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@xxxxxxxxx>
> >
> > 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@xxxxxxxxx>
> > ---
> > 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()?
Alternatively, I can just replace cpu_hotplug_driver_lock() with
lock_device_offline() everywhere.
Thanks,
Rafael
> > - switch (buf[0]) {
> > - case '0':
> > - ret = cpu_down(cpu->dev.id);
> > - if (!ret)
> > - kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
> > - break;
> > - case '1':
> > - ret = cpu_up(cpu->dev.id);
> > - if (!ret)
> > - kobject_uevent(&dev->kobj, KOBJ_ONLINE);
> > - break;
> > - default:
> > - ret = -EINVAL;
> > - }
> > - cpu_hotplug_driver_unlock();
> > -
> > - if (ret >= 0)
> > - ret = count;
> > - return ret;
> > + return cpu_down(dev->id);
> > }
> > -static DEVICE_ATTR(online, 0644, show_online, store_online);
>
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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