Adding upstream version 6.0.4-dfsg.upstream/6.0.4-dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 978 insertions, 0 deletions

diff --git a/src/VBox/Runtime/generic/semrw-generic.cpp b/src/VBox/Runtime/generic/semrw-generic.cpp
new file mode 100644
index 00000000..a8062673
--- /dev/null
+++ b/src/VBox/Runtime/generic/semrw-generic.cpp
@@ -0,0 +1,978 @@
+/* $Id: semrw-generic.cpp $ */
+/** @file
+ * IPRT - Read-Write Semaphore, Generic.
+ *
+ * This is a generic implementation for OSes which don't have
+ * native RW semaphores.
+ */
+
+/*
+ * Copyright (C) 2006-2019 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE 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.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMRW_WITHOUT_REMAPPING
+#include <iprt/semaphore.h>
+#include "internal/iprt.h"
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/critsect.h>
+#include <iprt/err.h>
+#include <iprt/lockvalidator.h>
+#include <iprt/mem.h>
+#include <iprt/time.h>
+#include <iprt/thread.h>
+
+#include "internal/magics.h"
+#include "internal/strict.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+
+/** Internal representation of a Read-Write semaphore for the
+ * Generic implementation. */
+struct RTSEMRWINTERNAL
+{
+    /** The usual magic. (RTSEMRW_MAGIC) */
+    uint32_t            u32Magic;
+    /* Alignment padding. */
+    uint32_t            u32Padding;
+    /** This critical section serializes the access to and updating of the structure members. */
+    RTCRITSECT          CritSect;
+    /** The current number of reads. (pure read recursion counts too) */
+    uint32_t            cReads;
+    /** The current number of writes. (recursion counts too) */
+    uint32_t            cWrites;
+    /** Number of read recursions by the writer. */
+    uint32_t            cWriterReads;
+    /** Number of writers waiting. */
+    uint32_t            cWritesWaiting;
+    /** The write owner of the lock. */
+    RTNATIVETHREAD      hWriter;
+    /** The handle of the event object on which the waiting readers block. (manual reset). */
+    RTSEMEVENTMULTI     ReadEvent;
+    /** The handle of the event object on which the waiting writers block. (automatic reset). */
+    RTSEMEVENT          WriteEvent;
+    /** Need to reset ReadEvent. */
+    bool                fNeedResetReadEvent;
+#ifdef RTSEMRW_STRICT
+    /** The validator record for the writer. */
+    RTLOCKVALRECEXCL    ValidatorWrite;
+    /** The validator record for the readers. */
+    RTLOCKVALRECSHRD    ValidatorRead;
+#endif
+};
+
+
+
+RTDECL(int) RTSemRWCreate(PRTSEMRW phRWSem)
+{
+    return RTSemRWCreateEx(phRWSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, RTLOCKVAL_SUB_CLASS_NONE, "RTSemRW");
+}
+RT_EXPORT_SYMBOL(RTSemRWCreate);
+
+
+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 memory.
+     */
+    int rc;
+    struct RTSEMRWINTERNAL *pThis = (struct RTSEMRWINTERNAL *)RTMemAlloc(sizeof(struct RTSEMRWINTERNAL));
+    if (pThis)
+    {
+        /*
+         * Create the semaphores.
+         */
+        rc = RTSemEventCreateEx(&pThis->WriteEvent, RTSEMEVENT_FLAGS_NO_LOCK_VAL, NIL_RTLOCKVALCLASS, NULL);
+        if (RT_SUCCESS(rc))
+        {
+            rc = RTSemEventMultiCreateEx(&pThis->ReadEvent, RTSEMEVENT_FLAGS_NO_LOCK_VAL, NIL_RTLOCKVALCLASS, NULL);
+            if (RT_SUCCESS(rc))
+            {
+                rc = RTCritSectInitEx(&pThis->CritSect, RTCRITSECT_FLAGS_NO_LOCK_VAL,
+                                      NIL_RTLOCKVALCLASS, RTLOCKVAL_SUB_CLASS_NONE, NULL);
+                if (RT_SUCCESS(rc))
+                {
+                    /*
+                     * Signal the read semaphore and initialize other variables.
