sched_ext: Don't trigger ops.quiescent/runnable() on migrations

A task moving across CPUs should not trigger quiescent/runnable task state
events as the task is staying runnable the whole time and just stopping and
then starting on different CPUs. Suppress quiescent/runnable task state
events if task_on_rq_migrating().

Signed-off-by: Tejun Heo <[e-mail]>
Suggested-by: David Vernet <[e-mail]>
Cc: Daniel Hodges <[e-mail]>
Cc: Changwoo Min <[e-mail]>
Cc: Andrea Righi <[e-mail]>
Cc: Dan Schatzberg <[e-mail]>
Signed-off-by: Tejun Heo <[e-mail]>

kernel/sched/ext.c

···
 	rq->scx.nr_running++;
 	add_nr_running(rq, 1);
 
-	if (SCX_HAS_OP(runnable))
+	if (SCX_HAS_OP(runnable) && !task_on_rq_migrating(p))
 		SCX_CALL_OP_TASK(SCX_KF_REST, runnable, p, enq_flags);
 
 	if (enq_flags & SCX_ENQ_WAKEUP)
···
 		SCX_CALL_OP_TASK(SCX_KF_REST, stopping, p, false);
 	}
 
-	if (SCX_HAS_OP(quiescent))
+	if (SCX_HAS_OP(quiescent) && !task_on_rq_migrating(p))
 		SCX_CALL_OP_TASK(SCX_KF_REST, quiescent, p, deq_flags);
 
 	if (deq_flags & SCX_DEQ_SLEEP)