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| author | Yong Zhang <yong.zhang0@gmail.com> | 2011-10-16 18:56:44 +0800 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2012-04-10 14:34:09 -0400 |
| commit | f18f1279875ac0a66d301989ba7490e28e3ea6fb (patch) | |
| tree | 0fc078a3ba7b5c101a9107cecccabf1fe445cf95 | |
| parent | c592b4c5d6902fcbc0d5dfa276317c4b0ffeea0d (diff) | |
| download | linux-rt-f18f1279875ac0a66d301989ba7490e28e3ea6fb.tar.gz | |
hotplug: Call cpu_unplug_begin() before DOWN_PREPARE
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>
| -rw-r--r-- | kernel/cpu.c | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 21790629bb44..fa4083478d75 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -338,22 +338,20 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) 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)); |