From 18f08dae19990f5fffde92e3a63e0d90cda0f1a8 Mon Sep 17 00:00:00 2001 From: Cheng Jian 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 Signed-off-by: Xie XiuQi Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1501838377-109720-1-git-send-email-cj.chengjian@huawei.com Signed-off-by: Ingo Molnar --- 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 c97e5f096927..79a2a744648d 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 052481fbe363..881d62438b1a 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 835a234d35e8..6d91c10b1814 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