From: Toshi Kani <toshi.kani@hp.com>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: linux-acpi@vger.kernel.org,
Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>,
Wen Congyang <wency@cn.fujitsu.com>,
Wen Congyang <wencongyang@gmail.com>,
isimatu.yasuaki@jp.fujitsu.com, lenb@kernel.org,
gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [RFC PATCH v3 3/3] acpi_memhotplug: Allow eject to proceed on rebind scenario
Date: Wed, 28 Nov 2012 15:16:22 -0700 [thread overview]
Message-ID: <1354140982.26955.341.camel@misato.fc.hp.com> (raw)
In-Reply-To: <1451747.3VlxbhJES4@vostro.rjw.lan>
> > > > > > I see. I do not think whether or not the device is removed on eject
> > > > > > makes any difference here. The issue is that after driver_unbind() is
> > > > > > done, acpi_bus_hot_remove_device() no longer calls the ACPI memory
> > > > > > driver (hence, it cannot fail in prepare_remove), and goes ahead to call
> > > > > > _EJ0. If driver_unbind() did off-line the memory, this is OK. However,
> > > > > > it cannot off-line kernel memory ranges. So, we basically need to
> > > > > > either 1) serialize acpi_bus_hot_remove_device() and driver_unbind(), or
> > > > > > 2) make acpi_bus_hot_remove_device() to fail if driver_unbind() is run
> > > > > > during the operation.
> > > > >
> > > > > OK, I see the problem now.
> > > > >
> > > > > What exactly is triggering the driver_unbind() in this scenario?
> > > >
> > > > User can request driver_unbind() from sysfs as follows. I do not see
> > > > much reason why user has to do for memory, though.
> > > >
> > > > echo "PNP0C80:XX" > /sys/bus/acpi/drivers/acpi_memhotplug/unbind
> > >
> > > This is wrong. Even if we want to permit user space to forcibly unbind
> > > drivers from anything like this, we should at least check for some
> > > situations in which it is plain dangerous. Like in this case. So I think
> > > the above should fail unless we know that the driver won't be necessary
> > > to handle hot-removal of memory.
> >
> > Well, we tried twice already... :)
> > https://lkml.org/lkml/2012/11/16/649
>
> I didn't mean driver_unbind() should fail. The code path that executes
> driver_unbind() eventually should fail _before_ executing it.
driver_unbind() is the handler, so it is called directly from this
unbind interface.
Thanks,
-Toshi
next prev parent reply other threads:[~2012-11-28 22:24 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-23 17:50 [RFC PATCH v3 0/3] acpi: Introduce prepare_remove device operation Vasilis Liaskovitis
2012-11-23 17:50 ` [RFC PATCH v3 1/3] acpi: Introduce prepare_remove operation in acpi_device_ops Vasilis Liaskovitis
2012-11-27 0:10 ` Toshi Kani
2012-11-27 18:36 ` Vasilis Liaskovitis
2012-11-27 23:18 ` Rafael J. Wysocki
2012-11-23 17:50 ` [RFC PATCH v3 2/3] acpi_memhotplug: Add prepare_remove operation Vasilis Liaskovitis
2012-11-24 16:23 ` Wen Congyang
