  Locking protocol is an essential component in resource management of
real-time systems, which coordinates mutually exclusive accesses to shared
resources from different tasks. Although the design and analysis of locking
protocols have been intensively studied for sequential real-time tasks, there
has been little work on this topic for parallel real-time tasks. In this paper,
we study the analysis of parallel real-time tasks using spin locks to protect
accesses to shared resources in three commonly used request serving orders
(unordered, FIFO-order and priority-order). A remarkable feature making our
analysis method more accurate is to systematically analyze the blocking time
which may delay a task's finishing time, where the impact to the total workload
and the longest path length is jointly considered, rather than analyzing them
separately and counting all blocking time as the workload that delays a task's
finishing time, as commonly assumed in the state-of-the-art.
