From: Tejun Heo <tj@kernel.org>
To: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
gregkh@linuxfoundation.org, rafael.j.wysocki@intel.com,
toshi.kani@hp.com
Subject: Re: [RFC PATCH v5 1/2] Use lock_device_hotplug() in cpu_probe_store() and cpu_release_store()
Date: Thu, 24 Apr 2014 10:32:08 -0400 [thread overview]
Message-ID: <20140424143208.GB14460@htj.dyndns.org> (raw)
In-Reply-To: <1398328643.2805.102.camel@ThinkPad-T5421.cn.ibm.com>
Hello,
On Thu, Apr 24, 2014 at 04:37:23PM +0800, Li Zhong wrote:
> On Wed, 2014-04-23 at 10:39 -0400, Tejun Heo wrote:
> After thinking it harder, I still couldn't see ABBA here ...
>
> the active protection taken here is for "probe/release" which will not
> be waited for removing something like "online" under cpu#? Or my
> assumption that s_active for different files are different locks are
> completely wrong? Or I missed something else?
I'm probably confused about the locking. I was thinking a scenario
like the following.
A. CPU on/offline
grabs s_active protection of online node
grabs cpu subsys mutex
perform on/offline
releases cpu subsys mutex
releases s_active protection of online node
B. CPU release
grabs s_active protection of release node
grabs cpu subsys mutex
performs removal of the CPU
removes the online node
releases cpu subsys mutex
releases s_active protection of release node
A nests cpu subsys mutex under s_active of the online node. B nests
s_active of the online node under the cpu subsys mutex. What am I
missing?
Thanks.
--
tejun
next prev parent reply other threads:[~2014-04-24 14:32 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-10 9:18 [RFC PATCH] Suppress a device hot remove related lockdep warning Li Zhong
2014-04-10 13:31 ` Tejun Heo
2014-04-11 4:10 ` [RFC PATCH v2] Use kernfs_break_active_protection() for device online store callbacks Li Zhong
2014-04-11 10:26 ` Tejun Heo
2014-04-14 7:47 ` [RFC PATCH v3] " Li Zhong
2014-04-14 20:13 ` Tejun Heo
2014-04-15 2:44 ` Li Zhong
2014-04-15 14:50 ` Tejun Heo
2014-04-16 1:41 ` Li Zhong
2014-04-16 15:17 ` Tejun Heo
2014-04-17 3:05 ` Li Zhong
2014-04-17 15:06 ` Tejun Heo
2014-04-17 6:50 ` [RFC PATCH v4] " Li Zhong
2014-04-17 15:17 ` Tejun Heo
2014-04-18 8:33 ` Li Zhong
2014-04-21 9:20 ` [RFC PATCH v5 1/2] Use lock_device_hotplug() in cpu_probe_store() and cpu_release_store() Li Zhong
2014-04-21 9:23 ` [RFC PATCH v5 2/2] Use kernfs_break_active_protection() for device online store callbacks Li Zhong
2014-04-21 22:46 ` Tejun Heo
2014-04-22 3:34 ` Li Zhong
2014-04-22 10:11 ` Rafael J. Wysocki
2014-04-23 1:50 ` Li Zhong
2014-04-23 10:54 ` Rafael J. Wysocki
2014-04-24 1:13 ` Li Zhong
2014-04-22 20:44 ` Tejun Heo
2014-04-22 22:21 ` Rafael J. Wysocki
2014-04-23 14:23 ` Tejun Heo
2014-04-23 16:12 ` Rafael J. Wysocki
2014-04-23 16:52 ` Tejun Heo
2014-04-24 8:59 ` Li Zhong
2014-04-24 10:02 ` Rafael J. Wysocki
2014-04-25 1:46 ` Li Zhong
2014-04-25 12:47 ` Rafael J. Wysocki
2014-04-28 1:49 ` Li Zhong
2014-04-23 5:03 ` Li Zhong
2014-04-23 10:58 ` Rafael J. Wysocki
2014-04-24 1:33 ` Li Zhong
2014-05-09 8:35 ` Li Zhong
2014-05-09 8:40 ` [RFC PATCH v6 1/2 ] Use lock_device_hotplug() in cpu_probe_store() and cpu_release_store() Li Zhong
2014-05-09 8:40 ` [RFC PATCH v6 2/2] Implement lock_device_hotplug_sysfs() by breaking active protection Li Zhong
2014-04-21 22:38 ` [RFC PATCH v5 1/2] Use lock_device_hotplug() in cpu_probe_store() and cpu_release_store() Tejun Heo
2014-04-22 2:29 ` Li Zhong
2014-04-22 20:40 ` Tejun Heo
2014-04-23 2:00 ` Li Zhong
2014-04-23 14:39 ` Tejun Heo
2014-04-24 8:37 ` Li Zhong
2014-04-24 14:32 ` Tejun Heo [this message]
2014-04-25 1:56 ` Li Zhong
2014-04-25 12:28 ` Tejun Heo
2014-04-28 0:51 ` Li Zhong
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