[PATCH] allow preemption in recursive migrate_disable call

[Nicholas Mc Guire <der.herr@hofr.at>]

>From a7259c360b6c8b873f5fcf6d5eed0ae78534a6c5 Mon Sep 17 00:00:00 2001
From: Nicholas Mc Guire <der.herr@hofr.at>
Date: Wed, 20 Nov 2013 07:22:09 +0800
Subject: [PATCH] allow preemption in recursive migrate_disable call

 Minor cleanup in migrate_disable/migrate_enable. The recursive case
 does not need to disable preemption as it is "pinned" to the current
 cpu any way so it is safe to preempt it.

 No functional change to migrate_disable/enable

Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
---
 kernel/sched/core.c |    6 ++----
 1 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a7fafc28..22fa2e2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2418,13 +2418,12 @@ void migrate_disable(void)
 	}
 #endif
 
-	preempt_disable();
 	if (p->migrate_disable) {
 		p->migrate_disable++;
-		preempt_enable();
 		return;
 	}
 
+	preempt_disable();
 	preempt_lazy_disable();
 	pin_current_cpu();
 	p->migrate_disable = 1;
@@ -2454,13 +2453,12 @@ void migrate_enable(void)
 #endif
 	WARN_ON_ONCE(p->migrate_disable <= 0);
 
-	preempt_disable();
 	if (migrate_disable_count(p) > 1) {
 		p->migrate_disable--;
-		preempt_enable();
 		return;
 	}
 
+	preempt_disable();
 	if (unlikely(migrate_disabled_updated(p))) {
 		/*
 		 * Undo whatever update_migrate_disable() did, also see there
-- 
1.7.3.4