flag) { 50141efec22Sraf DTRACE_PROBE3(plockstat, rw__blocked, rwlp, rd_wr, error == 0); 5027c478bd9Sstevel@tonic-gate } 5037c478bd9Sstevel@tonic-gate 5047c478bd9Sstevel@tonic-gate return (error); 5057c478bd9Sstevel@tonic-gate } 5067c478bd9Sstevel@tonic-gate 5077c478bd9Sstevel@tonic-gate /* 5087c478bd9Sstevel@tonic-gate * Common code for rdlock, timedrdlock, wrlock, timedwrlock, tryrdlock, 5097c478bd9Sstevel@tonic-gate * and trywrlock for process-private (USYNC_THREAD) rwlocks. 5107c478bd9Sstevel@tonic-gate */ 5117c478bd9Sstevel@tonic-gate int 5127c478bd9Sstevel@tonic-gate rwlock_lock(rwlock_t *rwlp, timespec_t *tsp, int rd_wr) 5137c478bd9Sstevel@tonic-gate { 51441efec22Sraf volatile uint32_t *rwstate = (volatile uint32_t *)&rwlp->rwlock_readers; 51541efec22Sraf uint32_t readers; 5167c478bd9Sstevel@tonic-gate ulwp_t *self = curthread; 5177c478bd9Sstevel@tonic-gate queue_head_t *qp; 5187c478bd9Sstevel@tonic-gate ulwp_t *ulwp; 5197c478bd9Sstevel@tonic-gate int try_flag; 5207c478bd9Sstevel@tonic-gate int error = 0; 5217c478bd9Sstevel@tonic-gate 5227c478bd9Sstevel@tonic-gate try_flag = (rd_wr & TRY_FLAG); 5237c478bd9Sstevel@tonic-gate rd_wr &= ~TRY_FLAG; 5247c478bd9Sstevel@tonic-gate ASSERT(rd_wr == READ_LOCK || rd_wr == WRITE_LOCK); 5257c478bd9Sstevel@tonic-gate 5267c478bd9Sstevel@tonic-gate if (!try_flag) { 5277c478bd9Sstevel@tonic-gate DTRACE_PROBE2(plockstat, rw__block, rwlp, rd_wr); 5287c478bd9Sstevel@tonic-gate } 5297c478bd9Sstevel@tonic-gate 5307c478bd9Sstevel@tonic-gate qp = queue_lock(rwlp, MX); 53141efec22Sraf retry: 5327c478bd9Sstevel@tonic-gate while (error == 0) { 53341efec22Sraf if (rd_wr == READ_LOCK) { 53441efec22Sraf if (read_lock_try(rwlp, 0)) 53541efec22Sraf goto out; 53641efec22Sraf } else { 53741efec22Sraf if (write_lock_try(rwlp, 0)) 53841efec22Sraf goto out; 53941efec22Sraf } 54041efec22Sraf atomic_or_32(rwstate, URW_HAS_WAITERS); 54141efec22Sraf readers = *rwstate; 54241efec22Sraf ASSERT_CONSISTENT_STATE(readers); 54341efec22Sraf if ((readers & URW_WRITE_LOCKED) || 54441efec22Sraf (rd_wr == WRITE_LOCK && 54541efec22Sraf (readers & URW_READERS_MASK) != 0)) 5467c478bd9Sstevel@tonic-gate /* EMPTY */; /* somebody holds the lock */ 5477c478bd9Sstevel@tonic-gate else if ((ulwp = queue_waiter(qp, rwlp)) == NULL) { 54841efec22Sraf atomic_and_32(rwstate, ~URW_HAS_WAITERS); 5497c478bd9Sstevel@tonic-gate break; /* no queued waiters */ 5507c478bd9Sstevel@tonic-gate } else { 5517c478bd9Sstevel@tonic-gate int our_pri = real_priority(self); 5527c478bd9Sstevel@tonic-gate int his_pri = real_priority(ulwp); 5537c478bd9Sstevel@tonic-gate 5547c478bd9Sstevel@tonic-gate if (rd_wr == WRITE_LOCK) { 5557c478bd9Sstevel@tonic-gate /* 5567c478bd9Sstevel@tonic-gate * We defer to a queued thread that has 5577c478bd9Sstevel@tonic-gate * a higher priority than ours. 5587c478bd9Sstevel@tonic-gate */ 5597c478bd9Sstevel@tonic-gate if (his_pri <= our_pri) 5607c478bd9Sstevel@tonic-gate break; 5617c478bd9Sstevel@tonic-gate } else { 5627c478bd9Sstevel@tonic-gate /* 5637c478bd9Sstevel@tonic-gate * We defer to a queued thread that has 5647c478bd9Sstevel@tonic-gate * a higher priority than ours or that 5657c478bd9Sstevel@tonic-gate * is a writer whose priority equals ours. 5667c478bd9Sstevel@tonic-gate */ 5677c478bd9Sstevel@tonic-gate if (his_pri < our_pri || 5687c478bd9Sstevel@tonic-gate (his_pri == our_pri && !ulwp->ul_writer)) 5697c478bd9Sstevel@tonic-gate break; 5707c478bd9Sstevel@tonic-gate } 5717c478bd9Sstevel@tonic-gate } 5727c478bd9Sstevel@tonic-gate /* 5737c478bd9Sstevel@tonic-gate * We are about to block. 