From: Bernard Blackham <b-linuxgit@largestprime.net>
Date: Thu, 6 Sep 2012 10:25:04 +0000 (+1000)
Subject: staging: usbip: avoid deadlock in vhci_device_unlink_cleanup()
X-Git-Tag: omap-for-v3.7-rc1/fixes-cpufreq-signed~75^2~560
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=236742de5bfd2af772004ec829518856ff12b469;p=pandora-kernel.git

staging: usbip: avoid deadlock in vhci_device_unlink_cleanup()

Almost all of usbip assumes that the_controller->lock is acquired
before vdev->priv_lock. The exception is in
vhci_device_unlink_cleanup(), where locks are acquired in the
reverse order. This leads to occasional deadlocks.

Fixing this is a bit fiddly, as the_controller->lock can't be held
when calling usb_hcd_unlink_urb_from_ep() in the middle of the list
traversal. As I can't rule out concurrent callers to this function
(perhaps it is safe?), the code here becomes slightly uglier - when
locks are dropped in the middle so the list may have emptied itself
(not even list_for_each_entry_safe is safe here).

Signed-off-by: Bernard Blackham <b-linuxgit@largestprime.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

Reading git-diff-tree failed