[PATCH 2/3] sched_ext: Drop the stale keep_prev fixup in dispatch_pick()

[Tejun Heo]

The fixup demoting a keep verdict when @prev is not on ext_sched_class
guarded against the rq-level SCX_RQ_BAL_KEEP flag going stale back when
balancing and picking were separate operations.

The verdict now travels in the return value, created and consumed in one
invocation against the @prev it evaluated, and every keep decision tests
SCX_TASK_QUEUED under the rq lock, which implies ext_sched_class as a class
switch dequeues first. Drop the fixup along with dispatch_core_pick()'s
copy.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
 kernel/sched/ext/ext.c | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c
index 4867517b71a4..19db98f0e727 100644
--- a/kernel/sched/ext/ext.c
+++ b/kernel/sched/ext/ext.c
@@ -3355,11 +3355,6 @@ static enum scx_dsp_verdict dispatch_pick(struct rq *rq, struct rq_flags *rf,
 				       kick_sync_wait_bal_cb);
 	}
 
-	if (unlikely(verdict == SCX_DSP_PREV && prev->sched_class != &ext_sched_class)) {
-		WARN_ON_ONCE(scx_enable_state() == SCX_ENABLED);
-		verdict = SCX_DSP_LOCAL;
-	}
-
 	return verdict;
 }
 
@@ -3410,13 +3405,6 @@ static enum scx_dsp_verdict dispatch_core_pick(struct rq *rq, struct rq_flags *r
 	if (rq->scx.lock_drop_seq != seq)
 		return SCX_DSP_RETRY;
 
-	/* see dispatch_pick() */
-	if (unlikely(verdict == SCX_DSP_PREV &&
-		     prev->sched_class != &ext_sched_class)) {
-		WARN_ON_ONCE(scx_enable_state() == SCX_ENABLED);
-		verdict = SCX_DSP_LOCAL;
-	}
-
 	return verdict;
 }
 #else	/* CONFIG_SCHED_CORE */
-- 
2.55.0