1. A method of data processing in a data processing system having a processor core, store queue, dispatch logic, a read-claim (RC) machine and a cache array, the method comprising: in response to receipt of a store-conditional (STCX) request of the processor core: buffering the STCX request in an entry of the store queue for eventual service by the RC machine by reference to the cache array; concurrently transmitting the STCX request via a bypass path bypassing the store queue; and in response to the dispatch logic dispatching the STCX request transmitted via the bypass path to the RC machine for service by reference to the cache array, updating the entry of the STCX request in the store queue to prohibit selection of the STCX request in the store queue for service; and in response to the STCX request transmitted via the bypass path not being dispatched by the dispatch logic, thereafter transmitting the STCX from the store queue to the dispatch logic and dispatching the STCX to the RC machine for service by reference to the cache array.