rtems: Rework rate-monotonic scheduler

Use the default thread lock to protect rate-monotonic state changes.
This avoids use of the Giant lock.  Split rtems_rate_monotonic_period()
body into several static functions.  Introduce a new thread wait class
THREAD_WAIT_CLASS_PERIOD for period objects to synchronize the blocking
operation.

Close #2631.

1 files changed, 6 insertions, 14 deletions

diff --git a/cpukit/rtems/include/rtems/rtems/ratemon.h b/cpukit/rtems/include/rtems/rtems/ratemon.h
index 0159e5c1e6..87bd064c98 100644
--- a/cpukit/rtems/include/rtems/rtems/ratemon.h
+++ b/cpukit/rtems/include/rtems/rtems/ratemon.h
@@ -84,24 +84,12 @@ typedef enum {
 
   /**
    * This value indicates the period is on the watchdog chain, and
-   * the owner is blocked waiting on it.
-   */
-  RATE_MONOTONIC_OWNER_IS_BLOCKING,
-
-  /**
-   * This value indicates the period is on the watchdog chain, and
    * running.  The owner should be executed or blocked waiting on
    * another object.
    */
   RATE_MONOTONIC_ACTIVE,
 
   /**
-   * This value indicates the period is on the watchdog chain, and
-   * has expired.  The owner should be blocked waiting for the next period.
-   */
-  RATE_MONOTONIC_EXPIRED_WHILE_BLOCKING,
-
-  /**
    * This value indicates the period is off the watchdog chain, and
    * has expired.  The owner is still executing and has taken too much
    * all time to complete this iteration of the period.
@@ -194,8 +182,12 @@ typedef struct {
 }  rtems_rate_monotonic_period_status;
 
 /**
- *  The following structure defines the control block used to manage
- *  each period.
+ * @brief The following structure defines the control block used to manage each
+ * period.
+ *
+ * State changes are protected by the default thread lock of the owner thread.
+ * The owner thread is the thread that created the period object.  The owner
+ * thread field is immutable after object creation.
  */
 typedef struct {
   /** This field is the object management portion of a Period instance. */