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Commit f058cdf4 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

ACPI / scan: Make acpi_bus_hot_remove_device() acquire the scan lock 



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: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarToshi Kani <toshi.kani@hp.com>
parent 87d4a4da

drivers/acpi/scan.c

+17 −14
Original line number Diff line number Diff line
@@ -95,6 +95,8 @@ acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, cha 
}

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 *context) 
	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 *context) 
	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;

}
@@ -1683,10 +1683,8 @@ static acpi_status acpi_bus_remove(acpi_handle handle, u32 lvl_not_used, 
	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.
@@ -1701,7 +1699,12 @@ void acpi_bus_trim(struct acpi_device *start) 
	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);