reactos/hal/halx86/generic/fmutex.c

   1 /*
   2  * COPYRIGHT:       See COPYING in the top level directory
   3  * PROJECT:         ReactOS HAL
   4  * FILE:            ntoskrnl/hal/x86/fmutex.c
   5  * PURPOSE:         Deprecated HAL Fast Mutex
   6  * PROGRAMMERS:     Alex Ionescu (alex@relsoft.net)
   7  */
   8
   9 /*
  10  * NOTE: Even HAL itself has #defines to use the Exi* APIs inside NTOSKRNL.
  11  *       These are only exported here for compatibility with really old
  12  *       drivers. Also note that in theory, these can be made much faster
  13  *       by using assembly and inlining all the operations, including
  14  *       raising and lowering irql.
  15  */
  16
  17 /* INCLUDES *****************************************************************/
  18
  19 #include <hal.h>
  20 #define NDEBUG
  21 #include <debug.h>
  22
  23 #undef ExAcquireFastMutex
  24 #undef ExReleaseFastMutex
  25 #undef ExTryToAcquireFastMutex
  26
  27 /* FUNCTIONS *****************************************************************/
  28
  29 VOID
  30 FASTCALL
  31 ExAcquireFastMutex(PFAST_MUTEX FastMutex)
  32 {
  33     KIRQL OldIrql;
  34
  35     /* Raise IRQL to APC */
  36     OldIrql = KfRaiseIrql(APC_LEVEL);
  37
  38     /* Decrease the count */
  39     if (InterlockedDecrement(&FastMutex->Count))
  40     {
  41         /* Someone is still holding it, use slow path */
  42         FastMutex->Contention++;
  43         KeWaitForSingleObject(&FastMutex->Gate,
  44                               WrExecutive,
  45                               KernelMode,
  46                               FALSE,
  47                               NULL);
  48     }
  49
  50     /* Set the owner and IRQL */
  51     FastMutex->Owner = KeGetCurrentThread();
  52     FastMutex->OldIrql = OldIrql;
  53 }
  54
  55 VOID
  56 FASTCALL
  57 ExReleaseFastMutex(PFAST_MUTEX FastMutex)
  58 {
  59     KIRQL OldIrql;
  60
  61     /* Erase the owner */
  62     FastMutex->Owner = (PVOID)1;
  63     OldIrql = FastMutex->OldIrql;
  64
  65     /* Increase the count */
  66     if (InterlockedIncrement(&FastMutex->Count) <= 0)
  67     {
  68         /* Someone was waiting for it, signal the waiter */
  69         KeSetEventBoostPriority(&FastMutex->Gate, IO_NO_INCREMENT);
  70     }
  71
  72     /* Lower IRQL back */
  73     KfLowerIrql(OldIrql);
  74 }
  75
  76 BOOLEAN
  77 FASTCALL
  78 ExTryToAcquireFastMutex(PFAST_MUTEX FastMutex)
  79 {
  80     KIRQL OldIrql;
  81
  82     /* Raise to APC_LEVEL */
  83     OldIrql = KfRaiseIrql(APC_LEVEL);
  84
  85     /* Check if we can quickly acquire it */
  86     if (InterlockedCompareExchange(&FastMutex->Count, 0, 1) == 1)
  87     {
  88         /* We have, set us as owners */
  89         FastMutex->Owner = KeGetCurrentThread();
  90         FastMutex->OldIrql = OldIrql;
  91         return TRUE;
  92     }
  93     else
  94     {
  95         /* Acquire attempt failed */
  96         KfLowerIrql(OldIrql);
  97         return FALSE;
  98     }
  99 }
 100
 101 /* EOF */