2012-11-23 17:50 ` [RFC PATCH v3 3/3] acpi_memhotplug: Allow eject to proceed on rebind scenario Vasilis Liaskovitis
2012-11-24 16:20 ` Wen Congyang
2012-11-26 8:36 ` Vasilis Liaskovitis
2012-11-26 9:11 ` Wen Congyang
2012-11-27 0:19 ` Toshi Kani
2012-11-27 18:32 ` Vasilis Liaskovitis
2012-11-27 22:03 ` Toshi Kani
2012-11-27 23:41 ` Rafael J. Wysocki
2012-11-28 16:01 ` Toshi Kani
2012-11-28 18:40 ` Rafael J. Wysocki
2012-11-28 21:02 ` Toshi Kani
2012-11-28 21:40 ` Rafael J. Wysocki
2012-11-28 21:40 ` Toshi Kani
2012-11-28 22:01 ` Rafael J. Wysocki
2012-11-28 22:04 ` Toshi Kani
2012-11-28 22:21 ` Rafael J. Wysocki
2012-11-28 22:16 ` Toshi Kani [this message]
2012-11-28 22:39 ` Rafael J. Wysocki
2012-11-28 22:46 ` Greg KH
2012-11-28 23:05 ` Rafael J. Wysocki
2012-11-28 23:10 ` Greg KH
2012-11-28 23:31 ` Rafael J. Wysocki
2012-11-28 23:49 ` Rafael J. Wysocki
2012-11-29 1:02 ` Toshi Kani
2012-11-29 1:15 ` Toshi Kani
2012-11-29 10:03 ` Rafael J. Wysocki
2012-11-29 11:30 ` Vasilis Liaskovitis
2012-11-29 16:57 ` Rafael J. Wysocki
2012-11-29 17:56 ` Toshi Kani
2012-11-29 20:25 ` Rafael J. Wysocki
2012-11-29 20:38 ` Toshi Kani
2012-11-29 21:23 ` Rafael J. Wysocki
2012-11-29 21:46 ` Toshi Kani
2012-11-29 22:11 ` Rafael J. Wysocki
2012-11-29 23:17 ` Toshi Kani
2012-11-30 0:13 ` Rafael J. Wysocki
2012-11-30 1:09 ` Toshi Kani
2012-11-29 16:43 ` Toshi Kani
2012-11-29 11:04 ` Vasilis Liaskovitis
2012-11-29 17:44 ` Toshi Kani
2012-12-06 9:30 ` Vasilis Liaskovitis
2012-12-06 12:50 ` Rafael J. Wysocki
2012-12-06 15:41 ` Toshi Kani
2012-12-06 20:32 ` Rafael J. Wysocki
2012-11-28 11:05 ` [RFC PATCH v3 0/3] acpi: Introduce prepare_remove device operation Hanjun Guo
2012-11-28 18:41 ` Toshi Kani
2012-11-29 4:48 ` Hanjun Guo
2012-11-29 22:27 ` Toshi Kani
2012-12-03 4:25 ` Hanjun Guo
2012-12-04 0:10 ` Toshi Kani
2012-12-04 9:16 ` Hanjun Guo
2012-12-04 23:23 ` Toshi Kani
2012-12-05 12:10 ` Hanjun Guo
2012-12-05 22:31 ` Toshi Kani
2012-12-06 16:47 ` Jiang Liu
2012-12-07 2:25 ` Toshi Kani
2012-12-06 16:40 ` Jiang Liu
2012-12-06 20:30 ` Rafael J. Wysocki
2012-12-07 2:57 ` Toshi Kani
2012-12-07 5:57 ` Jiang Liu
2012-12-08 1:08 ` Toshi Kani
2012-12-11 14:34 ` Jiang Liu
2012-12-13 14:42 ` Toshi Kani
2012-12-13 15:15 ` Jiang Liu
2012-12-15 1:19 ` Toshi Kani
2012-11-29 10:15 ` Rafael J. Wysocki
2012-11-29 11:36 ` Vasilis Liaskovitis
2012-12-06 16:59 ` Jiang Liu
2012-11-29 17:03 ` Toshi Kani
2012-11-29 20:30 ` Rafael J. Wysocki
2012-11-29 20:39 ` Toshi Kani
2012-11-29 20:56 ` Toshi Kani
2012-11-29 21:25 ` Rafael J. Wysocki
2012-12-06 17:10 ` Jiang Liu
2012-12-06 17:07 ` Jiang Liu
2012-12-06 17:01 ` Jiang Liu
2012-12-06 16:56 ` Jiang Liu
2012-12-06 16:00 ` Jiang Liu
2012-12-06 16:03 ` Toshi Kani
2012-12-06 16:25 ` Jiang Liu
2012-12-06 16:31 ` Toshi Kani
2012-12-06 16:52 ` Jiang Liu
2012-12-06 17:09 ` Toshi Kani
2012-12-06 17:30 ` Jiang Liu
2012-12-06 17:28 ` Toshi Kani
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