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From: Johannes Berg <johannes@sipsolutions.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>, Alex Chiang <achiang@hp.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Oleg Nesterov <oleg@redhat.com>,
	jbarnes@virtuousgeek.org, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org, kaneshige.kenji@jp.fujitsu.com,
	Lai Jiangshan <laijs@cn.fujitsu.com>
Subject: Re: [PATCH v5 09/13] PCI: Introduce /sys/bus/pci/devices/.../remove
Date: Tue, 24 Mar 2009 13:32:52 +0100	[thread overview]
Message-ID: <1237897972.4320.79.camel@johannes.local> (raw)
In-Reply-To: <20090324034659.9e1f97dc.akpm@linux-foundation.org>

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On Tue, 2009-03-24 at 03:46 -0700, Andrew Morton wrote:

> But I don't think we've seen a coherent description of what's actually
> _wrong_ with the current code.  flush_cpu_workqueue() has been handling
> this case for many years with no problems reported as far as I know.
> 
> So what has caused this sudden flurry of reports?  Did something change in
> lockdep?  What is this
> 
> [  537.380128]  (events){--..}, at: [<ffffffff80257fc0>] flush_workqueue+0x0/0xa0
> [  537.380128]
> [  537.380128] but task is already holding lock:
> [  537.380128]  (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230
> 
> supposed to mean?  "events" isn't a lock - it's the name of a kernel
> thread, isn't it?  If this is supposed to be deadlockable then how?

events is indeed the schedule_work workqueue thread name -- I just used
that for lack of a better name.

> Because I don't immediately see what's wrong with e1000_remove() calling
> flush_work().  It's undesirable, and we can perhaps improve it via some
> means, but where is the bug?

There is no bug -- it's a false positive in a way. I've pointed this out
in the original thread, see
http://thread.gmane.org/gmane.linux.kernel/550877/focus=550932

johannes

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  parent reply	other threads:[~2009-03-24 12:34 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-03-20 20:55 [PATCH v5 00/13] PCI core learns hotplug Alex Chiang
2009-03-20 20:55 ` [PATCH v5 01/13] PCI: pci_is_root_bus helper Alex Chiang
2009-03-20 22:00   ` Jesse Barnes
2009-03-20 20:56 ` [PATCH v5 02/13] PCI: don't scan existing devices Alex Chiang
2009-03-20 20:56 ` [PATCH v5 03/13] PCI: pci_scan_slot() returns newly found devices Alex Chiang
2009-03-20 20:56 ` [PATCH v5 04/13] PCI: always scan child buses Alex Chiang
2009-03-20 20:56 ` [PATCH v5 05/13] PCI: do not initialize bridges more than once Alex Chiang
2009-03-20 20:56 ` [PATCH v5 06/13] PCI: do not enable " Alex Chiang
2009-03-20 20:56 ` [PATCH v5 07/13] PCI: Introduce pci_rescan_bus() Alex Chiang
2009-03-20 20:56 ` [PATCH v5 08/13] PCI: Introduce /sys/bus/pci/rescan Alex Chiang
2009-03-20 20:56 ` [PATCH v5 09/13] PCI: Introduce /sys/bus/pci/devices/.../remove Alex Chiang
2009-03-23  9:01   ` Kenji Kaneshige
2009-03-24  3:23     ` Alex Chiang
2009-03-24  9:25       ` Ingo Molnar
2009-03-24 10:46         ` Andrew Morton
2009-03-24 11:17           ` Peter Zijlstra
2009-03-24 13:21             ` Johannes Berg
2009-03-24 12:32           ` Johannes Berg [this message]
2009-03-24 17:23             ` Alex Chiang
2009-03-24 20:22               ` Johannes Berg
2009-03-24 16:12         ` Oleg Nesterov
2009-03-24 17:32           ` Alex Chiang
2009-03-24 19:29     ` Alex Chiang
2009-03-25  5:06       ` Kenji Kaneshige
2009-03-25  5:20         ` Alex Chiang
2009-03-25  5:39           ` Kenji Kaneshige
2009-03-20 20:56 ` [PATCH v5 10/13] PCI: Introduce /sys/bus/pci/devices/.../rescan Alex Chiang
2009-03-20 20:56 ` [PATCH v5 11/13] PCI Hotplug: restore fakephp interface with complete reimplementation Alex Chiang
2009-03-20 20:56 ` [PATCH v5 12/13] PCI Hotplug: rename legacy_fakephp to fakephp Alex Chiang
2009-03-20 20:56 ` [PATCH v5 13/13] PCI Hotplug: schedule fakephp for feature removal Alex Chiang
2012-03-10 21:20   ` Yinghai Lu

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