Hardware Dev Center

Collapse the table of content
Expand the table of content
Expand Minimize

VideoPortAcquireSpinLock function

The VideoPortAcquireSpinLock function obtains the specified spin lock.

Syntax


VOID VideoPortAcquireSpinLock(
  _Inout_ PVOID      HwDeviceExtension,
  _In_    PSPIN_LOCK SpinLock,
  _Out_   PUCHAR     OldIrql
);

Parameters

HwDeviceExtension [in, out]

Pointer to the miniport driver's device extension.

SpinLock [in]

Pointer to a memory location that contains the spin lock.

OldIrql [out]

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

Target platform

Desktop

Version

Available in Windows XP and later versions of the Windows operating systems.

Header

Video.h (include Video.h)

Library

Videoprt.lib

DLL

Videoprt.sys

IRQL

<=DISPATCH_LEVEL

See also

VideoPortReleaseSpinLock
VideoPortAcquireSpinLockAtDpcLevel

 

 

Send comments about this topic to Microsoft

Show:
© 2015 Microsoft