From 38dfa1feedd5c4b9bc321532dcdcb6151f0271d3 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@google.com>
Date: Wed, 11 Sep 2024 14:48:36 +0000
Subject: [PATCH] Revert "sched/fair: set_load_weight() must also call
 reweight_task() for SCHED_IDLE tasks"

This reverts commit e63c0422d2474ebbab31aae375a11f13b8c1cf5d which is
commit d329605287020c3d1c3b0dadc63d8208e7251382 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I53506770d54046f8b8c62edf1342aed9797f33f8
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
---
 kernel/sched/core.c  | 23 +++++++++++++----------
 kernel/sched/fair.c  |  7 ++++---
 kernel/sched/sched.h |  2 +-
 3 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5520fdc7c529..508423887370 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1294,24 +1294,27 @@ int tg_nop(struct task_group *tg, void *data)
 static void set_load_weight(struct task_struct *p, bool update_load)
 {
 	int prio = p->static_prio - MAX_RT_PRIO;
-	struct load_weight lw;
+	struct load_weight *load = &p->se.load;
 
+	/*
+	 * SCHED_IDLE tasks get minimal weight:
+	 */
 	if (task_has_idle_policy(p)) {
-		lw.weight = scale_load(WEIGHT_IDLEPRIO);
-		lw.inv_weight = WMULT_IDLEPRIO;
-	} else {
-		lw.weight = scale_load(sched_prio_to_weight[prio]);
-		lw.inv_weight = sched_prio_to_wmult[prio];
+		load->weight = scale_load(WEIGHT_IDLEPRIO);
+		load->inv_weight = WMULT_IDLEPRIO;
+		return;
 	}
 
 	/*
 	 * SCHED_OTHER tasks have to update their load when changing their
 	 * weight
 	 */
-	if (update_load && p->sched_class == &fair_sched_class)
-		reweight_task(p, &lw);
-	else
-		p->se.load = lw;
+	if (update_load && p->sched_class == &fair_sched_class) {
+		reweight_task(p, prio);
+	} else {
+		load->weight = scale_load(sched_prio_to_weight[prio]);
+		load->inv_weight = sched_prio_to_wmult[prio];
+	}
 }
 
 #ifdef CONFIG_UCLAMP_TASK
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 5fc322008ad1..c5f5e0f6bac9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3343,14 +3343,15 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
 
 }
 
-void reweight_task(struct task_struct *p, const struct load_weight *lw)
+void reweight_task(struct task_struct *p, int prio)
 {
 	struct sched_entity *se = &p->se;
 	struct cfs_rq *cfs_rq = cfs_rq_of(se);
 	struct load_weight *load = &se->load;
+	unsigned long weight = scale_load(sched_prio_to_weight[prio]);
 
-	reweight_entity(cfs_rq, se, lw->weight);
-	load->inv_weight = lw->inv_weight;
+	reweight_entity(cfs_rq, se, weight);
+	load->inv_weight = sched_prio_to_wmult[prio];
 }
 EXPORT_SYMBOL_GPL(reweight_task);
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index cf525eea3a4b..8ccf52d0bf2b 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2394,7 +2394,7 @@ extern void init_sched_dl_class(void);
 extern void init_sched_rt_class(void);
 extern void init_sched_fair_class(void);
 
-extern void reweight_task(struct task_struct *p, const struct load_weight *lw);
+extern void reweight_task(struct task_struct *p, int prio);
 
 extern void resched_curr(struct rq *rq);
 extern void resched_cpu(int cpu);