score: Simplify _Thread_Change_priority()

The function to change a thread priority was too complex.  Simplify it
with a new scheduler operation.  This increases the average case
performance due to the simplified logic.  The interrupt disabled
critical section is a bit prolonged since now the extract, update and
enqueue steps are executed atomically.  This should however not impact
the worst-case interrupt latency since at least for the Deterministic
Priority Scheduler this sequence can be carried out with a wee bit of
instructions and no loops.

Add _Scheduler_Change_priority() to replace the sequence of
  - _Thread_Set_transient(),
  - _Scheduler_Extract(),
  - _Scheduler_Enqueue(), and
  - _Scheduler_Enqueue_first().

Delete STATES_TRANSIENT, _States_Is_transient() and
_Thread_Set_transient() since this state is now superfluous.

With this change it is possible to get rid of the
SCHEDULER_SMP_NODE_IN_THE_AIR state.  This considerably simplifies the
implementation of the new SMP locking protocols.

1 files changed, 4 insertions, 12 deletions

diff --git a/cpukit/score/Makefile.am b/cpukit/score/Makefile.am
index 8fb11d7bdf..ed68ee0072 100644
--- a/cpukit/score/Makefile.am
+++ b/cpukit/score/Makefile.am
@@ -208,9 +208,7 @@ libscore_a_SOURCES += src/schedulerdefaultupdate.c
 ## SCHEDULERPRIORITY_C_FILES
 libscore_a_SOURCES += src/schedulerpriority.c \
     src/schedulerpriorityblock.c \
-    src/schedulerpriorityenqueue.c \
-    src/schedulerpriorityenqueuefirst.c \
-    src/schedulerpriorityextract.c \
+    src/schedulerprioritychangepriority.c \
     src/schedulerpriorityprioritycompare.c \
     src/schedulerpriorityschedule.c \
     src/schedulerpriorityunblock.c \
@@ -220,11 +218,7 @@ libscore_a_SOURCES += src/schedulerpriority.c \
 ## SCHEDULERSIMPLE_C_FILES
 libscore_a_SOURCES += src/schedulersimple.c \
     src/schedulersimpleblock.c \
-    src/schedulersimpleenqueue.c \
-    src/schedulersimpleenqueuefirst.c \
-    src/schedulersimpleextract.c \
-    src/schedulersimplereadyqueueenqueue.c \
-    src/schedulersimplereadyqueueenqueuefirst.c \
+    src/schedulersimplechangepriority.c \
     src/schedulersimpleschedule.c \
     src/schedulersimpleunblock.c \
     src/schedulersimpleyield.c
@@ -233,9 +227,7 @@ libscore_a_SOURCES += src/schedulersimple.c \
 libscore_a_SOURCES += src/scheduleredf.c \
     src/scheduleredfallocate.c \
     src/scheduleredfblock.c \
-    src/scheduleredfenqueue.c \
-    src/scheduleredfenqueuefirst.c \
-    src/scheduleredfextract.c \
+    src/scheduleredfchangepriority.c \
     src/scheduleredfprioritycompare.c \
     src/scheduleredfreleasejob.c \
     src/scheduleredfschedule.c \
@@ -282,7 +274,7 @@ libscore_a_SOURCES += src/thread.c src/threadchangepriority.c \
     src/threadget.c src/threadhandler.c src/threadinitialize.c \
     src/threadloadenv.c src/threadready.c \
     src/threadrestart.c src/threadsetpriority.c \
-    src/threadsetstate.c src/threadsettransient.c \
+    src/threadsetstate.c \
     src/threadstackallocate.c src/threadstackfree.c src/threadstart.c \
     src/threadstartmultitasking.c src/iterateoverthreads.c \
     src/threadblockingoperationcancel.c