Adding upstream version 7.0.6-dfsg.upstream/7.0.6-dfsgupstream

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

1 files changed, 1450 insertions, 0 deletions

diff --git a/include/iprt/semaphore.h b/include/iprt/semaphore.h
new file mode 100644
index 00000000..6d3e5f6a
--- /dev/null
+++ b/include/iprt/semaphore.h
@@ -0,0 +1,1450 @@
+/** @file
+ * IPRT - Semaphore.
+ */
+
+/*
+ * Copyright (C) 2006-2022 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 <https://www.gnu.org/licenses>.
+ *
+ * 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
+ */
+
+#ifndef IPRT_INCLUDED_semaphore_h
+#define IPRT_INCLUDED_semaphore_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/cdefs.h>
+#include <iprt/types.h>
+#if defined(RT_LOCK_STRICT_ORDER) && defined(IN_RING3)
+# include <iprt/lockvalidator.h>
+#endif
+
+
+RT_C_DECLS_BEGIN
+
+/** @defgroup grp_rt_sems    RTSem - Semaphores
+ *
+ * This module implements all kinds of event and mutex semaphores; in addition
+ * to these, IPRT implements "critical sections", which are fast recursive
+ * mutexes (see @ref grp_rt_critsect ).  C++ users may find @ref grp_rt_cpp_lock
+ * interesting.
+ *
+ * @ingroup grp_rt
+ * @{
+ */
+
+
+/** @name Generic Semaphore Wait Flags.
+ *
+ * @remarks Exactly one of RTSEMWAIT_FLAGS_RELATIVE and
+ *          RTSEMWAIT_FLAGS_ABSOLUTE must be set, unless
+ *          RTSEMWAIT_FLAGS_INDEFINITE is used.
+ *
+ *          Exactly one of RTSEMWAIT_FLAGS_NANOSECS and
+ *          RTSEMWAIT_FLAGS_MILLISECS must be set, unless
+ *          RTSEMWAIT_FLAGS_INDEFINITE is used.
+ *
+ *          Exactly one of RTSEMWAIT_FLAGS_RESUME and RTSEMWAIT_FLAGS_NORESUME
+ *          must be set.
+ *
+ *          The interruptible vs resume stuff is ring-0 vs ring-3 semantics.
+ *
+ * @{ */
+/** The timeout is relative. */
+#define RTSEMWAIT_FLAGS_RELATIVE            RT_BIT_32(0)
+/** The timeout is absolute. */
+#define RTSEMWAIT_FLAGS_ABSOLUTE            RT_BIT_32(1)
+/** The timeout is specified in nanoseconds. */
+#define RTSEMWAIT_FLAGS_NANOSECS            RT_BIT_32(2)
+/** The timeout is specified in milliseconds. */
+#define RTSEMWAIT_FLAGS_MILLISECS           RT_BIT_32(3)
+/** Indefinite wait.
+ * The relative/absolute and nano-/millisecond flags are ignored. */
+#define RTSEMWAIT_FLAGS_INDEFINITE          RT_BIT_32(4)
+/** Mask covering the time related bits. */
+#define RTSEMWAIT_FLAGS_TIME_MASK           UINT32_C(0x0000001f)
+
+/** Interruptible wait. */
+#define RTSEMWAIT_FLAGS_INTERRUPTIBLE       RT_BIT_32(5)
+/** No automatic resume, same as interruptible. */
+#define RTSEMWAIT_FLAGS_NORESUME            RTSEMWAIT_FLAGS_INTERRUPTIBLE
+/** Uninterruptible wait. */
+#define RTSEMWAIT_FLAGS_UNINTERRUPTIBLE     RT_BIT_32(6)
+/** Resume on interrupt, same as uninterruptible. */
+#define RTSEMWAIT_FLAGS_RESUME              RTSEMWAIT_FLAGS_UNINTERRUPTIBLE
+
+/** Macro for validate the flags. */
+#define RTSEMWAIT_FLAGS_ARE_VALID(fFlags) \
+    (   !((fFlags) & UINT32_C(0xffffff80)) \
+     &&  (  ((fFlags) & RTSEMWAIT_FLAGS_INDEFINITE) \
+          ? ( (((fFlags) & UINT32_C(0x20))) ^ (((fFlags) >> 1) & UINT32_C(0x20)) ) == UINT32_C(0x20) \
+          : ( (((fFlags) & UINT32_C(0x25))) ^ (((fFlags) >> 1) & UINT32_C(0x25)) ) == UINT32_C(0x25) ))
+/** @}  */
+
+
+
+/** @defgroup grp_rt_sems_event    RTSemEvent - Single Release Event Semaphores
+ *
+ * Event semaphores can be used for inter-thread communication when one thread
+ * wants to notify another thread that something happened.  A thread can block
+ * ("wait") on an event semaphore until it is signalled by another thread; see
+ * RTSemEventCreate, RTSemEventSignal and RTSemEventWait.
+ *
+ * @{ */
+
+/**
+ * Create an event semaphore.
+ *
+ * @returns iprt status code.
+ * @param   phEventSem          Where to store the handle to the newly created
+ *                              event semaphore.
+ */
+RTDECL(int)  RTSemEventCreate(PRTSEMEVENT phEventSem);
+
+/**
+ * Create an event semaphore.
+ *
+ * @returns iprt status code.
+ * @param   phEventSem          Where to store the handle to the newly created
+ *                              event semaphore.
+ * @param   fFlags              Flags, any combination of the
+ *                              RTSEMEVENT_FLAGS_XXX \#defines.
+ * @param   hClass              The class (no reference consumed).  Since we
+ *                              don't do order checks on event semaphores, the
+ *                              use of the class is limited to controlling the
+ *                              timeout threshold for deadlock detection.
+ * @param   pszNameFmt          Name format string for the lock validator,
+ *                              optional (NULL).  Max length is 32 bytes.
+ * @param   ...                 Format string arguments.
+ */
+RTDECL(int)  RTSemEventCreateEx(PRTSEMEVENT phEventSem, uint32_t fFlags, RTLOCKVALCLASS hClass,
+                                const char *pszNameFmt, ...) RT_IPRT_FORMAT_ATTR_MAYBE_NULL(4, 5);
+
+/** @name RTSemMutexCreateEx flags
+ * @{ */
+/** Disables lock validation. */
+#define RTSEMEVENT_FLAGS_NO_LOCK_VAL    UINT32_C(0x00000001)
+/** Bootstrap hack for use with certain memory allocator locks only! */
+#define RTSEMEVENT_FLAGS_BOOTSTRAP_HACK UINT32_C(0x00000004)
+/** @} */
+
+/**
+ * Destroy an event semaphore.
+ *
+ * @returns iprt status code.
+ * @param   hEventSem           Handle of the event semaphore.  NIL_RTSEMEVENT
+ *                              is quietly ignored (VINF_SUCCESS).
+ */
+RTDECL(int)  RTSemEventDestroy(RTSEMEVENT hEventSem);
+
+/**
+ * Signal an event semaphore.
+ *
+ * The event semaphore will be signaled and automatically reset after exactly
+ * one thread have successfully returned from RTSemEventWait() after
+ * waiting/polling on that semaphore.
+ *
+ * @returns iprt status code.
+ * @param   hEventSem           The event semaphore to signal.
+ *
+ * @remarks ring-0: This works when preemption is disabled.  However it is
+ *          system specific whether it works in interrupt context or with
+ *          interrupts disabled.
+ *
+ *          ring-0/Darwin: This works when interrupts are disabled and thereby
+ *          in interrupt context, except it cannot race semaphore destruction as
+ *          the allocator does not work under these circumstances.
+ */
+RTDECL(int)  RTSemEventSignal(RTSEMEVENT hEventSem);
+
+/**
+ * Whether RTSemEventSignal can be safely called w/o risk of preemption.
+ *
+ * Checks whether the caller can safely signal a single release semaphore
+ * without any risk of getting preempted on locks or similar while doing so.
+ * This also checks whether the context is suitable in general.
+ *
+ * @returns true if safe, false if not.
