On Mon, Apr 3, 2017 at 5:55 PM, Lee, Chun-Yi <joeyli.kernel@xxxxxxxxx> wrote: > The caa73ea1 patch, "ACPI / hotplug / driver core: Handle containers > in a special way", introduced the offline callback of acpi container. > In the patch description, it mentions: > > For ACPI containers that callback simply walks the list of ACPI > device objects right below the container object (its children) and > checks if all of their physical companion devices are offline. If > that's not the case, it returns -EBUSY and the container system > devivce cannot be put offline. Consequently, to put the container > system device offline, it is necessary to put all of the physical > devices depending on its ACPI companion object offline beforehand. > > Looks that it means acpi_container_offline() should walks all physical > companion devices of container's children and checks their offline > state. And, the comment in source code is "Check all of the dependent > devices' physical companions", which means it should checks _all_ > physical companions. > > But, the checking code just stops at the first not-offlined physical > companion device of the first not-offlined child, then kernel only > emits KOBJ_CHANGE uevent to the one device. It doesn't really walk > all children's all physical companion devices and doesn't send change > uevent to them. It is unclear to me from the description whether or not this is a practical issue. Also there is an alternative, which is not to send KOBJ_CHANGE uevents to any children at all. Why is the approach you chose better? Thanks, Rafael -- 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