+                     */
+                    rc = RTSemEventMultiSignal(pThis->ReadEvent);
+                    if (RT_SUCCESS(rc))
+                    {
+                        pThis->u32Padding           = UINT32_C(0xa5a55a5a);
+                        pThis->cReads               = 0;
+                        pThis->cWrites              = 0;
+                        pThis->cWriterReads         = 0;
+                        pThis->cWritesWaiting       = 0;
+                        pThis->hWriter              = NIL_RTNATIVETHREAD;
+                        pThis->fNeedResetReadEvent  = true;
+                        pThis->u32Magic             = RTSEMRW_MAGIC;
+#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;
+                    }
+                    RTCritSectDelete(&pThis->CritSect);
+                }
+                RTSemEventMultiDestroy(pThis->ReadEvent);
+            }
+            RTSemEventDestroy(pThis->WriteEvent);
+        }
+        RTMemFree(pThis);
+    }
+    else
+        rc = VERR_NO_MEMORY;
+
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTSemRWCreate);
+
+
+RTDECL(int) RTSemRWDestroy(RTSEMRW hRWSem)
+{
+    struct RTSEMRWINTERNAL *pThis = hRWSem;
+
+    /*
+     * Validate handle.
+     */
+    if (pThis == NIL_RTSEMRW)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
+
+    /*
+     * Check if busy.
+     */
+    int rc = RTCritSectTryEnter(&pThis->CritSect);
+    if (RT_SUCCESS(rc))
+    {
+        if (!pThis->cReads && !pThis->cWrites)
+        {
+            /*
+             * Make it invalid and unusable.
+             */
+            ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMRW_MAGIC);
+            pThis->cReads = UINT32_MAX;
+
+            /*
+             * Do actual cleanup. None of these can now fail.
+             */
+            rc = RTSemEventMultiDestroy(pThis->ReadEvent);
+            AssertMsgRC(rc, ("RTSemEventMultiDestroy failed! rc=%Rrc\n", rc));
+            pThis->ReadEvent = NIL_RTSEMEVENTMULTI;
+
+            rc = RTSemEventDestroy(pThis->WriteEvent);
+            AssertMsgRC(rc, ("RTSemEventDestroy failed! rc=%Rrc\n", rc));
+            pThis->WriteEvent = NIL_RTSEMEVENT;
+
+            RTCritSectLeave(&pThis->CritSect);
+            rc = RTCritSectDelete(&pThis->CritSect);
+            AssertMsgRC(rc, ("RTCritSectDelete failed! rc=%Rrc\n", rc));
+
+#ifdef RTSEMRW_STRICT
+            RTLockValidatorRecSharedDelete(&pThis->ValidatorRead);
+            RTLockValidatorRecExclDelete(&pThis->ValidatorWrite);
+#endif
+            RTMemFree(pThis);
+            rc = VINF_SUCCESS;
+        }
+        else
+        {
+            rc = VERR_SEM_BUSY;
+            RTCritSectLeave(&pThis->CritSect);
+        }
+    }
+    else
+    {
+        AssertMsgRC(rc, ("RTCritSectTryEnter failed! rc=%Rrc\n", rc));
+        rc = VERR_SEM_BUSY;
+    }
+
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTSemRWDestroy);
+
+
+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
+}
+RT_EXPORT_SYMBOL(RTSemRWSetSubClass);
+
+
+DECL_FORCE_INLINE(int) rtSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies, bool fInterruptible, PCRTLOCKVALSRCPOS pSrcPos)
+{
+    /*
+     * Validate handle.
+     */
+    struct RTSEMRWINTERNAL *pThis = hRWSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
+
+    RTMSINTERVAL    cMilliesInitial = cMillies;
+    uint64_t        tsStart = 0;
+    if (cMillies != RT_INDEFINITE_WAIT && cMillies != 0)
+        tsStart = RTTimeNanoTS();
+
+#ifdef RTSEMRW_STRICT
+    RTTHREAD hThreadSelf = RTThreadSelfAutoAdopt();
+    if (cMillies > 0)
+    {
+        int rc9;
+        if (pThis->hWriter != NIL_RTTHREAD && pThis->hWriter == RTThreadNativeSelf())
+            rc9 = RTLockValidatorRecExclCheckOrder(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, cMillies);
+        else
+            rc9 = RTLockValidatorRecSharedCheckOrder(&pThis->ValidatorRead, hThreadSelf, pSrcPos, cMillies);
+        if (RT_FAILURE(rc9))
+            return rc9;
+    }
+#endif
+
+    /*
+     * Take critsect.
