tree 56f08ca551c38d9ef18f699874f1b1bb3bb8e4f3
parent 9dca9c490146e787472bc05b264e043311a4c67b
author Johannes Berg <johannes.berg@intel.com> 1279702360 +0200
committer John W. Linville <linville@tuxdriver.com> 1279739622 -0400

mac80211: fix IBSS lockdep complaint

Bob reported a lockdep complaint originating in
the mac80211 IBSS code due to the common work
struct patch. The reason is that the IBSS and
station mode code have different locking orders
for the cfg80211 wdev lock and the work struct
(where "locking" implies running/canceling).

Fix this by simply not canceling the work in
the IBSS code, it is not necessary since when
the REQ_RUN bit is cleared, the work will run
without effect if it runs. When the interface
is set down, it is flushed anyway, so there's
no concern about it running after memory has
been invalidated either.

This fixes
https://bugzilla.kernel.org/show_bug.cgi?id=16419

Additionally, looking into this I noticed that
there's a small window while the IBSS is torn
down in which the work may be rescheduled and
the REQ_RUN bit be set again after leave() has
cleared it when a scan finishes at exactly the
same time. Avoid that by setting the ssid_len
to zero before clearing REQ_RUN which signals
to the scan finish code that this interface is
not active.

Reported-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>