Shared I/O problem

[willisfield]

	We know tasks can be preempted in RTEMS. If one task is using an io 
device, at the same time the task is preempted by another task which will 
use the io device. The state of the io device will be changed and when the 
first task restarts, how to recover the state of the io device? that is to 
say how to resolve the situation that one io device can be used between 
different tasks of RTEMS?
	Thanks for your reading and any answer is appreatiated!