1. A computer implemented method for a checkpoint process associated with a device driver in a workload partitioned environment, the computer implemented method comprising: responsive to initiation of the checkpoint process in a workload partition in the workload partitioned environment, freezing a stream between a plurality of kernel modules within the device driver associated with a device used by the workload partition in a first data processing system to prevent any module in the plurality of kernel modules within the device driver from sending any messages, other than a checkpoint message, to another module in the plurality of kernel modules; updating a message block allocated for each module in the plurality of kernel modules within the device driver with internal data describing a state of each module and external data describing a state of in-flight messages sent between the plurality of kernel modules that were not received by intended recipient modules in the plurality of kernel modules when the checkpoint process was initiated to form a restart message; restarting the stream and the plurality of kernel modules on a second data processing system using the restart message; and responsive to a determination that the stream is able to restart, determining whether a correct number of modules in the plurality of kernel modules within the device driver is present and in a correct order.