5747c478bd9Sstevel@tonic-gate * If we're doing a trylock, return EBUSY instead. 5757c478bd9Sstevel@tonic-gate */ 5767c478bd9Sstevel@tonic-gate if (try_flag) { 5777c478bd9Sstevel@tonic-gate error = EBUSY; 5787c478bd9Sstevel@tonic-gate break; 5797c478bd9Sstevel@tonic-gate } 5807c478bd9Sstevel@tonic-gate /* 5817c478bd9Sstevel@tonic-gate * Enqueue writers ahead of readers of the 5827c478bd9Sstevel@tonic-gate * same priority. 5837c478bd9Sstevel@tonic-gate */ 5847c478bd9Sstevel@tonic-gate self->ul_writer = rd_wr; /* *must* be 0 or 1 */ 5857c478bd9Sstevel@tonic-gate enqueue(qp, self, rwlp, MX); 5867c478bd9Sstevel@tonic-gate set_parking_flag(self, 1); 5877c478bd9Sstevel@tonic-gate queue_unlock(qp); 5887c478bd9Sstevel@tonic-gate if ((error = __lwp_park(tsp, 0)) == EINTR) 5897c478bd9Sstevel@tonic-gate error = 0; 5907c478bd9Sstevel@tonic-gate self->ul_writer = 0; 5917c478bd9Sstevel@tonic-gate set_parking_flag(self, 0); 5927c478bd9Sstevel@tonic-gate qp = queue_lock(rwlp, MX); 59341efec22Sraf if (self->ul_sleepq && dequeue_self(qp, rwlp) == 0) 59441efec22Sraf atomic_and_32(rwstate, ~URW_HAS_WAITERS); 5957c478bd9Sstevel@tonic-gate } 5967c478bd9Sstevel@tonic-gate 5977c478bd9Sstevel@tonic-gate if (error == 0) { 59841efec22Sraf if (rd_wr == READ_LOCK) { 59941efec22Sraf if (!read_lock_try(rwlp, 1)) 60041efec22Sraf goto retry; 60141efec22Sraf } else { 60241efec22Sraf if (!write_lock_try(rwlp, 1)) 60341efec22Sraf goto retry; 6047c478bd9Sstevel@tonic-gate } 6057c478bd9Sstevel@tonic-gate } 6067c478bd9Sstevel@tonic-gate 60741efec22Sraf out: 60841efec22Sraf queue_unlock(qp); 60941efec22Sraf 61041efec22Sraf if (!try_flag) { 61141efec22Sraf DTRACE_PROBE3(plockstat, rw__blocked, rwlp, rd_wr, error == 0); 61241efec22Sraf } 6137c478bd9Sstevel@tonic-gate 6147c478bd9Sstevel@tonic-gate return (error); 6157c478bd9Sstevel@tonic-gate } 6167c478bd9Sstevel@tonic-gate 6177c478bd9Sstevel@tonic-gate int 6187c478bd9Sstevel@tonic-gate rw_rdlock_impl(rwlock_t *rwlp, timespec_t *tsp) 6197c478bd9Sstevel@tonic-gate { 6207c478bd9Sstevel@tonic-gate ulwp_t *self = curthread; 6217c478bd9Sstevel@tonic-gate uberdata_t *udp = self->ul_uberdata; 6227c478bd9Sstevel@tonic-gate readlock_t *readlockp; 6237c478bd9Sstevel@tonic-gate tdb_rwlock_stats_t *rwsp = RWLOCK_STATS(rwlp, udp); 6247c478bd9Sstevel@tonic-gate int error; 6257c478bd9Sstevel@tonic-gate 6267c478bd9Sstevel@tonic-gate /* 6277c478bd9Sstevel@tonic-gate * If we already hold a readers lock on this rwlock, 6287c478bd9Sstevel@tonic-gate * just increment our reference count and return. 6297c478bd9Sstevel@tonic-gate */ 63041efec22Sraf sigoff(self); 6317c478bd9Sstevel@tonic-gate readlockp = rwl_entry(rwlp); 6327c478bd9Sstevel@tonic-gate if (readlockp->rd_count != 0) { 63341efec22Sraf if (readlockp->rd_count == READ_LOCK_MAX) { 63441efec22Sraf sigon(self); 63541efec22Sraf error = EAGAIN; 63641efec22Sraf goto out; 6377c478bd9Sstevel@tonic-gate } 63841efec22Sraf sigon(self); 63941efec22Sraf error = 0; 64041efec22Sraf goto out; 64141efec22Sraf } 64241efec22Sraf sigon(self); 6437c478bd9Sstevel@tonic-gate 6447c478bd9Sstevel@tonic-gate /* 6457c478bd9Sstevel@tonic-gate * If we hold the writer lock, bail out. 6467c478bd9Sstevel@tonic-gate */ 