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Date: Wed, 01 May 2013 16:49:36 +0200 From: "Rafael J. Wysocki" <rjw@...k.pl> To: Toshi Kani <toshi.kani@...com> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, ACPI Devel Maling List <linux-acpi@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>, isimatu.yasuaki@...fujitsu.com, vasilis.liaskovitis@...fitbricks.com Subject: Re: [PATCH 2/3 RFC] Driver core: Use generic offline/online for CPU offline/online 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@...el.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@...el.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()? 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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