2013/02/26 8:39, Rafael J. Wysocki wrote:
On Monday, February 25, 2013 11:07:52 AM Toshi Kani wrote:
On Sat, 2013-02-23 at 22:38 +0000, Rafael J. Wysocki wrote:
From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
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.wysocki@xxxxxxxxx>
---
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.
Well, I put that in there only to be able to make the container driver behave
in a backwards compatible way (which is to emit KOBJ_ONLINE at this point).
If the container driver doesn't need to emit KOBJ_ONLINE at all, I agree with
your suggestion.
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%.
That's correct, but I don't know what the user space expectations are
currently.
My system expects this event to be notified when hot adding container device.
My container device has cpu and memory. As Toshi said, these devices are
offline when hot adding container device. So in my system, when notifying
container device's KOBJ_ONLINE event, my application runs for onlining these
devices. If this event is not notified to user land, we cannot online these
devices automatically.
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.
Well, what about avoiding to expose uevents and autoeject for now and
exposing enabled only? Drivers would still be able to set the other flags on
init on init to enforce the backwards-compatible behavior.
I agree that it would be sufficient to use one additional flag then, to start
with, but its meaning would be something like "keep backwards compatibility
with the old container driver", so perhaps "autoeject" is not a good name.
What about "user_eject" (that won't be exposed to user space) instead? Where,
if set, it would meand "do not autoeject and emit KOBJ_OFFLINE/ONLINE uevents
like the old container driver did"?
It's good idea.
Thanks,
Yasuaki Ishimatsu
Rafael
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