/* $Id: semrw-posix.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */ /** @file * IPRT - Read-Write Semaphore, POSIX. */ /* * Copyright (C) 2006-2023 Oracle and/or its affiliates. * * This file is part of VirtualBox base platform packages, as * available from https://www.virtualbox.org. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation, in version 3 of the * License. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see . * * The contents of this file may alternatively be used under the terms * of the Common Development and Distribution License Version 1.0 * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included * in the VirtualBox distribution, in which case the provisions of the * CDDL are applicable instead of those of the GPL. * * You may elect to license modified versions of this file under the * terms and conditions of either the GPL or the CDDL or both. * * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0 */ /********************************************************************************************************************************* * Header Files * *********************************************************************************************************************************/ #include #include "internal/iprt.h" #include #include #include #include #include #include #include #include #include #include #include "internal/magics.h" #include "internal/strict.h" /********************************************************************************************************************************* * Defined Constants And Macros * *********************************************************************************************************************************/ /** @todo move this to r3/posix/something.h. */ #ifdef RT_OS_SOLARIS # define ATOMIC_GET_PTHREAD_T(ppvVar, pThread) ASMAtomicReadSize(ppvVar, pThread) # define ATOMIC_SET_PTHREAD_T(ppvVar, pThread) ASMAtomicWriteSize(ppvVar, pThread) #else AssertCompileSize(pthread_t, sizeof(void *)); # define ATOMIC_GET_PTHREAD_T(ppvVar, pThread) do { *(pThread) = (pthread_t)ASMAtomicReadPtr((void * volatile *)ppvVar); } while (0) # define ATOMIC_SET_PTHREAD_T(ppvVar, pThread) ASMAtomicWritePtr((void * volatile *)ppvVar, (void *)pThread) #endif /********************************************************************************************************************************* * Structures and Typedefs * *********************************************************************************************************************************/ /** Posix internal representation of a read-write semaphore. */ struct RTSEMRWINTERNAL { /** The usual magic. (RTSEMRW_MAGIC) */ uint32_t u32Magic; /** The number of readers. * (For preventing screwing up the lock on linux). */ uint32_t volatile cReaders; /** Number of write recursions. */ uint32_t cWrites; /** Number of read recursions by the writer. */ uint32_t cWriterReads; /** The write owner of the lock. */ volatile pthread_t Writer; /** pthread rwlock. */ pthread_rwlock_t RWLock; #ifdef RTSEMRW_STRICT /** The validator record for the writer. */ RTLOCKVALRECEXCL ValidatorWrite; /** The validator record for the readers. */ RTLOCKVALRECSHRD ValidatorRead; #endif }; #undef RTSemRWCreate RTDECL(int) RTSemRWCreate(PRTSEMRW phRWSem) { return RTSemRWCreateEx(phRWSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, RTLOCKVAL_SUB_CLASS_NONE, "RTSemRW"); } RTDECL(int) RTSemRWCreateEx(PRTSEMRW phRWSem, uint32_t fFlags, RTLOCKVALCLASS hClass, uint32_t uSubClass, const char *pszNameFmt, ...) { AssertReturn(!