wifi: mac80211: maintain link-sta hash table

Maintain a hash table of link-sta addresses so we can find
them for management frames etc. where addresses haven't
been replaced by the drivers to the MLD address yet.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -1366,6 +1366,7 @@ struct ieee80211_local {
 	unsigned long num_sta;
 	struct list_head sta_list;
 	struct rhltable sta_hash;
+	struct rhltable link_sta_hash;
 	struct timer_list sta_cleanup;
 	int sta_generation;
 

net/mac80211/sta_info.c

@@ -79,6 +79,15 @@ static const struct rhashtable_params sta_rht_params = {
 	.max_size = CONFIG_MAC80211_STA_HASH_MAX_SIZE,
 };
 
+static const struct rhashtable_params link_sta_rht_params = {
+	.nelem_hint = 3, /* start small */
+	.automatic_shrinking = true,
+	.head_offset = offsetof(struct link_sta_info, link_hash_node),
+	.key_offset = offsetof(struct link_sta_info, addr),
+	.key_len = ETH_ALEN,
+	.max_size = CONFIG_MAC80211_STA_HASH_MAX_SIZE,
+};
+
 /* Caller must hold local->sta_mtx */
 static int sta_info_hash_del(struct ieee80211_local *local,
 			     struct sta_info *sta)
@@ -87,6 +96,14 @@ static int sta_info_hash_del(struct ieee80211_local *local,
 			       sta_rht_params);
 }
 
+static int link_sta_info_hash_del(struct ieee80211_local *local,
+				  struct link_sta_info *link_sta)
+{
+	return rhltable_remove(&local->link_sta_hash,
+			       &link_sta->link_hash_node,
+			       link_sta_rht_params);
+}
+
 static void __cleanup_single_sta(struct sta_info *sta)
 {
 	int ac, i;
@@ -216,6 +233,37 @@ struct sta_info *sta_info_get_bss(struct ieee80211_sub_if_data *sdata,
 	return NULL;
 }
 
+struct rhlist_head *link_sta_info_hash_lookup(struct ieee80211_local *local,
+					      const u8 *addr)
+{
+	return rhltable_lookup(&local->link_sta_hash, addr,
+			       link_sta_rht_params);
+}
+
+struct link_sta_info *
+link_sta_info_get_bss(struct ieee80211_sub_if_data *sdata, const u8 *addr)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct rhlist_head *tmp;
+	struct link_sta_info *link_sta;
+
+	rcu_read_lock();
+	for_each_link_sta_info(local, addr, link_sta, tmp) {
+		struct sta_info *sta = link_sta->sta;
+
+		if (sta->sdata == sdata ||
+		    (sta->sdata->bss && sta->sdata->bss == sdata->bss)) {
+			rcu_read_unlock();
+			/* this is safe as the caller must already hold
+			 * another rcu read section or the mutex
+			 */
+			return link_sta;
+		}
+	}
+	rcu_read_unlock();
+	return NULL;
+}
+
 struct sta_info *sta_info_get_by_addrs(struct ieee80211_local *local,
 				       const u8 *sta_addr, const u8 *vif_addr)
 {
@@ -256,7 +304,8 @@ static void sta_info_free_link(struct link_sta_info *link_sta)
 	free_percpu(link_sta->pcpu_rx_stats);
 }
 
-static void sta_remove_link(struct sta_info *sta, unsigned int link_id)
+static void sta_remove_link(struct sta_info *sta, unsigned int link_id,
+			    bool unhash)
 {
 	struct sta_link_alloc *alloc = NULL;
 	struct link_sta_info *link_sta;
@@ -267,6 +316,9 @@ static void sta_remove_link(struct sta_info *sta, unsigned int link_id)
 	if (WARN_ON(!link_sta))
 		return;
 
+	if (unhash)
+		link_sta_info_hash_del(sta->local, link_sta);
+
 	if (link_sta != &sta->deflink)
 		alloc = container_of(link_sta, typeof(*alloc), info);
 
@@ -298,7 +350,7 @@ void sta_info_free(struct ieee80211_local *local, struct sta_info *sta)
 		if (!(sta->sta.valid_links & BIT(i)))
 			continue;
 
