On Sat, 2013-02-09 at 15:29 +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> The ACPI scan lock has been introduced to prevent acpi_bus_scan()
> and acpi_bus_trim() from running in parallel with each other for
> overlapping ACPI namespace scopes. However, it is not sufficient
> to do that, because if acpi_bus_scan() is run (for an overlapping
> namespace scope) right after the acpi_bus_trim() in
> acpi_bus_hot_remove_device(), the subsequent eject will remove
> devices without removing the corresponding struct acpi_device
> objects (and possibly companion "physical" device objects).
> Therefore acpi_bus_hot_remove_device() has to acquire the scan
> lock before carrying out the bus trimming and hold it through
> the evaluation of _EJ0, so make that happen.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Looks good.
Acked-by: Toshi Kani <toshi.kani@xxxxxx>
Thanks,
-Toshi
> ---
> drivers/acpi/scan.c | 31 +++++++++++++++++--------------
> 1 file changed, 17 insertions(+), 14 deletions(-)
>
> Index: test/drivers/acpi/scan.c
> ===================================================================
> --- test.orig/drivers/acpi/scan.c
> +++ test/drivers/acpi/scan.c
> @@ -95,6 +95,8 @@ acpi_device_modalias_show(struct device
> }
> static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
>
> +static void __acpi_bus_trim(struct acpi_device *start);
> +
> /**
> * acpi_bus_hot_remove_device: hot-remove a device and its children
> * @context: struct acpi_eject_event pointer (freed in this func)
> @@ -114,10 +116,12 @@ void acpi_bus_hot_remove_device(void *co
> acpi_status status = AE_OK;
> u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
>
> + mutex_lock(&acpi_scan_lock);
> +
> ACPI_DEBUG_PRINT((ACPI_DB_INFO,
> "Hot-removing device %s...\n", dev_name(&device->dev)));
>
> - acpi_bus_trim(device);
> + __acpi_bus_trim(device);
> /* Device node has been released. */
> device = NULL;
>
> @@ -146,18 +150,14 @@ void acpi_bus_hot_remove_device(void *co
> status = acpi_evaluate_object(handle, "_EJ0", &arg_list, NULL);
> if (ACPI_FAILURE(status)) {
> if (status != AE_NOT_FOUND)
> - printk(KERN_WARNING PREFIX
> - "Eject device failed\n");
> - goto err_out;
> - }
> + acpi_handle_warn(handle, "Eject failed\n");
>
> - kfree(context);
> - return;
> + /* Tell the firmware the hot-remove operation has failed. */
> + acpi_evaluate_hotplug_ost(handle, ej_event->event,
> + ost_code, NULL);
> + }
>
> -err_out:
> - /* Inform firmware the hot-remove operation has completed w/ error */
> - (void) acpi_evaluate_hotplug_ost(handle,
> - ej_event->event, ost_code, NULL);
> + mutex_unlock(&acpi_scan_lock);
> kfree(context);
> return;
> }
> @@ -1686,10 +1686,8 @@ static acpi_status acpi_bus_remove(acpi_
> return AE_OK;
> }
>
> -void acpi_bus_trim(struct acpi_device *start)
> +static void __acpi_bus_trim(struct acpi_device *start)
> {
> - mutex_lock(&acpi_scan_lock);
> -
> /*
> * Execute acpi_bus_device_detach() as a post-order callback to detach
> * all ACPI drivers from the device nodes being removed.
> @@ -1704,7 +1702,12 @@ void acpi_bus_trim(struct acpi_device *s
> acpi_walk_namespace(ACPI_TYPE_ANY, start->handle, ACPI_UINT32_MAX, NULL,
> acpi_bus_remove, NULL, NULL);
> acpi_bus_remove(start->handle, 0, NULL, NULL);
> +}
>
> +void acpi_bus_trim(struct acpi_device *start)
> +{
> + mutex_lock(&acpi_scan_lock);
> + __acpi_bus_trim(start);
> mutex_unlock(&acpi_scan_lock);
> }
> EXPORT_SYMBOL_GPL(acpi_bus_trim);
>
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