[weiden] 23806: Implement Slim Reader/Writer (SRW) locks: - Implement AcquireSRWLockExclusive(), AcquireSRWLockShared(), InitializeSRWLock(), ReleaseSRWLockExclusive(), ReleaseSRWLockShared() - NOTE: Some versions of GCC have a code generation bug with specially aligned structures on the stack. If compiled with such a compiler, the code might trigger special assertions. Pushlocks are also affected by this compiler bug. - NOTE: The algorithms are most likely not the same as in Windows. Applicatio

Author: weiden
Date: Wed Aug 30 23:02:42 2006
New Revision: 23806

URL: http://svn.reactos.org/svn/reactos?rev=23806&view=rev
Log:
Implement Slim Reader/Writer (SRW) locks:
- Implement AcquireSRWLockExclusive(), AcquireSRWLockShared(), InitializeSRWLock(),
ReleaseSRWLockExclusive(), ReleaseSRWLockShared()
- NOTE: Some versions of GCC have a code generation bug with specially aligned structures
on the stack. If compiled with such a compiler, the code might trigger special assertions.
Pushlocks are also affected by this compiler bug.
- NOTE: The algorithms are most likely not the same as in Windows. Applications are
supposed to treat the lock variables as opaque data, therefore it shouldn't matter.

Added:
    trunk/reactos/lib/rtl/srw.c   (with props)
Modified:
    trunk/reactos/dll/ntdll/def/ntdll.def
    trunk/reactos/dll/win32/kernel32/kernel32.def
    trunk/reactos/include/psdk/winbase.h
    trunk/reactos/include/psdk/winnt.h
    trunk/reactos/lib/rtl/rtl.rbuild

Modified: trunk/reactos/dll/ntdll/def/ntdll.def
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/dll/ntdll/def/ntdll.def?re…
==============================================================================
--- trunk/reactos/dll/ntdll/def/ntdll.def (original)
+++ trunk/reactos/dll/ntdll/def/ntdll.def Wed Aug 30 23:02:42 2006
@@ -295,6 +295,8 @@
 RtlAcquirePebLock@0
 RtlAcquireResourceExclusive@8
 RtlAcquireResourceShared@8
+RtlAcquireSRWLockExclusive@4
+RtlAcquireSRWLockShared@4
 RtlAddAccessAllowedAce@16
 RtlAddAccessAllowedAceEx@20
 RtlAddAccessAllowedObjectAce@28
@@ -513,6 +515,7 @@
 RtlInitializeResource@4
 ;RtlInitializeRXact
 RtlInitializeSid@12
+RtlInitializeSRWLock@4
 RtlInsertElementGenericTable@16
 RtlInsertElementGenericTableAvl@16
 RtlInsertElementGenericTableFull@24
@@ -612,6 +615,8 @@
 RtlReleasePebLock@0
 RtlReleaseRelativeName@4
 RtlReleaseResource@4
+RtlReleaseSRWLockExclusive@4
+RtlReleaseSRWLockShared@4
 ;RtlRemoteCall
 RtlRemoveVectoredExceptionHandler@4
 RtlResetRtlTranslations@4

Modified: trunk/reactos/dll/win32/kernel32/kernel32.def
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/dll/win32/kernel32/kernel3…
==============================================================================
--- trunk/reactos/dll/win32/kernel32/kernel32.def (original)
+++ trunk/reactos/dll/win32/kernel32/kernel32.def Wed Aug 30 23:02:42 2006
@@ -30,6 +30,8 @@
 ;
 LIBRARY KERNEL32.DLL
 EXPORTS
+AcquireSRWLockExclusive(a)4=NTDLL.RtlAcquireSRWLockExclusive
+AcquireSRWLockShared(a)4=NTDLL.RtlAcquireSRWLockShared
 ActivateActCtx@8
 AddAtomA@4
 AddAtomW@4
@@ -587,6 +589,7 @@
 InitializeCriticalSection@4
 InitializeCriticalSectionAndSpinCount@8
 InitializeSListHead(a)4=NTDLL.RtlInitializeSListHead
+InitializeSRWLock(a)4=NTDLL.RtlInitializeSRWLock
 InterlockedCompareExchange@12
 InterlockedDecrement@4
 InterlockedExchange@8
@@ -749,6 +752,8 @@
 ReleaseActCtx@4
 ReleaseMutex@4
 ReleaseSemaphore@12
+ReleaseSRWLockExclusive(a)4=NTDLL.RtlReleaseSRWLockExclusive
+ReleaseSRWLockShared(a)4=NTDLL.RtlReleaseSRWLockShared
 RemoveDirectoryA@4
 RemoveDirectoryW@4
 ;RemoveLocalAlternateComputerNameA

Modified: trunk/reactos/include/psdk/winbase.h
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/include/psdk/winbase.h?rev…
==============================================================================
--- trunk/reactos/include/psdk/winbase.h (original)
+++ trunk/reactos/include/psdk/winbase.h Wed Aug 30 23:02:42 2006
@@ -540,6 +540,9 @@
 #define CREATE_EVENT_INITIAL_SET    0x2
 #define CREATE_MUTEX_INITIAL_OWNER  0x1
