nl80211: fix dumpit error path RTNL deadlocks

commit ea90e0dc8cecba6359b481e24d9c37160f6f524f upstream.

Sowmini pointed out Dmitry's RTNL deadlock report to me, and it turns out
to be perfectly accurate - there are various error paths that miss unlock
of the RTNL.

To fix those, change the locking a bit to not be conditional in all those
nl80211_prepare_*_dump() functions, but make those require the RTNL to
start with, and fix the buggy error paths. This also let me use sparse
(by appropriately overriding the rtnl_lock/rtnl_unlock functions) to
validate the changes.

Reported-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
[bwh: Backported to 3.16:
 - Drop changes to nl80211_dump_interface(), nl80211_dump_mpp(),
   nl80211_prepare_vendor_dump(), nl80211_vendor_cmd_dump()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

0 files changed, 0 insertions, 0 deletions