FILTER_RESTART callback function

The FilterRestart function initiates a restart operation for the specified filter module.

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



NDIS_STATUS FilterRestart(
  NDIS_HANDLE FilterModuleContext,



A handle to the context area for the filter module that the filter driver should restart. The filter driver created and initialized this context area in the FilterAttach function.


Return Value

FilterRestart returns one of the following status values:

Return code Description
FilterRestart successfully restarted the specified filter module.
The filter driver will complete the request asynchronously with a call to the NdisFRestartComplete function after it completes the restart operation.
FilterRestart failed because of insufficient resources.
None of the preceding status values applies. The filter driver should call the NdisWriteEventLogEntry function together with parameters that specify the reason for the failure.


FilterRestart is a required function for filter drivers. NDIS can call FilterRestart when a filter module is in the Paused state. The filter module enters the Restarting state at the start of the execution of FilterRestart.

When NDIS calls FilterRestart, a filter driver:

  • Must complete the operations that are required to restart normal send and receive operations.
  • Optionally reads or writes configuration parameters.
  • Optionally reallocates buffer pools.
  • Optionally modifies the restart attributes that are specified in the RestartAttributes member of the NDIS_FILTER_RESTART_PARAMETERS structure. If the pointer in RestartAttributes is NULL, the filter driver should not modify or add to the restart attributes list. If the pointer in RestartAttributes is non-NULL, it points to the first NDIS_RESTART_ATTRIBUTES structure in the list of restart attributes. If a filter driver does not restart, it should not modify any attributes.
  • Optionally uses OID requests to query or set information in the underlying drivers. Filter drivers should not issue OID requests for information that is already provided in the list of restart attributes.
  • Returns NDIS_STATUS_SUCCESS or a failure status.
If a filter driver modifies the list of restart attributes, the filter driver:
  • Should not modify any media-specific attributes if it does not recognize the OID in the Oid member of the NDIS_RESTART_ATTRIBUTES structure.
  • Can add new media-specific attributes to the list of restart attributes. In this situation, the filter driver must allocate a new NDIS_RESTART_ATTRIBUTES structure--for example, with the NdisAllocateMemoryWithTagPriority function--and provide memory space for the new attributes. After propagating the restart attributes to overlying drivers, NDIS frees the attributes memory for filter drivers.
  • Can modify the media-specific attributes in the list of restart attributes. If the filter driver requires more memory space, it can free the NDIS_RESTART_ATTRIBUTES structure with the NdisFreeMemory function and allocate a new structure to contain the modified information. After propagating the restart attributes to overlying drivers, NDIS frees the attributes memory for filter drivers.
  • Should, if the Oid member in the NDIS_RESTART_ATTRIBUTES structure is OID_GEN_MINIPORT_RESTART_ATTRIBUTES, make sure that the NDIS_RESTART_GENERAL_ATTRIBUTES structure contains the information that the filter driver requires. To make sure that the NDIS_RESTART_GENERAL_ATTRIBUTES structure contains the required information, you should check the Revision member in the NDIS_OBJECT_HEADER structure that is specified in the Header member of the NDIS_RESTART_GENERAL_ATTRIBUTES structure.
    Note  A filter driver can modify any member in the NDIS_RESTART_GENERAL_ATTRIBUTES structure. If some attributes that the filter driver should modify are not included in the revision of the structure that NDIS provided, the filter driver should rely on overlying drivers to issue OID requests for the missing attributes. The filter driver can modify the attributes when it completes the OID request.
  • Must, if the filter driver changes restart attributes, provide a FilterOidRequest function. The filter driver must make sure that the information that overlying drivers receive in the restart attributes is consistent with the information that they receive in response to OID requests.
After the filter driver returns its status or calls the NdisFRestartComplete function, the restart operation is complete. If the operation completed successfully, the filter module is in the Running state and normal send and receive processing is resumed. If the restart operation failed, the filter module returns to the Paused state.

NDIS calls FilterRestart at IRQL = PASSIVE_LEVEL.


To define a FilterRestart 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 FilterRestart function that is named "MyRestart", use the FILTER_RESTART type as shown in this code example:

Then, implement your function as follows:
    NDIS_HANDLE  FilterModuleContext,
The FILTER_RESTART 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 FILTER_RESTART 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.


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

See Also