A miniport driver's HwScsiWmiExecuteMethod routine is called to execute a method associated with a data block. This routine is optional.
BOOLEAN HwScsiWmiExecuteMethod( _In_ PVOID DeviceContext, _In_ PSCSIWMI_REQUEST_CONTEXT RequestContext, _In_ ULONG GuidIndex, _In_ ULONG InstanceIndex, _In_ ULONG MethodId, _In_ ULONG InBufferSize, _In_ ULONG OutBufferSize, _Inout_ PUCHAR Buffer );
- DeviceContext [in]
Points to the miniport driver-defined context value passed to ScsiPortWmiDispatchFunction.
- RequestContext [in]
Points to the SCSIWMI_REQUEST_CONTEXT structure that the miniport driver passed to ScsiPortWmiDispatchFunction.
- GuidIndex [in]
Specifies the data block by its index into the list of GUIDs in the SCSI_WMILIB_CONTEXT structure that the miniport driver passed to ScsiPortWmiDispatchFunction.
- InstanceIndex [in]
If the block specified by GuidIndex has multiple instances, InstanceIndex specifies the instance.
- MethodId [in]
Specifies the ID of the method to execute. The miniport driver defines the method ID as an item in a data block.
- InBufferSize [in]
Indicates the size in bytes of the input data. If there is no input data, InBufferSize is zero.
- OutBufferSize [in]
Indicates the number of bytes available in the buffer for output data.
- Buffer [in, out]
Points to a buffer that holds the input data and receives the output data, if any, from the method. If the buffer is too small to receive all of the output, the miniport driver calls ScsiPortWmiPostProcess with SRB_STATUS_DATA_OVERRUN and the size required.
HwScsiWmiExecuteMethod returns SRB_STATUS_PENDING if the request is pending, or a nonzero SRB status value if the request was completed. The SRB status value returned by this routine is the same as what was passed in to ScsiPortWmiPostProcess. Although the return value data type is BOOLEAN, the HwScsiWmiExecuteMethod routine actually returns an SRB status value.
When a miniport driver receives an SRB in which the Function member is set to SRB_FUNCTION_WMI, it calls ScsiPortWmiDispatchFunction with a pointer to an initialized SCSI_WMILIB_CONTEXT structure and MinorFunction set to Srb->WmiSubFunction. The SCSI port driver calls the miniport driver's HwScsiWmiExecuteMethod routine if MinorFunction indicates a request to execute a method.
If a miniport driver does not implement a HwScsiWmiExecuteMethod routine, it must set ExecuteWmiMethod to NULL in the SCSI_WMILIB_CONTEXT the miniport driver passes to ScsiPortWmiDispatchFunction. In this case, the port driver returns SRB_STATUS_ERROR to the caller.
If the method generates output, the miniport driver should check the size of the output buffer in OutBufferSize before performing any operation that might have side effects or that should not be performed twice. For example, if a method returns the values of a group of counters and then resets the counters, the miniport driver should check the buffer size before resetting the counters. This ensures that the port driver can safely resend the request with a larger buffer. If the buffer is too small, the miniport driver should call ScsiPortWmiPostProcess with SRB_STATUS_DATA_OVERRUN and the size of the output buffer needed to fulfill the request.
The miniport driver executes the method and writes output, if any, to the buffer. Before returning from HwScsiWmiExecuteMethod, the miniport driver calls ScsiPortWmiPostProcess with an appropriate SrbStatus value and the number of bytes used in the output buffer.