linux-kernel - [PATCH 1/2] cpu, idle: move init_idle() out of idle_thread

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Date:	Wed, 2 Mar 2016 16:51:58 +0300
From:	Andrey Ryabinin <aryabinin@...tuozzo.com>
To:	<linux-kernel@...r.kernel.org>
CC:	Mark Rutland <mark.rutland@....com>,
	Alexander Potapenko <glider@...gle.com>,
	Andrey Konovalov <adech.fo@...il.com>,
	Dmitriy Vyukov <dvyukov@...gle.com>, <will.deacon@....com>,
	<catalin.marinas@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	<kasan-dev@...glegroups.com>, Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrey Ryabinin <aryabinin@...tuozzo.com>
Subject: [PATCH 1/2] cpu, idle: move init_idle() out of idle_thread_get()

Currently idle_thread_get() not only gets the idle task but also
initializes it. This is fine for _cpu_up() which is the only caller
of idle_thread_get().

idle_thread_get() is going to be used in the next patch, but it
would be nice to avoid double initialization of idle task.
Hence this patch removes init_idle() call from idle_thread_get()
and invokes it directly from _cpu_up().

No functional changes here.

Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
---
 kernel/cpu.c     | 2 ++
 kernel/smpboot.c | 1 -
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 5b9d396..63d8e7b 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -503,6 +503,8 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen)
 		goto out;
 	}
 
+	init_idle(idle, cpu);
+
 	ret = smpboot_create_threads(cpu);
 	if (ret)
 		goto out;
diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index d264f59..74687e8 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -31,7 +31,6 @@ struct task_struct *idle_thread_get(unsigned int cpu)
 
 	if (!tsk)
 		return ERR_PTR(-ENOMEM);
-	init_idle(tsk, cpu);
 	return tsk;
 }
 
-- 
2.4.10