From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tiejun Chen Subject: [v1][PATCH] cpu_down: move migrate_enable() back Date: Thu, 7 Nov 2013 10:06:07 +0800 Message-ID: <1383789967-5885-1-git-send-email-tiejun.chen@windriver.com> Mime-Version: 1.0 Content-Type: text/plain Cc: , To: Return-path: Received: from mail1.windriver.com ([147.11.146.13]:38238 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751361Ab3KGCHI (ORCPT ); Wed, 6 Nov 2013 21:07:08 -0500 Sender: linux-rt-users-owner@vger.kernel.org List-ID: Commit 08c1ab68, "hotplug-use-migrate-disable.patch", intends to use migrate_enable()/migrate_disable() to replace that combination of preempt_enable() and preempt_disable(), but actually in !CONFIG_PREEMPT_RT_FULL case, migrate_enable()/migrate_disable() are still equal to preempt_enable()/preempt_disable(). So that followed cpu_hotplug_begin()/cpu_unplug_begin(cpu) would go schedule() to trigger schedule_debug() like this: _cpu_down() | + migrate_disable() = preempt_disable() | + cpu_hotplug_begin() or cpu_unplug_begin() | + schedule() | + __schedule() | + preempt_disable(); | + __schedule_bug() is true! So we should move migrate_enable() as the original scheme. Signed-off-by: Tiejun Chen --- kernel/cpu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index 98f2ea3..da6e128 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -594,6 +594,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) err = -EBUSY; goto restore_cpus; } + migrate_enable(); cpu_hotplug_begin(); err = cpu_unplug_begin(cpu); @@ -647,7 +648,6 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) out_release: cpu_unplug_done(cpu); out_cancel: - migrate_enable(); cpu_hotplug_done(); if (!err) cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu); -- 1.7.9.5