From: Hanjun Guo <guohanjun@huawei.com>
To: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
Cc: <linux-acpi@vger.kernel.org>, <isimatu.yasuaki@jp.fujitsu.com>,
<wency@cn.fujitsu.com>, <rjw@sisk.pl>, <lenb@kernel.org>,
<toshi.kani@hp.com>, <gregkh@linuxfoundation.org>,
<linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
Tang Chen <tangchen@cn.fujitsu.com>
Subject: Re: [RFC PATCH v3 0/3] acpi: Introduce prepare_remove device operation
Date: Wed, 28 Nov 2012 19:05:13 +0800 [thread overview]
Message-ID: <50B5EFE9.3040206@huawei.com> (raw)
In-Reply-To: <1353693037-21704-1-git-send-email-vasilis.liaskovitis@profitbricks.com>
On 2012/11/24 1:50, Vasilis Liaskovitis wrote:
> As discussed in https://patchwork.kernel.org/patch/1581581/
> the driver core remove function needs to always succeed. This means we need
> to know that the device can be successfully removed before acpi_bus_trim /
> acpi_bus_hot_remove_device are called. This can cause panics when OSPM-initiated
> or SCI-initiated eject of memory devices fail e.g with:
> echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject
>
> since the ACPI core goes ahead and ejects the device regardless of whether the
> the memory is still in use or not.
>
> For this reason a new acpi_device operation called prepare_remove is introduced.
> This operation should be registered for acpi devices whose removal (from kernel
> perspective) can fail. Memory devices fall in this category.
>
> acpi_bus_remove() is changed to handle removal in 2 steps:
> - preparation for removal i.e. perform part of removal that can fail. Should
> succeed for device and all its children.
> - if above step was successfull, proceed to actual device removal
Hi Vasilis,
We met the same problem when we doing computer node hotplug, It is a good idea
to introduce prepare_remove before actual device removal.
I think we could do more in prepare_remove, such as rollback. In most cases, we can
offline most of memory sections except kernel used pages now, should we rollback
and online the memory sections when prepare_remove failed ?
As you may know, the ACPI based hotplug framework we are working on already addressed
this problem, and the way we slove this problem is a bit like yours.
We introduce hp_ops in struct acpi_device_ops:
struct acpi_device_ops {
acpi_op_add add;
acpi_op_remove remove;
acpi_op_start start;
acpi_op_bind bind;
acpi_op_unbind unbind;
acpi_op_notify notify;
#ifdef CONFIG_ACPI_HOTPLUG
struct acpihp_dev_ops *hp_ops;
#endif /* CONFIG_ACPI_HOTPLUG */
};
in hp_ops, we divide the prepare_remove into six small steps, that is:
1) pre_release(): optional step to mark device going to be removed/busy
2) release(): reclaim device from running system
3) post_release(): rollback if cancelled by user or error happened
4) pre_unconfigure(): optional step to solve possible dependency issue
5) unconfigure(): remove devices from running system
6) post_unconfigure(): free resources used by devices
In this way, we can easily rollback if error happens.
How do you think of this solution, any suggestion ? I think we can achieve
a better way for sharing ideas. :)
Thanks
Hanjun Guo
>
> With this patchset, only acpi memory devices use the new prepare_remove
> device operation. The actual memory removal (VM-related offline and other memory
> cleanups) is moved to prepare_remove. The old remove operation just cleans up
> the acpi structures. Directly ejecting PNP0C80 memory devices works safely. I
> haven't tested yet with an ACPI container which contains memory devices.
>
> Note that unbinding the acpi driver from a memory device with:
> echo "PNP0C80:XX" > /sys/bus/acpi/drivers/acpi_memhotplug/unbind
>
> will no longer try to remove the memory. This is in compliance with normal
> unbind driver core semantics, see the discussion in v2 of this patchset:
> https://lkml.org/lkml/2012/11/16/649
>
> After a successful unbind of the driver:
> - OSPM ejects of the memory device cannot proceed, as acpi_eject_store will
> return -ENODEV on missing driver.
> - SCI ejects of the memory device also cannot proceed, as they will also get
> a "driver data is NULL" error.
> So the memory can continue to be used safely after unbind.
>
> Patchset based on Rafael's linux-pm/linux-next (commit 78c38651).
> Comments welcome.
>
> v2->v3:
> - remove driver core changes. Only acpi core changes needed. Unbind semantics
> follow driver core rules. Unbind does not remove memory.
> - new patch to set enable bit in order to proceed with ejects on driver
> re-binding scenario.
>
> v1->v2:
> - new patch to introduce bus_type prepare_remove callback. Needed to prepare
> removal on driver unbinding from device-driver core.
> - v1 patches 1 and 2 simplified and merged in one. acpi_bus_trim does not require
> argument changes.
>
> Vasilis Liaskovitis (3):
> acpi: Introduce prepare_remove operation in acpi_device_ops
> acpi_memhotplug: Add prepare_remove operation
> acpi_memhotplug: Allow eject to proceed on rebind scenario
>
> drivers/acpi/acpi_memhotplug.c | 21 +++++++++++++++++----
> drivers/acpi/scan.c | 9 ++++++++-
> include/acpi/acpi_bus.h | 2 ++
> 3 files changed, 27 insertions(+), 5 deletions(-)
>
next prev parent reply other threads:[~2012-11-28 11:05 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
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 ` Hanjun Guo [this message]
2012-11-28 18:41 ` [RFC PATCH v3 0/3] acpi: Introduce prepare_remove device operation 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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