ex.h

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 * INTERNAL MACRO
 *
 *     The ExInitializeRundownProtection routine initializes a rundown
 *     protection descriptor.
 *
 * @param RunRef
 *        Pointer to a rundown reference descriptor.
 *
 * @return None.
 *
 * @remarks This is the internal macro for system use only.
 *
 *--*/
VOID
FORCEINLINE
ExInitializeRundownProtection(IN PEX_RUNDOWN_REF RunRef)
{
    /* Set the count to zero */
    RunRef->Count = 0;
}

/*++
 * @name ExWaitForRundownProtectionRelease
 * INTERNAL MACRO
 *
 *     The ExWaitForRundownProtectionRelease routine waits until the specified
 *     rundown descriptor has been released.
 *
 * @param RunRef
 *        Pointer to a rundown reference descriptor.
 *
 * @return None.
 *
 * @remarks This is the internal macro for system use only. If a wait is actually
 *          necessary, then the slow path is taken through the exported function.
 *
 *--*/
VOID
FORCEINLINE
ExWaitForRundownProtectionRelease(IN PEX_RUNDOWN_REF RunRef)
{
    ULONG_PTR Value;

    /* Set the active bit */
    Value = ExpChangeRundown(RunRef, EX_RUNDOWN_ACTIVE, 0);
    if ((Value) || (Value != EX_RUNDOWN_ACTIVE))
    {
        /* If the the rundown wasn't already active, then take the long path */
        ExfWaitForRundownProtectionRelease(RunRef);
    }
}

/*++
 * @name ExRundownCompleted
 * INTERNAL MACRO
 *
 *     The ExRundownCompleted routine completes the rundown of the specified
 *     descriptor by setting the active bit.
 *
 * @param RunRef
 *        Pointer to a rundown reference descriptor.
 *
 * @return None.
 *
 * @remarks This is the internal macro for system use only.
 *
 *--*/
VOID
FORCEINLINE
ExRundownCompleted(IN PEX_RUNDOWN_REF RunRef)
{
    /* Sanity check */
    ASSERT((RunRef->Count & EX_RUNDOWN_ACTIVE) != 0);

    /* Mark the counter as active */
    ExpSetRundown(&RunRef->Count, EX_RUNDOWN_ACTIVE);
}

/* PUSHLOCKS *****************************************************************/

/*++
 * @name ExAcquirePushLockExclusive
 * INTERNAL MACRO
 *
 *     The ExAcquirePushLockExclusive macro exclusively acquires a PushLock.
 *
 * @params PushLock
 *         Pointer to the pushlock which is to be acquired.
 *
 * @return None.
 *
 * @remarks The function attempts the quickest route to acquire the lock, which is
 *          to simply set the lock bit.
 *          However, if the pushlock is already shared, the slower path is taken.
 *
 *          Callers of ExAcquirePushLockShared must be running at IRQL <= APC_LEVEL.
 *          This macro should usually be paired up with KeAcquireCriticalRegion.
 *
 *--*/
VOID
FORCEINLINE
ExAcquirePushLockExclusive(PEX_PUSH_LOCK PushLock)
{
    /* Try acquiring the lock */
    if (InterlockedBitTestAndSet((PLONG)PushLock, EX_PUSH_LOCK_LOCK_V))
    {
        /* Someone changed it, use the slow path */
        ExfAcquirePushLockExclusive(PushLock);
    }

    /* Sanity check */
    ASSERT(PushLock->Locked);
}

/*++
 * @name ExAcquirePushLockShared
 * INTERNAL MACRO
 *
 *     The ExAcquirePushLockShared macro acquires a shared PushLock.
 *
 * @params PushLock
 *         Pointer to the pushlock which is to be acquired.
 *
 * @return None.
 *
 * @remarks The function attempts the quickest route to acquire the lock, which is
 *          to simply set the lock bit and set the share count to one.
 *          However, if the pushlock is already shared, the slower path is taken.
 *
 *          Callers of ExAcquirePushLockShared must be running at IRQL <= APC_LEVEL.
 *          This macro should usually be paired up with KeAcquireCriticalRegion.
 *
 *--*/
VOID
FORCEINLINE
ExAcquirePushLockShared(PEX_PUSH_LOCK PushLock)
{
    EX_PUSH_LOCK NewValue;

