From: Toshi Kani <toshi.kani@hp.com>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
isimatu.yasuaki@jp.fujitsu.com,
vasilis.liaskovitis@profitbricks.com
Subject: Re: [PATCH 1/3 RFC] Driver core: Add offline/online device operations
Date: Thu, 02 May 2013 17:29:33 -0600 [thread overview]
Message-ID: <1367537373.16154.185.camel@misato.fc.hp.com> (raw)
In-Reply-To: <1431630.dgj2h0U6M6@vostro.rjw.lan>
On Thu, 2013-05-02 at 02:58 +0200, Rafael J. Wysocki wrote:
> On Tuesday, April 30, 2013 05:38:38 PM Toshi Kani wrote:
> > On Mon, 2013-04-29 at 14:26 +0200, Rafael J. Wysocki wrote:
> > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
:
> > > + */
> > > +int device_offline(struct device *dev)
> > > +{
> > > + int ret;
> > > +
> > > + if (dev->offline_disabled)
> > > + return -EPERM;
> > > +
> > > + ret = device_for_each_child(dev, NULL, device_check_offline);
> > > + if (ret)
> > > + return ret;
> > > +
> > > + device_lock(dev);
> > > + if (device_supports_offline(dev)) {
> > > + if (dev->offline) {
> > > + ret = 1;
> > > + } else {
> > > + ret = dev->bus->offline(dev);
> > > + if (!ret) {
> > > + kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
> > > + dev->offline = true;
> >
> > Shouldn't this offline flag be set before sending KOBJ_OFFLINE?
> >
> > > + }
> > > + }
> > > + }
> > > + device_unlock(dev);
> > > +
> > > + return ret;
> > > +}
> > > +
> > > +/**
> > > + * device_online - Put the device back online after successful device_offline().
> > > + * @dev: Device to be put back online.
> > > + *
> > > + * If device_offline() has been successfully executed for @dev, but the device
> > > + * has not been removed subsequently, execute its bus type's .online() callback
> > > + * to indicate that the device can be used again.
> >
> > There is another use-case for online(). When a device like CPU is
> > hot-added, it is added in offline. I am not sure why, but it has been
> > this way. So, we need to call online() to make a new device available
> > for use after a hot-add.
>
> Actually, in the CPU case that is left to user space as far as I can say.
> That is, the device appears initially offline and user space is supposed to
> bring it online via sysfs.
>
> > > + *
> > > + * Call under device_offline_lock.
> > > + */
> > > +int device_online(struct device *dev)
> > > +{
> > > + int ret = 0;
> > > +
> > > + device_lock(dev);
> > > + if (device_supports_offline(dev)) {
> > > + if (dev->offline) {
> > > + ret = dev->bus->online(dev);
> > > + if (!ret) {
> > > + kobject_uevent(&dev->kobj, KOBJ_ONLINE);
> > > + dev->offline = false;
> >
> > Same comment as KOBJ_OFFLINE.
>
> I wonder why the ordering may be important?
I do not think it causes any race condition (so this isn't a big deal),
but it seems to make more sense to emit an ONLINE/OFFLINE event after
its object is marked online/offline.
Thanks,
-Toshi
next prev parent reply other threads:[~2013-05-02 23:42 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-29 12:23 [PATCH 0/3 RFC] Driver core / ACPI: Add offline/online for graceful hot-removal of devices Rafael J. Wysocki
2013-04-29 12:26 ` [PATCH 1/3 RFC] Driver core: Add offline/online device operations Rafael J. Wysocki
2013-04-29 23:10 ` Greg Kroah-Hartman
2013-04-30 11:59 ` Rafael J. Wysocki
2013-04-30 15:32 ` Greg Kroah-Hartman
2013-04-30 20:05 ` Rafael J. Wysocki
2013-04-30 23:38 ` Toshi Kani
2013-05-02 0:58 ` Rafael J. Wysocki
2013-05-02 23:29 ` Toshi Kani [this message]
2013-05-03 11:48 ` Rafael J. Wysocki
2013-04-29 12:28 ` [PATCH 2/3 RFC] Driver core: Use generic offline/online for CPU offline/online Rafael J. Wysocki
2013-04-29 23:11 ` Greg Kroah-Hartman
