On Tuesday, December 03, 2013 11:46:24 AM Yasuaki Ishimatsu wrote: > (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.
It is easy to figure out, though. Since the KOBJ_CHANGE will be emitted for container devices only in that situation, user space can see that (1) it is from a container and (2) it is KOBJ_CHANGE, so it must mean "container offline has been attempted". My concern with using KOBJ_OFFLINE for that is that device_offline() emits it too on success and it may be easily confused with the one emitted on failure for containers. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