    /* Try acquiring the lock */
    NewValue.Value = EX_PUSH_LOCK_LOCK | EX_PUSH_LOCK_SHARE_INC;
    if (!InterlockedCompareExchangePointer(PushLock, NewValue.Ptr, 0))
    {
        /* Someone changed it, use the slow path */
        ExfAcquirePushLockShared(PushLock);
    }

    /* Sanity checks */
    ASSERT(PushLock->Locked);
    ASSERT(PushLock->Waiting || PushLock->Shared > 0);
}

/*++
 * @name ExWaitOnPushLock
 * INTERNAL MACRO
 *
 *     The ExWaitOnPushLock macro acquires and instantly releases a pushlock.
 *
 * @params PushLock
 *         Pointer to a pushlock.
 *
 * @return None.
 *
 * @remarks The function attempts to get any exclusive waiters out of their slow
 *          path by forcing an instant acquire/release operation.
 *
 *          Callers of ExWaitOnPushLock must be running at IRQL <= APC_LEVEL.
 *
 *--*/
VOID
FORCEINLINE
ExWaitOnPushLock(PEX_PUSH_LOCK PushLock)
{
    /* Acquire the lock */
    ExfAcquirePushLockExclusive(PushLock);
    ASSERT(PushLock->Locked);

    /* Release it */
    ExfReleasePushLockExclusive(PushLock);
}

/*++
 * @name ExReleasePushLockShared
 * INTERNAL MACRO
 *
 *     The ExReleasePushLockShared macro releases a previously acquired PushLock.
 *
 * @params PushLock
 *         Pointer to a previously acquired pushlock.
 *
 * @return None.
 *
 * @remarks The function attempts the quickest route to release the lock, which is 
 *          to simply decrease the share count and remove the lock bit.
 *          However, if the pushlock is being waited on then the long path is taken.
 *
 *          Callers of ExReleasePushLockShared must be running at IRQL <= APC_LEVEL.
 *          This macro should usually be paired up with KeLeaveCriticalRegion.
 *
 *--*/
VOID
FORCEINLINE
ExReleasePushLockShared(PEX_PUSH_LOCK PushLock)
{
    EX_PUSH_LOCK OldValue;

    /* Sanity checks */
    ASSERT(PushLock->Locked);
    ASSERT(PushLock->Waiting || PushLock->Shared > 0);

    /* Try to clear the pushlock */
    OldValue.Value = EX_PUSH_LOCK_LOCK | EX_PUSH_LOCK_SHARE_INC;
    if (InterlockedCompareExchangePointer(PushLock, 0, OldValue.Ptr) !=
        OldValue.Ptr)
    {
        /* There are still other people waiting on it */
        ExfReleasePushLockShared(PushLock);
    }
}

/*++
 * @name ExReleasePushLockExclusive
 * INTERNAL MACRO
 *
 *     The ExReleasePushLockExclusive macro releases a previously
 *     exclusively acquired PushLock.
 *
 * @params PushLock
 *         Pointer to a previously acquired pushlock.
 *
 * @return None.
 *
 * @remarks The function attempts the quickest route to release the lock, which is
 *          to simply clear the locked bit.
 *          However, if the pushlock is being waited on, the slow path is taken
 *          in an attempt to wake up the lock.
 *
 *          Callers of ExReleasePushLockExclusive must be running at IRQL <= APC_LEVEL.
 *          This macro should usually be paired up with KeLeaveCriticalRegion.
 *
 *--*/
VOID
FORCEINLINE
ExReleasePushLockExclusive(PEX_PUSH_LOCK PushLock)
{
    EX_PUSH_LOCK OldValue;

    /* Sanity checks */
    ASSERT(PushLock->Locked);
    ASSERT(PushLock->Waiting || PushLock->Shared == 0);