(fFlags & ~RTSEMRW_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER); /* * Allocate handle. */ int rc; struct RTSEMRWINTERNAL *pThis = (struct RTSEMRWINTERNAL *)RTMemAlloc(sizeof(struct RTSEMRWINTERNAL)); if (pThis) { /* * Create the rwlock. */ rc = pthread_rwlock_init(&pThis->RWLock, NULL); if (!rc) { pThis->u32Magic = RTSEMRW_MAGIC; pThis->cReaders = 0; pThis->cWrites = 0; pThis->cWriterReads = 0; pThis->Writer = (pthread_t)-1; #ifdef RTSEMRW_STRICT bool const fLVEnabled = !(fFlags & RTSEMRW_FLAGS_NO_LOCK_VAL); if (!pszNameFmt) { static uint32_t volatile s_iSemRWAnon = 0; uint32_t i = ASMAtomicIncU32(&s_iSemRWAnon) - 1; RTLockValidatorRecExclInit(&pThis->ValidatorWrite, hClass, uSubClass, pThis, fLVEnabled, "RTSemRW-%u", i); RTLockValidatorRecSharedInit(&pThis->ValidatorRead, hClass, uSubClass, pThis, false /*fSignaller*/, fLVEnabled, "RTSemRW-%u", i); } else { va_list va; va_start(va, pszNameFmt); RTLockValidatorRecExclInitV(&pThis->ValidatorWrite, hClass, uSubClass, pThis, fLVEnabled, pszNameFmt, va); va_end(va); va_start(va, pszNameFmt); RTLockValidatorRecSharedInitV(&pThis->ValidatorRead, hClass, uSubClass, pThis, false /*fSignaller*/, fLVEnabled, pszNameFmt, va); va_end(va); } RTLockValidatorRecMakeSiblings(&pThis->ValidatorWrite.Core, &pThis->ValidatorRead.Core); #else RT_NOREF_PV(hClass); RT_NOREF_PV(uSubClass); RT_NOREF_PV(pszNameFmt); #endif *phRWSem = pThis; return VINF_SUCCESS; } rc = RTErrConvertFromErrno(rc); RTMemFree(pThis); } else rc = VERR_NO_MEMORY; return rc; } RTDECL(int) RTSemRWDestroy(RTSEMRW hRWSem) { /* * Validate input, nil handle is fine. */ struct RTSEMRWINTERNAL *pThis = hRWSem; if (pThis == NIL_RTSEMRW) return VINF_SUCCESS; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE); Assert(pThis->Writer == (pthread_t)-1); Assert(!pThis->cReaders); Assert(!pThis->cWrites); Assert(!pThis->cWriterReads); /* * Try destroy it. */ AssertReturn(ASMAtomicCmpXchgU32(&pThis->u32Magic, ~RTSEMRW_MAGIC, RTSEMRW_MAGIC), VERR_INVALID_HANDLE); int rc = pthread_rwlock_destroy(&pThis->RWLock); if (!rc) { #ifdef RTSEMRW_STRICT RTLockValidatorRecSharedDelete(&pThis->ValidatorRead); RTLockValidatorRecExclDelete(&pThis->ValidatorWrite); #endif RTMemFree(pThis); rc = VINF_SUCCESS; } else { ASMAtomicWriteU32(&pThis->u32Magic, RTSEMRW_MAGIC); AssertMsgFailed(("Failed to destroy read-write sem %p, rc=%d.\n", hRWSem, rc)); rc = RTErrConvertFromErrno(rc); } return rc; } RTDECL(uint32_t) RTSemRWSetSubClass(RTSEMRW hRWSem, uint32_t uSubClass) { #ifdef RTSEMRW_STRICT /* * Validate handle. */ struct RTSEMRWINTERNAL *pThis = hRWSem; AssertPtrReturn(pThis, RTLOCKVAL_SUB_CLASS_INVALID); AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, RTLOCKVAL_SUB_CLASS_INVALID); RTLockValidatorRecSharedSetSubClass(&pThis->ValidatorRead, uSubClass); return RTLockValidatorRecExclSetSubClass(&pThis->ValidatorWrite, uSubClass); #else RT_NOREF_PV(hRWSem); RT_NOREF_PV(uSubClass); return RTLOCKVAL_SUB_CLASS_INVALID; #endif } DECL_FORCE_INLINE(int) rtSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies, PCRTLOCKVALSRCPOS pSrcPos) { /* * Validate input. */ struct RTSEMRWINTERNAL *pThis = hRWSem; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE); /* * Check if it's the writer (implement write+read recursion). */ pthread_t Self = pthread_self(); pthread_t Writer; ATOMIC_GET_PTHREAD_T(&pThis->Writer, &Writer); if (Writer == Self) { #ifdef RTSEMRW_STRICT int rc9 = RTLockValidatorRecExclRecursionMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core, pSrcPos); if (RT_FAILURE(rc9)) return rc9; #endif Assert(pThis->cWriterReads < INT32_MAX); pThis->cWriterReads++; return VINF_SUCCESS; } /* * Try lock it. */ RTTHREAD hThreadSelf = NIL_RTTHREAD; if (cMillies > 0) { #ifdef RTSEMRW_STRICT hThreadSelf = RTThreadSelfAutoAdopt(); int rc9 = RTLockValidatorRecSharedCheckOrderAndBlocking(&pThis->ValidatorRead, hThreadSelf, pSrcPos, true, cMillies, RTTHREADSTATE_RW_READ, true); if (RT_FAILURE(rc9)) return rc9; #else hThreadSelf = RTThreadSelf(); RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_READ, true); RT_NOREF_PV(pSrcPos); #endif } if (cMillies == RT_INDEFINITE_WAIT) { /* take rwlock */ int rc = pthread_rwlock_rdlock(&pThis->RWLock); RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_READ); if (rc) { AssertMsgFailed(("Failed read lock read-write sem %p, rc=%d.\n", hRWSem, rc)); return RTErrConvertFromErrno(rc); } } else { #ifdef RT_OS_DARWIN AssertMsgFailed(("Not implemented on Darwin yet because of incomplete pthreads API.")); return VERR_NOT_IMPLEMENTED; #else /* !RT_OS_DARWIN */ /* * Get current time and calc end of wait time. */ struct timespec ts = {0,0}; clock_gettime(CLOCK_REALTIME, &ts); if (cMillies != 0) { ts.tv_nsec += (cMillies % 1000) * 1000000; ts.tv_sec += cMillies / 1000; if (ts.tv_nsec >= 1000000000) { ts.tv_nsec -= 1000000000; ts.tv_sec++; } } /* take rwlock */ int rc = pthread_rwlock_timedrdlock(&pThis->RWLock, &ts); RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_READ); if (rc) { AssertMsg(rc == ETIMEDOUT, ("Failed read lock read-write sem %p, rc=%d.\n", hRWSem, rc)); return RTErrConvertFromErrno(rc); } #endif /* !RT_OS_DARWIN */ } ASMAtomicIncU32(&pThis->cReaders); #ifdef RTSEMRW_STRICT RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos); #endif return VINF_SUCCESS; } #undef RTSemRWRequestRead RTDECL(int) RTSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies) { #ifndef RTSEMRW_STRICT return rtSemRWRequestRead(hRWSem, cMillies, NULL); #else RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API(); return rtSemRWRequestRead(hRWSem, cMillies, &SrcPos); #endif } RTDECL(int) RTSemRWRequestReadDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL) { RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API(); return rtSemRWRequestRead(hRWSem, cMillies, &SrcPos); } #undef RTSemRWRequestReadNoResume RTDECL(int) RTSemRWRequestReadNoResume(RTSEMRW hRWSem, RTMSINTERVAL cMillies) { /* EINTR isn't returned by the wait functions we're using. */ #ifndef RTSEMRW_STRICT return rtSemRWRequestRead(hRWSem, cMillies, NULL); #else RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API(); return rtSemRWRequestRead(hRWSem, cMillies, &SrcPos); #endif } RTDECL(int) RTSemRWRequestReadNoResumeDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL) { RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API(); return rtSemRWRequestRead(hRWSem, cMillies, &SrcPos); } RTDECL(int) RTSemRWReleaseRead(RTSEMRW hRWSem) { /* * Validate input. */ struct RTSEMRWINTERNAL *pThis = hRWSem; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE); /* * Check if it's the writer. */ pthread_t Self = pthread_self(); pthread_t Writer; ATOMIC_GET_PTHREAD_T(&pThis->Writer, &Writer); if (Writer == Self) { AssertMsgReturn(pThis->cWriterReads > 0, ("pThis=%p\n", pThis), VERR_NOT_OWNER); #ifdef RTSEMRW_STRICT int rc9 = RTLockValidatorRecExclUnwindMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core); if (RT_FAILURE(rc9)) return rc9; #endif pThis->cWriterReads--; return VINF_SUCCESS; } /* * Try unlock it. */ #ifdef RTSEMRW_STRICT int rc9 = RTLockValidatorRecSharedCheckAndRelease(&pThis->ValidatorRead, RTThreadSelf()); if (RT_FAILURE(rc9)) return rc9; #endif #ifdef RT_OS_LINUX /* glibc (at least 2.8) may screw up when unlocking a lock we don't own. */ if (ASMAtomicReadU32(&pThis->cReaders) == 0) { AssertMsgFailed(("Not owner of %p\n", pThis)); return VERR_NOT_OWNER; } #endif ASMAtomicDecU32(&pThis->cReaders); int rc = pthread_rwlock_unlock(&pThis->RWLock); if (rc) { ASMAtomicIncU32(&pThis->cReaders); AssertMsgFailed(("Failed read unlock read-write sem %p, rc=%d.