[bug report] wifi: ath12k: Attach and detach ath12k_dp_link_peer to ath12k_dp_peer

[Dan Carpenter <dan.carpenter@linaro.org>]

Hello Harsh Kumar Bijlani,

Commit 5525f12fa671 ("wifi: ath12k: Attach and detach
ath12k_dp_link_peer to ath12k_dp_peer") from Oct 24, 2025
(linux-next), leads to the following Smatch static checker warning:

	drivers/net/wireless/ath/ath12k/mac.c:1231 ath12k_mac_peer_cleanup_all()
	error: we previously assumed 'dp_peer' could be null (see line 1229)

drivers/net/wireless/ath/ath12k/mac.c
    1206 void ath12k_mac_peer_cleanup_all(struct ath12k *ar)
    1207 {
    1208         struct ath12k_dp_link_peer *peer, *tmp;
    1209         struct ath12k_base *ab = ar->ab;
    1210         struct ath12k_dp *dp = ath12k_ab_to_dp(ab);
    1211         struct ath12k_link_vif *arvif, *tmp_vif;
    1212         struct ath12k_dp_hw *dp_hw = &ar->ah->dp_hw;
    1213         struct ath12k_dp_peer *dp_peer = NULL;
    1214         u16 peerid_index;
    1215         struct list_head peers;
    1216 
    1217         INIT_LIST_HEAD(&peers);
    1218 
    1219         lockdep_assert_wiphy(ath12k_ar_to_hw(ar)->wiphy);
    1220 
    1221         spin_lock_bh(&dp->dp_lock);
    1222         list_for_each_entry_safe(peer, tmp, &dp->peers, list) {
    1223                 /* Skip Rx TID cleanup for self peer */
    1224                 if (peer->sta && peer->dp_peer)
                                          ^^^^^^^^^^^^^
This assumes that dp_peer can be NULL.

    1225                         ath12k_dp_rx_peer_tid_cleanup(ar, peer);
    1226 
    1227                 /* cleanup dp peer */
    1228                 spin_lock_bh(&dp_hw->peer_lock);
    1229                 dp_peer = peer->dp_peer;
                         ^^^^^^^^^^^^^^^^^^^^^^^

    1230                 peerid_index = ath12k_dp_peer_get_peerid_index(dp, peer->peer_id);
--> 1231                 rcu_assign_pointer(dp_peer->link_peers[peer->link_id], NULL);
                                            ^^^^^^^^^
Unchecked dereference.  It's not clear if it can be NULL or not.

    1232                 rcu_assign_pointer(dp_hw->dp_peers[peerid_index], NULL);
    1233                 spin_unlock_bh(&dp_hw->peer_lock);
    1234 
    1235                 ath12k_dp_link_peer_rhash_delete(dp, peer);
    1236 
    1237                 list_move(&peer->list, &peers);
    1238         }
    1239         spin_unlock_bh(&dp->dp_lock);
    1240 
    1241         synchronize_rcu();
    1242 
    1243         list_for_each_entry_safe(peer, tmp, &peers, list) {
    1244                 ath12k_dp_link_peer_free(peer);
    1245         }
    1246 
    1247         ar->num_peers = 0;
    1248         ar->num_stations = 0;
    1249 
    1250         /* Cleanup rhash table maintained for arsta by iterating over sta */
    1251         ieee80211_iterate_stations_mtx(ar->ah->hw, ath12k_mac_link_sta_rhash_cleanup,
    1252                                        ar);
    1253 
    1254         /* Delete all the self dp_peers on asserted radio */
    1255         list_for_each_entry_safe_reverse(arvif, tmp_vif, &ar->arvifs, list) {
    1256                 if ((arvif->ahvif->vdev_type == WMI_VDEV_TYPE_AP) &&
    1257                     (arvif->link_id < IEEE80211_MLD_MAX_NUM_LINKS)) {
    1258                         ath12k_dp_peer_delete(dp_hw, arvif->bssid, NULL);
    1259                         arvif->num_stations = 0;
    1260                 }
    1261         }
    1262 }

regards,
dan carpenter