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Commit 6245838f authored by Hugh Daschbach's avatar Hugh Daschbach Committed by Greg Kroah-Hartman
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Driver core: Protect device shutdown from hot unplug events. 



While device_shutdown() walks through devices_kset to shutdown all
devices, device unplug events may race to shutdown individual devices.
Specifically, sd_shutdown(), on behalf of fc_starget_delete(), has
been observed deleting devices during device_shutdown()'s list
traversal.  So we factor out list_for_each_entry_safe_reverse(...) in
favor of while (!list_empty(...)).

Signed-off-by: default avatarHugh Daschbach <hdasch@broadcom.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent e177123f

drivers/base/core.c

+22 −3
Original line number Diff line number Diff line
@@ -1734,10 +1734,25 @@ EXPORT_SYMBOL_GPL(device_move); 
 */

void device_shutdown(void)

{

	struct device *dev, *devn;

	struct device *dev;



	spin_lock(&devices_kset->list_lock);

	/*

	 * Walk the devices list backward, shutting down each in turn.

	 * Beware that device unplug events may also start pulling

	 * devices offline, even as the system is shutting down.

	 */

	while (!list_empty(&devices_kset->list)) {

		dev = list_entry(devices_kset->list.prev, struct device,

				kobj.entry);

		get_device(dev);

		/*

		 * Make sure the device is off the kset list, in the

		 * event that dev->*->shutdown() doesn't remove it.

		 */

		list_del_init(&dev->kobj.entry);

		spin_unlock(&devices_kset->list_lock);



	list_for_each_entry_safe_reverse(dev, devn, &devices_kset->list,

				kobj.entry) {

		if (dev->bus && dev->bus->shutdown) {

			dev_dbg(dev, "shutdown\n");

			dev->bus->shutdown(dev);
@@ -1745,6 +1760,10 @@ void device_shutdown(void) 
			dev_dbg(dev, "shutdown\n");

			dev->driver->shutdown(dev);

		}

		put_device(dev);



		spin_lock(&devices_kset->list_lock);

	}

	spin_unlock(&devices_kset->list_lock);

	async_synchronize_full();

}