6477c478bd9Sstevel@tonic-gate if (rw_write_is_held(rwlp)) { 6487c478bd9Sstevel@tonic-gate if (self->ul_error_detection) 6497c478bd9Sstevel@tonic-gate rwlock_error(rwlp, "rwlock_rdlock", 6507c478bd9Sstevel@tonic-gate "calling thread owns the writer lock"); 65141efec22Sraf error = EDEADLK; 65241efec22Sraf goto out; 6537c478bd9Sstevel@tonic-gate } 6547c478bd9Sstevel@tonic-gate 65541efec22Sraf if (read_lock_try(rwlp, 0)) 65641efec22Sraf error = 0; 65741efec22Sraf else if (rwlp->rwlock_type == USYNC_PROCESS) /* kernel-level */ 6587c478bd9Sstevel@tonic-gate error = shared_rwlock_lock(rwlp, tsp, READ_LOCK); 6597c478bd9Sstevel@tonic-gate else /* user-level */ 6607c478bd9Sstevel@tonic-gate error = rwlock_lock(rwlp, tsp, READ_LOCK); 6617c478bd9Sstevel@tonic-gate 66241efec22Sraf out: 6637c478bd9Sstevel@tonic-gate if (error == 0) { 66441efec22Sraf sigoff(self); 66541efec22Sraf rwl_entry(rwlp)->rd_count++; 66641efec22Sraf sigon(self); 6677c478bd9Sstevel@tonic-gate if (rwsp) 6687c478bd9Sstevel@tonic-gate tdb_incr(rwsp->rw_rdlock); 66941efec22Sraf DTRACE_PROBE2(plockstat, rw__acquire, rwlp, READ_LOCK); 67041efec22Sraf } else { 67141efec22Sraf DTRACE_PROBE3(plockstat, rw__error, rwlp, READ_LOCK, error); 6727c478bd9Sstevel@tonic-gate } 6737c478bd9Sstevel@tonic-gate 6747c478bd9Sstevel@tonic-gate return (error); 6757c478bd9Sstevel@tonic-gate } 6767c478bd9Sstevel@tonic-gate 6777c478bd9Sstevel@tonic-gate #pragma weak rw_rdlock = __rw_rdlock 6787c478bd9Sstevel@tonic-gate #pragma weak _rw_rdlock = __rw_rdlock 6797c478bd9Sstevel@tonic-gate #pragma weak pthread_rwlock_rdlock = __rw_rdlock 6807c478bd9Sstevel@tonic-gate #pragma weak _pthread_rwlock_rdlock = __rw_rdlock 6817c478bd9Sstevel@tonic-gate int 6827c478bd9Sstevel@tonic-gate __rw_rdlock(rwlock_t *rwlp) 6837c478bd9Sstevel@tonic-gate { 6847c478bd9Sstevel@tonic-gate ASSERT(!curthread->ul_critical || curthread->ul_bindflags); 6857c478bd9Sstevel@tonic-gate return (rw_rdlock_impl(rwlp, NULL)); 6867c478bd9Sstevel@tonic-gate } 6877c478bd9Sstevel@tonic-gate 6887c478bd9Sstevel@tonic-gate void 6897c478bd9Sstevel@tonic-gate lrw_rdlock(rwlock_t *rwlp) 6907c478bd9Sstevel@tonic-gate { 6917c478bd9Sstevel@tonic-gate enter_critical(curthread); 6927c478bd9Sstevel@tonic-gate (void) rw_rdlock_impl(rwlp, NULL); 6937c478bd9Sstevel@tonic-gate } 6947c478bd9Sstevel@tonic-gate 6957c478bd9Sstevel@tonic-gate #pragma weak pthread_rwlock_reltimedrdlock_np = \ 6967c478bd9Sstevel@tonic-gate _pthread_rwlock_reltimedrdlock_np 6977c478bd9Sstevel@tonic-gate int 6987c478bd9Sstevel@tonic-gate _pthread_rwlock_reltimedrdlock_np(rwlock_t *rwlp, const timespec_t *reltime) 6997c478bd9Sstevel@tonic-gate { 7007c478bd9Sstevel@tonic-gate timespec_t tslocal = *reltime; 7017c478bd9Sstevel@tonic-gate int error; 7027c478bd9Sstevel@tonic-gate 7037c478bd9Sstevel@tonic-gate ASSERT(!curthread->ul_critical || curthread->ul_bindflags); 7047c478bd9Sstevel@tonic-gate error = rw_rdlock_impl(rwlp, &tslocal); 7057c478bd9Sstevel@tonic-gate if (error == ETIME) 7067c478bd9Sstevel@tonic-gate error = ETIMEDOUT; 7077c478bd9Sstevel@tonic-gate return (error); 7087c478bd9Sstevel@tonic-gate } 7097c478bd9Sstevel@tonic-gate 7107c478bd9Sstevel@tonic-gate #pragma weak pthread_rwlock_timedrdlock = _pthread_rwlock_timedrdlock 7117c478bd9Sstevel@tonic-gate int 7127c478bd9Sstevel@tonic-gate _pthread_rwlock_timedrdlock(rwlock_t *rwlp, const timespec_t *abstime) 