\n", hRWSem, rc)); return RTErrConvertFromErrno(rc); } return VINF_SUCCESS; } DECL_FORCE_INLINE(int) rtSemRWRequestWrite(RTSEMRW hRWSem, RTMSINTERVAL cMillies, PCRTLOCKVALSRCPOS pSrcPos) { /* * Validate input. */ struct RTSEMRWINTERNAL *pThis = hRWSem; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE); /* * Recursion? */ pthread_t Self = pthread_self(); pthread_t Writer; ATOMIC_GET_PTHREAD_T(&pThis->Writer, &Writer); if (Writer == Self) { #ifdef RTSEMRW_STRICT int rc9 = RTLockValidatorRecExclRecursion(&pThis->ValidatorWrite, pSrcPos); if (RT_FAILURE(rc9)) return rc9; #endif Assert(pThis->cWrites < INT32_MAX); pThis->cWrites++; return VINF_SUCCESS; } /* * Try lock it. */ RTTHREAD hThreadSelf = NIL_RTTHREAD; if (cMillies) { #ifdef RTSEMRW_STRICT hThreadSelf = RTThreadSelfAutoAdopt(); int rc9 = RTLockValidatorRecExclCheckOrderAndBlocking(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, true, cMillies, RTTHREADSTATE_RW_WRITE, true); if (RT_FAILURE(rc9)) return rc9; #else hThreadSelf = RTThreadSelf(); RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_WRITE, true); RT_NOREF_PV(pSrcPos); #endif } if (cMillies == RT_INDEFINITE_WAIT) { /* take rwlock */ int rc = pthread_rwlock_wrlock(&pThis->RWLock); RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_WRITE); if (rc) { AssertMsgFailed(("Failed write lock read-write sem %p, rc=%d.\n", hRWSem, rc)); return RTErrConvertFromErrno(rc); } } else { #ifdef RT_OS_DARWIN AssertMsgFailed(("Not implemented on Darwin yet because of incomplete pthreads API.")); return VERR_NOT_IMPLEMENTED; #else /* !RT_OS_DARWIN */ /* * Get current time and calc end of wait time. */ struct timespec ts = {0,0}; clock_gettime(CLOCK_REALTIME, &ts); if (cMillies != 0) { ts.tv_nsec += (cMillies % 1000) * 1000000; ts.tv_sec += cMillies / 1000; if (ts.tv_nsec >= 1000000000) { ts.tv_nsec -= 1000000000; ts.tv_sec++; } } /* take rwlock */ int rc = pthread_rwlock_timedwrlock(&pThis->RWLock, &ts); RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_WRITE); if (rc) { AssertMsg(rc == ETIMEDOUT, ("Failed read lock read-write sem %p, rc=%d.\n", hRWSem, rc)); return RTErrConvertFromErrno(rc); } #endif /* !RT_OS_DARWIN */ } ATOMIC_SET_PTHREAD_T(&pThis->Writer, Self); pThis->cWrites = 1; Assert(!pThis->cReaders); #ifdef RTSEMRW_STRICT RTLockValidatorRecExclSetOwner(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, true); #endif return VINF_SUCCESS; } #undef RTSemRWRequestWrite RTDECL(int) RTSemRWRequestWrite(RTSEMRW hRWSem, RTMSINTERVAL cMillies) { #ifndef RTSEMRW_STRICT return rtSemRWRequestWrite(hRWSem, cMillies, NULL); #else RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API(); return rtSemRWRequestWrite(hRWSem, cMillies, &SrcPos); #endif } RTDECL(int) RTSemRWRequestWriteDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL) { RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API(); return rtSemRWRequestWrite(hRWSem, cMillies, &SrcPos); } #undef RTSemRWRequestWriteNoResume RTDECL(int) RTSemRWRequestWriteNoResume(RTSEMRW hRWSem, RTMSINTERVAL cMillies) { /* EINTR isn't returned by the wait functions we're using. */ #ifndef RTSEMRW_STRICT return