Restructure pi_semaphore struct for generic inheritance framework.

First patch in a series to implement a generic priority inheritance
framework that can be used by semaphores that use priority inheritance.

This patch makes pi_semaphore a 'base class' for pi-protocols. pi_semaphore
is updated to include a pi_sem_record field named stack_node. This stack_node
is a linked-list node that a task holding the pi_semaphore instance adds to
their semaphore stack.  Note that the task's semaphore stack (or linked-list)
simply chains stack_node's of held semaphores into a single linked-list.
This is safe since there is only one semaphore holder at any given moment.

Finally, FMLP-specific data members out to child class fmlp_semaphore.

1 files changed, 8 insertions, 0 deletions

diff --git a/litmus/Kconfig b/litmus/Kconfig
index 9888589ef126..e00887e672df 100644
--- a/litmus/Kconfig
+++ b/litmus/Kconfig
@@ -58,9 +58,17 @@ config SRP
           Say Yes if you want FMLP local long critical section
           synchronization support.
 
+config PI_SEMAPHORES
+        bool "Semaphores with Priority Inheritance"
+        default n
+        help
+          Generalized support for all Litmus priority inheriting semaphore
+          protocols.
+
 config FMLP
         bool "FMLP support"
         depends on NP_SECTION
+        depends on PI_SEMAPHORES
         default n
         help
           Include support for deterministic multiprocessor real-time