Drivers that maintain process-specific context information must handle cleanup requests in DispatchCleanup routines.
Receipt of this request indicates that the last handle for a file object that is associated with the target device object has been closed (but, due to outstanding I/O requests, might not have been released).
This IRP is sent in the context of the process that closed the file object handle. Therefore, the driver should release process-specific resources, such as user memory, that the driver previously locked or mapped.
If the driver's device objects were set up as exclusive, so that only a single thread can use the device at a time, the driver must complete every IRP that is currently queued to the target device object and set STATUS_CANCELLED in each IRP's I/O status block.
Otherwise, the driver must cancel and complete only the currently queued IRPs that are associated with the file object handle that is being released. (A pointer to the file object is located in the FileObject member of the driver's IO_STACK_LOCATION of the IRP.) After canceling these queued IRPs, the driver completes the cleanup IRP and sets STATUS_SUCCESS in its I/O status block.
For more information about handling this request, see DispatchCleanup Routines.