2013-04-30 12:01 ` Rafael J. Wysocki
2013-04-30 15:27 ` Greg Kroah-Hartman
2013-04-30 20:06 ` Rafael J. Wysocki
2013-04-30 23:42 ` Toshi Kani
2013-05-01 14:49 ` Rafael J. Wysocki
2013-05-01 20:07 ` Toshi Kani
2013-05-02 0:26 ` Rafael J. Wysocki
2013-04-29 12:29 ` [PATCH 3/3 RFC] ACPI / hotplug: Use device offline/online for graceful hot-removal Rafael J. Wysocki
2013-04-30 23:49 ` Toshi Kani
2013-05-01 15:05 ` Rafael J. Wysocki
2013-05-01 20:20 ` Toshi Kani
2013-05-02 0:53 ` Rafael J. Wysocki
2013-05-02 12:26 ` [PATCH 0/4] Driver core / ACPI: Add offline/online for graceful hot-removal of devices Rafael J. Wysocki
2013-05-02 12:27 ` [PATCH 1/4] Driver core: Add offline/online device operations Rafael J. Wysocki
2013-05-02 13:57 ` Greg Kroah-Hartman
2013-05-02 23:11 ` Toshi Kani
2013-05-02 23:36 ` Rafael J. Wysocki
2013-05-02 23:23 ` Toshi Kani
2013-05-02 12:28 ` [PATCH 2/4] Driver core: Use generic offline/online for CPU offline/online Rafael J. Wysocki
2013-05-02 13:57 ` Greg Kroah-Hartman
2013-05-02 12:29 ` [PATCH 3/4] ACPI / hotplug: Use device offline/online for graceful hot-removal Rafael J. Wysocki
2013-05-02 12:31 ` [PATCH 4/4] ACPI / processor: Use common hotplug infrastructure Rafael J. Wysocki
2013-05-02 13:59 ` Greg Kroah-Hartman
2013-05-02 23:20 ` Toshi Kani
2013-05-03 12:05 ` Rafael J. Wysocki
2013-05-03 12:21 ` Rafael J. Wysocki
2013-05-03 18:27 ` Toshi Kani
2013-05-03 19:31 ` Rafael J. Wysocki
2013-05-03 19:34 ` Toshi Kani
2013-05-04 1:01 ` [PATCH 0/3 RFC] Driver core: Add offline/online callbacks for memory_subsys Rafael J. Wysocki
2013-05-04 1:03 ` [PATCH 1/3 RFC] ACPI / memhotplug: Bind removable memory blocks to ACPI device nodes Rafael J. Wysocki
2013-05-04 1:04 ` [PATCH 2/3 RFC] Driver core: Introduce types of device "online" Rafael J. Wysocki
2013-05-04 1:06 ` [PATCH 3/3 RFC] Driver core: Introduce offline/online callbacks for memory blocks Rafael J. Wysocki
2013-05-04 11:11 ` [PATCH 0/2 v2, RFC] Driver core: Add offline/online callbacks for memory_subsys Rafael J. Wysocki
2013-05-04 11:12 ` [PATCH 1/2 v2, RFC] ACPI / memhotplug: Bind removable memory blocks to ACPI device nodes Rafael J. Wysocki
2013-05-21 6:50 ` Tang Chen
2013-05-04 11:21 ` [PATCH 2/2 v2, RFC] Driver core: Introduce offline/online callbacks for memory blocks Rafael J. Wysocki
2013-05-06 16:28 ` Vasilis Liaskovitis
2013-05-07 0:59 ` Rafael J. Wysocki
2013-05-07 10:59 ` Vasilis Liaskovitis
2013-05-07 12:11 ` Rafael J. Wysocki
2013-05-07 21:03 ` Toshi Kani
2013-05-07 22:10 ` Rafael J. Wysocki
2013-05-07 22:45 ` Toshi Kani
2013-05-07 23:17 ` Rafael J. Wysocki
2013-05-07 23:59 ` Toshi Kani
2013-05-08 0:24 ` Rafael J. Wysocki
2013-05-08 0:37 ` Toshi Kani
2013-05-08 11:53 ` Rafael J. Wysocki
2013-05-08 14:38 ` Toshi Kani
2013-05-06 17:20 ` Greg Kroah-Hartman
2013-05-06 19:46 ` Rafael J. Wysocki
2013-05-21 6:37 ` Tang Chen
2013-05-21 11:15 ` Rafael J. Wysocki
2013-05-22 4:45 ` Tang Chen
2013-05-22 10:42 ` Rafael J. Wysocki
2013-05-22 22:06 ` [PATCH] Driver core / memory: Simplify __memory_block_change_state() Rafael J. Wysocki
2013-05-22 22:14 ` Greg Kroah-Hartman
2013-05-22 23:29 ` Rafael J. Wysocki
2013-05-23 4:37 ` Tang Chen
2013-05-06 10:48 ` [PATCH 0/2 v2, RFC] Driver core: Add offline/online callbacks for memory_subsys Rafael J. Wysocki
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1367537373.16154.185.camel@misato.fc.hp.com \
--to=toshi.kani@hp.com \
--cc=gregkh@linuxfoundation.org \
--cc=isimatu.yasuaki@jp.fujitsu.com \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rjw@sisk.pl \
--cc=vasilis.liaskovitis@profitbricks.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).