Index: kern/kern_task.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_task.c,v
retrieving revision 1.30
diff -u -p -r1.30 kern_task.c
--- kern/kern_task.c	11 Jun 2020 06:06:55 -0000	1.30
+++ kern/kern_task.c	11 Jun 2020 12:52:20 -0000
@@ -288,7 +288,7 @@ taskq_do_barrier(struct taskq *tq)
 	while (tq->tq_bthreads < tq->tq_nthreads) {
 		/* shove the task into the queue for a worker to pick up */
 		SET(t.t_flags, TASK_ONQUEUE);
-		TAILQ_INSERT_TAIL(&tq->tq_worklist, &t, t_entry);
+		TAILQ_INSERT_HEAD(&tq->tq_worklist, &t, t_entry);
 		wakeup_one(tq);
 
 		msleep_nsec(&tq->tq_bthreads, &tq->tq_mtx,
Index: dev/pci/drm/drm_linux.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/drm/drm_linux.c,v
retrieving revision 1.59
diff -u -p -r1.59 drm_linux.c
--- dev/pci/drm/drm_linux.c	8 Jun 2020 04:47:58 -0000	1.59
+++ dev/pci/drm/drm_linux.c	11 Jun 2020 12:52:20 -0000
@@ -147,13 +147,32 @@ wake_up_process(struct proc *p)
 	return wakeup_proc(p, NULL);
 }
 
+struct flush_workqueue_state {
+	struct taskq	*tq;
+	struct cond	 cv;
+};
+
+static void
+flush_workqueue_task(void *p)
+{
+	struct flush_workqueue_state *s = p;
+
+	taskq_barrier(s->tq);
+	cond_signal(&s->cv);
+}
+
 void
 flush_workqueue(struct workqueue_struct *wq)
 {
+	struct taskq *tq = (struct taskq *)wq;
+	struct flush_workqueue_state s = { tq, COND_INITIALIZER() };
+	struct task t = TASK_INITIALIZER(flush_workqueue_task, &s);
+		
 	if (cold)
 		return;
 
-	taskq_barrier((struct taskq *)wq);
+	task_add(tq, &t);
+	cond_wait(&s.cv, "flushwq");
 }
 
 bool