 #define CREATE_WAITABLE_TIMER_MANUAL_RESET  0x1
+#define SRWLOCK_INIT    RTL_SRWLOCK_INIT
+#define CONDITION_VARIABLE_INIT RTL_CONDITION_VARIABLE_INIT
+#define CONDITION_VARIABLE_LOCKMODE_SHARED  RTL_CONDITION_VARIABLE_LOCKMODE_SHARED
 #endif
 
 #ifndef RC_INVOKED
@@ -1053,6 +1056,9 @@
 	DWORD MemberLevel;
 	DWORD Flags;
 } JOB_SET_ARRAY, *PJOB_SET_ARRAY;
+#if (_WIN32_WINNT >= 0x0600)
+typedef RTL_SRWLOCK SRWLOCK, *PSRWLOCK;
+#endif
 typedef DWORD(WINAPI
*LPPROGRESS_ROUTINE)(LARGE_INTEGER,LARGE_INTEGER,LARGE_INTEGER,LARGE_INTEGER,DWORD,DWORD,HANDLE,HANDLE,LPVOID);
 typedef void(WINAPI *LPFIBER_START_ROUTINE)(PVOID);
 typedef VOID (WINAPI *PFLS_CALLBACK_FUNCTION)(PVOID);
@@ -1093,6 +1099,10 @@
 BOOL WINAPI
AccessCheck(PSECURITY_DESCRIPTOR,HANDLE,DWORD,PGENERIC_MAPPING,PPRIVILEGE_SET,PDWORD,PDWORD,PBOOL);
 BOOL WINAPI
AccessCheckAndAuditAlarmA(LPCSTR,LPVOID,LPSTR,LPSTR,PSECURITY_DESCRIPTOR,DWORD,PGENERIC_MAPPING,BOOL,PDWORD,PBOOL,PBOOL);
 BOOL WINAPI
AccessCheckAndAuditAlarmW(LPCWSTR,LPVOID,LPWSTR,LPWSTR,PSECURITY_DESCRIPTOR,DWORD,PGENERIC_MAPPING,BOOL,PDWORD,PBOOL,PBOOL);
+#if (_WIN32_WINNT >= 0x0600)
+VOID WINAPI AcquireSRWLockExclusive(PSRWLOCK);
+VOID WINAPI AcquireSRWLockShared(PSRWLOCK);
+#endif
 #if (_WIN32_WINNT >= 0x0501)
 BOOL WINAPI ActivateActCtx(HANDLE,ULONG_PTR*);
 #endif
@@ -1659,6 +1669,9 @@
 BOOL WINAPI InitializeSid (PSID,PSID_IDENTIFIER_AUTHORITY,BYTE);
 #if !defined(__WINDDK_H) && _WIN32_WINNT >= 0x0501
 VOID WINAPI InitializeSListHead(PSLIST_HEADER);
+#endif
+#if (_WIN32_WINNT >= 0x0600)
+VOID WINAPI InitializeSRWLock(PSRWLOCK);
 #endif
 #ifndef __INTERLOCKED_DECLARED
 #define __INTERLOCKED_DECLARED
@@ -1842,6 +1855,10 @@
 #endif
 BOOL WINAPI ReleaseMutex(HANDLE);
 BOOL WINAPI ReleaseSemaphore(HANDLE,LONG,LPLONG);
+#if (_WIN32_WINNT >= 0x0600)
+VOID WINAPI ReleaseSRWLockExclusive(PSRWLOCK);
+VOID WINAPI ReleaseSRWLockShared(PSRWLOCK);
+#endif
 BOOL WINAPI RemoveDirectoryA(LPCSTR);
 BOOL WINAPI RemoveDirectoryW(LPCWSTR);
 #if (_WIN32_WINNT >= 0x0500)

Modified: trunk/reactos/include/psdk/winnt.h
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/include/psdk/winnt.h?rev=2…
==============================================================================
--- trunk/reactos/include/psdk/winnt.h (original)
+++ trunk/reactos/include/psdk/winnt.h Wed Aug 30 23:02:42 2006
@@ -2626,6 +2626,19 @@
 } RTL_CRITICAL_SECTION,*PRTL_CRITICAL_SECTION;
 #endif
 
+#define RTL_SRWLOCK_INIT {0}
+typedef struct _RTL_SRWLOCK
+{
+    PVOID Ptr;
+} RTL_SRWLOCK, *PRTL_SRWLOCK;
+
+#define RTL_CONDITION_VARIABLE_INIT {0}
+#define RTL_CONDITION_VARIABLE_LOCKMODE_SHARED  0x1
+typedef struct _RTL_CONDITION_VARIABLE
+{
+    PVOID Ptr;
+} RTL_CONDITION_VARIABLE, *PRTL_CONDITION_VARIABLE;
+
 typedef LONG
 (NTAPI *PVECTORED_EXCEPTION_HANDLER)(
     struct _EXCEPTION_POINTERS *ExceptionInfo

Modified: trunk/reactos/lib/rtl/rtl.rbuild
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/lib/rtl/rtl.rbuild?rev=238…
==============================================================================
--- trunk/reactos/lib/rtl/rtl.rbuild (original)
+++ trunk/reactos/lib/rtl/rtl.rbuild Wed Aug 30 23:02:42 2006
@@ -84,6 +84,7 @@
 	<file>security.c</file>
 	<file>sid.c</file>
 	<file>sprintf.c</file>
+	<file>srw.c</file>
 	<file>swprintf.c</file>
 	<file>splaytree.c</file>
 	<file>thread.c</file>

Added: trunk/reactos/lib/rtl/srw.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/lib/rtl/srw.c?rev=23806&am…
==============================================================================
--- trunk/reactos/lib/rtl/srw.c (added)
+++ trunk/reactos/lib/rtl/srw.c Wed Aug 30 23:02:42 2006
@@ -1,0 +1,832 @@
+/*
+ * COPYRIGHT:         See COPYING in the top level directory
+ * PROJECT:           ReactOS system libraries
+ * PURPOSE:           Slim Reader/Writer (SRW) Routines
+ * PROGRAMMER:        Thomas Weidenmueller &lt;w3seek(a)reactos.com&gt;
+ *
+ * NOTES:             The algorithms used in this implementation
+ *                    may be different from Vista's implementation.
