mac80211: remove STA entries when taking down interface

When we take down an interface, we need to remove the STA info
items that belong to it because otherwise we might invoke a
sta_notify() callback in the driver when we later delete the
STA entries, but in that case the driver will already have
removed its knowledge of the interface they belonged to leading
to confusion. Also, we could invoke the set_tim() callback after
the driver removed its knowledge of the interface, which can
lead to a crash if it requests a beacon with a then-invalid vif
pointer!

A side effect of this patch is that, because it was easier, it
disallows changing the WDS peer while an interface is up. Should
that actually be necessary, it can be added back, but the WDS
peer STA entry may not be added while the interface is UP so for
now I've simplified the WDS peer's STA entry lifetime management.

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

1 files changed, 14 insertions, 4 deletions

diff --git a/net/mac80211/ieee80211_ioctl.c b/net/mac80211/ieee80211_ioctl.c
index 5147152b9268..1d91575a0fe9 100644
--- a/net/mac80211/ieee80211_ioctl.c
+++ b/net/mac80211/ieee80211_ioctl.c
@@ -468,10 +468,20 @@ static int ieee80211_ioctl_siwap(struct net_device *dev,
 		ieee80211_sta_req_auth(dev, &sdata->u.sta);
 		return 0;
 	} else if (sdata->vif.type == IEEE80211_IF_TYPE_WDS) {
-		if (memcmp(sdata->u.wds.remote_addr, (u8 *) &ap_addr->sa_data,
-			   ETH_ALEN) == 0)
-			return 0;
-		return ieee80211_if_update_wds(dev, (u8 *) &ap_addr->sa_data);
+		/*
+		 * If it is necessary to update the WDS peer address
+		 * while the interface is running, then we need to do
+		 * more work here, namely if it is running we need to
+		 * add a new and remove the old STA entry, this is
+		 * normally handled by _open() and _stop().
+		 */
+		if (netif_running(dev))
+			return -EBUSY;
+
+		memcpy(&sdata->u.wds.remote_addr, (u8 *) &ap_addr->sa_data,
+		       ETH_ALEN);
+
+		return 0;
 	}
 
 	return -EOPNOTSUPP;