rtSemRWRequestWrite(hRWSem, cMillies, NULL); #else RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API(); return rtSemRWRequestWrite(hRWSem, cMillies, &SrcPos); #endif } RTDECL(int) RTSemRWRequestWriteNoResumeDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL) { /* EINTR isn't returned by the wait functions we're using. */ RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API(); return rtSemRWRequestWrite(hRWSem, cMillies, &SrcPos); } RTDECL(int) RTSemRWReleaseWrite(RTSEMRW hRWSem) { /* * Validate input. */ struct RTSEMRWINTERNAL *pThis = hRWSem; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE); /* * Verify ownership and implement recursion. */ pthread_t Self = pthread_self(); pthread_t Writer; ATOMIC_GET_PTHREAD_T(&pThis->Writer, &Writer); AssertMsgReturn(Writer == Self, ("pThis=%p\n", pThis), VERR_NOT_OWNER); AssertReturn(pThis->cWriterReads == 0 || pThis->cWrites > 1, VERR_WRONG_ORDER); if (pThis->cWrites > 1) { #ifdef RTSEMRW_STRICT int rc9 = RTLockValidatorRecExclUnwind(&pThis->ValidatorWrite); if (RT_FAILURE(rc9)) return rc9; #endif pThis->cWrites--; return VINF_SUCCESS; } /* * Try unlock it. */ #ifdef RTSEMRW_STRICT int rc9 = RTLockValidatorRecExclReleaseOwner(&pThis->ValidatorWrite, true); if (RT_FAILURE(rc9)) return rc9; #endif pThis->cWrites--; ATOMIC_SET_PTHREAD_T(&pThis->Writer, (pthread_t)-1); int rc = pthread_rwlock_unlock(&pThis->RWLock); if (rc) { AssertMsgFailed(("Failed write unlock read-write sem %p, rc=%d.\n", hRWSem, rc)); return RTErrConvertFromErrno(rc); } return VINF_SUCCESS; } RTDECL(bool) RTSemRWIsWriteOwner(RTSEMRW hRWSem) { /* * Validate input. */ struct RTSEMRWINTERNAL *pThis = hRWSem; AssertPtrReturn(pThis, false); AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), false); /* * Check ownership. */ pthread_t Self = pthread_self(); pthread_t Writer; ATOMIC_GET_PTHREAD_T(&pThis->Writer, &Writer); return Writer == Self; } RTDECL(bool) RTSemRWIsReadOwner(RTSEMRW hRWSem, bool fWannaHear) { /* * Validate handle. */ struct RTSEMRWINTERNAL *pThis = hRWSem; AssertPtrReturn(pThis, false); AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, false); /* * Check write ownership. The writer is also a valid reader. */ pthread_t Self = pthread_self(); pthread_t Writer; ATOMIC_GET_PTHREAD_T(&pThis->Writer, &Writer); if (Writer == Self) return true; if (Writer != (pthread_t)-1) return false; /* * If there are no readers, we cannot be one of them, can we? */ if (ASMAtomicReadU32(&pThis->cReaders) == 0) return false; #ifdef RTSEMRW_STRICT /* * Ask the lock validator. */ NOREF(fWannaHear); return RTLockValidatorRecSharedIsOwner(&pThis->ValidatorRead, NIL_RTTHREAD); #else /* * Just tell the caller what he want to hear. */ return fWannaHear; #endif } RT_EXPORT_SYMBOL(RTSemRWIsReadOwner); RTDECL(uint32_t) RTSemRWGetWriteRecursion(RTSEMRW hRWSem) { /* * Validate input. */ struct RTSEMRWINTERNAL *pThis = hRWSem; AssertPtrReturn(pThis, 0); AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), 0); /* * Return the requested data. */ return pThis->cWrites; } RTDECL(uint32_t) RTSemRWGetWriterReadRecursion(RTSEMRW hRWSem) { /* * Validate input. */ struct RTSEMRWINTERNAL *pThis = hRWSem; AssertPtrReturn(pThis, 0); AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), 0); /* * Return the requested data. */ return pThis->cWriterReads; } RTDECL(uint32_t) RTSemRWGetReadCount(RTSEMRW hRWSem) { /* * Validate input. */ struct RTSEMRWINTERNAL *pThis = hRWSem; AssertPtrReturn(pThis, 0); AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), 0); /* * Return the requested data. */ return pThis->cReaders; }