+     */
+    int rc = RTCritSectEnter(&pThis->CritSect);
+    if (RT_FAILURE(rc))
+    {
+        AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
+        return rc;
+    }
+
+    /*
+     * Check if the state of affairs allows read access.
+     * Do not block further readers if there is a writer waiting, as
+     * that will break/deadlock reader recursion.
+     */
+    if (    pThis->hWriter == NIL_RTNATIVETHREAD
+#if 0
+        && (   !pThis->cWritesWaiting
+            ||  pThis->cReads)
+#endif
+       )
+    {
+        pThis->cReads++;
+        Assert(pThis->cReads > 0);
+#ifdef RTSEMRW_STRICT
+        RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
+#endif
+
+        RTCritSectLeave(&pThis->CritSect);
+        return VINF_SUCCESS;
+    }
+
+    RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
+    if (pThis->hWriter == hNativeSelf)
+    {
+#ifdef RTSEMRW_STRICT
+        int rc9 = RTLockValidatorRecExclRecursionMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core, pSrcPos);
+        if (RT_FAILURE(rc9))
+        {
+            RTCritSectLeave(&pThis->CritSect);
+            return rc9;
+        }
+#endif
+
+        pThis->cWriterReads++;
+        Assert(pThis->cWriterReads > 0);
+
+        RTCritSectLeave(&pThis->CritSect);
+        return VINF_SUCCESS;
+    }
+
+    RTCritSectLeave(&pThis->CritSect);
+
+    /*
+     * Wait till it's ready for reading.
+     */
+    if (cMillies == 0)
+        return VERR_TIMEOUT;
+
+#ifndef RTSEMRW_STRICT
+    RTTHREAD hThreadSelf = RTThreadSelf();
+#endif
+    for (;;)
+    {
+        if (cMillies != RT_INDEFINITE_WAIT)
+        {
+            int64_t tsDelta = RTTimeNanoTS() - tsStart;
+            if (tsDelta >= 1000000)
+            {
+                tsDelta /= 1000000;
+                if ((uint64_t)tsDelta < cMilliesInitial)
+                    cMilliesInitial = (RTMSINTERVAL)tsDelta;
+                else
+                    cMilliesInitial = 1;
+            }
+        }
+#ifdef RTSEMRW_STRICT
+        rc = RTLockValidatorRecSharedCheckBlocking(&pThis->ValidatorRead, hThreadSelf, pSrcPos, true,
+                                                   cMillies, RTTHREADSTATE_RW_READ, false);
+        if (RT_FAILURE(rc))
+            break;
+#else
+        RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_READ, false);
+        RT_NOREF_PV(pSrcPos);
+#endif
+        int rcWait;
+        if (fInterruptible)
+            rcWait = rc = RTSemEventMultiWaitNoResume(pThis->ReadEvent, cMillies);
+        else
+            rcWait = rc = RTSemEventMultiWait(pThis->ReadEvent, cMillies);
+        RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_READ);
+        if (RT_FAILURE(rc) && rc != VERR_TIMEOUT) /* handle timeout below */
+        {
+            AssertMsgRC(rc, ("RTSemEventMultiWait failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
+            break;
+        }
+
+        if (pThis->u32Magic != RTSEMRW_MAGIC)
+        {
+            rc = VERR_SEM_DESTROYED;
+            break;
+        }
+
+        /*
+         * Re-take critsect and repeat the check we did before the loop.
