From 18f08dae19990f5fffde92e3a63e0d90cda0f1a8 Mon Sep 17 00:00:00 2001
From: Cheng Jian <cj.chengjian@huawei.com>
Date: Fri, 4 Aug 2017 17:19:37 +0800
Subject: [PATCH] sched/core: Remove unnecessary initialization
init_idle_bootup_task()
init_idle_bootup_task( ) is called in rest_init( ) to switch
the scheduling class of the boot thread to the idle class.
the function only sets:
idle->sched_class = &idle_sched_class;
which has been set in init_idle() called by sched_init():
/*
* The idle tasks have their own, simple scheduling class:
*/
idle->sched_class = &idle_sched_class;
We've already set the boot thread to idle class in
start_kernel()->sched_init()->init_idle()
so it's unnecessary to set it again in
start_kernel()->rest_init()->init_idle_bootup_task()
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <akpm@linux-foundation.org>
Cc: <huawei.libin@huawei.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1501838377-109720-1-git-send-email-cj.chengjian@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
include/linux/sched/task.h | 1 -
init/main.c | 1 -
kernel/sched/core.c | 5 -----
3 files changed, 7 deletions(-)
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index c97e5f0969276..79a2a744648dd 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -30,7 +30,6 @@ extern int lockdep_tasklist_lock_is_held(void);
extern asmlinkage void schedule_tail(struct task_struct *prev);
extern void init_idle(struct task_struct *idle, int cpu);
-extern void init_idle_bootup_task(struct task_struct *idle);
extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
extern void sched_dead(struct task_struct *p);
diff --git a/init/main.c b/init/main.c
index 052481fbe3633..881d62438b1a7 100644
--- a/init/main.c
+++ b/init/main.c
@@ -430,7 +430,6 @@ static noinline void __ref rest_init(void)
* The boot idle thread must execute schedule()
* at least once to get things moving:
*/
- init_idle_bootup_task(current);
schedule_preempt_disabled();
/* Call into cpu_idle with preempt disabled */
cpu_startup_entry(CPUHP_ONLINE);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 835a234d35e8d..6d91c10b18144 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5177,11 +5177,6 @@ void show_state_filter(unsigned long state_filter)
debug_show_all_locks();
}
-void init_idle_bootup_task(struct task_struct *idle)
-{
- idle->sched_class = &idle_sched_class;
-}
-
/**
* init_idle - set up an idle thread for a given CPU
* @idle: task in question
--
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