GSN-EDF: do not requeue jobs without budget

This patch changes how preemptions of jobs without
budget work. Instead of requeuing them, they are now
only added if they are not subject to budget enforcement
or if they have non-zero budget. This allows us to process
job completions that race with preemptions.

This appears to fix a BUG in budget.c:65 reported by Giovani Gracioli.

1 files changed, 6 insertions, 7 deletions

diff --git a/litmus/sched_gsn_edf.c b/litmus/sched_gsn_edf.c
index ea96a48b4185..c3344b9d288f 100644
--- a/litmus/sched_gsn_edf.c
+++ b/litmus/sched_gsn_edf.c
@@ -297,11 +297,11 @@ static void check_for_preemptions(void)
                                                 &per_cpu(gsnedf_cpu_entries, task_cpu(task)));
                         if (affinity)
                                 last = affinity;
-                        else if (last->linked)
+                        else if (requeue_preempted_job(last->linked))
                                 requeue(last->linked);
                 }
 #else
-                if (last->linked)
+                if (requeue_preempted_job(last->linked))
                         requeue(last->linked);
 #endif
 
@@ -427,9 +427,8 @@ static struct task_struct* gsnedf_schedule(struct task_struct * prev)
         /* (0) Determine state */
         exists      = entry->scheduled != NULL;
         blocks      = exists && !is_running(entry->scheduled);
-        out_of_time = exists &&
-                                  budget_enforced(entry->scheduled) &&
-                                  budget_exhausted(entry->scheduled);
+        out_of_time = exists && budget_enforced(entry->scheduled)
+                && budget_exhausted(entry->scheduled);
         np          = exists && is_np(entry->scheduled);
         sleep       = exists && get_rt_flags(entry->scheduled) == RT_F_SLEEP;
         preempt     = entry->scheduled != entry->linked;
@@ -467,9 +466,9 @@ static struct task_struct* gsnedf_schedule(struct task_struct * prev)
         /* Any task that is preemptable and either exhausts its execution
          * budget or wants to sleep completes. We may have to reschedule after
          * this. Don't do a job completion if we block (can't have timers running
-         * for blocked jobs). Preemption go first for the same reason.
+         * for blocked jobs).
          */
-        if (!np && (out_of_time || sleep) && !blocks && !preempt)
+        if (!np && (out_of_time || sleep) && !blocks)
                 job_completion(entry->scheduled, !sleep);
 
         /* Link pending task if we became unlinked.