+ * @remarks Only ring-0.
+ */
+RTR0DECL(bool) RTSemEventIsSignalSafe(void);
+
+/**
+ * Wait for the event semaphore to be signaled, resume on interruption.
+ *
+ * This function will resume if the wait is interrupted by an async system event
+ * (like a unix signal) or similar.
+ *
+ * @returns iprt status code.
+ *          Will not return VERR_INTERRUPTED.
+ * @param   hEventSem           The event semaphore to wait on.
+ * @param   cMillies            Number of milliseconds to wait.
+ */
+RTDECL(int)  RTSemEventWait(RTSEMEVENT hEventSem, RTMSINTERVAL cMillies);
+
+/**
+ * Wait for the event semaphore to be signaled, return on interruption.
+ *
+ * This function will not resume the wait if interrupted.
+ *
+ * @returns iprt status code.
+ * @param   hEventSem           The event semaphore to wait on.
+ * @param   cMillies            Number of milliseconds to wait.
+ */
+RTDECL(int)  RTSemEventWaitNoResume(RTSEMEVENT hEventSem, RTMSINTERVAL cMillies);
+
+/**
+ * Extended API for waiting on an event semaphore to be signaled.
+ *
+ * @returns IPRT status code.
+ * @param   hEventSem           The event semaphore to wait on.
+ * @param   fFlags              Combination of RTSEMWAIT_FLAGS_XXX.
+ * @param   uTimeout            The timeout, ignored if
+ *                              RTSEMWAIT_FLAGS_INDEFINITE is set in @a flags.
+ *                              Whether this is absolute or relative,
+ *                              milliseconds or nanoseconds depends on the @a
+ *                              fFlags value.  Do not pass RT_INDEFINITE_WAIT
+ *                              here, use RTSEMWAIT_FLAGS_INDEFINITE instead.
+ */
+RTDECL(int)  RTSemEventWaitEx(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout);
+
+/**
+ * Debug version of RTSemEventWaitEx that tracks the location.
+ *
+ * @returns IPRT status code, see RTSemEventWaitEx.
+ * @param   hEventSem           The event semaphore to wait on.
+ * @param   fFlags              See RTSemEventWaitEx.
+ * @param   uTimeout            See RTSemEventWaitEx.
+ * @param   uId                 Some kind of locking location ID.  Typically a
+ *                              return address up the stack.  Optional (0).
+ * @param   SRC_POS             The source position where call is being made
+ *                              from.  Use RT_SRC_POS when possible.  Optional.
+ */
+RTDECL(int)  RTSemEventWaitExDebug(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout,
+                                   RTHCUINTPTR uId, RT_SRC_POS_DECL);
+
+/**
+ * Gets the best timeout resolution that RTSemEventWaitEx can do.
+ *
+ * @returns The resolution in nanoseconds.
+ */
+RTDECL(uint32_t) RTSemEventGetResolution(void);
+
+/**
+ * Sets the signaller thread to one specific thread.
+ *
+ * This is only used for validating usage and deadlock detection.  When used
+ * after calls to RTSemEventAddSignaller, the specified thread will be the only
+ * signalling thread.
+ *
+ * @param   hEventSem           The event semaphore.
+ * @param   hThread             The thread that will signal it.  Pass
+ *                              NIL_RTTHREAD to indicate that there is no
+ *                              special signalling thread.
+ */
+RTDECL(void) RTSemEventSetSignaller(RTSEMEVENT hEventSem, RTTHREAD hThread);
+
+/**
+ * To add more signalling threads.
+ *
+ * First call RTSemEventSetSignaller then add further threads with this.
+ *
+ * @param   hEventSem           The event semaphore.
+ * @param   hThread             The thread that will signal it. NIL_RTTHREAD is
+ *                              not accepted.
+ */
+RTDECL(void) RTSemEventAddSignaller(RTSEMEVENT hEventSem, RTTHREAD hThread);
+
+/**
+ * To remove a signalling thread.
+ *
+ * Reverts work done by RTSemEventAddSignaller and RTSemEventSetSignaller.
+ *
+ * @param   hEventSem           The event semaphore.
+ * @param   hThread             A previously added thread.
+ */
+RTDECL(void) RTSemEventRemoveSignaller(RTSEMEVENT hEventSem, RTTHREAD hThread);
+
+/** @} */
+
+
+/** @defgroup grp_rt_sems_event_multi   RTSemEventMulti - Multiple Release Event Semaphores
+ *
+ * A variant of @ref  grp_rt_sems_event where all threads will be unblocked when
+ * signalling the semaphore.
+ *
+ * @{ */
+
+/**
+ * Creates a multiple release event semaphore.
+ *
+ * @returns iprt status code.
+ * @param   phEventMultiSem     Where to store the handle to the newly created
+ *                              multiple release event semaphore.
+ */
+RTDECL(int)  RTSemEventMultiCreate(PRTSEMEVENTMULTI phEventMultiSem);
+
+/**
+ * Creates a multiple release event semaphore.
+ *
+ * @returns iprt status code.
+ * @param   phEventMultiSem     Where to store the handle to the newly created
+ *                              multiple release event semaphore.
+ * @param   fFlags              Flags, any combination of the
+ *                              RTSEMEVENTMULTI_FLAGS_XXX \#defines.
+ * @param   hClass              The class (no reference consumed).  Since we
+ *                              don't do order checks on event semaphores, the
+ *                              use of the class is limited to controlling the
+ *                              timeout threshold for deadlock detection.
+ * @param   pszNameFmt          Name format string for the lock validator,
+ *                              optional (NULL).  Max length is 32 bytes.
+ * @param   ...                 Format string arguments.
+ */
+RTDECL(int)  RTSemEventMultiCreateEx(PRTSEMEVENTMULTI phEventMultiSem, uint32_t fFlags, RTLOCKVALCLASS hClass,
+                                     const char *pszNameFmt, ...) RT_IPRT_FORMAT_ATTR_MAYBE_NULL(4, 5);
+
+/** @name RTSemMutexCreateEx flags
+ * @{ */
+/** Disables lock validation. */
+#define RTSEMEVENTMULTI_FLAGS_NO_LOCK_VAL   UINT32_C(0x00000001)
+/** @} */
+
+/**
+ * Destroy an event multi semaphore.
+ *
+ * @returns iprt status code.
+ * @param   hEventMultiSem      The multiple release event semaphore.  NIL is
+ *                              quietly ignored (VINF_SUCCESS).
+ */
+RTDECL(int)  RTSemEventMultiDestroy(RTSEMEVENTMULTI hEventMultiSem);
+
+/**
+ * Signal an event multi semaphore.
+ *
+ * @returns iprt status code.
+ * @param   hEventMultiSem      The multiple release event semaphore.
+ *
+ * @remarks ring-0: This works when preemption is disabled.  However it is
+ *          system specific whether it works in interrupt context or with
+ *          interrupts disabled.
+ *
+ *          ring-0/Darwin: This works when interrupts are disabled and thereby
+ *          in interrupt context, except it cannot race semaphore destruction as
+ *          the allocator does not work under these circumstances.
+ */
+RTDECL(int)  RTSemEventMultiSignal(RTSEMEVENTMULTI hEventMultiSem);
+
+/**
+ * Whether RTSemEventMultiSignal can be safely called w/o risk of preemption.
+ *
+ * Checks whether the caller can safely signal a multiple release semaphore
+ * without any risk of getting preempted on locks or similar while doing so.
+ * This also checks whether the context is suitable in general.
+ *
+ * @returns true if safe, false if not.
+ * @remarks Only ring-0.
+ */
+RTR0DECL(bool) RTSemEventMultiIsSignalSafe(void);
+
+/**
+ * Resets an event multi semaphore to non-signaled state.
+ *
+ * @returns iprt status code.
+ * @param   hEventMultiSem      The multiple release event semaphore.
+ */
+RTDECL(int)  RTSemEventMultiReset(RTSEMEVENTMULTI hEventMultiSem);
+
+/**
+ * Wait for the event multi semaphore to be signaled, resume on interruption.
