EvtDeviceQueryStop function
[Applies to KMDF and UMDF]
A driver's EvtDeviceQueryStop event callback function determines whether a specified device can be stopped so that the PnP manager can redistribute system hardware resources.
Syntax
EVT_WDF_DEVICE_QUERY_STOP EvtDeviceQueryStop;
NTSTATUS EvtDeviceQueryStop(
_In_ WDFDEVICE Device
)
{ ... }
Parameters
- Device [in]
-
A handle to a framework device object.
Return value
If the driver determines that the device can be stopped, the EvtDeviceQueryStop callback function must return STATUS_SUCCESS or another status value for which NT_SUCCESS(status) equals TRUE. Otherwise it must return a status value for which NT_SUCCESS(status) equals FALSE. Do not return STATUS_NOT_SUPPORTED.
Remarks
To register an EvtDeviceQueryStop callback function, a driver must call WdfDeviceInitSetPnpPowerEventCallbacks.
If the device and driver support idle power-down, the device might not be in its working state when the framework calls the driver's EvtDeviceQueryStop callback function. The callback function can call WdfDeviceStopIdle to force the device into its working (D0) state, and then the callback function can call WdfDeviceResumeIdle before it returns.
For more information about the EvtDeviceQueryStop callback function, see Handling Requests to Stop a Device.
The framework does not synchronize the EvtDeviceQueryStop callback function with other PnP and power management callback functions. For information about how the framework synchronizes the execution of a driver's event callback functions, see Using Automatic Synchronization.
Examples
To define an EvtDeviceQueryStop 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 EvtDeviceQueryStop callback function that is named MyDeviceQueryStop, use the EVT_WDF_DEVICE_QUERY_STOP type as shown in this code example:
EVT_WDF_DEVICE_QUERY_STOP MyDeviceQueryStop;
Then, implement your callback function as follows:
_Use_decl_annotations_
NTSTATUS
MyDeviceQueryStop (
WDFDEVICE Device
)
{...}
The EVT_WDF_DEVICE_QUERY_STOP function type is defined in the Wdfdevice.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_DEVICE_QUERY_STOP 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
|
Minimum KMDF version | 1.0 |
|---|---|
|
Minimum UMDF version | 2.0 |
|
Header |
|
|
IRQL | PASSIVE_LEVEL |
See also
