PSN-EDF: fix admission of suspended task

The PSN-EDF plugin used to crash when trying to admit a suspended
task. This patch fixes the task_new() handler to tolerate this case.

1 files changed, 13 insertions, 6 deletions

diff --git a/litmus/sched_psn_edf.c b/litmus/sched_psn_edf.c
index 65c85a3a4c64..4c3ee8f68bc1 100644
--- a/litmus/sched_psn_edf.c
+++ b/litmus/sched_psn_edf.c
@@ -281,7 +281,7 @@ static struct task_struct* psnedf_schedule(struct task_struct * prev)
 
 /*      Prepare a task for running in RT mode
  */
-static void psnedf_task_new(struct task_struct * t, int on_rq, int running)
+static void psnedf_task_new(struct task_struct * t, int on_rq, int is_scheduled)
 {
         rt_domain_t*            edf  = task_edf(t);
         psnedf_domain_t*        pedf = task_pedf(t);
@@ -297,14 +297,21 @@ static void psnedf_task_new(struct task_struct * t, int on_rq, int running)
          * code will try to wake it up with fatal consequences.
          */
         raw_spin_lock_irqsave(&pedf->slock, flags);
-        if (running) {
-                /* there shouldn't be anything else running at the time */
+        if (is_scheduled) {
+                /* there shouldn't be anything else scheduled at the time */
                 BUG_ON(pedf->scheduled);
                 pedf->scheduled = t;
         } else {
-                requeue(t, edf);
-                /* maybe we have to reschedule */
-                psnedf_preempt_check(pedf);
+                /* !is_scheduled means it is not scheduled right now, but it
+                 * does not mean that it is suspended. If it is not suspended,
+                 * it still needs to be requeued. If it is suspended, there is
+                 * nothing that we need to do as it will be handled by the
+                 * wake_up() handler. */
+                if (is_running(t)) {
+                        requeue(t, edf);
+                        /* maybe we have to reschedule */
+                        psnedf_preempt_check(pedf);
+                }
         }
         raw_spin_unlock_irqrestore(&pedf->slock, flags);
 }