+ *
+ * This function will resume if the wait is interrupted by an async
+ * system event (like a unix signal) or similar.
+ *
+ * @returns iprt status code.
+ *          Will not return VERR_INTERRUPTED.
+ * @param   hEventMultiSem      The multiple release event semaphore.
+ * @param   cMillies            Number of milliseconds to wait.
+ */
+RTDECL(int)  RTSemEventMultiWait(RTSEMEVENTMULTI hEventMultiSem, RTMSINTERVAL cMillies);
+
+/**
+ * Wait for the event multi semaphore to be signaled, return on interruption.
+ *
+ * This function will not resume the wait if interrupted.
+ *
+ * @returns iprt status code.
+ * @param   hEventMultiSem      The multiple release event semaphore.
+ * @param   cMillies            Number of milliseconds to wait.
+ * @todo    Rename to RTSemEventMultiWaitIntr since it is mainly for
+ *          ring-0 consumption.
+ */
+RTDECL(int)  RTSemEventMultiWaitNoResume(RTSEMEVENTMULTI hEventMultiSem, RTMSINTERVAL cMillies);
+
+/**
+ * Extended API for waiting on an event semaphore to be signaled.
+ *
+ * @returns IPRT status code.
+ * @param   hEventMultiSem      The multiple release event semaphore to wait
+ *                              on.
+ * @param   fFlags              Combination of the RTSEMWAIT_FLAGS_XXX.
+ * @param   uTimeout            The timeout, ignored if
+ *                              RTSEMWAIT_FLAGS_INDEFINITE is set in @a flags.
+ *                              Whether this is absolute or relative,
+ *                              milliseconds or nanoseconds depends on the @a
+ *                              fFlags value.  Do not pass RT_INDEFINITE_WAIT
+ *                              here, use RTSEMWAIT_FLAGS_INDEFINITE instead.
+ */
+RTDECL(int)  RTSemEventMultiWaitEx(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout);
+
+/**
+ * Debug version of RTSemEventMultiWaitEx that tracks the location.
+
+ * @returns IPRT status code, see RTSemEventMultiWaitEx.
+ * @param   hEventMultiSem      The multiple release event semaphore handle.
+ * @param   fFlags              See RTSemEventMultiWaitEx.
+ * @param   uTimeout            See RTSemEventMultiWaitEx.
+ * @param   uId                 Some kind of locking location ID.  Typically a
+ *                              return address up the stack.  Optional (0).
+ * @param   SRC_POS             The source position where call is being made
+ *                              from.  Use RT_SRC_POS when possible.  Optional.
+ */
+RTDECL(int)  RTSemEventMultiWaitExDebug(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout,
+                                        RTHCUINTPTR uId, RT_SRC_POS_DECL);
+
+/**
+ * Gets the best timeout resolution that RTSemEventMultiWaitEx can do.
+ *
+ * @returns The resolution in nanoseconds.
+ */
+RTDECL(uint32_t) RTSemEventMultiGetResolution(void);
+
+/**
+ * Sets the signaller thread to one specific thread.
+ *
+ * This is only used for validating usage and deadlock detection.  When used
+ * after calls to RTSemEventAddSignaller, the specified thread will be the only
+ * signalling thread.
+ *
+ * @param   hEventMultiSem      The multiple release event semaphore.
+ * @param   hThread             The thread that will signal it.  Pass
+ *                              NIL_RTTHREAD to indicate that there is no
+ *                              special signalling thread.
+ */
+RTDECL(void) RTSemEventMultiSetSignaller(RTSEMEVENTMULTI hEventMultiSem, RTTHREAD hThread);
+
+/**
+ * To add more signalling threads.
+ *
+ * First call RTSemEventSetSignaller then add further threads with this.
+ *
+ * @param   hEventMultiSem      The multiple release event semaphore.
+ * @param   hThread             The thread that will signal it. NIL_RTTHREAD is
+ *                              not accepted.
+ */
+RTDECL(void) RTSemEventMultiAddSignaller(RTSEMEVENTMULTI hEventMultiSem, RTTHREAD hThread);
+
+/**
+ * To remove a signalling thread.
+ *
+ * Reverts work done by RTSemEventAddSignaller and RTSemEventSetSignaller.
+ *
+ * @param   hEventMultiSem      The multiple release event semaphore.
+ * @param   hThread             A previously added thread.
+ */
+RTDECL(void) RTSemEventMultiRemoveSignaller(RTSEMEVENTMULTI hEventMultiSem, RTTHREAD hThread);
+
+/** @} */
+
+
+/** @defgroup grp_rt_sems_mutex     RTSemMutex - Mutex semaphores.
+ *
+ * Mutex semaphores protect a section of code or data to which access must be
+ * exclusive.  Only one thread can hold access to a critical section at one
+ * time.  See RTSemMutexCreate, RTSemMutexRequest and RTSemMutexRelease.
+ *
+ * @remarks These are less efficient than "fast mutexes" and "critical
+ *          sections", which IPRT implements as well; see @ref
+ *          grp_rt_sems_fast_mutex and @ref grp_rt_critsect .
+ *
+ * @{ */
+
+/**
+ * Create a mutex semaphore.
+ *
+ * @returns iprt status code.
+ * @param   phMutexSem      Where to store the mutex semaphore handle.
+ */
+RTDECL(int)  RTSemMutexCreate(PRTSEMMUTEX phMutexSem);
+
+/**
+ * Creates a read/write semaphore.
+ *
+ * @returns iprt status code.
+ * @param   phMutexSem          Where to store the handle to the newly created
+ *                              mutex semaphore.
+ * @param   fFlags              Flags, any combination of the
+ *                              RTSEMMUTEX_FLAGS_XXX \#defines.
+ * @param   hClass              The class (no reference consumed).  If NIL, no
+ *                              lock order validation will be performed on this
+ *                              lock.
+ * @param   uSubClass           The sub-class.  This is used to define lock
+ *                              order within a class.  RTLOCKVAL_SUB_CLASS_NONE
+ *                              is the recommended value here.
+ * @param   pszNameFmt          Name format string for the lock validator,
+ *                              optional (NULL).  Max length is 32 bytes.
+ * @param   ...                 Format string arguments.
+ */
+RTDECL(int) RTSemMutexCreateEx(PRTSEMMUTEX phMutexSem, uint32_t fFlags, RTLOCKVALCLASS hClass, uint32_t uSubClass,
+                               const char *pszNameFmt, ...) RT_IPRT_FORMAT_ATTR_MAYBE_NULL(5, 6);
+
+/** @name RTSemMutexCreateEx flags
+ * @{ */
+/** Disables lock validation. */
+#define RTSEMMUTEX_FLAGS_NO_LOCK_VAL    UINT32_C(0x00000001)
+/** @} */
+
+
+/**
+ * Destroy a mutex semaphore.
+ *
+ * @returns iprt status code.
+ * @param   hMutexSem           The mutex semaphore to destroy.  NIL is quietly
+ *                              ignored (VINF_SUCCESS).
+ */
+RTDECL(int)  RTSemMutexDestroy(RTSEMMUTEX hMutexSem);
+
+/**
+ * Changes the lock validator sub-class of the mutex semaphore.
+ *
+ * It is recommended to try make sure that nobody is using this semaphore while
+ * changing the value.
+ *
+ * @returns The old sub-class.  RTLOCKVAL_SUB_CLASS_INVALID is returns if the
+ *          lock validator isn't compiled in or either of the parameters are
+ *          invalid.
+ * @param   hMutexSem           The handle to the mutex semaphore.
+ * @param   uSubClass           The new sub-class value.
+ */
+RTDECL(uint32_t) RTSemMutexSetSubClass(RTSEMMUTEX hMutexSem, uint32_t uSubClass);
+
+/**
+ * Request ownership of a mutex semaphore, resume on interruption.
+ *
+ * This function will resume if the wait is interrupted by an async
+ * system event (like a unix signal) or similar.
+ *
+ * The same thread may request a mutex semaphore multiple times,
+ * a nested counter is kept to make sure it's released on the right
+ * RTSemMutexRelease() call.
+ *
+ * @returns iprt status code.
