From: Tiejun Chen <tiejun.chen@windriver.com>
Date: Thu, 7 Nov 2013 10:06:07 +0800
Subject: cpu_down: move migrate_enable() back
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: ec6a532eee6ebf503b0e0b54fbcab45c865e47c3
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension
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 <tiejun.chen@windriver.com>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
kernel/cpu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1097,6 +1097,7 @@ static int __ref _cpu_down(unsigned int
goto restore_cpus;
}
+ migrate_enable();
cpu_hotplug_begin();
ret = cpu_unplug_begin(cpu);
if (ret) {
@@ -1143,7 +1144,6 @@ static int __ref _cpu_down(unsigned int
cpu_unplug_done(cpu);
out_cancel:
cpu_hotplug_done();
- migrate_enable();
restore_cpus:
set_cpus_allowed_ptr(current, cpumask_org);
free_cpumask_var(cpumask_org);