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Commit ed88747c authored by Alexander Duyck's avatar Alexander Duyck Committed by Greg Kroah-Hartman
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device core: Consolidate locking and unlocking of parent and device 



Try to consolidate all of the locking and unlocking of both the parent and
device when attaching or removing a driver from a given device.

To do that I first consolidated the lock pattern into two functions
__device_driver_lock and __device_driver_unlock. After doing that I then
created functions specific to attaching and detaching the driver while
acquiring these locks. By doing this I was able to reduce the number of
spots where we touch need_parent_lock from 12 down to 4.

This patch should produce no functional changes, it is meant to be a code
clean-up/consolidation only.

Reviewed-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
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 3451a495

drivers/base/base.h

+2 −0
Original line number Diff line number Diff line
@@ -132,6 +132,8 @@ extern int driver_add_groups(struct device_driver *drv, 
			     const struct attribute_group **groups);

extern void driver_remove_groups(struct device_driver *drv,

				 const struct attribute_group **groups);

int device_driver_attach(struct device_driver *drv, struct device *dev);

void device_driver_detach(struct device *dev);



extern char *make_class_name(const char *name, struct kobject *kobj);

drivers/base/bus.c

+4 −19
Original line number Diff line number Diff line
@@ -187,11 +187,7 @@ static ssize_t unbind_store(struct device_driver *drv, const char *buf, 


	dev = bus_find_device_by_name(bus, NULL, buf);

	if (dev && dev->driver == drv) {

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

			device_lock(dev->parent);

		device_release_driver(dev);

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

			device_unlock(dev->parent);

		device_driver_detach(dev);

		err = count;

	}

	put_device(dev);
@@ -214,13 +210,7 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf, 


	dev = bus_find_device_by_name(bus, NULL, buf);

	if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {

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

			device_lock(dev->parent);

		device_lock(dev);

		err = driver_probe_device(drv, dev);

		device_unlock(dev);

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

			device_unlock(dev->parent);

		err = device_driver_attach(drv, dev);



		if (err > 0) {

			/* success */
@@ -773,13 +763,8 @@ EXPORT_SYMBOL_GPL(bus_rescan_devices); 
 */

int device_reprobe(struct device *dev)

{

	if (dev->driver) {

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

			device_lock(dev->parent);

		device_release_driver(dev);

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

			device_unlock(dev->parent);

	}

	if (dev->driver)

		device_driver_detach(dev);

	return bus_rescan_devices_helper(dev, NULL);

}

EXPORT_SYMBOL_GPL(device_reprobe);

drivers/base/dd.c

+75 −20
Original line number Diff line number Diff line
@@ -867,6 +867,64 @@ void device_initial_probe(struct device *dev) 
	__device_attach(dev, true);

}



/*

 * __device_driver_lock - acquire locks needed to manipulate dev->drv

 * @dev: Device we will update driver info for

 * @parent: Parent device. Needed if the bus requires parent lock

 *

 * This function will take the required locks for manipulating dev->drv.

 * Normally this will just be the @dev lock, but when called for a USB

 * interface, @parent lock will be held as well.

 */

static void __device_driver_lock(struct device *dev, struct device *parent)

{

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

		device_lock(parent);

	device_lock(dev);

}



/*

 * __device_driver_unlock - release locks needed to manipulate dev->drv

 * @dev: Device we will update driver info for

 * @parent: Parent device. Needed if the bus requires parent lock

 *

 * This function will release the required locks for manipulating dev->drv.

 * Normally this will just be the the @dev lock, but when called for a

 * USB interface, @parent lock will be released as well.

 */

static void __device_driver_unlock(struct device *dev, struct device *parent)

{

	device_unlock(dev);

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

		device_unlock(parent);

}



/**

 * device_driver_attach - attach a specific driver to a specific device

 * @drv: Driver to attach

 * @dev: Device to attach it to

 *

 * Manually attach driver to a device. Will acquire both @dev lock and

 * @dev->parent lock if needed.

 */

int device_driver_attach(struct device_driver *drv, struct device *dev)

{

	int ret = 0;



	__device_driver_lock(dev, dev->parent);



	/*

	 * If device has been removed or someone has already successfully

	 * bound a driver before us just skip the driver probe call.

	 */

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

		ret = driver_probe_device(drv, dev);



	__device_driver_unlock(dev, dev->parent);



	return ret;

}



static int __driver_attach(struct device *dev, void *data)

{

	struct device_driver *drv = data;
@@ -894,14 +952,7 @@ static int __driver_attach(struct device *dev, void *data) 
		return ret;

	} /* ret > 0 means positive match */



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

		device_lock(dev->parent);

	device_lock(dev);

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

		driver_probe_device(drv, dev);

	device_unlock(dev);

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

		device_unlock(dev->parent);

	device_driver_attach(drv, dev);



	return 0;

}
@@ -932,15 +983,11 @@ static void __device_release_driver(struct device *dev, struct device *parent) 
	drv = dev->driver;

	if (drv) {

		while (device_links_busy(dev)) {

			device_unlock(dev);

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

				device_unlock(parent);

			__device_driver_unlock(dev, parent);



			device_links_unbind_consumers(dev);

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

				device_lock(parent);



			device_lock(dev);

			__device_driver_lock(dev, parent);

			/*

			 * A concurrent invocation of the same function might

			 * have released the driver successfully while this one
@@ -993,16 +1040,12 @@ void device_release_driver_internal(struct device *dev, 
				    struct device_driver *drv,

				    struct device *parent)

{

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

		device_lock(parent);

	__device_driver_lock(dev, parent);



	device_lock(dev);

	if (!drv || drv == dev->driver)

		__device_release_driver(dev, parent);



	device_unlock(dev);

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

		device_unlock(parent);

	__device_driver_unlock(dev, parent);

}



/**
@@ -1027,6 +1070,18 @@ void device_release_driver(struct device *dev) 
}

EXPORT_SYMBOL_GPL(device_release_driver);



/**

 * device_driver_detach - detach driver from a specific device

 * @dev: device to detach driver from

 *

 * Detach driver from device. Will acquire both @dev lock and @dev->parent

 * lock if needed.

 */

void device_driver_detach(struct device *dev)

{

	device_release_driver_internal(dev, NULL, dev->parent);

}



/**

 * driver_detach - detach driver from all devices it controls.

 * @drv: driver.