+ *          Will not return VERR_INTERRUPTED.
+ * @param   hMutexSem           The mutex semaphore to request ownership over.
+ * @param   cMillies            The number of milliseconds to wait.
+ */
+RTDECL(int)  RTSemMutexRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies);
+
+/**
+ * Request ownership of a mutex semaphore, return on interruption.
+ *
+ * This function will not resume the wait if interrupted.
+ *
+ * The same thread may request a mutex semaphore multiple times,
+ * a nested counter is kept to make sure it's released on the right
+ * RTSemMutexRelease() call.
+ *
+ * @returns iprt status code.
+ * @param   hMutexSem           The mutex semaphore to request ownership over.
+ * @param   cMillies            The number of milliseconds to wait.
+ */
+RTDECL(int)  RTSemMutexRequestNoResume(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies);
+
+/**
+ * Debug version of RTSemMutexRequest that tracks the location.
+ *
+ * @returns iprt status code.
+ *          Will not return VERR_INTERRUPTED.
+ * @param   hMutexSem           The mutex semaphore to request ownership over.
+ * @param   cMillies            The number of milliseconds to wait.
+ * @param   uId                 Some kind of locking location ID.  Typically a
+ *                              return address up the stack.  Optional (0).
+ * @param   SRC_POS             The source position where call is being made
+ *                              from.  Use RT_SRC_POS when possible.  Optional.
+ */
+RTDECL(int)  RTSemMutexRequestDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL);
+
+/**
+ * Debug version of RTSemMutexRequestNoResume that tracks the location.
+ *
+ * @returns iprt status code.
+ * @param   hMutexSem           The mutex semaphore to request ownership over.
+ * @param   cMillies            The number of milliseconds to wait.
+ * @param   uId                 Some kind of locking location ID.  Typically a
+ *                              return address up the stack.  Optional (0).
+ * @param   SRC_POS             The source position where call is being made
+ *                              from.  Use RT_SRC_POS when possible.  Optional.
+ */
+RTDECL(int)  RTSemMutexRequestNoResumeDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL);
+
+/**
+ * Request ownership of a mutex semaphore, extended edition.
+ *
+ * The same thread may request a mutex semaphore multiple times,
+ * a nested counter is kept to make sure it's released on the right
+ * RTSemMutexRelease() call.
+ *
+ * @returns iprt status code.
+ * @param   hMutexSem           The mutex semaphore to request ownership over.
+ * @param   fFlags              Combination of the RTSEMWAIT_FLAGS_XXX.
+ * @param   uTimeout            The timeout, ignored if
+ *                              RTSEMWAIT_FLAGS_INDEFINITE is set in @a flags.
+ *                              Whether this is absolute or relative,
+ *                              milliseconds or nanoseconds depends on the @a
+ *                              fFlags value.  Do not pass RT_INDEFINITE_WAIT
+ *                              here, use RTSEMWAIT_FLAGS_INDEFINITE instead.
+ */
+RTDECL(int)  RTSemMutexRequestEx(RTSEMMUTEX hMutexSem, uint32_t fFlags, uint64_t uTimeout);
+
+/**
+ * Debug version of RTSemMutexRequestEx that tracks the location.
+ *
+ * @returns iprt status code.
+ * @param   hMutexSem           The mutex semaphore to request ownership over.
+ * @param   fFlags              See RTSemMutexRequestEx.
+ * @param   uTimeout            See RTSemMutexRequestEx.
+ * @param   uId                 Some kind of locking location ID.  Typically a
+ *                              return address up the stack.  Optional (0).
+ * @param   SRC_POS             The source position where call is being made
+ *                              from.  Use RT_SRC_POS when possible.  Optional.
+ */
+RTDECL(int)  RTSemMutexRequestExDebug(RTSEMMUTEX hMutexSem, uint32_t fFlags, uint64_t uTimeout,
+                                      RTHCUINTPTR uId, RT_SRC_POS_DECL);
+
+/**
+ * Release the ownership of a mutex semaphore.
+ *
+ * @returns iprt status code.
+ * @param   hMutexSem           The mutex to release the ownership of.  It goes
+ *                              without saying the the calling thread must own
+ *                              it.
+ */
+RTDECL(int)  RTSemMutexRelease(RTSEMMUTEX hMutexSem);
+
+/**
+ * Checks if the mutex semaphore is owned or not.
+ *
+ * @returns true if owned, false if not.
+ * @param   hMutexSem           The mutex semaphore.
+ */
+RTDECL(bool) RTSemMutexIsOwned(RTSEMMUTEX hMutexSem);
+
+/* Strict build: Remap the two request calls to the debug versions. */
+#if   defined(RT_STRICT) && !defined(RTSEMMUTEX_WITHOUT_REMAPPING) && !defined(RT_WITH_MANGLING)
+# ifdef IPRT_INCLUDED_asm_h
+#  define RTSemMutexRequest(hMutexSem, cMillies)            RTSemMutexRequestDebug((hMutexSem), (cMillies), (uintptr_t)ASMReturnAddress(), RT_SRC_POS)
+#  define RTSemMutexRequestNoResume(hMutexSem, cMillies)    RTSemMutexRequestNoResumeDebug((hMutexSem), (cMillies), (uintptr_t)ASMReturnAddress(), RT_SRC_POS)
+#  define RTSemMutexRequestEx(hMutexSem, fFlags, uTimeout)  RTSemMutexRequestExDebug((hMutexSem), (fFlags), (uTimeout), (uintptr_t)ASMReturnAddress(), RT_SRC_POS)
+# else
+#  define RTSemMutexRequest(hMutexSem, cMillies)            RTSemMutexRequestDebug((hMutexSem), (cMillies), 0, RT_SRC_POS)
+#  define RTSemMutexRequestNoResume(hMutexSem, cMillies)    RTSemMutexRequestNoResumeDebug((hMutexSem), (cMillies), 0, RT_SRC_POS)
+#  define RTSemMutexRequestEx(hMutexSem, fFlags, uTimeout)  RTSemMutexRequestExDebug((hMutexSem), (fFlags), (uTimeout), 0, RT_SRC_POS)
+# endif
+#endif
+
+/* Strict lock order: Automatically classify locks by init location. */
+#if   defined(RT_LOCK_STRICT_ORDER) && defined(IN_RING3) && !defined(RTSEMMUTEX_WITHOUT_REMAPPING) && !defined(RT_WITH_MANGLING)
+# define RTSemMutexCreate(phMutexSem) \
+    RTSemMutexCreateEx((phMutexSem), 0 /*fFlags*/, \
+                       RTLockValidatorClassForSrcPos(RT_SRC_POS, NULL), \
+                       RTLOCKVAL_SUB_CLASS_NONE, NULL)
+#endif
+
+/** @} */
+
+
+/** @defgroup grp_rt_sems_fast_mutex    RTSemFastMutex - Fast Mutex Semaphores
+ *
+ * Fast mutexes work like regular mutexes in that they allow only a single
+ * thread access to a critical piece of code or data.  As opposed to mutexes,
+ * they require no syscall if the fast mutex is not held (like critical
+ * sections).  Unlike critical sections however, they are *not* recursive.
+ *
+ * @remarks The fast mutexes has sideeffects on IRQL on Windows hosts.  So use
+ *          with care and test on windows with the driver verifier enabled.
+ *
+ * @{ */
+
+/**
+ * Create a fast mutex semaphore.
+ *
+ * @returns iprt status code.
+ * @param   phFastMtx           Where to store the handle to the newly created
+ *                              fast mutex semaphore.
+ *
+ * @remarks Fast mutex semaphores are not recursive.
+ */
+RTDECL(int)  RTSemFastMutexCreate(PRTSEMFASTMUTEX phFastMtx);
+
+/**
+ * Destroy a fast mutex semaphore.
+ *
+ * @returns iprt status code.
+ * @param   hFastMtx            Handle to the fast mutex semaphore.  NIL is
+ *                              quietly ignored (VINF_SUCCESS).
