On Sat, 2013-02-23 at 22:38 +0000, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
>
> Multiple drivers handling hotplug-capable ACPI device nodes install
> notify handlers covering the same types of events in a very similar
> way. Moreover, those handlers are installed in separate namespace
> walks, although that really should be done during namespace scans
> carried out by acpi_bus_scan(). This leads to substantial code
> duplication, unnecessary overhead and behavior that is hard to
> follow.
>
> For this reason, introduce common code in drivers/acpi/scan.c for
> handling hotplug-related notification and carrying out device
> insertion and eject operations in a generic fashion, such that it
> may be used by all of the relevant drivers in the future. To cover
> the existing differences between those drivers introduce struct
> acpi_hotplug_profile for representing collections of hotplug
> settings associated with different ACPI scan handlers that can be
> used by the drivers to make the common code reflect their current
> behavior.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
> ---
>
> This update causes acpi_bus_device_eject() to only emit KOBJ_OFFLINE uevent if
> autoexec is unset for the given scan handler.
>
> This will require the doc in patch [5/7] to be updated which I'm going to do
> if
> everyone is OK with the $subject patch.
>
> Thanks,
> Rafael
:
> +
> +static void acpi_scan_bus_device_check(acpi_handle handle, u32 ost_source)
> +{
> + struct acpi_device *device = NULL;
> + u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
> + int error;
> +
> + mutex_lock(&acpi_scan_lock);
> +
> + acpi_bus_get_device(handle, &device);
> + if (device) {
> + dev_warn(&device->dev, "Attempt to re-insert\n");
> + goto out;
> + }
> + acpi_evaluate_hotplug_ost(handle, ost_source,
> + ACPI_OST_SC_INSERT_IN_PROGRESS, NULL);
> + error = acpi_bus_scan(handle);
> + if (error) {
> + acpi_handle_warn(handle, "Namespace scan failure\n");
> + goto out;
> + }
> + error = acpi_bus_get_device(handle, &device);
> + if (error) {
> + acpi_handle_warn(handle, "Missing device node object\n");
> + goto out;
> + }
> + ost_code = ACPI_OST_SC_SUCCESS;
> + if (device->handler && device->handler->hotplug.uevents)
> + kobject_uevent(&device->dev.kobj, KOBJ_ONLINE);
I confirmed that the uevent crash issue was solved. Thinking further, I
wonder if we need to emit KOBJ_ONLINE here. This behavior is asymmetric
since we do not emit KOBJ_OFFLINE when autoeject is set. The definition
of ONLINE/OFFLINE event to an ACPI device object seems also bogus since
there is no online/offline operation to the ACPI device object itself.
Online/offline operation is only possible to actual device, such as
system/cpu/cpu% and system/memory/memory%.
So, I'd suggest the following changes.
- Remove the "uevents" attribute. KOBJ_ONLINE/OFFLINE are not used for
ACPI device objects.
- Make the !autoeject case as an exception for now, and emit
KOBJ_OFFLINE as a way to request off-lining to user. This uevent is
tied with the !autoeject case. We can then revisit if this use-case
needs to be supported going forward. If so, we may want to consider a
different event type.
Thanks,
-Toshi
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