ntoskrnl/ke/spinlock.c

   1 /* $Id$
   2  *
   3  * COPYRIGHT:       See COPYING in the top level directory
   4  * PROJECT:         ReactOS kernel
   5  * FILE:            ntoskrnl/ke/spinlock.c
   6  * PURPOSE:         Implements spinlocks
   7  * PROGRAMMER:      David Welch (welch@cwcom.net)
   8  * UPDATE HISTORY:
   9  *                  3/6/98: Created
  10  */
  11
  12 /*
  13  * NOTE: On a uniprocessor machine spinlocks are implemented by raising
  14  * the irq level
  15  */
  16
  17 /* INCLUDES ****************************************************************/
  18
  19 #include <ddk/ntddk.h>
  20 #include <roscfg.h>
  21
  22 #include <internal/debug.h>
  23
  24 /* FUNCTIONS ***************************************************************/
  25
  26 /*
  27  * @implemented
  28  */
  29 BOOLEAN STDCALL
  30 KeSynchronizeExecution (PKINTERRUPT             Interrupt,
  31                         PKSYNCHRONIZE_ROUTINE   SynchronizeRoutine,
  32                         PVOID                   SynchronizeContext)
  33 /*
  34  * FUNCTION: Synchronizes the execution of a given routine with the ISR
  35  * of a given interrupt object
  36  * ARGUMENTS:
  37  *       Interrupt = Interrupt object to synchronize with
  38  *       SynchronizeRoutine = Routine to call whose execution is
  39  *                            synchronized with the ISR
  40  *       SynchronizeContext = Parameter to pass to the synchronized routine
  41  * RETURNS: TRUE if the operation succeeded
  42  */
  43 {
  44    KIRQL oldlvl;
  45    BOOLEAN ret;
  46
  47    KeRaiseIrql(Interrupt->SynchLevel,&oldlvl);
  48    KeAcquireSpinLockAtDpcLevel(Interrupt->IrqLock);
  49
  50    ret = SynchronizeRoutine(SynchronizeContext);
  51
  52    KeReleaseSpinLockFromDpcLevel(Interrupt->IrqLock);
  53    KeLowerIrql(oldlvl);
  54
  55    return(ret);
  56 }
  57
  58 /*
  59  * @implemented
  60  */
  61 VOID STDCALL
  62 KeInitializeSpinLock (PKSPIN_LOCK       SpinLock)
  63 /*
  64  * FUNCTION: Initalizes a spinlock
  65  * ARGUMENTS:
  66  *           SpinLock = Caller supplied storage for the spinlock
  67  */
  68 {
  69    *SpinLock = 0;
  70 }
  71
  72 #undef KeAcquireSpinLockAtDpcLevel
  73
  74 /*
  75  * @implemented
  76  */
  77 VOID STDCALL
  78 KeAcquireSpinLockAtDpcLevel (PKSPIN_LOCK        SpinLock)
  79 /*
  80  * FUNCTION: Acquires a spinlock when the caller is already running at
  81  * dispatch level
  82  * ARGUMENTS:
  83  *        SpinLock = Spinlock to acquire
  84  */
  85 {
  86    ULONG i;
  87
  88    /*
  89     * FIXME: This depends on gcc assembling this test to a single load from
  90     * the spinlock's value.
  91     */
  92    if (*SpinLock >= 2)
  93      {
  94         DbgPrint("Lock %x has bad value %x\n", SpinLock, *SpinLock);
  95         KEBUGCHECK(0);
  96      }
  97
  98    while ((i = InterlockedExchange((LONG *)SpinLock, 1)) == 1)
  99      {
 100 #ifndef MP
 101        DbgPrint("Spinning on spinlock %x current value %x\n", SpinLock, i);
 102        KEBUGCHECK(0);
 103 #else /* not MP */
 104        /* Avoid reading the value again too fast */
 105 #endif /* MP */
 106      }
 107 }
 108
 109 #undef KeReleaseSpinLockFromDpcLevel
 110
 111 /*
 112  * @implemented
 113  */
 114 VOID STDCALL
 115 KeReleaseSpinLockFromDpcLevel (PKSPIN_LOCK      SpinLock)
 116 /*
 117  * FUNCTION: Releases a spinlock when the caller was running at dispatch
 118  * level before acquiring it
 119  * ARGUMENTS:
 120  *         SpinLock = Spinlock to release
 121  */
 122 {
 123    if (*SpinLock != 1)
 124      {
 125         DbgPrint("Releasing unacquired spinlock %x\n", SpinLock);
 126         KEBUGCHECK(0);
 127      }
 128    (void)InterlockedExchange((LONG *)SpinLock, 0);
 129 }
 130
 131 /* EOF */