+ */
+RTDECL(int)  RTSemFastMutexDestroy(RTSEMFASTMUTEX hFastMtx);
+
+/**
+ * Request ownership of a fast mutex semaphore.
+ *
+ * @returns iprt status code.
+ * @param   hFastMtx            Handle to the fast mutex semaphore.
+ */
+RTDECL(int)  RTSemFastMutexRequest(RTSEMFASTMUTEX hFastMtx);
+
+/**
+ * Release the ownership of a fast mutex semaphore.
+ *
+ * @returns iprt status code.
+ * @param   hFastMtx            Handle to the fast mutex semaphore.  It goes
+ *                              without saying the the calling thread must own
+ *                              it.
+ */
+RTDECL(int)  RTSemFastMutexRelease(RTSEMFASTMUTEX hFastMtx);
+
+/** @} */
+
+
+/** @defgroup grp_rt_sems_spin_mutex RTSemSpinMutex - Spinning Mutex Semaphores
+ *
+ * A very adaptive variant of mutex semaphore that is tailored for the ring-0
+ * logger.
+ *
+ * @{ */
+
+/**
+ * Creates a spinning mutex semaphore.
+ *
+ * @returns iprt status code.
+ * @retval  VERR_INVALID_PARAMETER on invalid flags.
+ * @retval  VERR_NO_MEMORY if out of memory for the semaphore structure and
+ *          handle.
+ *
+ * @param   phSpinMtx   Where to return the handle to the create semaphore.
+ * @param   fFlags      Flags, see RTSEMSPINMUTEX_FLAGS_XXX.
+ */
+RTDECL(int) RTSemSpinMutexCreate(PRTSEMSPINMUTEX phSpinMtx, uint32_t fFlags);
+
+/** @name RTSemSpinMutexCreate flags.
+ * @{ */
+/** Always take the semaphore in a IRQ safe way.
+ * (In plain words: always disable interrupts.) */
+#define RTSEMSPINMUTEX_FLAGS_IRQ_SAFE       RT_BIT_32(0)
+/** Mask of valid flags. */
+#define RTSEMSPINMUTEX_FLAGS_VALID_MASK     UINT32_C(0x00000001)
+/** @} */
+
+/**
+ * Destroys a spinning mutex semaphore.
+ *
+ * @returns iprt status code.
+ * @retval  VERR_INVALID_HANDLE (or crash) if the handle is invalid. (NIL will
+ *          not cause this status.)
+ *
+ * @param   hSpinMtx    The semaphore handle. NIL_RTSEMSPINMUTEX is ignored
+ *                      quietly (VINF_SUCCESS).
+ */
+RTDECL(int) RTSemSpinMutexDestroy(RTSEMSPINMUTEX hSpinMtx);
+
+/**
+ * Request the spinning mutex semaphore.
+ *
+ * This may block if the context we're called in allows this. If not it will
+ * spin. If called in an interrupt context, we will only spin if the current
+ * owner isn't interrupted. Also, on some systems it is not always possible to
+ * wake up blocking threads in all contexts, so, which will either be indicated
+ * by returning VERR_SEM_BAD_CONTEXT or by temporarily switching the semaphore
+ * into pure spinlock state.
+ *
+ * Preemption will be disabled upon return. IRQs may also be disabled.
+ *
+ * @returns iprt status code.
+ * @retval  VERR_SEM_BAD_CONTEXT if the context it's called in isn't suitable
+ *          for releasing it if someone is sleeping on it.
+ * @retval  VERR_SEM_DESTROYED if destroyed.
+ * @retval  VERR_SEM_NESTED if held by the caller. Asserted.
+ * @retval  VERR_INVALID_HANDLE if the handle is invalid. Asserted
+ *
+ * @param   hSpinMtx    The semaphore handle.
+ */
+RTDECL(int) RTSemSpinMutexRequest(RTSEMSPINMUTEX hSpinMtx);
+
+/**
+ * Like RTSemSpinMutexRequest but it won't block or spin if the semaphore is
+ * held by someone else.
+ *
+ * @returns iprt status code.
+ * @retval  VERR_SEM_BUSY if held by someone else.
+ * @retval  VERR_SEM_DESTROYED if destroyed.
+ * @retval  VERR_SEM_NESTED if held by the caller. Asserted.
+ * @retval  VERR_INVALID_HANDLE if the handle is invalid. Asserted
+ *
+ * @param   hSpinMtx    The semaphore handle.
+ */
+RTDECL(int) RTSemSpinMutexTryRequest(RTSEMSPINMUTEX hSpinMtx);
+
+/**
+ * Releases the semaphore previously acquired by RTSemSpinMutexRequest or
+ * RTSemSpinMutexTryRequest.
+ *
+ * @returns iprt status code.
+ * @retval  VERR_SEM_DESTROYED if destroyed.
+ * @retval  VERR_NOT_OWNER if not owner. Asserted.
+ * @retval  VERR_INVALID_HANDLE if the handle is invalid. Asserted.
+ *
+ * @param   hSpinMtx    The semaphore handle.
+ */
+RTDECL(int) RTSemSpinMutexRelease(RTSEMSPINMUTEX hSpinMtx);
+
+/** @} */
+
+
+/** @defgroup grp_rt_sem_rw             RTSemRW - Read / Write Semaphores
+ *
+ * Read/write semaphores are a fancier version of mutexes in that they grant
+ * read access to the protected data to several threads at the same time but
+ * allow only one writer at a time.  This can make code scale better at the
+ * expense of slightly more overhead in mutex management.
+ *
+ * @{ */
+
+/**
+ * Creates a read/write semaphore.
+ *
+ * @returns iprt status code.
+ * @param   phRWSem             Where to store the handle to the newly created
+ *                              RW semaphore.
+ */
+RTDECL(int)   RTSemRWCreate(PRTSEMRW phRWSem);
+
+/**
+ * Creates a read/write semaphore.
+ *
+ * @returns iprt status code.
+ * @param   phRWSem             Where to store the handle to the newly created
+ *                              RW semaphore.
+ * @param   fFlags              Flags, any combination of the RTSEMRW_FLAGS_XXX
+ *                              \#defines.
+ * @param   hClass              The class (no reference consumed).  If NIL, no
+ *                              lock order validation will be performed on this
+ *                              lock.
+ * @param   uSubClass           The sub-class.  This is used to define lock
+ *                              order within a class.  RTLOCKVAL_SUB_CLASS_NONE
+ *                              is the recommended value here.
+ * @param   pszNameFmt          Name format string for the lock validator,
+ *                              optional (NULL).  Max length is 32 bytes.
+ * @param   ...                 Format string arguments.
+ */
+RTDECL(int)   RTSemRWCreateEx(PRTSEMRW phRWSem, uint32_t fFlags, RTLOCKVALCLASS hClass, uint32_t uSubClass,
+                              const char *pszNameFmt, ...) RT_IPRT_FORMAT_ATTR_MAYBE_NULL(5, 6);
+
+/** @name RTSemRWCreateEx flags
+ * @{ */
+/** Disables lock validation. */
+#define RTSEMRW_FLAGS_NO_LOCK_VAL   UINT32_C(0x00000001)
+/** @} */
+
+/**
+ * Destroys a read/write semaphore.
+ *
+ * @returns iprt status code.
+ * @param   hRWSem              Handle to the read/write semaphore.  NIL is
+ *                              quietly ignored (VINF_SUCCESS).
+ */
+RTDECL(int)   RTSemRWDestroy(RTSEMRW hRWSem);
+
+/**
+ * Changes the lock validator sub-class of the read/write semaphore.
+ *
+ * It is recommended to try make sure that nobody is using this semaphore while
+ * changing the value.
+ *
+ * @returns The old sub-class.  RTLOCKVAL_SUB_CLASS_INVALID is returns if the
+ *          lock validator isn't compiled in or either of the parameters are
+ *          invalid.
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   uSubClass           The new sub-class value.
+ */
+RTDECL(uint32_t) RTSemRWSetSubClass(RTSEMRW hRWSem, uint32_t uSubClass);
+
+/**
+ * Request read access to a read/write semaphore, resume on interruption
+ *
+ * @returns iprt status code.