+         */
+        rc = RTCritSectEnter(&pThis->CritSect);
+        if (RT_FAILURE(rc))
+        {
+            AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
+            break;
+        }
+
+        if (    pThis->hWriter == NIL_RTNATIVETHREAD
+#if 0
+            && (   !pThis->cWritesWaiting
+                ||  pThis->cReads)
+#endif
+           )
+        {
+            pThis->cReads++;
+            Assert(pThis->cReads > 0);
+#ifdef RTSEMRW_STRICT
+            RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
+#endif
+
+            RTCritSectLeave(&pThis->CritSect);
+            return VINF_SUCCESS;
+        }
+
+        RTCritSectLeave(&pThis->CritSect);
+
+        /*
+         * Quit if the wait already timed out.
+         */
+        if (rcWait == VERR_TIMEOUT)
+        {
+            rc = VERR_TIMEOUT;
+            break;
+        }
+    }
+
+    /* failed */
+    return rc;
+}
+
+
+RTDECL(int) RTSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
+{
+#ifndef RTSEMRW_STRICT
+    return rtSemRWRequestRead(hRWSem, cMillies, false, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtSemRWRequestRead(hRWSem, cMillies, false, &SrcPos);
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemRWRequestRead);
+
+
+RTDECL(int) RTSemRWRequestReadDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtSemRWRequestRead(hRWSem, cMillies, false, &SrcPos);
+}
+RT_EXPORT_SYMBOL(RTSemRWRequestReadDebug);
+
+
+RTDECL(int) RTSemRWRequestReadNoResume(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
+{
+#ifndef RTSEMRW_STRICT
+    return rtSemRWRequestRead(hRWSem, cMillies, true, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtSemRWRequestRead(hRWSem, cMillies, true, &SrcPos);
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemRWRequestReadNoResume);
+
+
+RTDECL(int) RTSemRWRequestReadNoResumeDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtSemRWRequestRead(hRWSem, cMillies, true, &SrcPos);
+}
+RT_EXPORT_SYMBOL(RTSemRWRequestReadNoResumeDebug);
+
+
+RTDECL(int) RTSemRWReleaseRead(RTSEMRW hRWSem)
+{
+    struct RTSEMRWINTERNAL *pThis = hRWSem;
+
+    /*
+     * Validate handle.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
+
+    /*
+     * Take critsect.
+     */
+    int rc = RTCritSectEnter(&pThis->CritSect);
+    if (RT_SUCCESS(rc))
+    {
+        if (pThis->hWriter == NIL_RTNATIVETHREAD)
+        {
+#ifdef RTSEMRW_STRICT
+            rc = RTLockValidatorRecSharedCheckAndRelease(&pThis->ValidatorRead, NIL_RTTHREAD);
+            if (RT_SUCCESS(rc))
+#endif
+            {
+                if (RT_LIKELY(pThis->cReads > 0))
+                {
+                    pThis->cReads--;
+
+                    /* Kick off a writer if appropriate. */
+                    if (    pThis->cWritesWaiting > 0
+                        &&  !pThis->cReads)
+                    {
+                        rc = RTSemEventSignal(pThis->WriteEvent);
+                        AssertMsgRC(rc, ("Failed to signal writers on rwsem %p, rc=%Rrc\n", hRWSem, rc));
+                    }
+                }
+                else
+                {
+                    AssertFailed();
+                    rc = VERR_NOT_OWNER;
+                }
+            }
+        }
+        else
+        {
+            RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
+            if (pThis->hWriter == hNativeSelf)
+            {
+                if (pThis->cWriterReads > 0)
+                {
+#ifdef RTSEMRW_STRICT
+                    rc = RTLockValidatorRecExclUnwindMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core);
+                    if (RT_SUCCESS(rc))
+#endif
+                    {
+                        pThis->cWriterReads--;
+                    }
+                }
+                else
+                {
+                    AssertFailed();
+                    rc = VERR_NOT_OWNER;
+                }
+            }
+            else
+            {
+                AssertFailed();
+                rc = VERR_NOT_OWNER;
+            }
+        }
+
+        RTCritSectLeave(&pThis->CritSect);
+    }
+    else
+        AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
+
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTSemRWReleaseRead);
+
+
+DECL_FORCE_INLINE(int) rtSemRWRequestWrite(RTSEMRW hRWSem, RTMSINTERVAL cMillies, bool fInterruptible, PCRTLOCKVALSRCPOS pSrcPos)
+{
+    /*
+     * Validate handle.
