Hi, On Wed, Apr 19, 2017 at 02:30:18AM +0200, Rafael J. Wysocki wrote: > 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? > Please ignore this patch! Thanks for your review. I'd say sorry for that I confused with the code in acpi_scan_hot_remove() when I was sending this patch. At that time I didn't aware that the acpi_container_offline() does not need to send uevent to not-offline-yet devices. Before two weeks ago (around Apr. 5), I sent a mail to linux-acpi for reminding to ignore this patch. I don't know why the mail got filtered... Thanks a lot! Joey Lee -- 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