+ * @retval  VINF_SUCCESS on success.
+ * @retval  VERR_INTERRUPT if the wait was interrupted.
+ * @retval  VERR_INVALID_HANDLE if hRWSem is invalid.
+ *
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   cMillies            The number of milliseconds to wait.
+ */
+RTDECL(int)   RTSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies);
+
+/**
+ * Request read access to a read/write semaphore, return on interruption
+ *
+ * @returns iprt status code.
+ * @retval  VINF_SUCCESS on success.
+ * @retval  VERR_INTERRUPT if the wait was interrupted.
+ * @retval  VERR_INVALID_HANDLE if hRWSem is invalid.
+ *
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   cMillies            The number of milliseconds to wait.
+ */
+RTDECL(int)   RTSemRWRequestReadNoResume(RTSEMRW hRWSem, RTMSINTERVAL cMillies);
+
+/**
+ * Debug version of RTSemRWRequestRead that tracks the location.
+ *
+ * @returns iprt status code.
+ * @retval  VINF_SUCCESS on success.
+ * @retval  VERR_INTERRUPT if the wait was interrupted.
+ * @retval  VERR_INVALID_HANDLE if hRWSem is invalid.
+ *
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   cMillies            The number of milliseconds to wait.
+ * @param   uId                 Some kind of locking location ID.  Typically a
+ *                              return address up the stack.  Optional (0).
+ * @param   SRC_POS             The source position where call is being made
+ *                              from.  Use RT_SRC_POS when possible.  Optional.
+ */
+RTDECL(int)   RTSemRWRequestReadDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL);
+
+/**
+ * Debug version of RTSemRWRequestWriteNoResume that tracks the location.
+ *
+ * @returns iprt status code.
+ * @retval  VINF_SUCCESS on success.
+ * @retval  VERR_INTERRUPT if the wait was interrupted.
+ * @retval  VERR_INVALID_HANDLE if hRWSem is invalid.
+ *
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   cMillies            The number of milliseconds to wait.
+ * @param   uId                 Some kind of locking location ID.  Typically a
+ *                              return address up the stack.  Optional (0).
+ * @param   SRC_POS             The source position where call is being made
+ *                              from.  Use RT_SRC_POS when possible.  Optional.
+ */
+RTDECL(int)   RTSemRWRequestReadNoResumeDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL);
+
+/**
+ * Request read access to a read/write semaphore, extended edition.
+ *
+ * @returns iprt status code.
+ * @retval  VINF_SUCCESS on success.
+ * @retval  VERR_INTERRUPT if the wait was interrupted.
+ * @retval  VERR_TIMEOUT if the wait timed out.
+ * @retval  VERR_INVALID_HANDLE if hRWSem is invalid.
+ *
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   fFlags              Combination of the RTSEMWAIT_FLAGS_XXX.
+ * @param   uTimeout            The timeout, ignored if
+ *                              RTSEMWAIT_FLAGS_INDEFINITE is set in @a flags.
+ *                              Whether this is absolute or relative,
+ *                              milliseconds or nanoseconds depends on the @a
+ *                              fFlags value.  Do not pass RT_INDEFINITE_WAIT
+ *                              here, use RTSEMWAIT_FLAGS_INDEFINITE instead.
+ */
+RTDECL(int)   RTSemRWRequestReadEx(RTSEMRW hRWSem, uint32_t fFlags, uint64_t uTimeout);
+
+
+/**
+ * Debug version of RTSemRWRequestReadEx that tracks the location.
+ *
+ * @returns iprt status code.
+ * @retval  VINF_SUCCESS on success.
+ * @retval  VERR_INTERRUPT if the wait was interrupted.
+ * @retval  VERR_TIMEOUT if the wait timed out.
+ * @retval  VERR_INVALID_HANDLE if hRWSem is invalid.
+ *
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   fFlags              See RTSemRWRequestReadEx.
+ * @param   uTimeout            See RTSemRWRequestReadEx.
+ * @param   uId                 Some kind of locking location ID.  Typically a
+ *                              return address up the stack.  Optional (0).
+ * @param   SRC_POS             The source position where call is being made
+ *                              from.  Use RT_SRC_POS when possible.  Optional.
+ */
+RTDECL(int)   RTSemRWRequestReadExDebug(RTSEMRW hRWSem, uint32_t fFlags, uint64_t uTimeout,
+                                        RTHCUINTPTR uId, RT_SRC_POS_DECL);
+
+/**
+ * Release read access to a read/write semaphore.
+ *
+ * @returns iprt status code.
+ * @param   hRWSem              Handle to the read/write semaphore.  It goes
+ *                              without saying that caller must own read
+ *                              privileges to the semaphore.
+ */
+RTDECL(int)   RTSemRWReleaseRead(RTSEMRW hRWSem);
+
+/**
+ * Request write access to a read/write semaphore, resume on interruption.
+ *
+ * @returns iprt status code.
+ * @retval  VINF_SUCCESS on success.
+ * @retval  VERR_DEADLOCK if the caller owned the read lock.
+ * @retval  VERR_INVALID_HANDLE if hRWSem is invalid.
+ *
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   cMillies            The number of milliseconds to wait.
+ */
+RTDECL(int)   RTSemRWRequestWrite(RTSEMRW hRWSem, RTMSINTERVAL cMillies);
+
+/**
+ * Request write access to a read/write semaphore, return on interruption.
+ *
+ * @returns iprt status code.
+ * @retval  VINF_SUCCESS on success.
+ * @retval  VERR_INTERRUPT if the wait was interrupted.
+ * @retval  VERR_DEADLOCK if the caller owned the read lock.
+ * @retval  VERR_INVALID_HANDLE if hRWSem is invalid.
+ *
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   cMillies            The number of milliseconds to wait.
+ */
+RTDECL(int)   RTSemRWRequestWriteNoResume(RTSEMRW hRWSem, RTMSINTERVAL cMillies);
+
+/**
+ * Debug version of RTSemRWRequestWrite that tracks the location.
+ *
+ * @returns IPRT status code, see RTSemRWRequestWrite.
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   cMillies            The number of milliseconds to wait.
+ * @param   uId                 Some kind of locking location ID.  Typically a
+ *                              return address up the stack.  Optional (0).
+ * @param   SRC_POS             The source position where call is being made
+ *                              from.  Use RT_SRC_POS when possible.  Optional.
+ */
+RTDECL(int)  RTSemRWRequestWriteDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL);
+
+/**
+ * Debug version of RTSemRWRequestWriteNoResume that tracks the location.
+ *
+ * @returns IPRT status code, see RTSemRWRequestWriteNoResume.
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   cMillies            The number of milliseconds to wait.
+ * @param   uId                 Some kind of locking location ID.  Typically a
+ *                              return address up the stack.  Optional (0).
+ * @param   SRC_POS             The source position where call is being made
+ *                              from.  Use RT_SRC_POS when possible.  Optional.
+ */
+RTDECL(int)  RTSemRWRequestWriteNoResumeDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL);
+
+/**
+ * Request write access to a read/write semaphore, extended edition.
+ *
+ * @returns iprt status code.
+ * @retval  VINF_SUCCESS on success.
+ * @retval  VERR_INTERRUPTED if the wait was interrupted.
+ * @retval  VERR_TIMEOUT if the wait timed out.
+ * @retval  VERR_DEADLOCK if the caller owned the read lock.  Do not depend on
+ *          this as it is implementation specific.
+ * @retval  VERR_INVALID_HANDLE if hRWSem is invalid.
+ *
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   fFlags              Combination of the RTSEMWAIT_FLAGS_XXX.
+ * @param   uTimeout            The timeout, ignored if
+ *                              RTSEMWAIT_FLAGS_INDEFINITE is set in @a flags.
+ *                              Whether this is absolute or relative,
+ *                              milliseconds or nanoseconds depends on the @a
+ *                              fFlags value.  Do not pass RT_INDEFINITE_WAIT
+ *                              here, use RTSEMWAIT_FLAGS_INDEFINITE instead.
