KeAcquireSpinLock function

The KeAcquireSpinLock routine acquires a spin lock so the caller can synchronize access to shared data in a multiprocessor-safe way by raising IRQL.

Syntax

VOID KeAcquireSpinLock(
  _In_  PKSPIN_LOCK SpinLock,
  _Out_ PKIRQL      OldIrql
);

Parameters

a

TBD

b

TBD

Return Value

None

Remarks

KeAcquireSpinLock first resets the IRQL to DISPATCH_LEVEL and then acquires the lock. The previous IRQL is written to OldIrql after the lock is acquired.

The OldIrql value must be specified when the spin lock is released with KeReleaseSpinLock.

Most drivers use a local variable to store the old IRQL value. A driver can also use a shared memory location, such as a global variable, but the driver must not use the same location for two different locks. Otherwise, a race condition can occur.

Spin locks can cause serious problems if not used judiciously. In particular, no deadlock protection is performed and dispatching is disabled while the spin lock is held. Therefore:

  • The code within a critical region guarded by an spin lock must neither be pageable nor make any references to pageable data.

  • The code within a critical region guarded by a spin lock can neither call any external function that might access pageable data or raise an exception, nor can it generate any exceptions.

  • The caller should release the spin lock with KeReleaseSpinLock as quickly as possible.

Attempting to acquire a spin lock recursively is guaranteed to cause a deadlock. For more information about spin locks, see Spin Locks.

Requirements

   
Windows version Available starting with Windows 2000.
Target Platform Universal
Header wdm.h (include Wdm.h, Ntddk.h, Ntifs.h)
Library Hal.lib
IRQL "<= DISPATCH_LEVEL"
DDI compliance rules IrqlKeDispatchLte, MarkingQueuedIrps, SpinLock, SpinLockDpc, SpinlockRelease, SpinLockSafe, ReqSendWhileSpinlock, Spinlock(kmdf), SpinlockDpc(kmdf), SpinlockRelease(kmdf), HwStorPortProhibitedDDIs, SpinLock(storport), SpinLockDpc(storport), SpinLockRelease(storport), SpinLockSafe(storport)

See Also

KeInitializeSpinLock

KeAcquireInStackQueuedSpinLock

KeAcquireInStackQueuedSpinLock

KeAcquireSpinLockAtDpcLevel

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