7137c478bd9Sstevel@tonic-gate { 7147c478bd9Sstevel@tonic-gate timespec_t tslocal; 7157c478bd9Sstevel@tonic-gate int error; 7167c478bd9Sstevel@tonic-gate 7177c478bd9Sstevel@tonic-gate ASSERT(!curthread->ul_critical || curthread->ul_bindflags); 7187c478bd9Sstevel@tonic-gate abstime_to_reltime(CLOCK_REALTIME, abstime, &tslocal); 7197c478bd9Sstevel@tonic-gate error = rw_rdlock_impl(rwlp, &tslocal); 7207c478bd9Sstevel@tonic-gate if (error == ETIME) 7217c478bd9Sstevel@tonic-gate error = ETIMEDOUT; 7227c478bd9Sstevel@tonic-gate return (error); 7237c478bd9Sstevel@tonic-gate } 7247c478bd9Sstevel@tonic-gate 7257c478bd9Sstevel@tonic-gate int 7267c478bd9Sstevel@tonic-gate rw_wrlock_impl(rwlock_t *rwlp, timespec_t *tsp) 7277c478bd9Sstevel@tonic-gate { 7287c478bd9Sstevel@tonic-gate ulwp_t *self = curthread; 7297c478bd9Sstevel@tonic-gate uberdata_t *udp = self->ul_uberdata; 7307c478bd9Sstevel@tonic-gate tdb_rwlock_stats_t *rwsp = RWLOCK_STATS(rwlp, udp); 7317c478bd9Sstevel@tonic-gate int error; 7327c478bd9Sstevel@tonic-gate 7337c478bd9Sstevel@tonic-gate /* 7347c478bd9Sstevel@tonic-gate * If we hold a readers lock on this rwlock, bail out. 7357c478bd9Sstevel@tonic-gate */ 7367c478bd9Sstevel@tonic-gate if (rw_read_is_held(rwlp)) { 7377c478bd9Sstevel@tonic-gate if (self->ul_error_detection) 7387c478bd9Sstevel@tonic-gate rwlock_error(rwlp, "rwlock_wrlock", 7397c478bd9Sstevel@tonic-gate "calling thread owns the readers lock"); 74041efec22Sraf error = EDEADLK; 74141efec22Sraf goto out; 7427c478bd9Sstevel@tonic-gate } 7437c478bd9Sstevel@tonic-gate 7447c478bd9Sstevel@tonic-gate /* 7457c478bd9Sstevel@tonic-gate * If we hold the writer lock, bail out. 7467c478bd9Sstevel@tonic-gate */ 7477c478bd9Sstevel@tonic-gate if (rw_write_is_held(rwlp)) { 7487c478bd9Sstevel@tonic-gate if (self->ul_error_detection) 7497c478bd9Sstevel@tonic-gate rwlock_error(rwlp, "rwlock_wrlock", 7507c478bd9Sstevel@tonic-gate "calling thread owns the writer lock"); 75141efec22Sraf error = EDEADLK; 75241efec22Sraf goto out; 7537c478bd9Sstevel@tonic-gate } 7547c478bd9Sstevel@tonic-gate 75541efec22Sraf if (write_lock_try(rwlp, 0)) 75641efec22Sraf error = 0; 75741efec22Sraf else if (rwlp->rwlock_type == USYNC_PROCESS) /* kernel-level */ 7587c478bd9Sstevel@tonic-gate error = shared_rwlock_lock(rwlp, tsp, WRITE_LOCK); 75941efec22Sraf else /* user-level */ 7607c478bd9Sstevel@tonic-gate error = rwlock_lock(rwlp, tsp, WRITE_LOCK); 7617c478bd9Sstevel@tonic-gate 76241efec22Sraf out: 76341efec22Sraf if (error == 0) { 76441efec22Sraf rwlp->rwlock_owner = (uintptr_t)self; 76541efec22Sraf if (rwlp->rwlock_type == USYNC_PROCESS) 76641efec22Sraf rwlp->rwlock_ownerpid = udp->pid; 76741efec22Sraf if (rwsp) { 7687c478bd9Sstevel@tonic-gate tdb_incr(rwsp->rw_wrlock); 7697c478bd9Sstevel@tonic-gate rwsp->rw_wrlock_begin_hold = gethrtime(); 7707c478bd9Sstevel@tonic-gate } 77141efec22Sraf DTRACE_PROBE2(plockstat, rw__acquire, rwlp, WRITE_LOCK); 77241efec22Sraf } else { 77341efec22Sraf DTRACE_PROBE3(plockstat, rw__error, rwlp, WRITE_LOCK, error); 77441efec22Sraf } 7757c478bd9Sstevel@tonic-gate return (error); 7767c478bd9Sstevel@tonic-gate } 7777c478bd9Sstevel@tonic-gate 7787c478bd9Sstevel@tonic-gate #pragma weak rw_wrlock = __rw_wrlock 7797c478bd9Sstevel@tonic-gate #pragma weak _rw_wrlock = __rw_wrlock 7807c478bd9Sstevel@tonic-gate #pragma weak pthread_rwlock_wrlock = __rw_wrlock 