sched/eevdf: Fix RUN_TO_PARITY vs PREEMPT_SHORT

Vincent noted that RUN_TO_PARITY can prevent preemption by a shorter
slice under some conditions.

Reported-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

kernel/sched/fair.c

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 72f0ba5..84916c8 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -918,7 +918,7 @@ static inline bool __pick_eevdf_curr(struct cfs_rq *cfs_rq, struct sched_entity
 	if (sched_feat(RUN_TO_PARITY) &&
 	    protect_slice(curr) &&
 	    entity_eligible(cfs_rq, curr))
-		return true;
+		return !sched_feat(PREEMPT_SHORT) || curr->slice < best->slice;
 
 	return entity_before(curr, best);
 }
@@ -1195,7 +1195,7 @@ static inline bool did_preempt_short(struct cfs_rq *cfs_rq, struct sched_entity
 	if (!sched_feat(PREEMPT_SHORT))
 		return false;
 
-	if (curr->vlag == curr->deadline)
+	if (protect_slice(curr))
 		return false;
 
 	return !entity_eligible(cfs_rq, curr);