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SubjectRe: [PATCH 7/10] ACPI / hotplug: Move container-specific code out of the core
(2013/12/13 13:56), Rafael J. Wysocki wrote:
> On Friday, December 13, 2013 11:56:32 AM Yasuaki Ishimatsu wrote:
>> Hi Rafael,
>
> Hi,
>
>> Please share your more detailed idea. I started to implement the following
>> idea. But the idea has one problem.
>>
>>>>> The eject work flow can be:
>>>>> (1) an eject event occurs,
>>>>> (2) the container "physical" device fails offline in acpi_scan_hot_remove()
>>>>> emmitting, say, KOBJ_CHANGE for the "physical" device,
>>>>> (3) user space notices the KOBJ_CHANGE and does the cleanup as needed,
>>>>> (4) user space changes the "physical" container device flag controlling
>>>>> offline to 0,
>>>>> (5) user space uses the sysfs "eject" attribute of the ACPI container object
>>>>> to finally eject the container,
>>>>> (6) the offline in acpi_scan_hot_remove() is now successful, because the
>>>>> flag controlling it has been set to 0 in step (4),
>>>>> (7) the "physical" container device goes away before executing _EJ0,
>>>>> (8) the container is ejected.
>>
>> I want to emit KOBJ_CHANGE before offlining devices on container device at (2).
>> But acpi_scan_hot_remove() offlines devices on container device at first.
>> So when offline container device, devices on container has been offlined.
>>
>> Thus the idea cannot fulfill my necessary feature.
>
> Well, in that case we need to treat containers in a special way at the ACPI
> level. Which is a bit unfortunate so to speak.
>
> To that end I'd try to add a new flag to struct acpi_hotplug_profile, say
> .verify_offline, such that if set, it would cause acpi_scan_hot_remove() to
> check if all of the "physical" companions of the top-level device are offline
> to start with, and if not, it would just emit KOBJ_CHANGE for the companions
> that are not offline and bail out.
>
> So the above algorithm would become:
>
> (1) an eject event occurs,
> (2) acpi_scan_hot_remove() checks the verify_offline flag in the target device's
> scan_handler structure,
> (3) if set (it would always be set for containers), acpi_scan_hot_remove()
> checks the status of the target device's "physical" companions; if at least
> one of them is offline, KOBJ_CHANGE is emitted for that "physical" device,
> and acpi_scan_hot_remove() returns, [I guess we can just emit KOBJ_CHANGE
> for the first companion that is not offline at this point.]
> (4) user space notices the KOBJ_CHANGE and does the cleanup as needed; in the
> process it carries out the offline operation for the container's "physical"
> companion (there's only one such companion for each container), [That
> operation for the container itself is trivial, but to succeed it requires
> all devices below the container to be taken offline in advance.]
> (5) user space uses the sysfs "eject" attribute of the ACPI container object
> to finally eject the container,
> (6) acpi_scan_hot_remove() is now successful, because the container's "physical"
> companion is now offline,
> (7) the "physical" container device goes away before executing _EJ0,
> (8) the container is ejected.
>
> I think that should work for you.

This idea seems to same as your previous work.
http://lkml.org/lkml/2013/2/23/97

How about add autoremove flag into acpi_hotplug_profile and check it as follow:

---
drivers/acpi/scan.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 5383c81..c43d110 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -409,6 +409,11 @@ static void acpi_hotplug_notify_cb(acpi_handle handle, u32 type, void *data)
ost_code = ACPI_OST_SC_EJECT_NOT_SUPPORTED;
goto err_out;
}
+ if (!handler->hotplug.autoremove) {
+ kobject_uevent(&device->dev.kobj, KOBJ_CHANGE);
+ ost_code = ACPI_OST_SC_EJECT_NON_SPECIFIC_FAILURE;
+ goto err_out;
+ }
acpi_evaluate_hotplug_ost(handle, ACPI_NOTIFY_EJECT_REQUEST,
ACPI_OST_SC_EJECT_IN_PROGRESS, NULL);
break;
Adding the check into "acpi_hotplug_notify_cb()", user need not change the
flag for removing container device by "sysfs eject".

Thanks,
Yasuaki Ishimatsu

>
> Thanks,
> Rafael
>




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