Fix wake_up() preemptions under P-FP and PSN-EDF

Due to some mistake in the past, PSN-EDF was missing a check for
preemptions when a task resumes. P-FP adopted it by virtue of
copy&paste. This patch makes sure that a preemption is triggered when
a higher-priority task is added to the ready queue.

1 files changed, 10 insertions, 2 deletions

diff --git a/litmus/sched_pfp.c b/litmus/sched_pfp.c
index 62be699629b1..b1d5b4326a0e 100644
--- a/litmus/sched_pfp.c
+++ b/litmus/sched_pfp.c
@@ -95,6 +95,12 @@ static void pfp_release_jobs(rt_domain_t* rt, struct bheap* tasks)
         raw_spin_unlock_irqrestore(&pfp->slock, flags);
 }
 
+static void pfp_preempt_check(pfp_domain_t *pfp)
+{
+        if (fp_higher_prio(fp_prio_peek(&pfp->ready_queue), pfp->scheduled))
+                preempt(pfp);
+}
+
 static void pfp_domain_init(pfp_domain_t* pfp,
                                int cpu)
 {
@@ -291,7 +297,7 @@ static void pfp_task_new(struct task_struct * t, int on_rq, int running)
         } else {
                 requeue(t, pfp);
                 /* maybe we have to reschedule */
-                preempt(pfp);
+                pfp_preempt_check(pfp);
         }
         raw_spin_unlock_irqrestore(&pfp->slock, flags);
 }
@@ -337,8 +343,10 @@ static void pfp_task_wake_up(struct task_struct *task)
          * and won. Also, don't requeue if it is still queued, which can
          * happen under the DPCP due wake-ups racing with migrations.
          */
-        if (pfp->scheduled != task)
+        if (pfp->scheduled != task) {
                 requeue(task, pfp);
+                pfp_preempt_check(pfp);
+        }
 
 out_unlock:
         raw_spin_unlock_irqrestore(&pfp->slock, flags);