+     */
+    struct RTSEMRWINTERNAL *pThis   = hRWSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
+
+    RTMSINTERVAL    cMilliesInitial = cMillies;
+    uint64_t        tsStart         = 0;
+    if (cMillies != RT_INDEFINITE_WAIT && cMillies != 0)
+        tsStart = RTTimeNanoTS();
+
+#ifdef RTSEMRW_STRICT
+    RTTHREAD hThreadSelf = NIL_RTTHREAD;
+    if (cMillies)
+    {
+        hThreadSelf = RTThreadSelfAutoAdopt();
+        int rc9 = RTLockValidatorRecExclCheckOrder(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, cMillies);
+        if (RT_FAILURE(rc9))
+            return rc9;
+    }
+#endif
+
+    /*
+     * Take critsect.
+     */
+    int rc = RTCritSectEnter(&pThis->CritSect);
+    if (RT_FAILURE(rc))
+    {
+        AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
+        return rc;
+    }
+
+    /*
+     * Check if the state of affairs allows write access.
+     */
+    RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
+    if (    !pThis->cReads
+        &&  (   (   !pThis->cWrites
+                 && (   !pThis->cWritesWaiting /* play fair if we can wait */
+                     || !cMillies)
+                )
+             || pThis->hWriter == hNativeSelf
+            )
+       )
+    {
+        /*
+         * Reset the reader event semaphore if necessary.
+         */
+        if (pThis->fNeedResetReadEvent)
+        {
+            pThis->fNeedResetReadEvent = false;
+            rc = RTSemEventMultiReset(pThis->ReadEvent);
+            AssertMsgRC(rc, ("Failed to reset readers, rwsem %p, rc=%Rrc.\n", hRWSem, rc));
+        }
+
+        pThis->cWrites++;
+        pThis->hWriter = hNativeSelf;
+#ifdef RTSEMRW_STRICT
+        RTLockValidatorRecExclSetOwner(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, pThis->cWrites == 1);
+#endif
+        RTCritSectLeave(&pThis->CritSect);
+        return VINF_SUCCESS;
+    }
+
+    /*
+     * Signal writer presence.
+     */
+    if (cMillies != 0)
+        pThis->cWritesWaiting++;
+
+    RTCritSectLeave(&pThis->CritSect);
+
+    /*
+     * Wait till it's ready for writing.
+     */
+    if (cMillies == 0)
+        return VERR_TIMEOUT;
+
+#ifndef RTSEMRW_STRICT
+    RTTHREAD hThreadSelf = RTThreadSelf();
+#endif
+    for (;;)
+    {
+        if (cMillies != RT_INDEFINITE_WAIT)
+        {
+            int64_t tsDelta = RTTimeNanoTS() - tsStart;
+            if (tsDelta >= 1000000)
+            {
+                tsDelta /= 1000000;
+                if ((uint64_t)tsDelta < cMilliesInitial)
+                    cMilliesInitial = (RTMSINTERVAL)tsDelta;
+                else
+                    cMilliesInitial = 1;
+            }
+        }
+
+#ifdef RTSEMRW_STRICT
+        rc = RTLockValidatorRecExclCheckBlocking(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, true,
+                                                 cMillies, RTTHREADSTATE_RW_WRITE, false);
+        if (RT_FAILURE(rc))
+            break;
+#else
+        RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_WRITE, false);
+        RT_NOREF_PV(pSrcPos);
+#endif
+        int rcWait;
+        if (fInterruptible)
+            rcWait = rc = RTSemEventWaitNoResume(pThis->WriteEvent, cMillies);
+        else
+            rcWait = rc = RTSemEventWait(pThis->WriteEvent, cMillies);
+        RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_WRITE);
+        if (RT_UNLIKELY(RT_FAILURE_NP(rc) && rc != VERR_TIMEOUT)) /* timeouts are handled below */
+        {
+            AssertMsgRC(rc, ("RTSemEventWait failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
+            break;
+        }
+
+        if (RT_UNLIKELY(pThis->u32Magic != RTSEMRW_MAGIC))
+        {
+            rc = VERR_SEM_DESTROYED;
+            break;
+        }
+
+        /*
+         * Re-take critsect and repeat the check we did prior to this loop.