+ */
+RTDECL(int)   RTSemRWRequestWriteEx(RTSEMRW hRWSem, uint32_t fFlags, uint64_t uTimeout);
+
+/**
+ * Debug version of RTSemRWRequestWriteEx that tracks the location.
+ *
+ * @returns IPRT status code, see RTSemRWRequestWriteEx.
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   fFlags              See RTSemRWRequestWriteEx.
+ * @param   uTimeout            See RTSemRWRequestWriteEx.
+ * @param   uId                 Some kind of locking location ID.  Typically a
+ *                              return address up the stack.  Optional (0).
+ * @param   SRC_POS             The source position where call is being made
+ *                              from.  Use RT_SRC_POS when possible.  Optional.
+ */
+RTDECL(int)  RTSemRWRequestWriteExDebug(RTSEMRW hRWSem, uint32_t fFlags, uint64_t uTimeout,
+                                        RTHCUINTPTR uId, RT_SRC_POS_DECL);
+
+/**
+ * Release write access to a read/write semaphore.
+ *
+ * @returns iprt status code.
+ * @param   hRWSem              Handle to the read/write semaphore.  Goes
+ *                              without saying that caller must have write
+ *                              access to the semaphore.
+ */
+RTDECL(int)   RTSemRWReleaseWrite(RTSEMRW hRWSem);
+
+/**
+ * Checks if the caller is the exclusive semaphore owner.
+ *
+ * @returns true / false accoringly.
+ * @param   hRWSem              Handle to the read/write semaphore.
+ */
+RTDECL(bool)  RTSemRWIsWriteOwner(RTSEMRW hRWSem);
+
+/**
+ * Checks if the caller is one of the read owners of the semaphore.
+ *
+ * @note    !CAUTION!  This API doesn't work reliably if lock validation isn't
+ *          enabled. Meaning, the answer is not trustworhty unless
+ *          RT_LOCK_STRICT or RTSEMRW_STRICT was defined at build time.  Also,
+ *          make sure you do not use RTSEMRW_FLAGS_NO_LOCK_VAL when creating
+ *          the semaphore.  And finally, if you used a locking class, don't
+ *          disable deadlock detection by setting cMsMinDeadlock to
+ *          RT_INDEFINITE_WAIT.
+ *
+ *          In short, only use this for assertions.
+ *
+ * @returns true if reader, false if not.
+ * @param   hRWSem              Handle to the read/write semaphore.
+ * @param   fWannaHear          What you'd like to hear when lock validation is
+ *                              not available.  (For avoiding asserting all over
+ *                              the place.)
+ */
+RTDECL(bool)  RTSemRWIsReadOwner(RTSEMRW hRWSem, bool fWannaHear);
+
+/**
+ * Gets the write recursion count.
+ *
+ * @returns The write recursion count (0 if bad semaphore handle).
+ * @param   hRWSem              Handle to the read/write semaphore.
+ */
+RTDECL(uint32_t) RTSemRWGetWriteRecursion(RTSEMRW hRWSem);
+
+/**
+ * Gets the read recursion count of the current writer.
+ *
+ * @returns The read recursion count (0 if bad semaphore handle).
+ * @param   hRWSem              Handle to the read/write semaphore.
+ */
+RTDECL(uint32_t) RTSemRWGetWriterReadRecursion(RTSEMRW hRWSem);
+
+/**
+ * Gets the current number of reads.
+ *
+ * This includes all read recursions, so it might be higher than the number of
+ * read owners.  It does not include reads done by the current writer.
+ *
+ * @returns The read count (0 if bad semaphore handle).
+ * @param   hRWSem              Handle to the read/write semaphore.
+ */
+RTDECL(uint32_t) RTSemRWGetReadCount(RTSEMRW hRWSem);
+
+/* Strict build: Remap the four request calls to the debug versions. */
+#if defined(RT_STRICT) && !defined(RTSEMRW_WITHOUT_REMAPPING) && !defined(RT_WITH_MANGLING)
+# ifdef IPRT_INCLUDED_asm_h
+#  define RTSemRWRequestRead(hRWSem, cMillies)              RTSemRWRequestReadDebug((hRWSem), (cMillies), (uintptr_t)ASMReturnAddress(), RT_SRC_POS)
+#  define RTSemRWRequestReadNoResume(hRWSem, cMillies)      RTSemRWRequestReadNoResumeDebug((hRWSem), (cMillies), (uintptr_t)ASMReturnAddress(), RT_SRC_POS)
+#  define RTSemRWRequestWrite(hRWSem, cMillies)             RTSemRWRequestWriteDebug((hRWSem), (cMillies), (uintptr_t)ASMReturnAddress(), RT_SRC_POS)
+#  define RTSemRWRequestWriteNoResume(hRWSem, cMillies)     RTSemRWRequestWriteNoResumeDebug((hRWSem), (cMillies), (uintptr_t)ASMReturnAddress(), RT_SRC_POS)
+#  define RTSemRWRequestWriteEx(hRWSem, fFlags, uTimeout)   RTSemRWRequestWriteExDebug((hRWSem), (fFlags), (uTimeout), (uintptr_t)ASMReturnAddress(), RT_SRC_POS)
+# else
+#  define RTSemRWRequestRead(hRWSem, cMillies)              RTSemRWRequestReadDebug((hRWSem), (cMillies), 0, RT_SRC_POS)
+#  define RTSemRWRequestReadNoResume(hRWSem, cMillies)      RTSemRWRequestReadNoResumeDebug((hRWSem), (cMillies), 0, RT_SRC_POS)
+#  define RTSemRWRequestWrite(hRWSem, cMillies)             RTSemRWRequestWriteDebug((hRWSem), (cMillies), 0, RT_SRC_POS)
+#  define RTSemRWRequestWriteNoResume(hRWSem, cMillies)     RTSemRWRequestWriteNoResumeDebug((hRWSem), (cMillies), 0, RT_SRC_POS)
+#  define RTSemRWRequestWriteEx(hRWSem, fFlags, uTimeout)   RTSemRWRequestWriteExDebug((hRWSem), (fFlags), (uTimeout), 0, RT_SRC_POS)
+# endif
+#endif
+
+/* Strict lock order: Automatically classify locks by init location. */
+#if defined(RT_LOCK_STRICT_ORDER) && defined(IN_RING3) && !defined(RTSEMRW_WITHOUT_REMAPPING) && !defined(RT_WITH_MANGLING)
+# define RTSemRWCreate(phSemRW) \
+    RTSemRWCreateEx((phSemRW), 0 /*fFlags*/, \
+                    RTLockValidatorClassForSrcPos(RT_SRC_POS, NULL), \
+                    RTLOCKVAL_SUB_CLASS_NONE, NULL)
+#endif
+
+/** @} */
+
+
+/** @defgroup grp_rt_sems_pingpong      RTSemPingPong - Ping-Pong Construct
+ *
+ * Serialization of a two way communication.
+ *
+ * @{ */
+
+/**
+ * Ping-pong speaker
+ */
+typedef enum RTPINGPONGSPEAKER
+{
+    /** Not initialized. */
+    RTPINGPONGSPEAKER_UNINITIALIZE = 0,
+    /** Ping is speaking, Pong is waiting. */
+    RTPINGPONGSPEAKER_PING,
+    /** Pong is signaled, Ping is waiting. */
+    RTPINGPONGSPEAKER_PONG_SIGNALED,
+    /** Pong is speaking, Ping is waiting. */
+    RTPINGPONGSPEAKER_PONG,
+    /** Ping is signaled, Pong is waiting. */
+    RTPINGPONGSPEAKER_PING_SIGNALED,
+    /** Hack to ensure that it's at least 32-bits wide. */
+    RTPINGPONGSPEAKER_HACK = 0x7fffffff
+} RTPINGPONGSPEAKER;
+
+/**
+ * Ping-Pong construct.
+ *
+ * Two threads, one saying Ping and the other saying Pong. The construct
+ * makes sure they don't speak out of turn and that they can wait and poll
+ * on the conversation.
