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100 lines
2.4 KiB
C
100 lines
2.4 KiB
C
/*
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* COPYRIGHT: See COPYING in the top level directory
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* PROJECT: ReactOS HAL
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* FILE: ntoskrnl/hal/x86/fmutex.c
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* PURPOSE: Deprecated HAL Fast Mutex
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* PROGRAMMERS: Alex Ionescu (alex@relsoft.net)
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*/
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/*
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* NOTE: Even HAL itself has #defines to use the Exi* APIs inside NTOSKRNL.
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* These are only exported here for compatibility with really old
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* drivers. Also note that in theory, these can be made much faster
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* by using assembly and inlining all the operations, including
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* raising and lowering irql.
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*/
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/* INCLUDES *****************************************************************/
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#include <hal.h>
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#define NDEBUG
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#include <debug.h>
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#undef ExAcquireFastMutex
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#undef ExReleaseFastMutex
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/* FUNCTIONS *****************************************************************/
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VOID
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FASTCALL
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ExAcquireFastMutex(PFAST_MUTEX FastMutex)
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{
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KIRQL OldIrql;
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/* Raise IRQL to APC */
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KeRaiseIrql(APC_LEVEL, &OldIrql);
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/* Decrease the count */
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if (InterlockedDecrement(&FastMutex->Count))
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{
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/* Someone is still holding it, use slow path */
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FastMutex->Contention++;
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KeWaitForSingleObject(&FastMutex->Event,
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WrExecutive,
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KernelMode,
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FALSE,
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NULL);
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}
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/* Set the owner and IRQL */
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FastMutex->Owner = KeGetCurrentThread();
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FastMutex->OldIrql = OldIrql;
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}
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VOID
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FASTCALL
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ExReleaseFastMutex(PFAST_MUTEX FastMutex)
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{
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KIRQL OldIrql;
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/* Erase the owner */
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FastMutex->Owner = (PVOID)1;
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OldIrql = FastMutex->OldIrql;
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/* Increase the count */
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if (InterlockedIncrement(&FastMutex->Count) <= 0)
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{
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/* Someone was waiting for it, signal the waiter */
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KeSetEventBoostPriority(&FastMutex->Event, IO_NO_INCREMENT);
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}
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/* Lower IRQL back */
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KeLowerIrql(OldIrql);
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}
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BOOLEAN
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FASTCALL
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ExiTryToAcquireFastMutex(PFAST_MUTEX FastMutex)
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{
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KIRQL OldIrql;
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/* Raise to APC_LEVEL */
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KeRaiseIrql(APC_LEVEL, &OldIrql);
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/* Check if we can quickly acquire it */
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if (InterlockedCompareExchange(&FastMutex->Count, 0, 1) == 1)
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{
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/* We have, set us as owners */
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FastMutex->Owner = KeGetCurrentThread();
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FastMutex->OldIrql = OldIrql;
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return TRUE;
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}
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else
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{
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/* Acquire attempt failed */
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KeLowerIrql(OldIrql);
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return FALSE;
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}
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}
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/* EOF */
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