tree 3b023b960e010b7ce84d35d8e9b516f5cb285f77
parent 96909e97716de1d86e6e24d6aabce09980372771
author Johannes Berg <johannes@sipsolutions.net> 1250504737 +0200
committer John W. Linville <linville@tuxdriver.com> 1250782556 -0400

cfg80211: fix deadlock

When removing an interface with nl80211, cfg80211 will
deadlock in the netdev notifier because we're already
holding rdev->mtx and try to acquire it again to verify
the scan has been done.

This bug was introduced by my patch
"cfg80211: check for and abort dangling scan requests".

To fix this, move the dangling scan request check into
wiphy_unregister(). This will not be able to catch all
cases right away, but if the scan problem happens with
a manual ifdown or so it will be possible to remedy it
by removing the module/device.

Additionally, add comments about the deadlock scenario.

Reported-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Tested-by: Christian Lamparter <chunkeey@web.de>
Tested-by: Kalle Valo <kalle.valo@iki.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>