-		sta_remove_link(sta, i);
+		sta_remove_link(sta, i, true);
 	}
 
 	/*
@@ -1262,6 +1314,12 @@ int sta_info_init(struct ieee80211_local *local)
 	if (err)
 		return err;
 
+	err = rhltable_init(&local->link_sta_hash, &link_sta_rht_params);
+	if (err) {
+		rhltable_destroy(&local->sta_hash);
+		return err;
+	}
+
 	spin_lock_init(&local->tim_lock);
 	mutex_init(&local->sta_mtx);
 	INIT_LIST_HEAD(&local->sta_list);
@@ -1274,6 +1332,7 @@ void sta_info_stop(struct ieee80211_local *local)
 {
 	del_timer_sync(&local->sta_cleanup);
 	rhltable_destroy(&local->sta_hash);
+	rhltable_destroy(&local->link_sta_hash);
 }
 
 
@@ -2685,6 +2744,14 @@ int ieee80211_sta_allocate_link(struct sta_info *sta, unsigned int link_id)
 	return 0;
 }
 
+static int link_sta_info_hash_add(struct ieee80211_local *local,
+				  struct link_sta_info *link_sta)
+{
+	return rhltable_insert(&local->link_sta_hash,
+			       &link_sta->link_hash_node,
+			       link_sta_rht_params);
+}
+
 int ieee80211_sta_activate_link(struct sta_info *sta, unsigned int link_id)
 {
 	struct ieee80211_sub_if_data *sdata = sta->sdata;
@@ -2701,16 +2768,21 @@ int ieee80211_sta_activate_link(struct sta_info *sta, unsigned int link_id)
 
 	sta->sta.valid_links = new_links;
 
-	if (!test_sta_flag(sta, WLAN_STA_INSERTED))
-		return 0;
+	if (!test_sta_flag(sta, WLAN_STA_INSERTED)) {
+		ret = 0;
+		goto hash;
+	}
 
 	ret = drv_change_sta_links(sdata->local, sdata, &sta->sta,
 				   old_links, new_links);
 	if (ret) {
 		sta->sta.valid_links = old_links;
-		sta_remove_link(sta, link_id);
+		sta_remove_link(sta, link_id, false);
 	}
 
+hash:
+	link_sta_info_hash_add(sdata->local, link_sta);
+
 	return ret;
 }
 
@@ -2727,5 +2799,5 @@ void ieee80211_sta_remove_link(struct sta_info *sta, unsigned int link_id)
 				     sta->sta.valid_links,
 				     sta->sta.valid_links & ~BIT(link_id));
 
-	sta_remove_link(sta, link_id);
+	sta_remove_link(sta, link_id, true);
 }

net/mac80211/sta_info.h

@@ -491,6 +491,7 @@ struct ieee80211_fragment_cache {
  *	same for non-MLD STA. This is used as key for searching link STA
  * @link_id: Link ID uniquely identifying the link STA. This is 0 for non-MLD
  *	and set to the corresponding vif LinkId for MLD STA
+ * @link_hash_node: hash node for rhashtable
  * @sta: Points to the STA info
  * @gtk: group keys negotiated with this station, if any
  * @tx_stats: TX statistics
@@ -523,7 +524,7 @@ struct link_sta_info {
 	u8 addr[ETH_ALEN];
 	u8 link_id;
 
-	/* TODO rhash head/node for finding link_sta based on addr */
+	struct rhlist_head link_hash_node;
 
 	struct sta_info *sta;
 	struct ieee80211_key __rcu *gtk[NUM_DEFAULT_KEYS +
@@ -824,6 +825,17 @@ struct sta_info *sta_info_get_by_addrs(struct ieee80211_local *local,
 	rhl_for_each_entry_rcu(_sta, _tmp,				\
 			       sta_info_hash_lookup(local, _addr), hash_node)
 
+struct rhlist_head *link_sta_info_hash_lookup(struct ieee80211_local *local,
+					      const u8 *addr);
+
+#define for_each_link_sta_info(local, _addr, _sta, _tmp)		\
+	rhl_for_each_entry_rcu(_sta, _tmp,				\
+			       link_sta_info_hash_lookup(local, _addr),	\
+			       link_hash_node)
+
+struct link_sta_info *
+link_sta_info_get_bss(struct ieee80211_sub_if_data *sdata, const u8 *addr);
+
 /*
  * Get STA info by index, BROKEN!
  */