+         */
+        rc = RTCritSectEnter(&pThis->CritSect);
+        if (RT_FAILURE(rc))
+        {
+            AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
+            break;
+        }
+
+        if (!pThis->cReads && (!pThis->cWrites || pThis->hWriter == hNativeSelf))
+        {
+            /*
+             * Reset the reader event semaphore if necessary.
+             */
+            if (pThis->fNeedResetReadEvent)
+            {
+                pThis->fNeedResetReadEvent = false;
+                rc = RTSemEventMultiReset(pThis->ReadEvent);
+                AssertMsgRC(rc, ("Failed to reset readers, rwsem %p, rc=%Rrc.\n", hRWSem, rc));
+            }
+
+            pThis->cWrites++;
+            pThis->hWriter = hNativeSelf;
+            pThis->cWritesWaiting--;
+#ifdef RTSEMRW_STRICT
+            RTLockValidatorRecExclSetOwner(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, true);
+#endif
+
+            RTCritSectLeave(&pThis->CritSect);
+            return VINF_SUCCESS;
+        }
+
+        RTCritSectLeave(&pThis->CritSect);
+
+        /*
+         * Quit if the wait already timed out.
+         */
+        if (rcWait == VERR_TIMEOUT)
+        {
+            rc = VERR_TIMEOUT;
+            break;
+        }
+    }
+
+    /*
+     * Timeout/error case, clean up.
+     */
+    if (pThis->u32Magic == RTSEMRW_MAGIC)
+    {
+        RTCritSectEnter(&pThis->CritSect);
+        /* Adjust this counter, whether we got the critsect or not. */
+        pThis->cWritesWaiting--;
+        RTCritSectLeave(&pThis->CritSect);
+    }
+    return rc;
+}
+
+
+RTDECL(int) RTSemRWRequestWrite(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
+{
+#ifndef RTSEMRW_STRICT
+    return rtSemRWRequestWrite(hRWSem, cMillies, false, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtSemRWRequestWrite(hRWSem, cMillies, false, &SrcPos);
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemRWRequestWrite);
+
+
+RTDECL(int) RTSemRWRequestWriteDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtSemRWRequestWrite(hRWSem, cMillies, false, &SrcPos);
+}
+RT_EXPORT_SYMBOL(RTSemRWRequestWriteDebug);
+
+
+RTDECL(int) RTSemRWRequestWriteNoResume(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
+{
+#ifndef RTSEMRW_STRICT
+    return rtSemRWRequestWrite(hRWSem, cMillies, true, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtSemRWRequestWrite(hRWSem, cMillies, true, &SrcPos);
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemRWRequestWriteNoResume);
+
+
+RTDECL(int) RTSemRWRequestWriteNoResumeDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtSemRWRequestWrite(hRWSem, cMillies, true, &SrcPos);
+}
+RT_EXPORT_SYMBOL(RTSemRWRequestWriteNoResumeDebug);
+
+
+RTDECL(int) RTSemRWReleaseWrite(RTSEMRW hRWSem)
+{
+
+    /*
+     * Validate handle.
+     */
+    struct RTSEMRWINTERNAL *pThis = hRWSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
+
+    /*
+     * Take critsect.
+     */
+    int rc = RTCritSectEnter(&pThis->CritSect);
+    AssertRCReturn(rc, rc);
+
+    /*
+     * Check if owner.
+     */
+    RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
+    if (pThis->hWriter != hNativeSelf)
+    {
+        RTCritSectLeave(&pThis->CritSect);
+        AssertMsgFailed(("Not read-write owner of rwsem %p.\n", hRWSem));
+        return VERR_NOT_OWNER;
+    }
+
+#ifdef RTSEMRW_STRICT
+    if (pThis->cWrites > 1 || !pThis->cWriterReads) /* don't check+release if VERR_WRONG_ORDER */
+    {
+        int rc9 = RTLockValidatorRecExclReleaseOwner(&pThis->ValidatorWrite, pThis->cWrites == 1);
+        if (RT_FAILURE(rc9))
+        {
+            RTCritSectLeave(&pThis->CritSect);
+            return rc9;
+        }
+    }
+#endif
+
+    /*
+     * Release ownership and remove ourselves from the writers count.