7817c478bd9Sstevel@tonic-gate #pragma weak _pthread_rwlock_wrlock = __rw_wrlock 7827c478bd9Sstevel@tonic-gate int 7837c478bd9Sstevel@tonic-gate __rw_wrlock(rwlock_t *rwlp) 7847c478bd9Sstevel@tonic-gate { 7857c478bd9Sstevel@tonic-gate ASSERT(!curthread->ul_critical || curthread->ul_bindflags); 7867c478bd9Sstevel@tonic-gate return (rw_wrlock_impl(rwlp, NULL)); 7877c478bd9Sstevel@tonic-gate } 7887c478bd9Sstevel@tonic-gate 7897c478bd9Sstevel@tonic-gate void 7907c478bd9Sstevel@tonic-gate lrw_wrlock(rwlock_t *rwlp) 7917c478bd9Sstevel@tonic-gate { 7927c478bd9Sstevel@tonic-gate enter_critical(curthread); 7937c478bd9Sstevel@tonic-gate (void) rw_wrlock_impl(rwlp, NULL); 7947c478bd9Sstevel@tonic-gate } 7957c478bd9Sstevel@tonic-gate 7967c478bd9Sstevel@tonic-gate #pragma weak pthread_rwlock_reltimedwrlock_np = \ 7977c478bd9Sstevel@tonic-gate _pthread_rwlock_reltimedwrlock_np 7987c478bd9Sstevel@tonic-gate int 7997c478bd9Sstevel@tonic-gate _pthread_rwlock_reltimedwrlock_np(rwlock_t *rwlp, const timespec_t *reltime) 8007c478bd9Sstevel@tonic-gate { 8017c478bd9Sstevel@tonic-gate timespec_t tslocal = *reltime; 8027c478bd9Sstevel@tonic-gate int error; 8037c478bd9Sstevel@tonic-gate 8047c478bd9Sstevel@tonic-gate ASSERT(!curthread->ul_critical || curthread->ul_bindflags); 8057c478bd9Sstevel@tonic-gate error = rw_wrlock_impl(rwlp, &tslocal); 8067c478bd9Sstevel@tonic-gate if (error == ETIME) 8077c478bd9Sstevel@tonic-gate error = ETIMEDOUT; 8087c478bd9Sstevel@tonic-gate return (error); 8097c478bd9Sstevel@tonic-gate } 8107c478bd9Sstevel@tonic-gate 8117c478bd9Sstevel@tonic-gate #pragma weak pthread_rwlock_timedwrlock = _pthread_rwlock_timedwrlock 8127c478bd9Sstevel@tonic-gate int 8137c478bd9Sstevel@tonic-gate _pthread_rwlock_timedwrlock(rwlock_t *rwlp, const timespec_t *abstime) 8147c478bd9Sstevel@tonic-gate { 8157c478bd9Sstevel@tonic-gate timespec_t tslocal; 8167c478bd9Sstevel@tonic-gate int error; 8177c478bd9Sstevel@tonic-gate 8187c478bd9Sstevel@tonic-gate ASSERT(!curthread->ul_critical || curthread->ul_bindflags); 8197c478bd9Sstevel@tonic-gate abstime_to_reltime(CLOCK_REALTIME, abstime, &tslocal); 8207c478bd9Sstevel@tonic-gate error = rw_wrlock_impl(rwlp, &tslocal); 8217c478bd9Sstevel@tonic-gate if (error == ETIME) 8227c478bd9Sstevel@tonic-gate error = ETIMEDOUT; 8237c478bd9Sstevel@tonic-gate return (error); 8247c478bd9Sstevel@tonic-gate } 8257c478bd9Sstevel@tonic-gate 8267c478bd9Sstevel@tonic-gate #pragma weak rw_tryrdlock = __rw_tryrdlock 8277c478bd9Sstevel@tonic-gate #pragma weak _rw_tryrdlock = __rw_tryrdlock 8287c478bd9Sstevel@tonic-gate #pragma weak pthread_rwlock_tryrdlock = __rw_tryrdlock 8297c478bd9Sstevel@tonic-gate #pragma weak _pthread_rwlock_tryrdlock = __rw_tryrdlock 8307c478bd9Sstevel@tonic-gate int 8317c478bd9Sstevel@tonic-gate __rw_tryrdlock(rwlock_t *rwlp) 8327c478bd9Sstevel@tonic-gate { 8337c478bd9Sstevel@tonic-gate ulwp_t *self = curthread; 8347c478bd9Sstevel@tonic-gate uberdata_t *udp = self->ul_uberdata; 8357c478bd9Sstevel@tonic-gate tdb_rwlock_stats_t *rwsp = RWLOCK_STATS(rwlp, udp); 8367c478bd9Sstevel@tonic-gate readlock_t *readlockp; 8377c478bd9Sstevel@tonic-gate int error; 8387c478bd9Sstevel@tonic-gate 8397c478bd9Sstevel@tonic-gate ASSERT(!curthread->ul_critical || curthread->ul_bindflags); 8407c478bd9Sstevel@tonic-gate 8417c478bd9Sstevel@tonic-gate if (rwsp) 8427c478bd9Sstevel@tonic-gate tdb_incr(rwsp->rw_rdlock_try); 8437c478bd9Sstevel@tonic-gate 8447c478bd9Sstevel@tonic-gate /* 8457c478bd9Sstevel@tonic-gate * If we already hold a readers lock on this rwlock, 8467c478bd9Sstevel@tonic-gate * just increment our reference count and return. 