From: Thomas Gleixner <tglx@linutronix.de>
To: Yong Zhang <yong.zhang0@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: migrate_disable() race with cpu hotplug?
Date: Wed, 27 Jul 2011 23:52:18 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.02.1107272350560.2660@ionos> (raw)
In-Reply-To: <CAM2zO=AxRYEG=iJqrefOL34GW5ukoQKxYQdJ02mez=s5UZPoJg@mail.gmail.com>
On Tue, 26 Jul 2011, Yong Zhang wrote:
> When reading the code, I'm afraid there is a race between migrate_disable()
> and cpu hotplug. A scenario will like below:
>
> CPU0 CPU1
> _cpu_down();
> cpu_unplug_begin();
> wait_for_completion()
> sync_unplug_thread();
> complete();
> race_window? /*
> * migrate_disable() will
> * not take effect since
> * hotplug is in progress
> */
Rightfully so. The caller will just block on the cpu_hotplug.lock
mutex until the unplug operation will be done.
Thanks,
tglx
next prev parent reply other threads:[~2011-07-27 21:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-26 8:59 migrate_disable() race with cpu hotplug? Yong Zhang
2011-07-27 21:52 ` Thomas Gleixner [this message]
2011-07-28 3:16 ` Yong Zhang
2011-07-28 6:55 ` Thomas Gleixner
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