    /* Unlock the pushlock */
    OldValue.Value = InterlockedExchangeAddSizeT((PLONG)PushLock, -1);

    /* Sanity checks */
    ASSERT(OldValue.Locked);
    ASSERT(OldValue.Waiting || OldValue.Shared == 0);

    /* Check if anyone is waiting on it and it's not already waking*/
    if ((OldValue.Waiting) && !(OldValue.Waking))
    {
        /* Wake it up */
        ExfTryToWakePushLock(PushLock);
    }
}

/*++
 * @name ExReleasePushLock
 * INTERNAL MACRO
 *
 *     The ExReleasePushLock macro releases a previously acquired PushLock.
 *
 * @params PushLock
 *         Pointer to a previously acquired pushlock.
 *
 * @return None.
 *
 * @remarks The function attempts the quickest route to release the lock, which is 
 *          to simply clear all the fields and decrease the share count if required.
 *          However, if the pushlock is being waited on then the long path is taken.
 *
 *          Callers of ExReleasePushLock must be running at IRQL <= APC_LEVEL.
 *          This macro should usually be paired up with KeLeaveCriticalRegion.
 *
 *--*/
VOID
FORCEINLINE
ExReleasePushLock(PEX_PUSH_LOCK PushLock)
{
    EX_PUSH_LOCK OldValue = *PushLock;
    EX_PUSH_LOCK NewValue;

    /* Sanity checks */
    ASSERT(OldValue.Locked);

    /* Check if the pushlock is shared */
    if (OldValue.Shared > 1)
    {
        /* Decrease the share count */
        NewValue.Value = OldValue.Value &~ EX_PUSH_LOCK_SHARE_INC;
    }
    else
    {
        /* Clear the pushlock entirely */
        NewValue.Value = 0;
    }

    /* Check if nobody is waiting on us and try clearing the lock here */
    if ((OldValue.Waiting) ||
        (InterlockedCompareExchangePointer(PushLock, NewValue.Ptr, OldValue.Ptr) ==
         OldValue.Ptr))
    {
        /* We have waiters, use the long path */
        ExfReleasePushLock(PushLock);
    }
}

/* OTHER FUNCTIONS **********************************************************/

LONGLONG
FASTCALL
ExfpInterlockedExchange64(
    LONGLONG volatile * Destination,
    PLONGLONG Exchange
);

NTSTATUS
ExpSetTimeZoneInformation(PTIME_ZONE_INFORMATION TimeZoneInformation);

NTSTATUS
NTAPI
ExpAllocateLocallyUniqueId(OUT LUID *LocallyUniqueId);

VOID
STDCALL
ExTimerRundown(VOID);

#define InterlockedDecrementUL(Addend) \
   (ULONG)InterlockedDecrement((PLONG)(Addend))

#define InterlockedIncrementUL(Addend) \
   (ULONG)InterlockedIncrement((PLONG)(Addend))

#define InterlockedExchangeUL(Target, Value) \
   (ULONG)InterlockedExchange((PLONG)(Target), (LONG)(Value))

#define InterlockedExchangeAddUL(Addend, Value) \
   (ULONG)InterlockedExchangeAdd((PLONG)(Addend), (LONG)(Value))

#define InterlockedCompareExchangeUL(Destination, Exchange, Comperand) \
   (ULONG)InterlockedCompareExchange((PLONG)(Destination), (LONG)(Exchange), (LONG)(Comperand))

#define ExfInterlockedCompareExchange64UL(Destination, Exchange, Comperand) \
   (ULONGLONG)ExfInterlockedCompareExchange64((PLONGLONG)(Destination), (PLONGLONG)(Exchange), (PLONGLONG)(Comperand))

#define ExfpInterlockedExchange64UL(Target, Value) \
   (ULONGLONG)ExfpInterlockedExchange64((PLONGLONG)(Target), (PLONGLONG)(Value))

#endif /* __NTOSKRNL_INCLUDE_INTERNAL_EXECUTIVE_H */