+ *                    Since applications should treat the RTL_SRWLOCK
+ *                    structure as opaque data, it should not matter.
+ *                    The algorithms are probably not as optimized.
+ */
+
+/* INCLUDES *****************************************************************/
+
+#include <rtl.h>
+
+#define NDEBUG
+#include <debug.h>
+
+/* FIXME *********************************************************************/
+
+/* FIXME: Interlocked functions that need to be made into a public header */
+FORCEINLINE
+LONG
+InterlockedAnd(IN OUT volatile LONG *Target,
+               IN LONG Set)
+{
+    LONG i;
+    LONG j;
+
+    j = *Target;
+    do {
+        i = j;
+        j = InterlockedCompareExchange((PLONG)Target,
+                                       i & Set,
+                                       i);
+
+    } while (i != j);
+
+    return j;
+}
+
+FORCEINLINE
+LONG
+InterlockedOr(IN OUT volatile LONG *Target,
+              IN LONG Set)
+{
+    LONG i;
+    LONG j;
+
+    j = *Target;
+    do {
+        i = j;
+        j = InterlockedCompareExchange((PLONG)Target,
+                                       i | Set,
+                                       i);
+
+    } while (i != j);
+
+    return j;
+}
+
+/* FUNCTIONS *****************************************************************/
+
+#ifdef _WIN64
+#define InterlockedBitTestAndSetPointer(ptr,val)
InterlockedBitTestAndSet64((PLONGLONG)ptr,(LONGLONG)val)
+#define InterlockedAddPointer(ptr,val) InterlockedAdd64((PLONGLONG)ptr,(LONGLONG)val)
+#define InterlockedAndPointer(ptr,val) InterlockedAnd64((PLONGLONG)ptr,(LONGLONG)val)
+#define InterlockedOrPointer(ptr,val) InterlockedOr64((PLONGLONG)ptr,(LONGLONG)val)
+#else
+#define InterlockedBitTestAndSetPointer(ptr,val)
InterlockedBitTestAndSet((PLONG)ptr,(LONG)val)
+#define InterlockedAddPointer(ptr,val) InterlockedAdd((PLONG)ptr,(LONG)val)
+#define InterlockedAndPointer(ptr,val) InterlockedAnd((PLONG)ptr,(LONG)val)
+#define InterlockedOrPointer(ptr,val) InterlockedOr((PLONG)ptr,(LONG)val)
+#endif
+
+#define RTL_SRWLOCK_OWNED_BIT   0
+#define RTL_SRWLOCK_CONTENDED_BIT   1
+#define RTL_SRWLOCK_SHARED_BIT  2
+#define RTL_SRWLOCK_CONTENTION_LOCK_BIT 3
+#define RTL_SRWLOCK_OWNED   (1 << RTL_SRWLOCK_OWNED_BIT)
+#define RTL_SRWLOCK_CONTENDED   (1 << RTL_SRWLOCK_CONTENDED_BIT)
+#define RTL_SRWLOCK_SHARED  (1 << RTL_SRWLOCK_SHARED_BIT)
+#define RTL_SRWLOCK_CONTENTION_LOCK (1 << RTL_SRWLOCK_CONTENTION_LOCK_BIT)
+#define RTL_SRWLOCK_MASK    (RTL_SRWLOCK_OWNED | RTL_SRWLOCK_CONTENDED | \
+                             RTL_SRWLOCK_SHARED | RTL_SRWLOCK_CONTENTION_LOCK)
+#define RTL_SRWLOCK_BITS    4
+
+#if defined(__GNUC__)
+/* This macro will cause the code to assert if compiled with a buggy
+   version of GCC that doesn't align the wait blocks properly on the stack! */
+#define ASSERT_SRW_WAITBLOCK(ptr) \
+    ASSERT(((ULONG_PTR)ptr & ((1 << RTL_SRWLOCK_BITS) - 1)) == 0)
+#else
+#define ASSERT_SRW_WAITBLOCK(ptr)
+#endif
+
+typedef struct _RTLP_SRWLOCK_SHARED_WAKE
+{
+    LONG Wake;
+    volatile struct _RTLP_SRWLOCK_SHARED_WAKE *Next;
+} volatile RTLP_SRWLOCK_SHARED_WAKE, *PRTLP_SRWLOCK_SHARED_WAKE;
+
+typedef struct _RTLP_SRWLOCK_WAITBLOCK
+{
+    /* SharedCount is the number of shared acquirers. */
+    LONG SharedCount;
+
+    /* Last points to the last wait block in the chain. The value
+       is only valid when read from the first wait block. */
+    volatile struct _RTLP_SRWLOCK_WAITBLOCK *Last;
+
+    /* Next points to the next wait block in the chain. */
+    volatile struct _RTLP_SRWLOCK_WAITBLOCK *Next;
+
+    union
+    {
+        /* Wake is only valid for exclusive wait blocks */
+        LONG Wake;
+        /* The wake chain is only valid for shared wait blocks */
+        struct
+        {
+            PRTLP_SRWLOCK_SHARED_WAKE SharedWakeChain;
+            PRTLP_SRWLOCK_SHARED_WAKE LastSharedWake;
+        };
+    };
+
+    BOOLEAN Exclusive;
+} volatile RTLP_SRWLOCK_WAITBLOCK, *PRTLP_SRWLOCK_WAITBLOCK;
+
+
+static VOID
+NTAPI
+RtlpReleaseWaitBlockLockExclusive(IN OUT PRTL_SRWLOCK SRWLock,
+                                  IN PRTLP_SRWLOCK_WAITBLOCK FirstWaitBlock)
+{
+    PRTLP_SRWLOCK_WAITBLOCK Next;
+    LONG_PTR NewValue;
+
+    /* NOTE: We're currently in an exclusive lock in contended mode. */
+
+    Next = FirstWaitBlock->Next;
+    if (Next != NULL)
+    {