8477c478bd9Sstevel@tonic-gate */ 84841efec22Sraf sigoff(self); 8497c478bd9Sstevel@tonic-gate readlockp = rwl_entry(rwlp); 8507c478bd9Sstevel@tonic-gate if (readlockp->rd_count != 0) { 85141efec22Sraf if (readlockp->rd_count == READ_LOCK_MAX) { 85241efec22Sraf sigon(self); 85341efec22Sraf error = EAGAIN; 85441efec22Sraf goto out; 8557c478bd9Sstevel@tonic-gate } 85641efec22Sraf sigon(self); 85741efec22Sraf error = 0; 85841efec22Sraf goto out; 85941efec22Sraf } 86041efec22Sraf sigon(self); 8617c478bd9Sstevel@tonic-gate 86241efec22Sraf if (read_lock_try(rwlp, 0)) 86341efec22Sraf error = 0; 86441efec22Sraf else if (rwlp->rwlock_type == USYNC_PROCESS) /* kernel-level */ 8657c478bd9Sstevel@tonic-gate error = shared_rwlock_lock(rwlp, NULL, READ_LOCK_TRY); 8667c478bd9Sstevel@tonic-gate else /* user-level */ 8677c478bd9Sstevel@tonic-gate error = rwlock_lock(rwlp, NULL, READ_LOCK_TRY); 8687c478bd9Sstevel@tonic-gate 86941efec22Sraf out: 87041efec22Sraf if (error == 0) { 87141efec22Sraf sigoff(self); 87241efec22Sraf rwl_entry(rwlp)->rd_count++; 87341efec22Sraf sigon(self); 87441efec22Sraf DTRACE_PROBE2(plockstat, rw__acquire, rwlp, READ_LOCK); 87541efec22Sraf } else { 87641efec22Sraf if (rwsp) 8777c478bd9Sstevel@tonic-gate tdb_incr(rwsp->rw_rdlock_try_fail); 87841efec22Sraf if (error != EBUSY) { 87941efec22Sraf DTRACE_PROBE3(plockstat, rw__error, rwlp, READ_LOCK, 88041efec22Sraf error); 88141efec22Sraf } 88241efec22Sraf } 8837c478bd9Sstevel@tonic-gate 8847c478bd9Sstevel@tonic-gate return (error); 8857c478bd9Sstevel@tonic-gate } 8867c478bd9Sstevel@tonic-gate 8877c478bd9Sstevel@tonic-gate #pragma weak rw_trywrlock = __rw_trywrlock 8887c478bd9Sstevel@tonic-gate #pragma weak _rw_trywrlock = __rw_trywrlock 8897c478bd9Sstevel@tonic-gate #pragma weak pthread_rwlock_trywrlock = __rw_trywrlock 8907c478bd9Sstevel@tonic-gate #pragma weak _pthread_rwlock_trywrlock = __rw_trywrlock 8917c478bd9Sstevel@tonic-gate int 8927c478bd9Sstevel@tonic-gate __rw_trywrlock(rwlock_t *rwlp) 8937c478bd9Sstevel@tonic-gate { 8947c478bd9Sstevel@tonic-gate ulwp_t *self = curthread; 8957c478bd9Sstevel@tonic-gate uberdata_t *udp = self->ul_uberdata; 8967c478bd9Sstevel@tonic-gate tdb_rwlock_stats_t *rwsp = RWLOCK_STATS(rwlp, udp); 8977c478bd9Sstevel@tonic-gate int error; 8987c478bd9Sstevel@tonic-gate 89941efec22Sraf ASSERT(!self->ul_critical || self->ul_bindflags); 9007c478bd9Sstevel@tonic-gate 9017c478bd9Sstevel@tonic-gate if (rwsp) 9027c478bd9Sstevel@tonic-gate tdb_incr(rwsp->rw_wrlock_try); 9037c478bd9Sstevel@tonic-gate 90441efec22Sraf if (write_lock_try(rwlp, 0)) 90541efec22Sraf error = 0; 90641efec22Sraf else if (rwlp->rwlock_type == USYNC_PROCESS) /* kernel-level */ 9077c478bd9Sstevel@tonic-gate error = shared_rwlock_lock(rwlp, NULL, WRITE_LOCK_TRY); 90841efec22Sraf else /* user-level */ 9097c478bd9Sstevel@tonic-gate error = rwlock_lock(rwlp, NULL, WRITE_LOCK_TRY); 91041efec22Sraf 91141efec22Sraf if (error == 0) { 91241efec22Sraf rwlp->rwlock_owner = (uintptr_t)self; 91341efec22Sraf if (rwlp->rwlock_type == USYNC_PROCESS) 91441efec22Sraf rwlp->rwlock_ownerpid = udp->pid; 91541efec22Sraf if (rwsp) 9167c478bd9Sstevel@tonic-gate