EVT_WDF_DMA_ENABLER_FLUSH
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EVT_WDF_DMA_ENABLER_FLUSH callback function

[Applies to KMDF only]

A driver's EvtDmaEnablerFlush event callback function deallocates a device's DMA buffers.

Syntax


EVT_WDF_DMA_ENABLER_FLUSH EvtDmaEnablerFlush;

NTSTATUS EvtDmaEnablerFlush(
  _In_ WDFDMAENABLER DmaEnabler
)
{ ... }

Parameters

DmaEnabler [in]

A handle to a DMA enabler object.

Return value

EvtDmaEnablerFlush must return STATUS_SUCCESS or another status value for which NT_SUCCESS(status) equals TRUE, if it encounters no errors. Otherwise, this callback function must return a status value for which NT_SUCCESS(status) equals FALSE.

Remarks

To register an EvtDmaEnablerFlush callback function, a function driver for a DMA device places the callback function's address in a WDF_DMA_ENABLER_CONFIG structure before the driver calls WdfDmaEnablerCreate.

For more information about the EvtDmaEnablerFlush callback function, see Supporting Power Management for DMA Devices.

Examples

To define an EvtDmaEnablerFlush callback function, you must first provide a function declaration that identifies the type of callback function you’re defining. Windows provides a set of callback function types for drivers. Declaring a function using the callback function types helps Code Analysis for Drivers, Static Driver Verifier (SDV), and other verification tools find errors, and it’s a requirement for writing drivers for the Windows operating system.

For example, to define an EvtDmaEnablerFlush callback function that is named MyDmaEnablerFlush, use the EVT_WDF_DMA_ENABLER_FLUSH type as shown in this code example:


EVT_WDF_DMA_ENABLER_FLUSH MyDmaEnablerFlush;

Then, implement your callback function as follows:


_Use_decl_annotations_
NTSTATUS
 MyDmaEnablerFlush (
    WDFDMAENABLER  DmaEnabler
    )
  {...}

The EVT_WDF_DMA_ENABLER_FLUSH function type is defined in the WdfDmaEnabler.h header file. To more accurately identify errors when you run the code analysis tools, be sure to add the _Use_decl_annotations_ annotation to your function definition. The _Use_decl_annotations_ annotation ensures that the annotations that are applied to the EVT_WDF_DMA_ENABLER_FLUSH function type in the header file are used. For more information about the requirements for function declarations, see Declaring Functions by Using Function Role Types for KMDF Drivers. For information about _Use_decl_annotations_, see Annotating Function Behavior.

Requirements

Target platform

Universal

Minimum KMDF version

1.0

Header

WdfDmaEnabler.h (include Wdf.h)

IRQL

PASSIVE_LEVEL

See also

EvtDmaEnablerFill
WDF_DMA_ENABLER_CONFIG
WdfDmaEnablerCreate

 

 

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