mac80211: fix monitor_sdata RCU/locking assertions

Since commit a05829a ("cfg80211: avoid holding the RTNL when
calling the driver") we've not only been protecting the pointer
to monitor_sdata with the RTNL, but also with the wiphy->mtx. This
is relevant in a number of lockdep assertions, e.g. the one we hit
in ieee80211_set_monitor_channel(). However, we're now protecting
all the assignments/dereferences, even the one in interface iter,
with the wiphy->mtx, so switch over the lockdep assertions to that
lock.

Fixes: a05829a ("cfg80211: avoid holding the RTNL when calling the driver")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20211112135143.cb8e8ceffef3.Iaa210f16f6904c8a7a24954fb3396da0ef86ec08@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -80,7 +80,8 @@ static int ieee80211_set_mon_options(struct ieee80211_sub_if_data *sdata,
 	}
 
 	/* also validate MU-MIMO change */
-	monitor_sdata = rtnl_dereference(local->monitor_sdata);
+	monitor_sdata = wiphy_dereference(local->hw.wiphy,
+					  local->monitor_sdata);
 
 	if (!monitor_sdata &&
 	    (params->vht_mumimo_groups || params->vht_mumimo_follow_addr))
@@ -840,7 +841,8 @@ static int ieee80211_set_monitor_channel(struct wiphy *wiphy,
 
 	mutex_lock(&local->mtx);
 	if (local->use_chanctx) {
-		sdata = rtnl_dereference(local->monitor_sdata);
+		sdata = wiphy_dereference(local->hw.wiphy,
+					  local->monitor_sdata);
 		if (sdata) {
 			ieee80211_vif_release_channel(sdata);
 			ret = ieee80211_vif_use_channel(sdata, chandef,
@@ -2707,7 +2709,8 @@ static int ieee80211_set_tx_power(struct wiphy *wiphy,
 		sdata = IEEE80211_WDEV_TO_SUB_IF(wdev);
 
 		if (sdata->vif.type == NL80211_IFTYPE_MONITOR) {
-			sdata = rtnl_dereference(local->monitor_sdata);
+			sdata = wiphy_dereference(local->hw.wiphy,
+						  local->monitor_sdata);
 			if (!sdata)
 				return -EOPNOTSUPP;
 		}
@@ -2767,7 +2770,8 @@ static int ieee80211_set_tx_power(struct wiphy *wiphy,
 	mutex_unlock(&local->iflist_mtx);
 
 	if (has_monitor) {
-		sdata = rtnl_dereference(local->monitor_sdata);
+		sdata = wiphy_dereference(local->hw.wiphy,
+					  local->monitor_sdata);
 		if (sdata) {
 			sdata->user_power_level = local->user_power_level;
 			if (txp_type != sdata->vif.bss_conf.txpower_type)

net/mac80211/iface.c

@@ -588,7 +588,7 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata, bool going_do
 	 */
 	if (local->suspended) {
 		WARN_ON(local->wowlan);
-		WARN_ON(rtnl_dereference(local->monitor_sdata));
+		WARN_ON(rcu_access_pointer(local->monitor_sdata));
 		return;
 	}
 
@@ -961,6 +961,7 @@ int ieee80211_add_virtual_monitor(struct ieee80211_local *local)
 		return 0;
 
 	ASSERT_RTNL();
+	lockdep_assert_wiphy(local->hw.wiphy);
 
 	if (local->monitor_sdata)
 		return 0;
@@ -1028,6 +1029,7 @@ void ieee80211_del_virtual_monitor(struct ieee80211_local *local)
 		return;
 
 	ASSERT_RTNL();
+	lockdep_assert_wiphy(local->hw.wiphy);
 
 	mutex_lock(&local->iflist_mtx);
 

net/mac80211/util.c

@@ -796,7 +796,7 @@ static void __iterate_interfaces(struct ieee80211_local *local,
 
 	sdata = rcu_dereference_check(local->monitor_sdata,
 				      lockdep_is_held(&local->iflist_mtx) ||
-				      lockdep_rtnl_is_held());
+				      lockdep_is_held(&local->hw.wiphy->mtx));
 	if (sdata &&
 	    (iter_flags & IEEE80211_IFACE_ITER_RESUME_ALL || !active_only ||
 	     sdata->flags & IEEE80211_SDATA_IN_DRIVER))
@@ -2381,7 +2381,7 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 				   IEEE80211_TPT_LEDTRIG_FL_RADIO, 0);
 
 	/* add interfaces */
-	sdata = rtnl_dereference(local->monitor_sdata);
+	sdata = wiphy_dereference(local->hw.wiphy, local->monitor_sdata);
 	if (sdata) {
 		/* in HW restart it exists already */
 		WARN_ON(local->resuming);
@@ -2426,7 +2426,8 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 				WARN_ON(drv_add_chanctx(local, ctx));
 		mutex_unlock(&local->chanctx_mtx);
 
-		sdata = rtnl_dereference(local->monitor_sdata);
+		sdata = wiphy_dereference(local->hw.wiphy,
+					  local->monitor_sdata);
 		if (sdata && ieee80211_sdata_running(sdata))
 			ieee80211_assign_chanctx(local, sdata);
 	}