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USB: additional regression fix for device removal 

Commit e534c5b831 (USB: fix regression
occurring during device removal) didn't go far enough.  It failed to
take into account that when a driver claims multiple interfaces, it may
release them all at the same time.  As a result, some interfaces can
get released before they are unregistered, and we deadlock trying to
acquire the bandwidth_mutex that we already own.

This patch (asl478) handles this case by setting the "unregistering"
flag on all the interfaces before removing any of them.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Tested-by: Éric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2011-07-06 17:03:45 -04:00 committed by Greg Kroah-Hartman
parent e534c5b831
commit ca5c485f55
1 changed files with 8 additions and 1 deletions
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9
drivers/usb/core/message.c
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@ -1147,6 +1147,14 @@ void usb_disable_device(struct usb_device *dev, int skip_ep0)
* any drivers bound to them (a key side effect)
*/
if (dev->actconfig) {
/*
* FIXME: In order to avoid self-deadlock involving the
* bandwidth_mutex, we have to mark all the interfaces
* before unregistering any of them.
*/
for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++)
dev->actconfig->interface[i]->unregistering = 1;
for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++) {
struct usb_interface *interface;
@ -1156,7 +1164,6 @@ void usb_disable_device(struct usb_device *dev, int skip_ep0)
continue;
dev_dbg(&dev->dev, "unregistering interface %s\n",
dev_name(&interface->dev));
interface->unregistering = 1;
remove_intf_ep_devs(interface);
device_del(&interface->dev);
}