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Dmf_Rundown.md

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DMF_Rundown

Module Summary

This is used for rundown management when an object is being unregistered but its Methods may still be called or running. It allows DMF to make sure the resource is available while Methods that are already running continue running, but disallows new Methods from starting to run.

Module Configuration

Module Enumeration Types

Module Structures

Module Callbacks

Module Methods

DMF_Rundown_Dereference
_IRQL_requires_max_(DISPATCH_LEVEL)
VOID
DMF_Rundown_Dereference(
    _In_ DMFMODULE DmfModule
    );

Releases the Module acquired in DMF_Rundown_Reference.

Returns

None

Parameters
Parameter Description
DmfModule An open DMF_Rundown Module handle.
DMF_Rundown_EndAndWait
_IRQL_requires_max_(PASSIVE_LEVEL)
VOID
DMF_Rundown_EndAndWait(
    _In_ DMFMODULE DmfModule
    );

Waits for the Module's reference count to reach zero. This is used for rundown management when an object is being unregistered but its Methods may still be called or running. It allows DMF to make sure the resource is available while Methods that are already running continue running, but disallows new Methods from starting to run.

Returns

None

Parameters
Parameter Description
DmfModule An open DMF_Rundown Module handle.
DMF_Rundown_Reference
_IRQL_requires_max_(DISPATCH_LEVEL)
_Must_inspect_result_
NTSTATUS
DMF_Rundown_Reference(
    _In_ DMFMODULE DmfModule
    );

Can be wrapped around a resource to make sure it exists until Rundown_Dereference method is called.

Returns

NTSTATUS

Parameters
Parameter Description
DmfModule An open DMF_Rundown Module handle.
DMF_Rundown_Start
_IRQL_requires_max_(PASSIVE_LEVEL)
VOID
DMF_Rundown_Start(
    _In_ DMFMODULE DmfModule
    );

Used to set initial reference count at the start of the Rundown lifetime to 1. Needs to be called by the Client before the Rundown Reference and Dereference use.

Returns

None

Parameters
Parameter Description
DmfModule An open DMF_Rundown Module handle.

Module IOCTLs

Module Remarks

To use this Module the Start method needs to be invoked at the beginning of the resource creation/registration and the EndAndWait method needs to be invoked at the end of the resource use (deletion/unregistration).

During the lifetime of the resource if any other methods need access to it the Reference and Dereference Methods can be nested around those accesses which respectively increment and decrement the reference count of the resource.

Examples

To Do

Module Category

Task Execution