rwsp->rw_wrlock_begin_hold = gethrtime(); 91741efec22Sraf DTRACE_PROBE2(plockstat, rw__acquire, rwlp, WRITE_LOCK); 91841efec22Sraf } else { 91941efec22Sraf if (rwsp) 92041efec22Sraf tdb_incr(rwsp->rw_wrlock_try_fail); 92141efec22Sraf if (error != EBUSY) { 92241efec22Sraf DTRACE_PROBE3(plockstat, rw__error, rwlp, WRITE_LOCK, 92341efec22Sraf error); 92441efec22Sraf } 9257c478bd9Sstevel@tonic-gate } 9267c478bd9Sstevel@tonic-gate return (error); 9277c478bd9Sstevel@tonic-gate } 9287c478bd9Sstevel@tonic-gate 9297c478bd9Sstevel@tonic-gate #pragma weak rw_unlock = __rw_unlock 9307c478bd9Sstevel@tonic-gate #pragma weak _rw_unlock = __rw_unlock 9317c478bd9Sstevel@tonic-gate #pragma weak pthread_rwlock_unlock = __rw_unlock 9327c478bd9Sstevel@tonic-gate #pragma weak _pthread_rwlock_unlock = __rw_unlock 9337c478bd9Sstevel@tonic-gate int 9347c478bd9Sstevel@tonic-gate __rw_unlock(rwlock_t *rwlp) 9357c478bd9Sstevel@tonic-gate { 93641efec22Sraf volatile uint32_t *rwstate = (volatile uint32_t *)&rwlp->rwlock_readers; 93741efec22Sraf uint32_t readers; 9387c478bd9Sstevel@tonic-gate ulwp_t *self = curthread; 9397c478bd9Sstevel@tonic-gate uberdata_t *udp = self->ul_uberdata; 9407c478bd9Sstevel@tonic-gate tdb_rwlock_stats_t *rwsp; 94141efec22Sraf queue_head_t *qp; 94241efec22Sraf int rd_wr; 94341efec22Sraf int waked = 0; 9447c478bd9Sstevel@tonic-gate 94541efec22Sraf readers = *rwstate; 94641efec22Sraf ASSERT_CONSISTENT_STATE(readers); 94741efec22Sraf if (readers & URW_WRITE_LOCKED) { 94841efec22Sraf rd_wr = WRITE_LOCK; 94941efec22Sraf readers = 0; 95041efec22Sraf } else { 95141efec22Sraf rd_wr = READ_LOCK; 95241efec22Sraf readers &= URW_READERS_MASK; 9537c478bd9Sstevel@tonic-gate } 9547c478bd9Sstevel@tonic-gate 95541efec22Sraf if (rd_wr == WRITE_LOCK) { 9567c478bd9Sstevel@tonic-gate /* 9577c478bd9Sstevel@tonic-gate * Since the writer lock is held, we'd better be 9587c478bd9Sstevel@tonic-gate * holding it, else we cannot legitimately be here. 9597c478bd9Sstevel@tonic-gate */ 9607c478bd9Sstevel@tonic-gate if (!rw_write_is_held(rwlp)) { 9617c478bd9Sstevel@tonic-gate if (self->ul_error_detection) 9627c478bd9Sstevel@tonic-gate rwlock_error(rwlp, "rwlock_unlock", 9637c478bd9Sstevel@tonic-gate "writer lock held, " 9647c478bd9Sstevel@tonic-gate "but not by the calling thread"); 9657c478bd9Sstevel@tonic-gate return (EPERM); 9667c478bd9Sstevel@tonic-gate } 9677c478bd9Sstevel@tonic-gate if ((rwsp = RWLOCK_STATS(rwlp, udp)) != NULL) { 9687c478bd9Sstevel@tonic-gate if (rwsp->rw_wrlock_begin_hold) 9697c478bd9Sstevel@tonic-gate rwsp->rw_wrlock_hold_time += 9707c478bd9Sstevel@tonic-gate gethrtime() - rwsp->rw_wrlock_begin_hold; 9717c478bd9Sstevel@tonic-gate rwsp->rw_wrlock_begin_hold = 0; 9727c478bd9Sstevel@tonic-gate } 97341efec22Sraf rwlp->rwlock_owner = 0; 97441efec22Sraf rwlp->rwlock_ownerpid = 0; 97541efec22Sraf } else if (readers > 0) { 9767c478bd9Sstevel@tonic-gate /* 9777c478bd9Sstevel@tonic-gate * A readers lock is held; if we don't hold one, bail out. 9787c478bd9Sstevel@tonic-gate */ 97941efec22Sraf readlock_t *readlockp; 98041efec22Sraf 98141efec22Sraf sigoff(self); 98241efec22Sraf readlockp = rwl_entry(rwlp); 9837c478bd9Sstevel@tonic-gate if (readlockp->rd_count == 0) { 98441efec22Sraf sigon(self); 9857c478bd9Sstevel@tonic-gate if (self->ul_error_detection) 9867c478bd9Sstevel@tonic-gate rwlock_error(rwlp, "rwlock_unlock", 9877c478bd9Sstevel@tonic-gate "readers lock held, " 9887c478bd9Sstevel@tonic-gate "but not by the calling thread"); 9897c478bd9Sstevel@tonic-gate return (EPERM); 9907c478bd9Sstevel@tonic-gate } 9917c478bd9Sstevel@tonic-gate /* 9927c478bd9Sstevel@tonic-gate * If we hold more than one readers lock on this rwlock, 9937c478bd9Sstevel@tonic-gate * just decrement our reference count and return. 