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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: Petr Mladek <pmladek@suse.cz>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Petr Mladek 2014-09-19 17:32:24 +02:00 committed by Greg Kroah-Hartman
parent 37ebb54915
commit 638139eb95
1 changed files with 4 additions and 5 deletions
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9
drivers/usb/core/hub.c
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@ -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;