Messages in this thread |  | | Date | Tue, 3 Dec 2013 11:46:24 +0900 | From | Yasuaki Ishimatsu <> | Subject | Re: [PATCH 7/10] ACPI / hotplug: Move container-specific code out of the core |
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(2013/11/29 22:08), Rafael J. Wysocki wrote: > On Friday, November 29, 2013 11:36:55 AM Yasuaki Ishimatsu wrote: >> Hi Rafael, > > Hi, > >> Replying to this mail may be wrong. > > OK, so this particular patch doesn't break things any more?
Yes.
> >> Do you remember following your patch? >> http://lkml.org/lkml/2013/2/23/97 >> >> I want to add autoeject variable in acpi_hotplug_profile structure and >> set autoecjet of container device "false". > > Then after the series the $subject patch belongs to it will work almost the > same way as /sys/firmware/acpi/container/enabled (hot add will still work after > patch [4/10] if "enabled" is 0), but only for containers. > >> Currently, I have a problem on ejecting container device. Since linux-3.12, >> container device is removed by acpi_scan_hot_remove. >> >> I think this has two problems. >> >> 1. easily fail >> My container device has CPU device and Memory device, and maximum size of >> memory is 3Tbyte. In my environment, hot removing container device fails >> on offlining memory if memory is used by application. >> I think if offlininig memory, we must retly to offline memory several >> times. > > Yes, that's correct. But then you can try to offline the memory upfront > and only remove the container after that has been successful. > >> 2. cannot work with userland's application >> Hot removing CPU and memory on container device, we need take care of >> userland application. Before linux-3.12, container device just notifies >> KOBJ_OFFLINE to udev. So by using udev, if application binds to removed >> CPU or node, applications can change them before hot removing container >> device. >> Currently, KOBJ_OFFLINE is notified to udev. But acpi_scan_hot_remove >> also runs simultaneously for hot removing container device. So when >> applications runs for corresponding to the deletion of the devices, >> the devices may have been deleted. >
> So the expectation is that the container will refuse to offline, but instead > it will emit KOBJ_OFFLINE so that user space can do some cleanup and offline > it through the "eject" attribute, right?
Yes, that's right.
> >> I don't know what devices are on hotpluggable conatainer device of other >> vendors. At least, my container device cannot be hot removed correctly. >> Then I want to add autoeject variable in acpi_hotplug_profile so that user >> can change the parameter to "true" or "false". > > I have a different idea. > > Why don't we create a bus type for containers in analogy with CPUs and memory > and make it support offline. Then, the container scan handler will create a > "physical" container device under that bus type and the new bus type code will > implement the logic you need (that is, it will have a sysfs flag that will > cause the offline to fail emitting a uevent of some sort if set and will allow > the offline to happen when unset). That "physical" container device will go > away (again, via the container scan handler) during container removal. >
> The eject work flow can be: > (1) an eject event occurs, > (2) the container "physical" device fails offline in acpi_scan_hot_remove() > emmitting, say, KOBJ_CHANGE for the "physical" device, > (3) user space notices the KOBJ_CHANGE and does the cleanup as needed, > (4) user space changes the "physical" container device flag controlling > offline to 0, > (5) user space uses the sysfs "eject" attribute of the ACPI container object > to finally eject the container, > (6) the offline in acpi_scan_hot_remove() is now successful, because the > flag controlling it has been set to 0 in step (4), > (7) the "physical" container device goes away before executing _EJ0, > (8) the container is ejected. > > Of course, if the flag controlling container offline is 0 to start with, step > (6) will now occur directly after (1), so whoever wants containers to be > hot-removed automatically may just clear that flag for all of them on boot. > > How does that sound?
The above ideas are almost O.K. I want kernel to notify user space of KOBJ_OFFLINE. Even if user space catches "KOBJ_CHANGE", user doesn't know whether the notification is offline or not.
Thanks, Yasuaki Ishimatsu
> Rafael > > -- > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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