+        /* There's more blocks chained, we need to update the pointers
+           in the next wait block and update the wait block pointer. */
+        NewValue = (LONG_PTR)Next | RTL_SRWLOCK_OWNED | RTL_SRWLOCK_CONTENDED;
+        if (!FirstWaitBlock->Exclusive)
+        {
+            /* The next wait block has to be an exclusive lock! */
+            ASSERT(Next->Exclusive);
+
+            /* Save the shared count */
+            Next->SharedCount = FirstWaitBlock->SharedCount;
+
+            NewValue |= RTL_SRWLOCK_SHARED;
+        }
+
+        Next->Last = FirstWaitBlock->Last;
+    }
+    else
+    {
+        /* Convert the lock to a simple lock. */
+        if (FirstWaitBlock->Exclusive)
+            NewValue = RTL_SRWLOCK_OWNED;
+        else
+        {
+            ASSERT(FirstWaitBlock->SharedCount > 0);
+
+            NewValue = ((LONG_PTR)FirstWaitBlock->SharedCount <<
RTL_SRWLOCK_BITS) |
+                       RTL_SRWLOCK_SHARED | RTL_SRWLOCK_OWNED;
+        }
+    }
+
+    (void)InterlockedExchangePointer(&SRWLock->Ptr,
+                                     (PVOID)NewValue);
+
+    if (FirstWaitBlock->Exclusive)
+    {
+        (void)InterlockedOr(&FirstWaitBlock->Wake,
+                            TRUE);
+    }
+    else
+    {
+        PRTLP_SRWLOCK_SHARED_WAKE WakeChain, Next;
+
+        /* If we were the first one to acquire the shared
+           lock, we now need to wake all others... */
+        WakeChain = FirstWaitBlock->SharedWakeChain;
+        do
+        {
+            Next = WakeChain->Next;
+
+            (void)InterlockedOr((PLONG)&WakeChain->Wake,
+                                TRUE);
+
+            WakeChain = Next;
+        } while (WakeChain != NULL);
+    }
+}
+
+
+static VOID
+NTAPI
+RtlpReleaseWaitBlockLockLastShared(IN OUT PRTL_SRWLOCK SRWLock,
+                                   IN PRTLP_SRWLOCK_WAITBLOCK FirstWaitBlock)
+{
+    PRTLP_SRWLOCK_WAITBLOCK Next;
+    LONG_PTR NewValue;
+
+    /* NOTE: We're currently in a shared lock in contended mode. */
+
+    /* The next acquirer to be unwaited *must* be an exclusive lock! */
+    ASSERT(FirstWaitBlock->Exclusive);
+
+    Next = FirstWaitBlock->Next;
+    if (Next != NULL)
+    {
+        /* There's more blocks chained, we need to update the pointers
+           in the next wait block and update the wait block pointer. */
+        NewValue = (LONG_PTR)Next | RTL_SRWLOCK_OWNED | RTL_SRWLOCK_CONTENDED;
+
+        Next->Last = FirstWaitBlock->Last;
+    }
+    else
+    {
+        /* Convert the lock to a simple exclusive lock. */
+        NewValue = RTL_SRWLOCK_OWNED;
+    }
+
+    (void)InterlockedExchangePointer(&SRWLock->Ptr,
+                                     (PVOID)NewValue);
+
+    (void)InterlockedOr(&FirstWaitBlock->Wake,
+                        TRUE);
+}
+
+
+static VOID
+NTAPI
+RtlpReleaseWaitBlockLock(IN OUT PRTL_SRWLOCK SRWLock)
+{
+    InterlockedAndPointer(&SRWLock->Ptr,
+                          ~RTL_SRWLOCK_CONTENTION_LOCK);
+}
+
+
+static PRTLP_SRWLOCK_WAITBLOCK
+NTAPI
+RtlpAcquireWaitBlockLock(IN OUT PRTL_SRWLOCK SRWLock)
+{
+    LONG_PTR PrevValue;
+    PRTLP_SRWLOCK_WAITBLOCK WaitBlock;
+
+    while (1)
+    {
+        PrevValue = InterlockedOrPointer(&SRWLock->Ptr,
+                                         RTL_SRWLOCK_CONTENTION_LOCK);
+
+        if (!(PrevValue & RTL_SRWLOCK_CONTENTION_LOCK))
+            break;
+
+        YieldProcessor();
+    }
+
+    if (!(PrevValue & RTL_SRWLOCK_CONTENDED) ||
+        (PrevValue & ~RTL_SRWLOCK_MASK) == 0)
+    {
+        /* Too bad, looks like the wait block was removed in the
+           meanwhile, unlock again */
+        RtlpReleaseWaitBlockLock(SRWLock);
+        return NULL;
+    }
+
+    WaitBlock = (PRTLP_SRWLOCK_WAITBLOCK)(PrevValue & ~RTL_SRWLOCK_MASK);
+
+    ASSERT_SRW_WAITBLOCK(WaitBlock);
+    return WaitBlock;
+}
+
+
+static VOID
+NTAPI
+RtlpAcquireSRWLockExclusiveWait(IN OUT PRTL_SRWLOCK SRWLock,
+                                IN PRTLP_SRWLOCK_WAITBLOCK WaitBlock)
+{
+    LONG_PTR CurrentValue;
+
+    while (1)
+    {
+        CurrentValue = *(volatile LONG_PTR *)&SRWLock->Ptr;
+        if (!(CurrentValue & RTL_SRWLOCK_SHARED))
+        {
+            if (CurrentValue & RTL_SRWLOCK_CONTENDED)
+            {
+                if (WaitBlock->Wake != 0)
+                {
+                    /* Our wait block became the first one
+                       in the chain, we own the lock now! */
