| From: Tiejun Chen <tiejun.chen@windriver.com> |
| Subject: cpu_down: move migrate_enable() back |
| Date: Thu, 7 Nov 2013 10:06:07 +0800 |
| |
| 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> |
| --- |
| kernel/cpu.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/kernel/cpu.c |
| +++ b/kernel/cpu.c |
| @@ -1117,6 +1117,7 @@ static int __ref _cpu_down(unsigned int |
| goto restore_cpus; |
| } |
| |
| + migrate_enable(); |
| cpu_hotplug_begin(); |
| ret = cpu_unplug_begin(cpu); |
| if (ret) { |
| @@ -1164,7 +1165,6 @@ static int __ref _cpu_down(unsigned int |
| cpu_unplug_done(cpu); |
| out_cancel: |
| cpu_hotplug_done(); |
| - migrate_enable(); |
| /* This post dead nonsense must die */ |
| if (!ret && hasdied) |
| cpu_notify_nofail(CPU_POST_DEAD, cpu); |