Due to recent changes to usb_reset_device, the following hang occurs:

events/0      D 0000000000000000     0     6      2
 ffff880037477cc0 0000000000000046 ffff880037477c50 ffffffff80237434
 ffffffff80574c80 00000001000a015c 0000000000000286 ffff8800374757d0
 ffff88002a31c860 ffff880037475a00 0000000036779140 ffff880037475a00
Call Trace:
 [<ffffffff80237434>] try_to_del_timer_sync+0x52/0x5b
 [<ffffffff8026f86c>] dma_pool_free+0x1a7/0x1ec
 [<ffffffffa02a928a>] ub_disconnect+0x8e/0x1ad [ub]
 [<ffffffff802407c9>] autoremove_wake_function+0x0/0x2e
 [<ffffffff80378959>] usb_unbind_interface+0x5c/0xb7
 [<ffffffff8036ab70>] __device_release_driver+0x95/0xbd
 [<ffffffff8036ac70>] device_release_driver+0x21/0x2d
 [<ffffffff803789f8>] usb_driver_release_interface+0x44/0x83
 [<ffffffff80378ab9>] usb_forced_unbind_intf+0x17/0x1d
 [<ffffffff80371ba4>] usb_reset_device+0x7d/0x114
 [<ffffffffa02aaffd>] ub_reset_task+0x0/0x293 [ub]
 [<ffffffffa02ab1c1>] ub_reset_task+0x1c4/0x293 [ub]
 [<ffffffff8033dd1e>] flush_to_ldisc+0x0/0x1cd
 [<ffffffffa02aaffd>] ub_reset_task+0x0/0x293 [ub]
 [<ffffffff8023d302>] run_workqueue+0x87/0x114
 [<ffffffff8023d467>] worker_thread+0xd8/0xe7
 [<ffffffff802407c9>] autoremove_wake_function+0x0/0x2e
 [<ffffffff8023d38f>] worker_thread+0x0/0xe7
 [<ffffffff802404c1>] kthread+0x47/0x73
 [<ffffffff8022c8dd>] schedule_tail+0x27/0x60
 [<ffffffff8020c249>] child_rip+0xa/0x11
 [<ffffffff8024047a>] kthread+0x0/0x73
 [<ffffffff8020c23f>] child_rip+0x0/0x11

This is because usb_reset_device now unbinds, and that calls disconnect,
which in case of ub waits until the reset completes... which deadlocks.
Worse, this deadlocks keventd and this takes whole box down.

I'm going to fix this properly later, but let's unbreak the driver
quickly for non-composite devices at least.

Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>