MINIPORT_UNLOAD callback function (ndis.h)

Article
10/21/2021

NDIS calls a miniport driver's MiniportDriverUnload function to request the driver to release resources before the system completes a driver unload operation.

Note You must declare the function by using the MINIPORT_UNLOAD type. For more information, see the following Examples section.

Syntax

MINIPORT_UNLOAD MiniportUnload;

void MiniportUnload(
  [in] PDRIVER_OBJECT DriverObject
)
{...}

Parameters

[in] DriverObject

A pointer to a DRIVER_OBJECT structure that is the driver's driver object.

Return value

None

Remarks

A driver specifies the MiniportDriverUnload entry point when it calls the NdisMRegisterMiniportDriver function.

The driver object that is associated with an NDIS miniport driver specifies an Unload routine. The operating system calls the Unload routine when all the devices the miniport driver services have been removed. NDIS provides the Unload routine for NDIS drivers. NDIS calls a miniport driver's MiniportDriverUnload function from the Unload routine.

The functionality of the Unload routine is driver-specific. As a general rule, MiniportDriverUnload should undo the operations that were performed in the driver's DriverEntry routine.

A miniport driver calls the NdisMDeregisterMiniportDriver function from MiniportDriverUnload.

In addition to NdisMDeregisterMiniportDriver, an intermediate driver also calls the NdisDeregisterProtocolDriver function to deregister the protocol interface of the driver. MiniportDriverUnload should also perform any necessary cleanup operations, such as deallocating any protocol driver interface resources.

If a miniport driver manages more than one device instance, such as a load-balancing driver, NDIS will not call MiniportDriverUnload until after NDIS calls the MiniportHaltEx function one time for each device instance.

NDIS calls MiniportDriverUnload at IRQL = PASSIVE_LEVEL.

Examples

To define a MiniportDriverUnload function, you must first provide a function declaration that identifies the type of function you're defining. Windows provides a set of function types for drivers. Declaring a function using the 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 a MiniportDriverUnload function that is named "MyDriverUnload", use the MINIPORT_UNLOAD type as shown in this code example:

MINIPORT_UNLOAD MyDriverUnload;

Then, implement your function as follows:

_Use_decl_annotations_
VOID
 MyDriverUnload(
    PDRIVER_OBJECT  DriverObject
    )
  {...}

The MINIPORT_UNLOAD function type is defined in the Ndis.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 MINIPORT_UNLOAD 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 NDIS Drivers.

For information about Use_decl_annotations, see Annotating Function Behavior.

Requirements

Requirement	Value
Minimum supported client	Supported in NDIS 6.0 and later.
Target Platform	Windows
Header	ndis.h (include Ndis.h)
IRQL	PASSIVE_LEVEL