linux-kernel - Re: [Update 3][PATCH 2/7] ACPI / scan: Introduce common code for ACPI-based device hotplug

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Date:	Thu, 21 Feb 2013 18:12:21 -0700
From:	Toshi Kani <toshi.kani@...com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	Jiang Liu <liuj97@...il.com>
Subject: Re: [Update 3][PATCH 2/7] ACPI / scan: Introduce common code for
 ACPI-based device hotplug

On Fri, 2013-02-22 at 00:06 +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.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.wysocki@...el.com>
> ---
> 
> This update fixes an issue pointed out by Toshi Kani (that
> ACPI_OST_EC_OSPM_* event source codes should not be used with _OST for events
> that we received a notification for from the platform firmware).
> 
> Thanks,
> Rafael
> 
> ---
>  drivers/acpi/scan.c     |  270 ++++++++++++++++++++++++++++++++++++++----------
>  include/acpi/acpi_bus.h |    7 +
>  2 files changed, 224 insertions(+), 53 deletions(-)
 :
> +static void acpi_bus_device_eject(void *context)
> +{
> +	acpi_handle handle = context;
> +	struct acpi_device *device = NULL;
> +	struct acpi_scan_handler *handler;
> +	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
> +
> +	mutex_lock(&acpi_scan_lock);
> +
> +	acpi_bus_get_device(handle, &device);
> +	if (!device)
> +		goto err_out;
> +
> +	handler = device->handler;
> +	if (!handler || !handler->hotplug.enabled) {
> +		ost_code = ACPI_OST_SC_EJECT_NOT_SUPPORTED;
> +		goto err_out;
> +	}
> +	acpi_evaluate_hotplug_ost(handle, ACPI_NOTIFY_EJECT_REQUEST,
> +				  ACPI_OST_SC_EJECT_IN_PROGRESS, NULL);
> +	if (handler->hotplug.autoeject) {
> +		int error;
> +
> +		get_device(&device->dev);
> +		error = acpi_scan_hot_remove(device);
> +		if (error)
> +			goto err_out;
> +	} else {
> +		device->flags.eject_pending = true;
>  	}
> +	if (handler->hotplug.uevents)
> +		kobject_uevent(&device->dev.kobj, KOBJ_OFFLINE);

I confirmed that the _OST issue with hot-add is fixed.  Here is a new
one.  When autoeject is enabled, it crashes in kobject_uevent() since
the device is no longer valid. 

Thanks,
-Toshi


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