From 155cf657f6ddcade424253eb58d03a170dc9f64f Mon Sep 17 00:00:00 2001 From: Nicholas Mc Guire Date: Wed, 20 Nov 2013 07:22:09 +0800 Subject: [PATCH 1/2] allow preemption in recursive migrate_disable call Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/3.12/patches-3.12.6-rt9.tar.xz 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. Signed-off-by: Nicholas Mc Guire Signed-off-by: Sebastian Andrzej Siewior --- kernel/sched/core.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2419,13 +2419,12 @@ void migrate_disable(void) WARN_ON_ONCE(p->migrate_disable_atomic); #endif - preempt_disable(); if (p->migrate_disable) { p->migrate_disable++; - preempt_enable(); return; } + preempt_disable(); pin_current_cpu(); p->migrate_disable = 1; preempt_enable(); @@ -2451,13 +2450,12 @@ 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))) { /* * See comment in update_migrate_disable() about locking.