Commit 3451a495 authored by Alexander Duyck's avatar Alexander Duyck Committed by Greg Kroah-Hartman
Browse files

driver core: Establish order of operations for device_add and device_del via bitflag 



Add an additional bit flag to the device_private struct named "dead".

This additional flag provides a guarantee that when a device_del is
executed on a given interface an async worker will not attempt to attach
the driver following the earlier device_del call. Previously this
guarantee was not present and could result in the device_del call
attempting to remove a driver from an interface only to have the async
worker attempt to probe the driver later when it finally completes the
asynchronous probe call.

One additional change added was that I pulled the check for dev->driver
out of the __device_attach_driver call and instead placed it in the
__device_attach_async_helper call. This was motivated by the fact that the
only other caller of this, __device_attach, had already taken the
device_lock() and checked for dev->driver. Instead of testing for this
twice in this path it makes more sense to just consolidate the dev->dead
and dev->driver checks together into one set of checks.

Reviewed-by: default avatarDan Williams <dan.j.williams@intel.com>
Reviewed-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0fe6f787

drivers/base/base.h

+4 −0
Original line number Diff line number Diff line
@@ -67,6 +67,9 @@ struct driver_private { 
 *	probed first.

 * @device - pointer back to the struct device that this structure is

 * associated with.

 * @dead - This device is currently either in the process of or has been

 *	removed from the system. Any asynchronous events scheduled for this

 *	device should exit without taking any action.

 *

 * Nothing outside of the driver core should ever touch these fields.

 */
@@ -78,6 +81,7 @@ struct device_private { 
	struct klist_node knode_class;

	struct list_head deferred_probe;

	struct device *device;

	u8 dead:1;

};

#define to_device_private_parent(obj)	\

	container_of(obj, struct device_private, knode_parent)

drivers/base/core.c

+11 −0
Original line number Diff line number Diff line
@@ -2080,6 +2080,17 @@ 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;

	device_unlock(dev);



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

	 * before dpm_sysfs_remove().

	 */

drivers/base/dd.c

+11 −11
Original line number Diff line number Diff line
@@ -731,15 +731,6 @@ static int __device_attach_driver(struct device_driver *drv, void *_data) 
	bool async_allowed;

	int ret;



	/*

	 * Check if device has already been claimed. This may

	 * happen with driver loading, device discovery/registration,

	 * and deferred probe processing happens all at once with

	 * multiple threads.

	 */

	if (dev->driver)

		return -EBUSY;



	ret = driver_match_device(drv, dev);

	if (ret == 0) {

		/* no match */
@@ -774,6 +765,15 @@ static void __device_attach_async_helper(void *_dev, async_cookie_t cookie) 


	device_lock(dev);



	/*

	 * Check if device has already been removed or claimed. This may

	 * happen with driver loading, device discovery/registration,

	 * and deferred probe processing happens all at once with

	 * multiple threads.

	 */

	if (dev->p->dead || dev->driver)

		goto out_unlock;



	if (dev->parent)

		pm_runtime_get_sync(dev->parent);
@@ -784,7 +784,7 @@ static void __device_attach_async_helper(void *_dev, async_cookie_t cookie) 


	if (dev->parent)

		pm_runtime_put(dev->parent);



out_unlock:

	device_unlock(dev);



	put_device(dev);
@@ -897,7 +897,7 @@ static int __driver_attach(struct device *dev, void *data) 
	if (dev->parent && dev->bus->need_parent_lock)

		device_lock(dev->parent);

	device_lock(dev);

	if (!dev->driver)

	if (!dev->p->dead && !dev->driver)

		driver_probe_device(drv, dev);

	device_unlock(dev);

	if (dev->parent && dev->bus->need_parent_lock)

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