wifi: mac80211: add pointer from link STA to STA

While often not needed, this considerably simplifies going from a link
to the STA. This helps in cases such as debugfs where a single pointer
should allow accessing a specific link and the STA.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -2176,6 +2176,7 @@ struct ieee80211_sta_aggregates {
  * All link specific info for a STA link for a non MLD STA(single)
  * or a MLD STA(multiple entries) are stored here.
  *
+ * @sta: reference to owning STA
  * @addr: MAC address of the Link STA. For non-MLO STA this is same as the addr
  *	in ieee80211_sta. For MLO Link STA this addr can be same or different
  *	from addr in ieee80211_sta (representing MLD STA addr)
@@ -2196,6 +2197,8 @@ struct ieee80211_sta_aggregates {
  *
  */
 struct ieee80211_link_sta {
+	struct ieee80211_sta *sta;
+
 	u8 addr[ETH_ALEN];
 	u8 link_id;
 	enum ieee80211_smps_mode smps_mode;

net/mac80211/sta_info.c

@@ -511,6 +511,7 @@ static void sta_info_add_link(struct sta_info *sta,
 	link_info->sta = sta;
 	link_info->link_id = link_id;
 	link_info->pub = link_sta;
+	link_info->pub->sta = &sta->sta;
 	link_sta->link_id = link_id;
 	rcu_assign_pointer(sta->link[link_id], link_info);
 	rcu_assign_pointer(sta->sta.link[link_id], link_sta);