+                    break;
+                }
+            }
+            else
+            {
+                /* The last wait block was removed and/or we're 
+                   finally a simple exclusive lock. This means we
+                   don't need to wait anymore, we acquired the lock! */
+                break;
+            }
+        }
+
+        YieldProcessor();
+    }
+}
+
+
+static VOID
+NTAPI
+RtlpAcquireSRWLockSharedWait(IN OUT PRTL_SRWLOCK SRWLock,
+                             IN OUT PRTLP_SRWLOCK_WAITBLOCK FirstWait  OPTIONAL,
+                             IN OUT PRTLP_SRWLOCK_SHARED_WAKE WakeChain)
+{
+    if (FirstWait != NULL)
+    {
+        while (WakeChain->Wake == 0)
+        {
+            YieldProcessor();
+        }
+    }
+    else
+    {
+        LONG_PTR CurrentValue;
+
+        while (1)
+        {
+            CurrentValue = *(volatile LONG_PTR *)&SRWLock->Ptr;
+            if (CurrentValue & RTL_SRWLOCK_SHARED)
+            {
+                /* The RTL_SRWLOCK_OWNED bit always needs to be set when
+                   RTL_SRWLOCK_SHARED is set! */
+                ASSERT(CurrentValue & RTL_SRWLOCK_OWNED);
+
+                if (CurrentValue & RTL_SRWLOCK_CONTENDED)
+                {
+                    if (WakeChain->Wake != 0)
+                    {
+                        /* Our wait block became the first one
+                           in the chain, we own the lock now! */
+                        break;
+                    }
+                }
+                else
+                {
+                    /* The last wait block was removed and/or we're 
+                       finally a simple shared lock. This means we
+                       don't need to wait anymore, we acquired the lock! */
+                    break;
+                }
+            }
+
+            YieldProcessor();
+        }
+    }
+}
+
+
+VOID
+NTAPI
+RtlInitializeSRWLock(OUT PRTL_SRWLOCK SRWLock)
+{
+    SRWLock->Ptr = NULL;
+}
+
+
+VOID
+NTAPI
+RtlAcquireSRWLockShared(IN OUT PRTL_SRWLOCK SRWLock)
+{
+    __ALIGNED(16) RTLP_SRWLOCK_WAITBLOCK StackWaitBlock;
+    RTLP_SRWLOCK_SHARED_WAKE SharedWake;
+    LONG_PTR CurrentValue, NewValue;
+    PRTLP_SRWLOCK_WAITBLOCK First, Shared, FirstWait;
+
+    while (1)
+    {
+        CurrentValue = *(volatile LONG_PTR *)&SRWLock->Ptr;
+
+        if (CurrentValue & RTL_SRWLOCK_SHARED)
+        {
+            /* NOTE: It is possible that the RTL_SRWLOCK_OWNED bit is set! */
+
+            if (CurrentValue & RTL_SRWLOCK_CONTENDED)
+            {
+                /* There's other waiters already, lock the wait blocks and
+                   increment the shared count */
+                First = RtlpAcquireWaitBlockLock(SRWLock);
+                if (First != NULL)
+                {
+                    FirstWait = NULL;
+
+                    if (First->Exclusive)
+                    {
+                        /* We need to setup a new wait block! Although
+                           we're currently in a shared lock and we're acquiring
+                           a shared lock, there are exclusive locks queued. We need
+                           to wait until those are released. */
+                        Shared = First->Last;
+
+                        if (Shared->Exclusive)
+                        {
+                            StackWaitBlock.Exclusive = FALSE;
+                            StackWaitBlock.SharedCount = 1;
+                            StackWaitBlock.Next = NULL;
+                            StackWaitBlock.Last = &StackWaitBlock;
+                            StackWaitBlock.SharedWakeChain = &SharedWake;
+
+                            Shared->Next = &StackWaitBlock;
+                            First->Last = &StackWaitBlock;
+
+                            Shared = &StackWaitBlock;
+                            FirstWait = &StackWaitBlock;
+                        }
+                        else
+                        {
+                            Shared->LastSharedWake->Next = &SharedWake;
+                            Shared->SharedCount++;
+                        }
+                    }
+                    else
+                    {
+                        Shared = First;
+                        Shared->LastSharedWake->Next = &SharedWake;
+                        Shared->SharedCount++;
+                    }
+
