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Commit 638139eb authored by Petr Mladek's avatar Petr Mladek Committed by Greg Kroah-Hartman
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usb: hub: allow to process more usb hub events in parallel 



It seems that only choose_devnum() was not ready to process more hub
events at the same time.

All should be fine if we take bus->usb_address0_mutex there. It will
make sure that more devnums will not be chosen for the given bus and
the related devices at the same time.

Signed-off-by: default avatarPetr Mladek <pmladek@suse.cz>
Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 37ebb549

drivers/usb/core/hub.c

+4 −5
Original line number Diff line number Diff line
@@ -2045,7 +2045,8 @@ static void choose_devnum(struct usb_device *udev) 
	int		devnum;

	struct usb_bus	*bus = udev->bus;



	/* If hub_wq ever becomes multithreaded, this will need a lock */

	/* be safe when more hub events are proceed in parallel */

	mutex_lock(&bus->usb_address0_mutex);

	if (udev->wusb) {

		devnum = udev->portnum + 1;

		BUG_ON(test_bit(devnum, bus->devmap.devicemap));
@@ -2063,6 +2064,7 @@ static void choose_devnum(struct usb_device *udev) 
		set_bit(devnum, bus->devmap.devicemap);

		udev->devnum = devnum;

	}

	mutex_unlock(&bus->usb_address0_mutex);

}



static void release_devnum(struct usb_device *udev)
@@ -5164,11 +5166,8 @@ int usb_hub_init(void) 
	 * USB-PERSIST port handover. Otherwise it might see that a full-speed

	 * device was gone before the EHCI controller had handed its port

	 * over to the companion full-speed controller.

	 *

	 * Also we use ordered workqueue because the code is not ready

	 * for parallel execution of hub events, see choose_devnum().

	 */

	hub_wq = alloc_ordered_workqueue("usb_hub_wq", WQ_FREEZABLE);

	hub_wq = alloc_workqueue("usb_hub_wq", WQ_FREEZABLE, 0);

	if (hub_wq)

		return 0;