9947c478bd9Sstevel@tonic-gate */ 9957c478bd9Sstevel@tonic-gate if (--readlockp->rd_count != 0) { 99641efec22Sraf sigon(self); 99741efec22Sraf goto out; 9987c478bd9Sstevel@tonic-gate } 99941efec22Sraf sigon(self); 10007c478bd9Sstevel@tonic-gate } else { 10017c478bd9Sstevel@tonic-gate /* 10027c478bd9Sstevel@tonic-gate * This is a usage error. 10037c478bd9Sstevel@tonic-gate * No thread should release an unowned lock. 10047c478bd9Sstevel@tonic-gate */ 10057c478bd9Sstevel@tonic-gate if (self->ul_error_detection) 10067c478bd9Sstevel@tonic-gate rwlock_error(rwlp, "rwlock_unlock", "lock not owned"); 10077c478bd9Sstevel@tonic-gate return (EPERM); 10087c478bd9Sstevel@tonic-gate } 10097c478bd9Sstevel@tonic-gate 101041efec22Sraf if (rd_wr == WRITE_LOCK && write_unlock_try(rwlp)) { 101141efec22Sraf /* EMPTY */; 101241efec22Sraf } else if (rd_wr == READ_LOCK && read_unlock_try(rwlp)) { 101341efec22Sraf /* EMPTY */; 101441efec22Sraf } else if (rwlp->rwlock_type == USYNC_PROCESS) { 101541efec22Sraf (void) _private_mutex_lock(&rwlp->mutex); 101641efec22Sraf (void) __lwp_rwlock_unlock(rwlp); 101741efec22Sraf (void) _private_mutex_unlock(&rwlp->mutex); 101841efec22Sraf waked = 1; 10197c478bd9Sstevel@tonic-gate } else { 10207c478bd9Sstevel@tonic-gate qp = queue_lock(rwlp, MX); 102141efec22Sraf if (rd_wr == READ_LOCK) 102241efec22Sraf atomic_dec_32(rwstate); 102341efec22Sraf else 102441efec22Sraf atomic_and_32(rwstate, ~URW_WRITE_LOCKED); 10257c478bd9Sstevel@tonic-gate waked = rw_queue_release(qp, rwlp); 10267c478bd9Sstevel@tonic-gate } 10277c478bd9Sstevel@tonic-gate 102841efec22Sraf out: 102941efec22Sraf DTRACE_PROBE2(plockstat, rw__release, rwlp, rd_wr); 103041efec22Sraf 10317c478bd9Sstevel@tonic-gate /* 10327c478bd9Sstevel@tonic-gate * Yield to the thread we just waked up, just in case we might 10337c478bd9Sstevel@tonic-gate * be about to grab the rwlock again immediately upon return. 10347c478bd9Sstevel@tonic-gate * This is pretty weak but it helps on a uniprocessor and also 10357c478bd9Sstevel@tonic-gate * when cpu affinity has assigned both ourself and the other 10367c478bd9Sstevel@tonic-gate * thread to the same CPU. Note that lwp_yield() will yield 10377c478bd9Sstevel@tonic-gate * the processor only if the writer is at the same or higher 10387c478bd9Sstevel@tonic-gate * priority than ourself. This provides more balanced program 10397c478bd9Sstevel@tonic-gate * behavior; it doesn't guarantee acquisition of the lock by 10407c478bd9Sstevel@tonic-gate * the pending writer. 10417c478bd9Sstevel@tonic-gate */ 10427c478bd9Sstevel@tonic-gate if (waked) 10437c478bd9Sstevel@tonic-gate lwp_yield(); 10447c478bd9Sstevel@tonic-gate return (0); 10457c478bd9Sstevel@tonic-gate } 10467c478bd9Sstevel@tonic-gate 10477c478bd9Sstevel@tonic-gate void 10487c478bd9Sstevel@tonic-gate lrw_unlock(rwlock_t *rwlp) 10497c478bd9Sstevel@tonic-gate { 10507c478bd9Sstevel@tonic-gate (void) __rw_unlock(rwlp); 10517c478bd9Sstevel@tonic-gate exit_critical(curthread); 10527c478bd9Sstevel@tonic-gate } 1053