+                    SharedWake.Next = NULL;
+                    SharedWake.Wake = 0;
+
+                    Shared->LastSharedWake = &SharedWake;
+
+                    ASSERT_SRW_WAITBLOCK(Shared);
+
+                    RtlpReleaseWaitBlockLock(SRWLock);
+
+                    RtlpAcquireSRWLockSharedWait(SRWLock,
+                                                 FirstWait,
+                                                 &SharedWake);
+
+                    /* Successfully incremented the shared count, we acquired the lock
*/
+                    break;
+                }
+            }
+            else
+            {
+                /* This is a fastest path, just increment the number of
+                   current shared locks */
+
+                /* Since the RTL_SRWLOCK_SHARED bit is set, the RTL_SRWLOCK_OWNED bit
also has
+                   to be set! */
+
+                ASSERT(CurrentValue & RTL_SRWLOCK_OWNED);
+
+                NewValue = (CurrentValue >> RTL_SRWLOCK_BITS) + 1;
+                NewValue = (NewValue << RTL_SRWLOCK_BITS) | (CurrentValue &
RTL_SRWLOCK_MASK);
+
+                if (InterlockedCompareExchangePointer(&SRWLock->Ptr,
+                                                      (PVOID)NewValue,
+                                                      (PVOID)CurrentValue) ==
(PVOID)CurrentValue)
+                {
+                    /* Successfully incremented the shared count, we acquired the lock
*/
+                    break;
+                }
+            }
+        }
+        else
+        {
+            if (CurrentValue & RTL_SRWLOCK_OWNED)
+            {
+                /* The resource is currently acquired exclusively */
+                if (CurrentValue & RTL_SRWLOCK_CONTENDED)
+                {
+                    SharedWake.Next = NULL;
+                    SharedWake.Wake = 0;
+
+                    /* There's other waiters already, lock the wait blocks and
+                       increment the shared count. If the last block in the chain
+                       is an exclusive lock, add another block. */
+
+                    StackWaitBlock.Exclusive = FALSE;
+                    StackWaitBlock.SharedCount = 0;
+                    StackWaitBlock.Next = NULL;
+                    StackWaitBlock.Last = &StackWaitBlock;
+                    StackWaitBlock.SharedWakeChain = &SharedWake;
+
+                    First = RtlpAcquireWaitBlockLock(SRWLock);
+                    if (First != NULL)
+                    {
+                        Shared = First->Last;
+                        if (Shared->Exclusive)
+                        {
+                            Shared->Next = &StackWaitBlock;
+                            First->Last = &StackWaitBlock;
+
+                            Shared = &StackWaitBlock;
+                            FirstWait = &StackWaitBlock;
+                        }
+                        else
+                        {
+                            FirstWait = NULL;
+                            Shared->LastSharedWake->Next = &SharedWake;
+                        }
+
+                        ASSERT_SRW_WAITBLOCK(Shared);
+
+                        Shared->SharedCount++;
+                        Shared->LastSharedWake = &SharedWake;
+
+                        RtlpReleaseWaitBlockLock(SRWLock);
+
+                        RtlpAcquireSRWLockSharedWait(SRWLock,
+                                                     FirstWait,
+                                                     &SharedWake);
+
+                        /* Successfully incremented the shared count, we acquired the
lock */
+                        break;
+                    }
+                }
+                else
+                {
+                    SharedWake.Next = NULL;
+                    SharedWake.Wake = 0;
+
+                    /* We need to setup the first wait block. Currently an exclusive lock
is
+                       held, change the lock to contended mode. */
+                    StackWaitBlock.Exclusive = FALSE;
+                    StackWaitBlock.SharedCount = 1;
+                    StackWaitBlock.Next = NULL;
+                    StackWaitBlock.Last = &StackWaitBlock;
+                    StackWaitBlock.SharedWakeChain = &SharedWake;
+                    StackWaitBlock.LastSharedWake = &SharedWake;
+
+                    ASSERT_SRW_WAITBLOCK(&StackWaitBlock);
+
