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Commit 26d46867 authored by Zhang Rui's avatar Zhang Rui Committed by Andi Kleen
Browse files

fix a deadlock issue when poking "eject" file 

"/sys/devices/LNXSYSTM:00/.../eject" is used to evaluate _EJx method
and eject a device in user space.
But system hangs when poking the "eject" file because that
the device hot-removal code invoke the driver .remove method which will
try to remove the "eject" file as a result.

Queues the hot-removal function for deferred execution in this patch.
http://bugzilla.kernel.org/show_bug.cgi?id=9772



Signed-off-by: default avatarZhang Rui <rui.zhang@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
parent a3cf8593

drivers/acpi/scan.c

+32 −24
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/acpi.h>

#include <asm/signal.h>



#include <acpi/acpi_drivers.h>

#include <acpi/acinterp.h>	/* for acpi_ex_eisa_id_to_string() */
@@ -92,17 +93,37 @@ acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, cha 
}

static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);



static int acpi_eject_operation(acpi_handle handle, int lockable)

static int acpi_bus_hot_remove_device(void *context)

{

	struct acpi_device *device;

	acpi_handle handle = context;

	struct acpi_object_list arg_list;

	union acpi_object arg;

	acpi_status status = AE_OK;



	/*

	 * TBD: evaluate _PS3?

	 */

	if (acpi_bus_get_device(handle, &device))

		return 0;



	if (lockable) {

	if (!device)

		return 0;



	ACPI_DEBUG_PRINT((ACPI_DB_INFO,

		"Hot-removing device %s...\n", device->dev.bus_id));





	if (acpi_bus_trim(device, 1)) {

		ACPI_DEBUG_PRINT((ACPI_DB_ERROR,

				"Removing device failed\n"));

		return -1;

	}



	/* power off device */

	status = acpi_evaluate_object(handle, "_PS3", NULL, NULL);

	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND)

		ACPI_DEBUG_PRINT((ACPI_DB_WARN,

				"Power-off device failed\n"));



	if (device->flags.lockable) {

		arg_list.count = 1;

		arg_list.pointer = &arg;

		arg.type = ACPI_TYPE_INTEGER;
@@ -118,24 +139,19 @@ static int acpi_eject_operation(acpi_handle handle, int lockable) 
	/*

	 * TBD: _EJD support.

	 */



	status = acpi_evaluate_object(handle, "_EJ0", &arg_list, NULL);

	if (ACPI_FAILURE(status)) {

		return (-ENODEV);

	}

	if (ACPI_FAILURE(status))

		return -ENODEV;



	return (0);

	return 0;

}



static ssize_t

acpi_eject_store(struct device *d, struct device_attribute *attr,

		const char *buf, size_t count)

{

	int result;

	int ret = count;

	int islockable;

	acpi_status status;

	acpi_handle handle;

	acpi_object_type type = 0;

	struct acpi_device *acpi_device = to_acpi_device(d);
@@ -154,17 +170,9 @@ acpi_eject_store(struct device *d, struct device_attribute *attr, 
		goto err;

	}



	islockable = acpi_device->flags.lockable;

	handle = acpi_device->handle;



	result = acpi_bus_trim(acpi_device, 1);



	if (!result)

		result = acpi_eject_operation(handle, islockable);



	if (result) {

		ret = -EBUSY;

	}

	/* remove the device in another thread to fix the deadlock issue */

	ret = kernel_thread(acpi_bus_hot_remove_device,

				acpi_device->handle, SIGCHLD);

      err:

	return ret;

}