+     */
+    Assert(pThis->cWrites > 0);
+    pThis->cWrites--;
+    if (!pThis->cWrites)
+    {
+        if (RT_UNLIKELY(pThis->cWriterReads > 0))
+        {
+            pThis->cWrites++;
+            RTCritSectLeave(&pThis->CritSect);
+            AssertMsgFailed(("All recursive read locks need to be released prior to the final write lock! (%p)n\n", pThis));
+            return VERR_WRONG_ORDER;
+        }
+
+        pThis->hWriter = NIL_RTNATIVETHREAD;
+    }
+
+    /*
+     * Release the readers if no more writers waiting, otherwise the writers.
+     */
+    if (!pThis->cWritesWaiting)
+    {
+        rc = RTSemEventMultiSignal(pThis->ReadEvent);
+        AssertMsgRC(rc, ("RTSemEventMultiSignal failed for rwsem %p, rc=%Rrc.\n", hRWSem, rc));
+        pThis->fNeedResetReadEvent = true;
+    }
+    else
+    {
+        rc = RTSemEventSignal(pThis->WriteEvent);
+        AssertMsgRC(rc, ("Failed to signal writers on rwsem %p, rc=%Rrc\n", hRWSem, rc));
+    }
+    RTCritSectLeave(&pThis->CritSect);
+
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTSemRWReleaseWrite);
+
+
+RTDECL(bool) RTSemRWIsWriteOwner(RTSEMRW hRWSem)
+{
+    /*
+     * Validate handle.
+     */
+    struct RTSEMRWINTERNAL *pThis = hRWSem;
+    AssertPtrReturn(pThis, false);
+    AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, false);
+
+    /*
+     * Check ownership.
+     */
+    RTNATIVETHREAD hNativeSelf = RTThreadNativeSelf();
+    RTNATIVETHREAD hWriter;
+    ASMAtomicUoReadHandle(&pThis->hWriter, &hWriter);
+    return hWriter == hNativeSelf;
+}
+RT_EXPORT_SYMBOL(RTSemRWIsWriteOwner);
+
+
+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.
+     */
+    RTNATIVETHREAD hNativeSelf = RTThreadNativeSelf();
+    RTNATIVETHREAD hWriter;
+    ASMAtomicUoReadHandle(&pThis->hWriter, &hWriter);
+    if (hWriter == hNativeSelf)
+        return true;
+    if (hWriter != NIL_RTNATIVETHREAD)
+        return false;
+
+#ifdef RTSEMRW_STRICT
+    /*
+     * Ask the lock validator.
+     */
+    NOREF(fWannaHear);
+    return RTLockValidatorRecSharedIsOwner(&pThis->ValidatorRead, NIL_RTTHREAD);
+#else
+    /*
+     * If there are no reads we cannot be one of them... But if there are we
+     * cannot know and can only return what the caller want to hear.
+     */
+    if (pThis->cReads == 0)
+        return false;
+    return fWannaHear;
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemRWIsReadOwner);
+
+
+RTDECL(uint32_t) RTSemRWGetWriteRecursion(RTSEMRW hRWSem)
+{
+    struct RTSEMRWINTERNAL *pThis = hRWSem;
+
+    /*
+     * Validate handle.
+     */
+    AssertPtrReturn(pThis, 0);
+    AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, 0);
+
+    /*
+     * Return the requested data.
+     */
+    return pThis->cWrites;
+}
+RT_EXPORT_SYMBOL(RTSemRWGetWriteRecursion);
+
+
+RTDECL(uint32_t) RTSemRWGetWriterReadRecursion(RTSEMRW hRWSem)
+{
+    struct RTSEMRWINTERNAL *pThis = hRWSem;
+
+    /*
+     * Validate handle.
+     */
+    AssertPtrReturn(pThis, 0);
+    AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, 0);
+
+    /*
+     * Return the requested data.
+     */
+    return pThis->cWriterReads;
+}
+RT_EXPORT_SYMBOL(RTSemRWGetWriterReadRecursion);
+
+
+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->cReads;
+}
+RT_EXPORT_SYMBOL(RTSemRWGetReadCount);
+