+                    NewValue = (ULONG_PTR)&StackWaitBlock | RTL_SRWLOCK_OWNED |
RTL_SRWLOCK_CONTENDED;
+                    if (InterlockedCompareExchangePointer(&SRWLock->Ptr,
+                                                          (PVOID)NewValue,
+                                                          (PVOID)CurrentValue) ==
(PVOID)CurrentValue)
+                    {
+                        RtlpAcquireSRWLockSharedWait(SRWLock,
+                                                     &StackWaitBlock,
+                                                     &SharedWake);
+
+                        /* Successfully set the shared count, we acquired the lock */
+                        break;
+                    }
+                }
+            }
+            else
+            {
+                /* This is a fast path, we can simply try to set the shared count to 1
*/
+                NewValue = (1 << RTL_SRWLOCK_BITS) | RTL_SRWLOCK_SHARED |
RTL_SRWLOCK_OWNED;
+
+                /* The RTL_SRWLOCK_CONTENDED bit should never be set if neither the
+                   RTL_SRWLOCK_SHARED nor the RTL_SRWLOCK_OWNED bit is set */
+                ASSERT(!(CurrentValue & RTL_SRWLOCK_CONTENDED));
+
+                if (InterlockedCompareExchangePointer(&SRWLock->Ptr,
+                                                      (PVOID)NewValue,
+                                                      (PVOID)CurrentValue) ==
(PVOID)CurrentValue)
+                {
+                    /* Successfully set the shared count, we acquired the lock */
+                    break;
+                }
+            }
+        }
+
+        YieldProcessor();
+    }
+}
+
+
+VOID
+NTAPI
+RtlReleaseSRWLockShared(IN OUT PRTL_SRWLOCK SRWLock)
+{
+    LONG_PTR CurrentValue, NewValue;
+    PRTLP_SRWLOCK_WAITBLOCK WaitBlock;
+    BOOLEAN LastShared;
+
+    while (1)
+    {
+        CurrentValue = *(volatile LONG_PTR *)&SRWLock->Ptr;
+
+        if (CurrentValue & RTL_SRWLOCK_SHARED)
+        {
+            if (CurrentValue & RTL_SRWLOCK_CONTENDED)
+            {
+                /* There's a wait block, we need to wake a pending
+                   exclusive acquirer if this is the last shared release */
+                WaitBlock = RtlpAcquireWaitBlockLock(SRWLock);
+                if (WaitBlock != NULL)
+                {
+                    LastShared = (--WaitBlock->SharedCount == 0);
+
+                    if (LastShared)
+                        RtlpReleaseWaitBlockLockLastShared(SRWLock,
+                                                           WaitBlock);
+                    else
+                        RtlpReleaseWaitBlockLock(SRWLock);
+
+                    /* We released the lock */
+                    break;
+                }
+            }
+            else
+            {
+                /* This is a fast path, we can simply decrement the shared
+                   count and store the pointer */
+                NewValue = CurrentValue >> RTL_SRWLOCK_BITS;
+
+                if (--NewValue != 0)
+                {
+                    NewValue = (NewValue << RTL_SRWLOCK_BITS) | RTL_SRWLOCK_SHARED
| RTL_SRWLOCK_OWNED;
+                }
+
+                if (InterlockedCompareExchangePointer(&SRWLock->Ptr,
+                                                      (PVOID)NewValue,
+                                                      (PVOID)CurrentValue) ==
(PVOID)CurrentValue)
+                {
+                    /* Successfully released the lock */
+                    break;
+                }
+            }
+        }
+        else
+        {
+            /* The RTL_SRWLOCK_SHARED bit has to be present now,
+               even in the contended case! */
+            RtlRaiseStatus(STATUS_RESOURCE_NOT_OWNED);
+        }
+
+        YieldProcessor();
+    }
+}
+
+
+VOID
+NTAPI
+RtlAcquireSRWLockExclusive(IN OUT PRTL_SRWLOCK SRWLock)
+{
+    __ALIGNED(16) RTLP_SRWLOCK_WAITBLOCK StackWaitBlock;
+    PRTLP_SRWLOCK_WAITBLOCK First, Last;
+
+    if (InterlockedBitTestAndSetPointer(&SRWLock->Ptr,
+                                        RTL_SRWLOCK_OWNED_BIT))
+    {
+        LONG_PTR CurrentValue, NewValue;
+
+        while (1)
+        {
+            CurrentValue = *(volatile LONG_PTR *)&SRWLock->Ptr;
+
+            if (CurrentValue & RTL_SRWLOCK_SHARED)
+            {
+                /* A shared lock is being held right now. We need to add a wait block!
