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 BOOLEAN STDCALL
  27 KeSynchronizeExecution (PKINTERRUPT             Interrupt,
  28                         PKSYNCHRONIZE_ROUTINE   SynchronizeRoutine,
  29                         PVOID                   SynchronizeContext)
  30 /*
  31  * FUNCTION: Synchronizes the execution of a given routine with the ISR
  32  * of a given interrupt object
  33  * ARGUMENTS:
  34  *       Interrupt = Interrupt object to synchronize with
  35  *       SynchronizeRoutine = Routine to call whose execution is
  36  *                            synchronized with the ISR
  37  *       SynchronizeContext = Parameter to pass to the synchronized routine
  38  * RETURNS: TRUE if the operation succeeded
  39  */
  40 {
  41    KIRQL oldlvl;
  42    BOOLEAN ret;
  43
  44    KeRaiseIrql(Interrupt->SynchLevel,&oldlvl);
  45    KeAcquireSpinLockAtDpcLevel(Interrupt->IrqLock);
  46
  47    ret = SynchronizeRoutine(SynchronizeContext);
  48
  49    KeReleaseSpinLockFromDpcLevel(Interrupt->IrqLock);
  50    KeLowerIrql(oldlvl);
  51
  52    return(ret);
  53 }
  54
  55 VOID STDCALL
  56 KeInitializeSpinLock (PKSPIN_LOCK       SpinLock)
  57 /*
  58  * FUNCTION: Initalizes a spinlock
  59  * ARGUMENTS:
  60  *           SpinLock = Caller supplied storage for the spinlock
  61  */
  62 {
  63    SpinLock->Lock = 0;
  64 }
  65
  66 VOID STDCALL
  67 KeAcquireSpinLockAtDpcLevel (PKSPIN_LOCK        SpinLock)
  68 /*
  69  * FUNCTION: Acquires a spinlock when the caller is already running at
  70  * dispatch level
  71  * ARGUMENTS:
  72  *        SpinLock = Spinlock to acquire
  73  */
  74 {
  75    ULONG i;
  76
  77    /*
  78     * FIXME: This depends on gcc assembling this test to a single load from
  79     * the spinlock's value.
  80     */
  81    if ((ULONG)SpinLock->Lock >= 2)
  82      {
  83         DbgPrint("Lock %x has bad value %x\n", SpinLock, SpinLock->Lock);
  84         KeBugCheck(0);
  85      }
  86
  87    while ((i = InterlockedExchange(&SpinLock->Lock, 1)) == 1)
  88      {
  89 #ifndef MP
  90        DbgPrint("Spinning on spinlock %x current value %x\n", SpinLock, i);
  91        KeBugCheck(0);
  92 #else /* not MP */
  93        /* Avoid reading the value again too fast */
  94 #endif /* MP */
  95      }
  96 }
  97
  98 VOID STDCALL
  99 KeReleaseSpinLockFromDpcLevel (PKSPIN_LOCK      SpinLock)
 100 /*
 101  * FUNCTION: Releases a spinlock when the caller was running at dispatch
 102  * level before acquiring it
 103  * ARGUMENTS:
 104  *         SpinLock = Spinlock to release
 105  */
 106 {
 107    if (SpinLock->Lock != 1)
 108      {
 109         DbgPrint("Releasing unacquired spinlock %x\n", SpinLock);
 110         KeBugCheck(0);
 111      }
 112    (void)InterlockedExchange(&SpinLock->Lock, 0);
 113 }
 114
 115 /* EOF */