wifi: mac80211: RCU-ify link/link_conf pointers

Since links can be added and removed dynamically, we need to somehow protect the sdata->link[] and vif->link_conf[] array pointers from disappearing when accessing them without locks. RCU-ify the pointers to achieve this, which requires quite a bit of rework. Signed-off-by: Johannes Berg <[email protected]>
josf · Jul 15, 2022 · d8675a6 · d8675a6
1 parent 3d1cc7c
commit d8675a6
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Showing 22 changed files with 420 additions and 275 deletions.
diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
@@ -1477,9 +1477,10 @@ static void mac80211_hwsim_tx_iter(void *_data, u8 *addr,
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(vif->link_conf); i++) {
-		struct ieee80211_bss_conf *conf = vif->link_conf[i];
+		struct ieee80211_bss_conf *conf;
 		struct ieee80211_chanctx_conf *chanctx;
 
+		conf = rcu_dereference(vif->link_conf[i]);
 		if (!conf)
 			continue;
 
@@ -1917,7 +1918,7 @@ static void mac80211_hwsim_beacon_tx(void *arg, u8 *mac,
 {
 	struct mac80211_hwsim_link_data *link_data = arg;
 	u32 link_id = link_data->link_id;
-	struct ieee80211_bss_conf *link_conf = vif->link_conf[link_id];
+	struct ieee80211_bss_conf *link_conf;
 	struct mac80211_hwsim_data *data =
 		container_of(link_data, struct mac80211_hwsim_data,
 			     link_data[link_id]);
@@ -1931,6 +1932,10 @@ static void mac80211_hwsim_beacon_tx(void *arg, u8 *mac,
 
 	hwsim_check_magic(vif);
 
+	link_conf = rcu_dereference(vif->link_conf[link_id]);
+	if (!link_conf)
+		return;
+
 	if (vif->type != NL80211_IFTYPE_AP &&
 	    vif->type != NL80211_IFTYPE_MESH_POINT &&
 	    vif->type != NL80211_IFTYPE_ADHOC &&
@@ -2155,12 +2160,11 @@ static void mac80211_hwsim_vif_info_changed(struct ieee80211_hw *hw,
 
 static void mac80211_hwsim_link_info_changed(struct ieee80211_hw *hw,
 					     struct ieee80211_vif *vif,
-					     u32 link_id,
-					     u64 changed)
+					     struct ieee80211_bss_conf *info,
+					     u32 link_id, u64 changed)
 {
 	struct hwsim_vif_priv *vp = (void *)vif->drv_priv;
 	struct mac80211_hwsim_data *data = hw->priv;
-	struct ieee80211_bss_conf *info = vif->link_conf[link_id];
 	struct mac80211_hwsim_link_data *link_data = &data->link_data[link_id];
 
 	hwsim_check_magic(vif);

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
@@ -1789,7 +1789,7 @@ struct ieee80211_vif {
 	enum nl80211_iftype type;
 	struct ieee80211_vif_cfg cfg;
 	struct ieee80211_bss_conf bss_conf;
-	struct ieee80211_bss_conf *link_conf[IEEE80211_MLD_MAX_NUM_LINKS];
+	struct ieee80211_bss_conf __rcu *link_conf[IEEE80211_MLD_MAX_NUM_LINKS];
 	u16 valid_links;
 	u8 addr[ETH_ALEN] __aligned(2);
 	bool p2p;
@@ -4082,7 +4082,9 @@ struct ieee80211_ops {
 				u64 changed);
 	void (*link_info_changed)(struct ieee80211_hw *hw,
 				  struct ieee80211_vif *vif,
-				  unsigned int link_id, u64 changed);
+				  struct ieee80211_bss_conf *info,
+				  unsigned int link_id,
+				  u64 changed);
 
 	int (*start_ap)(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 			unsigned int link_id);