1. A computer program product for determining a state of an input/output (I/O) operation in an I/O processing system, comprising: a tangible storage medium readable by a processing circuit and storing instructions for executing by the processing circuit for performing a method comprising: receiving a request from a channel subsystem at a control unit for performing the I/O operation; after a predetermined amount of time passes without the I/O operation completing, receiving an interrogation request from the channel subsystem at the control unit for determining the state of the I/O operation; and sending a response from the control unit to the channel subsystem indicating the state of the I/O operation in response to the interrogation request, wherein the response also includes information indicating a state of an I/O device executing the I/O operation and information indicating a state of the control unit controlling the I/O device executing the I/O operation.