mac80211: add atomic uploaded keys iterator

add ieee80211_iter_keys_rcu() to iterate over uploaded
keys in atomic context (when rcu is locked)

The station removal code removes the keys only after
calling synchronize_net(), so it's not safe to iterate
the keys at this point (and postponing the actual key
deletion with call_rcu() might result in some
badly-ordered ops calls).

Add a flag to indicate a station is being removed,
and skip the configured keys if it's set.

Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/sta_info.c

@@ -883,6 +883,7 @@ static int __must_check __sta_info_destroy_part1(struct sta_info *sta)
 	}
 
 	list_del_rcu(&sta->list);
+	sta->removed = true;
 
 	drv_sta_pre_rcu_remove(local, sta->sdata, sta);