On Wed, Jul 03, 2019 at 10:14:39AM +0000, Chester Lin wrote: > Currently there are two ways to handle ACPI device ejection. When an eject > event happens on a container, the kernel just sends KOBJ_CHANGE to > userland and userland should handle offline operation. For other device > types, acpi_scan_try_to_offline() is called and it tries to put target > device(s) offline and then removes all nodes once they are all offline. > > However we found that sometimes applications could intensively access > resources on ejectable devices therefore they could have risk if ejection > suddenly happens and removes devices without any notification. In stead > of executing the offline callbakcs directly, we want to introduce a new > approach, which sends change events to notify all target nodes beforehand > and hands over offline handling to userland so that userland can have a > chance to schedule an offline task based on current workload. The online > function to recover from failure is also changed, it follows the same > approach to send change events rather than putting devices online directly > , which means userland will also need to take care of online handling. > > To ensure that eject function can work properly since normal users might > not have their own offline/online handling, we will submit a generic udev > rule to systemd upstream as default in order to deal with change events > and take [offline/online] action accordingly. But the Hot-Removing part > still remains so the hotplug function can run to it once target nodes are > all offline. > > To easily monitor eject status and start over an eject process, there's a > status trace mechanism in this eject flow, which helps to count current > online devices under the ejectable target, and it can reschedule an eject > event when all nodes within the device tree have been put offline. > > v2: > - device_sysfs: Add descriptions in /Document/ABI/testing/sysfs-bus-acpi > - device_sysfs: Replace the declartion with DEVICE_ATTR_RW and add cancel > option in eject_store. > - scan: Add a retry mechanism when userspace fail to put device offline. > - scan: Add ready-to-remove state. > > Chester Lin (3): > ACPI / hotplug: Send change events for offline/online requests when > eject is triggered > ACPI / hotplug: Eject status trace and auto-remove approach > ACPI / device_sysfs: Add eject_show and add a cancel option in > eject_store > > Documentation/ABI/testing/sysfs-bus-acpi | 9 +- > drivers/acpi/container.c | 2 +- > drivers/acpi/device_sysfs.c | 94 ++++++- > drivers/acpi/glue.c | 146 +++++++++++ > drivers/acpi/internal.h | 34 ++- > drivers/acpi/scan.c | 318 +++++++++++++++++------ > drivers/base/core.c | 4 + > include/acpi/acpi_bus.h | 3 +- > include/linux/acpi.h | 6 + > 9 files changed, 523 insertions(+), 93 deletions(-) > Gentle ping. I will appreciate any comment on this series. Thanks, Chester
