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 2/3 RFC] Driver core: Use generic offline/online for CPU offline/online
Date: Wed, 01 May 2013 14:07:45 -0600 [thread overview]
Message-ID: <1367438865.16154.160.camel@misato.fc.hp.com> (raw)
In-Reply-To: <4894519.gepD7lHY3G@vostro.rjw.lan>
On Wed, 2013-05-01 at 16:49 +0200, Rafael J. Wysocki wrote:
> On Tuesday, April 30, 2013 05:42:06 PM Toshi Kani wrote:
> > On Mon, 2013-04-29 at 14:28 +0200, Rafael J. Wysocki wrote:
> > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > >
> > > Rework the CPU hotplug code in drivers/base/cpu.c to use the
> > > generic offline/online support introduced previously instead of
> > > its own CPU-specific code.
> > >
> > > For this purpose, modify cpu_subsys to provide offline and online
> > > callbacks for CONFIG_HOTPLUG_CPU set and remove the code handling
> > > the CPU-specific 'online' sysfs attribute.
> > >
> > > This modification is not supposed to change the user-observable
> > > behavior of the kernel (i.e. the 'online' attribute will be present
> > > in exactly the same place in sysfs and should trigger exactly the
> > > same actions as before).
> > >
> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > ---
> > > drivers/base/cpu.c | 62 ++++++++++++-----------------------------------------
> > > 1 file changed, 15 insertions(+), 47 deletions(-)
> > >
> > > Index: linux-pm/drivers/base/cpu.c
> > > ===================================================================
> > > --- linux-pm.orig/drivers/base/cpu.c
> > > +++ linux-pm/drivers/base/cpu.c
> > > @@ -16,66 +16,25 @@
> > >
> > > #include "base.h"
> > >
> > > -struct bus_type cpu_subsys = {
> > > - .name = "cpu",
> > > - .dev_name = "cpu",
> > > -};
> > > -EXPORT_SYMBOL_GPL(cpu_subsys);
> > > -
> > > static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
> > >
> > > #ifdef CONFIG_HOTPLUG_CPU
> > > -static ssize_t show_online(struct device *dev,
> > > - struct device_attribute *attr,
> > > - char *buf)
> > > +static int cpu_subsys_online(struct device *dev)
> > > {
> > > - struct cpu *cpu = container_of(dev, struct cpu, dev);
> > > -
> > > - return sprintf(buf, "%u\n", !!cpu_online(cpu->dev.id));
> > > + return cpu_up(dev->id);
> > > }
> > >
> > > -static ssize_t __ref store_online(struct device *dev,
> > > - struct device_attribute *attr,
> > > - const char *buf, size_t count)
> > > +static int cpu_subsys_offline(struct device *dev)
> > > {
> > > - struct cpu *cpu = container_of(dev, struct cpu, dev);
> > > - ssize_t ret;
> > > -
> > > - cpu_hotplug_driver_lock();
> >
> > By replacing cpu_hotplug_driver_lock() with lock_device_offline() in
> > patch 1/3, it no longer protects from other places that still use
> > cpu_hotplug_device_lock(), such as save_mc_for_early().
>
> Yes.
>
> What about taking cpu_hotplug_driver_lock() around cpu_up() and
> cpu_down() in cpu_subsys_online() and cpu_subsys_offline()?
Sounds like a reasonable approach to me.
> Alternatively, I can just replace cpu_hotplug_driver_lock() with
> lock_device_offline() everywhere.
That works too. Not sure which way is better. If we go this option,
I'd suggest to rename lock_device_offline() since it could be misleading
that the lock is only used for offline, i.e. excluding online.
lock_device_hotplug() might be less confusing although we distinguish
online/offline and hotplug operations.
Thanks,
-Toshi
next prev parent reply other threads:[~2013-05-01 20:20 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
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 [this message]
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
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