Method for multiprocessor system of controlling a dynamically expandable shared queue in which ownership of a queue entry by a processor is indicated by a semaphore

In a multiprocessor data processing system including at least one main processor and one sub-processor utilizing a shared queue, queue integrity is maintained by associating a semaphore with each queue entry to indicate ownership of that queue entry. Ownership of a queue entry is checked by a processor attempting to post to the queue entry. Upon determining that the queue entry is available to the processor, the queue entry is loaded by an atomic write operation, ownership of the queue entry transferred to another processor, and the other processor may be alerted of the post to the queue. The other processor maintains ownership of the queue entry until the other processor has read and saved the data from the queue entry. Items may thus be posted to the queue and cleared from the queue by a processor independent of the state of the other processor. No locking mechanism or atomic read-modify-write capability is required to enforce mutual exclusion between the main processor and the sub-processor to maintain queue integrity.