rt_domain: do not allocate/free memory in release queue handling

This fixes a bunch of bugs:
- a memory leak (some heap nodes were never reclaimed)
- a locking rules violation (memory allocation can wake up kswapd,
  which causes a circular locking dependency between the release queue lock
  and the run queue locks

Also, allocating memory in a hot path was never particularly clever.
This patch pre-allocates memory at task-creation time, but does not change
how the release queue works overall.

2 files changed, 6 insertions, 0 deletions

diff --git a/include/litmus/rt_domain.h b/include/litmus/rt_domain.h
index 7356ec7ca4..9323892a87 100644
--- a/include/litmus/rt_domain.h
+++ b/include/litmus/rt_domain.h
@@ -21,6 +21,10 @@ struct release_heap {
         struct list_head                list;
         lt_t                            release_time;
         struct heap                     heap;
+        /* the node used to enqueue this heap in a
+         * release queue
+         */
+        struct heap_node*               hn;
 };
 
 struct release_queue {
diff --git a/include/litmus/rt_param.h b/include/litmus/rt_param.h
index 155543ea93..a0d5de2aa5 100644
--- a/include/litmus/rt_param.h
+++ b/include/litmus/rt_param.h
@@ -40,6 +40,7 @@ struct rt_task {
 
 struct _rt_domain;
 struct heap_node;
+struct release_heap;
 
 struct rt_job {
         /* Time instant the the job was or will be released.  */
@@ -160,6 +161,7 @@ struct rt_param {
          *          implementation).
          */
         struct heap_node*       heap_node;
+        struct release_heap*    rel_heap;
 
         /* Used by rt_domain to queue task in release list.
          */