BOOLEAN
PiFindServiceInstance(
  IN  HANDLE DeviceInstanceHandle,
  IN  PUNICODE_STRING DeviceInstancePath,
  IN OUT PVOID Context
  );

Routine Description:

    This routine is a callback function for IopApplyFunctionToServiceInstances.
    It is called for each device instance key referenced by a service instance
    value under the specified service's volatile Enum subkey. The purpose of this
    routine is to determine whether the current device instance path matches the
    device instance being searched for (as specified in the context structure),
    and if so, to set the 'DeviceFound' flag in the context structure, and abort
    enumeration.

    NOTE: The PnP device-specific registry resource must be acquired for shared
    (read) access before invoking this routine.

Arguments:

    DeviceInstanceHandle - Unused

    DeviceInstancePath - Supplies the registry path (relative to HKLM\System\Enum)
        to this device instance.

    Context - Supplies a pointer to a PI_FIND_SERVICE_INSTANCE_CONTEXT structure with
        the following fields:

        PUNICODE_STRING DeviceInstancePath - Supplies a pointer to a unicode string
            specifying the device instance being searched for.

        BOOLEAN DeviceFound - If the current device instance matches the one being
            searched for, then this flag is set to TRUE, and enumeration is aborted
            (by returning FALSE).

Return Value:

    TRUE to continue the enumeration.
    FALSE to abort it. Enumeration should be aborted when the matching device instance
        is encountered.