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Commit 00289cd8 authored by Dan Williams's avatar Dan Williams
Browse files

drivers/base: Introduce kill_device() 



The libnvdimm subsystem arranges for devices to be destroyed as a result
of a sysfs operation. Since device_unregister() cannot be called from
an actively running sysfs attribute of the same device libnvdimm
arranges for device_unregister() to be performed in an out-of-line async
context.

The driver core maintains a 'dead' state for coordinating its own racing
async registration / de-registration requests. Rather than add local
'dead' state tracking infrastructure to libnvdimm device objects, export
the existing state tracking via a new kill_device() helper.

The kill_device() helper simply marks the device as dead, i.e. that it
is on its way to device_del(), or returns that the device was already
dead. This can be used in advance of calling device_unregister() for
subsystems like libnvdimm that might need to handle multiple user
threads racing to delete a device.

This refactoring does not change any behavior, but it is a pre-requisite
for follow-on fixes and therefore marked for -stable.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Fixes: 4d88a97a ("libnvdimm, nvdimm: dimm driver and base libnvdimm device-driver...")
Cc: <stable@vger.kernel.org>
Tested-by: default avatarJane Chu <jane.chu@oracle.com>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/156341207332.292348.14959761496009347574.stgit@dwillia2-desk3.amr.corp.intel.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent d1fdb6d8

drivers/base/core.c

+19 −8
Original line number Diff line number Diff line
@@ -2211,6 +2211,24 @@ void put_device(struct device *dev) 
}

EXPORT_SYMBOL_GPL(put_device);



bool kill_device(struct device *dev)

{

	/*

	 * Require the device lock and set the "dead" flag to guarantee that

	 * the update behavior is consistent with the other bitfields near

	 * it and that we cannot have an asynchronous probe routine trying

	 * to run while we are tearing out the bus/class/sysfs from

	 * underneath the device.

	 */

	lockdep_assert_held(&dev->mutex);



	if (dev->p->dead)

		return false;

	dev->p->dead = true;

	return true;

}

EXPORT_SYMBOL_GPL(kill_device);



/**

 * device_del - delete device from system.

 * @dev: device.
@@ -2230,15 +2248,8 @@ void device_del(struct device *dev) 
	struct kobject *glue_dir = NULL;

	struct class_interface *class_intf;



	/*

	 * Hold the device lock and set the "dead" flag to guarantee that

	 * the update behavior is consistent with the other bitfields near

	 * it and that we cannot have an asynchronous probe routine trying

	 * to run while we are tearing out the bus/class/sysfs from

	 * underneath the device.

	 */

	device_lock(dev);

	dev->p->dead = true;

	kill_device(dev);

	device_unlock(dev);



	/* Notify clients of device removal.  This call must come

include/linux/device.h

+1 −0
Original line number Diff line number Diff line
@@ -1373,6 +1373,7 @@ extern int (*platform_notify_remove)(struct device *dev); 
 */

extern struct device *get_device(struct device *dev);

extern void put_device(struct device *dev);

extern bool kill_device(struct device *dev);



#ifdef CONFIG_DEVTMPFS

extern int devtmpfs_create_node(struct device *dev);