ath11k: acquire ab->base_lock in unassign when finding the peer by addr

ath11k_peer_find_by_addr states via lockdep that ab->base_lock must be
held when calling that function in order to protect the list. All
callers except ath11k_mac_op_unassign_vif_chanctx have that lock
acquired when calling ath11k_peer_find_by_addr. That lock is also not
transitively held by a path towards ath11k_mac_op_unassign_vif_chanctx.
The solution is to acquire the lock when calling
ath11k_peer_find_by_addr inside ath11k_mac_op_unassign_vif_chanctx.

I am currently working on a static analyser to detect missing locks and
this was a reported case. I manually verified the report by looking at
the code, but I do not have real hardware so this is compile tested
only.

Fixes: 701e48a4 ("ath11k: add packet log support for QCA6390")
Signed-off-by: Niels Dossche <dossche.niels@gmail.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220314215253.92658-1-dossche.niels@gmail.com

drivers/net/wireless/ath/ath11k/mac.c

@@ -7133,6 +7133,7 @@ ath11k_mac_op_unassign_vif_chanctx(struct ieee80211_hw *hw,
 	struct ath11k *ar = hw->priv;
 	struct ath11k_base *ab = ar->ab;
 	struct ath11k_vif *arvif = (void *)vif->drv_priv;
+	struct ath11k_peer *peer;
 	int ret;
 
 	mutex_lock(&ar->conf_mutex);
@@ -7144,9 +7145,13 @@ ath11k_mac_op_unassign_vif_chanctx(struct ieee80211_hw *hw,
 	WARN_ON(!arvif->is_started);
 
 	if (ab->hw_params.vdev_start_delay &&
-	    arvif->vdev_type == WMI_VDEV_TYPE_MONITOR &&
-	    ath11k_peer_find_by_addr(ab, ar->mac_addr))
-		ath11k_peer_delete(ar, arvif->vdev_id, ar->mac_addr);
+	    arvif->vdev_type == WMI_VDEV_TYPE_MONITOR) {
+		spin_lock_bh(&ab->base_lock);
+		peer = ath11k_peer_find_by_addr(ab, ar->mac_addr);
+		spin_unlock_bh(&ab->base_lock);
+		if (peer)
+			ath11k_peer_delete(ar, arvif->vdev_id, ar->mac_addr);
+	}
 
 	if (arvif->vdev_type == WMI_VDEV_TYPE_MONITOR) {
 		ret = ath11k_mac_monitor_stop(ar);