[PATCH] mac80211: fix virtual interface locking

Florian Lohoff noticed a bug in mac80211: when bringing the
master interface down while other virtual interfaces are up
we call dev_close() under a spinlock which is not allowed.
This patch removes the sub_if_lock used by mac80211 in favour
of using an RCU list. All list manipulations are already done
under rtnl so are well protected against each other, and the
read-side locks we took in the RX and TX code are already in
RCU read-side critical sections.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: Florian Lohoff <flo@rfc822.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Cc: Satyam Sharma <satyam@infradead.org>
Signed-off-by: Michael Wu <flamingice@sourmilk.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 2 insertions, 3 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 1a43f3e9b6bd..a5961f16f206 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -475,9 +475,8 @@ struct ieee80211_local {
         ieee80211_rx_handler *rx_handlers;
         ieee80211_tx_handler *tx_handlers;
 
-        rwlock_t sub_if_lock; /* Protects sub_if_list. Cannot be taken under
-                               * sta_bss_lock or sta_lock. */
-        struct list_head sub_if_list;
+        struct list_head interfaces;
+
         int sta_scanning;
         int scan_channel_idx;
         enum { SCAN_SET_CHANNEL, SCAN_SEND_PROBE } scan_state;