On Tue, Sep 6, 2011 at 7:40 PM, canquan.shen <shencanquan@xxxxxxxxxx> wrote: > On 2011/9/7 2:38, Bjorn Helgaas wrote: >> Is acpi_processor_remove() called when you remove a processor? I see >> a path where it will be called via acpi_eject_store(): >> >> acpi_eject_store >> acpi_os_hotplug_execute(acpi_bus_hot_remove_device) >> acpi_bus_hot_remove_device >> acpi_bus_trim >> acpi_bus_remove >> device_release_driver >> dev->driver->remove (acpi_processor_remove()) >> acpi_device_unregister >> device_unregister >> device_del >> kobject_uevent(KOBJ_REMOVE) >> >> but as far as I can tell, this path is only used when we write >> something to the "eject" sysfs file. I would think we'd want to use >> most of this same path when we hot remove a CPU via the ACPI SCI >> mechanism. >> > > Because in my patch will send the KOBJ_REMOVE event to udev module. and I > write a udev rule like the following: > ACTION=="remove",DRIVER=="processor",SUBSYSTEM=="acpi",RUN+="/bin/bash -c > 'echo 1 > /sys%p/eject'" > This rule will write "1" to the "eject" sysfs file. and then call > acpi_eject_store function. Hmmm. I think I understand your proposal, but it seems like a convoluted path to me. I guess the real question is whether we must give userspace a chance to decide whether to actually do the remove or not. Is there a requirement to do that? Neither the dynamic device removal flow (ACPI spec 4.0a, sec 6.3) nor the ejection flow example (fig 6-5) mentions doing that. I mentioned before that I think the ACPI hotplug code should be ripped out of the drivers and consolidated in the ACPI core. I think it's pretty clear from the spec that the 0-0x7f notifications (Bus Check, Device Check, Eject Request, etc.) are designed to be handled by the core, not by individual drivers. We handle hotplug in the drivers today, but I think that's mainly because we never implemented support in the Linux ACPI core. There are comments in acpi_bus_check_device() and acpi_bus_check_scope() about what we *should* be doing there. I am opposed to adding more hotplug support to individual drivers because I still hope that someday we'll support it in the ACPI core. Many ACPI drivers don't support hotplug at all, and the ones that do support hotplug do it in a variety of ways. It's all quite a mess. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
