62 lines
2.2 KiB
Diff
62 lines
2.2 KiB
Diff
Subject: hotplug: Call cpu_unplug_begin() before DOWN_PREPARE
|
|
From: Yong Zhang <yong.zhang0@gmail.com>
|
|
Date: Sun, 16 Oct 2011 18:56:44 +0800
|
|
|
|
cpu_unplug_begin() should be called before CPU_DOWN_PREPARE, because
|
|
at CPU_DOWN_PREPARE cpu_active is cleared and sched_domain is
|
|
rebuilt. Otherwise the 'sync_unplug' thread will be running on the cpu
|
|
on which it's created and not bound on the cpu which is about to go
|
|
down.
|
|
|
|
I found that by an incorrect warning on smp_processor_id() called by
|
|
sync_unplug/1, and trace shows below:
|
|
(echo 1 > /sys/device/system/cpu/cpu1/online)
|
|
bash-1664 [000] 83.136620: _cpu_down: Bind sync_unplug to cpu 1
|
|
bash-1664 [000] 83.136623: sched_wait_task: comm=sync_unplug/1 pid=1724 prio=120
|
|
bash-1664 [000] 83.136624: _cpu_down: Wake sync_unplug
|
|
bash-1664 [000] 83.136629: sched_wakeup: comm=sync_unplug/1 pid=1724 prio=120 success=1 target_cpu=000
|
|
|
|
Wants to be folded back....
|
|
|
|
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
|
|
Link: http://lkml.kernel.org/r/1318762607-2261-3-git-send-email-yong.zhang0@gmail.com
|
|
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
|
---
|
|
kernel/cpu.c | 16 +++++++---------
|
|
1 file changed, 7 insertions(+), 9 deletions(-)
|
|
|
|
Index: linux-3.2/kernel/cpu.c
|
|
===================================================================
|
|
--- linux-3.2.orig/kernel/cpu.c
|
|
+++ linux-3.2/kernel/cpu.c
|
|
@@ -338,22 +338,20 @@ static int __ref _cpu_down(unsigned int
|
|
return -EBUSY;
|
|
}
|
|
|
|
- err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
|
|
+ cpu_hotplug_begin();
|
|
+ err = cpu_unplug_begin(cpu);
|
|
if (err) {
|
|
- nr_calls--;
|
|
- __cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
|
|
- printk("%s: attempt to take down CPU %u failed\n",
|
|
- __func__, cpu);
|
|
+ printk("cpu_unplug_begin(%d) failed\n", cpu);
|
|
goto out_cancel;
|
|
}
|
|
|
|
- cpu_hotplug_begin();
|
|
- err = cpu_unplug_begin(cpu);
|
|
+ err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
|
|
if (err) {
|
|
nr_calls--;
|
|
__cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
|
|
- printk("cpu_unplug_begin(%d) failed\n", cpu);
|
|
- goto out_cancel;
|
|
+ printk("%s: attempt to take down CPU %u failed\n",
|
|
+ __func__, cpu);
|
|
+ goto out_release;
|
|
}
|
|
|
|
err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
|