VideoPortAcquireSpinLock function (video.h)

The VideoPortAcquireSpinLock function obtains the specified spin lock.

Syntax

VIDEOPORT_API VOID VideoPortAcquireSpinLock(
  [in, out] PVOID      HwDeviceExtension,
  [in]      PSPIN_LOCK SpinLock,
  [out]     PUCHAR     OldIrql
);

Parameters

[in, out] HwDeviceExtension

Pointer to the miniport driver's device extension.

[in] SpinLock

Pointer to a memory location that contains the spin lock.

[out] OldIrql

Pointer to a memory location that will receive the current IRQL.

Return value

None

Remarks

The current IRQL is saved in OldIrql. Then, the current IRQL is reset to DISPATCH_LEVEL, and the specified spin lock is acquired.

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

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 a 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 VideoPortReleaseSpinLock as quickly as possible.

Requirements

See also

VideoPortAcquireSpinLockAtDpcLevel

VideoPortReleaseSpinLock