[Minios-devel] [UNIKRAFT PATCH 18/23] lib/ukschedpreempt: Block threads

[Costin Lupu <costin.lupu@xxxxxxxxx>]

Similarly to cooperative scheduling, preemptive scheduling supports thread
blocking and waking. And just like cooperative scheduling, the sleeping threads
are put on a separate list. The sleeping threads will be woken up on timer
interrupts, but this will be added in the following patches.

Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
---
 lib/ukschedpreempt/schedpreempt.c | 32 +++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/lib/ukschedpreempt/schedpreempt.c 
b/lib/ukschedpreempt/schedpreempt.c
index ec8d50e4..fdd9681c 100644
--- a/lib/ukschedpreempt/schedpreempt.c
+++ b/lib/ukschedpreempt/schedpreempt.c
@@ -39,6 +39,7 @@
 
 struct schedpreempt_private {
        struct prioq ready_queue;
+       struct uk_thread_list sleeping_threads;
 };
 
 static
@@ -76,6 +77,32 @@ void schedpreempt_thread_remove(struct uk_sched *s, struct 
uk_thread *t)
        ukplat_lcpu_restore_irqf(flags);
 }
 
+static
+void schedpreempt_thread_blocked(struct uk_sched *s, struct uk_thread *t)
+{
+       struct schedpreempt_private *prv = s->prv;
+
+       UK_ASSERT(ukplat_lcpu_irqs_disabled());
+
+       if (t != uk_thread_current())
+               prioq_dequeue(&prv->ready_queue, t);
+       if (t->wakeup_time > 0)
+               UK_TAILQ_INSERT_TAIL(&prv->sleeping_threads, t, thread_list);
+}
+
+static
+void schedpreempt_thread_woken(struct uk_sched *s, struct uk_thread *t)
+{
+       struct schedpreempt_private *prv = s->prv;
+
+       UK_ASSERT(ukplat_lcpu_irqs_disabled());
+
+       if (t->wakeup_time > 0)
+               UK_TAILQ_REMOVE(&prv->sleeping_threads, t, thread_list);
+       if (t != uk_thread_current())
+               prioq_enqueue(&prv->ready_queue, t);
+}
+
 struct uk_sched *uk_schedpreempt_init(struct uk_alloc *a)
 {
        struct uk_sched *sched = NULL;
@@ -91,13 +118,14 @@ struct uk_sched *uk_schedpreempt_init(struct uk_alloc *a)
 
        prv = sched->prv;
        prioq_init(&prv->ready_queue);
+       UK_TAILQ_INIT(&prv->sleeping_threads);
 
        uk_sched_init(sched,
                        NULL,
                        schedpreempt_thread_add,
                        schedpreempt_thread_remove,
-                       NULL,
-                       NULL,
+                       schedpreempt_thread_blocked,
+                       schedpreempt_thread_woken,
                        NULL,
                        NULL,
                        NULL,
-- 
2.20.1


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