+ */
+typedef struct RTPINGPONG
+{
+    /** The semaphore the Ping thread waits on. */
+    RTSEMEVENT                  Ping;
+    /** The semaphore the Pong thread waits on. */
+    RTSEMEVENT                  Pong;
+    /** The current speaker. */
+    volatile RTPINGPONGSPEAKER  enmSpeaker;
+#if HC_ARCH_BITS == 64
+    /** Padding the structure to become a multiple of sizeof(RTHCPTR). */
+    uint32_t                    u32Padding;
+#endif
+} RTPINGPONG;
+/** Pointer to Ping-Pong construct. */
+typedef RTPINGPONG *PRTPINGPONG;
+
+/**
+ * Init a Ping-Pong construct.
+ *
+ * @returns iprt status code.
+ * @param   pPP         Pointer to the ping-pong structure which needs initialization.
+ */
+RTDECL(int) RTSemPingPongInit(PRTPINGPONG pPP);
+
+/**
+ * Deletes a Ping-Pong construct.
+ *
+ * @returns iprt status code.
+ * @param   pPP         Pointer to the ping-pong structure which is to be destroyed.
+ *                      (I.e. put into uninitialized state.)
+ */
+RTDECL(int) RTSemPingPongDelete(PRTPINGPONG pPP);
+
+/**
+ * Signals the pong thread in a ping-pong construct. (I.e. sends ping.)
+ * This is called by the ping thread.
+ *
+ * @returns iprt status code.
+ * @param   pPP         Pointer to the ping-pong structure to ping.
+ */
+RTDECL(int) RTSemPing(PRTPINGPONG pPP);
+
+/**
+ * Signals the ping thread in a ping-pong construct. (I.e. sends pong.)
+ * This is called by the pong thread.
+ *
+ * @returns iprt status code.
+ * @param   pPP         Pointer to the ping-pong structure to pong.
+ */
+RTDECL(int) RTSemPong(PRTPINGPONG pPP);
+
+/**
+ * Wait function for the ping thread.
+ *
+ * @returns iprt status code.
+ *          Will not return VERR_INTERRUPTED.
+ * @param   pPP         Pointer to the ping-pong structure to wait on.
+ * @param   cMillies    Number of milliseconds to wait.
+ */
+RTDECL(int) RTSemPingWait(PRTPINGPONG pPP, RTMSINTERVAL cMillies);
+
+/**
+ * Wait function for the pong thread.
+ *
+ * @returns iprt status code.
+ *          Will not return VERR_INTERRUPTED.
+ * @param   pPP         Pointer to the ping-pong structure to wait on.
+ * @param   cMillies    Number of milliseconds to wait.
+ */
+RTDECL(int) RTSemPongWait(PRTPINGPONG pPP, RTMSINTERVAL cMillies);
+
+
+/**
+ * Checks if the pong thread is speaking.
+ *
+ * @returns true / false.
+ * @param   pPP         Pointer to the ping-pong structure.
+ * @remark  This is NOT the same as !RTSemPongIsSpeaker().
+ */
+DECLINLINE(bool) RTSemPingIsSpeaker(PRTPINGPONG pPP)
+{
+    RTPINGPONGSPEAKER enmSpeaker = pPP->enmSpeaker;
+    return enmSpeaker == RTPINGPONGSPEAKER_PING;
+}
+
+
+/**
+ * Checks if the pong thread is speaking.
+ *
+ * @returns true / false.
+ * @param   pPP         Pointer to the ping-pong structure.
+ * @remark  This is NOT the same as !RTSemPingIsSpeaker().
+ */
+DECLINLINE(bool) RTSemPongIsSpeaker(PRTPINGPONG pPP)
+{
+    RTPINGPONGSPEAKER enmSpeaker = pPP->enmSpeaker;
+    return enmSpeaker == RTPINGPONGSPEAKER_PONG;
+}
+
+
+/**
+ * Checks whether the ping thread should wait.
+ *
+ * @returns true / false.
+ * @param   pPP         Pointer to the ping-pong structure.
+ * @remark  This is NOT the same as !RTSemPongShouldWait().
+ */
+DECLINLINE(bool) RTSemPingShouldWait(PRTPINGPONG pPP)
+{
+    RTPINGPONGSPEAKER enmSpeaker = pPP->enmSpeaker;
+    return enmSpeaker == RTPINGPONGSPEAKER_PONG
+        || enmSpeaker == RTPINGPONGSPEAKER_PONG_SIGNALED
+        || enmSpeaker == RTPINGPONGSPEAKER_PING_SIGNALED;
+}
+
+
+/**
+ * Checks whether the pong thread should wait.
+ *
+ * @returns true / false.
+ * @param   pPP         Pointer to the ping-pong structure.
+ * @remark  This is NOT the same as !RTSemPingShouldWait().
+ */
+DECLINLINE(bool) RTSemPongShouldWait(PRTPINGPONG pPP)
+{
+    RTPINGPONGSPEAKER enmSpeaker = pPP->enmSpeaker;
+    return enmSpeaker == RTPINGPONGSPEAKER_PING
+        || enmSpeaker == RTPINGPONGSPEAKER_PING_SIGNALED
+        || enmSpeaker == RTPINGPONGSPEAKER_PONG_SIGNALED;
+}
+
+/** @} */
+
+
+/** @defgroup grp_rt_sems_xroads    RTSemXRoads - Crossroads
+ *
+ * The crossroads semaphore is intended to prevent two classes of incompatible
+ * events from occurring simultaneously, like south/north bound traffic and
+ * west/east bound traffic at a 4-way junction.
+ *
+ * @remarks In order to simplify the implementation, the current flow is always
+ *          given priority.  So, it won't work at all well when busy!
+ *
+ * @remarks "XRoads" is used as a name because it is briefer than "crossroads"
+ *          and it slightly stresses that is a 4 way crossing to the users of
+ *          American English.
+ * @{
+ */
+
+/**
+ * Creates a crossroads semaphore.
+ *
+ * @returns IPRT status code.
+ *
+ * @param   phXRoads            Where to return the handle to the newly created
+ *                              crossroads semaphore.
+ */
+RTDECL(int) RTSemXRoadsCreate(PRTSEMXROADS phXRoads);
+
+/**
+ * Destroys a crossroads semaphore.
+ *
+ * @returns IPRT status code.
+ *
+ * @param   hXRoads             Handle to the crossroads semaphore that is to be
+ *                              destroyed.  NIL_RTSEMXROADS is quitetly ignored
+ *                              (VINF_SUCCESS).
+ */
+RTDECL(int) RTSemXRoadsDestroy(RTSEMXROADS hXRoads);
+
+/**
+ * Enter the crossroads from the south or north.
+ *
+ * (Coupled with RTSemXRoadsNSLeave.)
+ *
+ * @returns IPRT status code.
+ * @param   hXRoads             Handle to the crossroads semaphore.
+ */
+RTDECL(int) RTSemXRoadsNSEnter(RTSEMXROADS hXRoads);
+
+/**
+ * Leave the crossroads to the north or south.
+ *
+ * (Coupled with RTSemXRoadsNSEnter.)
+ *
+ * @returns IPRT status code.
+ * @param   hXRoads             Handle to the crossroads semaphore.
+ */
+RTDECL(int) RTSemXRoadsNSLeave(RTSEMXROADS hXRoads);
+
+/**
+ * Leave the crossroads from the east or west.
+ *
+ * (Coupled with RTSemXRoadsEWLeave.)
+ *
+ * @returns IPRT status code.
+ * @param   hXRoads             Handle to the crossroads semaphore.
+ */
+RTDECL(int) RTSemXRoadsEWEnter(RTSEMXROADS hXRoads);
+
+/**
+ * Leave the crossroads to the west or east.
+ *
+ * (Coupled with RTSemXRoadsEWEnter.)
+ *
+ * @returns IPRT status code.
+ * @param   hXRoads             Handle to the crossroads semaphore.
+ */
+RTDECL(int) RTSemXRoadsEWLeave(RTSEMXROADS hXRoads);
+
+/** @} */
+
+/** @} */
+
+RT_C_DECLS_END
+
+#endif /* !IPRT_INCLUDED_semaphore_h */
+