mac80211: disable beacons before removing the associated interface

When downing interfaces, it's a good idea to tell the driver to
stop sending beacons; that way the driver doesn't need special
code in ops->remove_interface() when it should already handle the
case in bss_info_changed().

This fixes a potential crash with at least ath5k since the vif
pointer will be nullified while beacon interrupts are still active.

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

1 files changed, 2 insertions, 1 deletions

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 9dd8d25611e..5e76dd1daf7 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -198,7 +198,8 @@ void ieee80211_bss_info_change_notify(struct ieee80211_sub_if_data *sdata,
         }
 
         if (changed & BSS_CHANGED_BEACON_ENABLED) {
-                if (test_bit(SCAN_SW_SCANNING, &local->scanning)) {
+                if (local->quiescing || !netif_running(sdata->dev) ||
+                    test_bit(SCAN_SW_SCANNING, &local->scanning)) {
                         sdata->vif.bss_conf.enable_beacon = false;
                 } else {
                         /*