*/
+
+                if (CurrentValue & RTL_SRWLOCK_CONTENDED)
+                {
+                    goto AddWaitBlock;
+                }
+                else
+                {
+                    /* There are no wait blocks so far, we need to add ourselves as the
first
+                       wait block. We need to keep the shared count! */
+                    StackWaitBlock.Exclusive = TRUE;
+                    StackWaitBlock.SharedCount = CurrentValue >> RTL_SRWLOCK_BITS;
+                    StackWaitBlock.Next = NULL;
+                    StackWaitBlock.Last = &StackWaitBlock;
+                    StackWaitBlock.Wake = 0;
+
+                    ASSERT_SRW_WAITBLOCK(&StackWaitBlock);
+
+                    NewValue = (ULONG_PTR)&StackWaitBlock | RTL_SRWLOCK_SHARED |
RTL_SRWLOCK_CONTENDED | RTL_SRWLOCK_OWNED;
+
+                    if (InterlockedCompareExchangePointer(&SRWLock->Ptr,
+                                                          (PVOID)NewValue,
+                                                          (PVOID)CurrentValue) ==
(PVOID)CurrentValue)
+                    {
+                        RtlpAcquireSRWLockExclusiveWait(SRWLock,
+                                                        &StackWaitBlock);
+
+                        /* Successfully acquired the exclusive lock */
+                        break;
+                    }
+                }
+            }
+            else
+            {
+                if (CurrentValue & RTL_SRWLOCK_OWNED)
+                {
+                    /* An exclusive lock is being held right now. We need to add a wait
block! */
+
+                    if (CurrentValue & RTL_SRWLOCK_CONTENDED)
+                    {
+AddWaitBlock:
+                        StackWaitBlock.Exclusive = TRUE;
+                        StackWaitBlock.SharedCount = 0;
+                        StackWaitBlock.Next = NULL;
+                        StackWaitBlock.Last = &StackWaitBlock;
+                        StackWaitBlock.Wake = 0;
+
+                        ASSERT_SRW_WAITBLOCK(&StackWaitBlock);
+
+                        First = RtlpAcquireWaitBlockLock(SRWLock);
+                        if (First != NULL)
+                        {
+                            Last = First->Last;
+                            Last->Next = &StackWaitBlock;
+                            First->Last = &StackWaitBlock;
+
+                            RtlpReleaseWaitBlockLock(SRWLock);
+
+                            RtlpAcquireSRWLockExclusiveWait(SRWLock,
+                                                            &StackWaitBlock);
+
+                            /* Successfully acquired the exclusive lock */
+                            break;
+                        }
+                    }
+                    else
+                    {
+                        /* There are no wait blocks so far, we need to add ourselves as
the first
+                           wait block. We need to keep the shared count! */
+                        StackWaitBlock.Exclusive = TRUE;
+                        StackWaitBlock.SharedCount = 0;
+                        StackWaitBlock.Next = NULL;
+                        StackWaitBlock.Last = &StackWaitBlock;
+                        StackWaitBlock.Wake = 0;
+
+                        ASSERT_SRW_WAITBLOCK(&StackWaitBlock);
+
+                        NewValue = (ULONG_PTR)&StackWaitBlock | RTL_SRWLOCK_OWNED |
RTL_SRWLOCK_CONTENDED;
+                        if (InterlockedCompareExchangePointer(&SRWLock->Ptr,
+                                                              (PVOID)NewValue,
+                                                              (PVOID)CurrentValue) ==
(PVOID)CurrentValue)
+                        {
+                            RtlpAcquireSRWLockExclusiveWait(SRWLock,
+                                                            &StackWaitBlock);
+
+                            /* Successfully acquired the exclusive lock */
+                            break;
+                        }
+                    }
+                }
+                else
+                {
+                    if (!InterlockedBitTestAndSetPointer(&SRWLock->Ptr,
+                                                         RTL_SRWLOCK_OWNED_BIT))
+                    {
+                        /* We managed to get hold of a simple exclusive lock! */
+                        break;
+                    }
+                }
+            }
+
+            YieldProcessor();
+        }
+    }
+}
+
+
+VOID
+NTAPI
+RtlReleaseSRWLockExclusive(IN OUT PRTL_SRWLOCK SRWLock)
+{
+    LONG_PTR CurrentValue, NewValue;
+    PRTLP_SRWLOCK_WAITBLOCK WaitBlock;
+
+    while (1)
+    {
+        CurrentValue = *(volatile LONG_PTR *)&SRWLock->Ptr;
+
+        if (!(CurrentValue & RTL_SRWLOCK_OWNED))
+        {
+            RtlRaiseStatus(STATUS_RESOURCE_NOT_OWNED);
+        }
+
+        if (!(CurrentValue & RTL_SRWLOCK_SHARED))
+        {
+            if (CurrentValue & RTL_SRWLOCK_CONTENDED)
+            {
+                /* There's a wait block, we need to wake the next pending
+                   acquirer (exclusive or shared) */
+                WaitBlock = RtlpAcquireWaitBlockLock(SRWLock);
+                if (WaitBlock != NULL)
+                {
+                    RtlpReleaseWaitBlockLockExclusive(SRWLock,
+                                                      WaitBlock);
+
+                    /* We released the lock */
+                    break;
+                }
+            }
+            else
+            {
+                /* This is a fast path, we can simply clear the RTL_SRWLOCK_OWNED
+                   bit. All other bits should be 0 now because this is a simple
+                   exclusive lock and no one is waiting. */
+
+                ASSERT(!(CurrentValue & ~RTL_SRWLOCK_OWNED));
+
+                NewValue = 0;
+                if (InterlockedCompareExchangePointer(&SRWLock->Ptr,
+                                                      (PVOID)NewValue,
+                                                      (PVOID)CurrentValue) ==
(PVOID)CurrentValue)
+                {
+                    /* We released the lock */
+                    break;
+                }
+            }
+        }
+        else
+        {
+            /* The RTL_SRWLOCK_SHARED bit must not be present now,
+               not even in the contended case! */
+            RtlRaiseStatus(STATUS_RESOURCE_NOT_OWNED);
+        }
+
+        YieldProcessor();
+    }
+}

Propchange: trunk/reactos/lib/rtl/srw.c
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