ath9k: Keep track of stations for debugfs.

The stations hold the ath_node, which holds the tid
and other xmit logic structures.  In order to debug
stuck xmit logic, we need a way to print out the tid
state for the stations.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index c03184e7..bed6eb9 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -548,6 +548,12 @@
 	struct ath_hw *ah = sc->sc_ah;
 	an = (struct ath_node *)sta->drv_priv;
 
+#ifdef CONFIG_ATH9K_DEBUGFS
+	spin_lock(&sc->nodes_lock);
+	list_add(&an->list, &sc->nodes);
+	spin_unlock(&sc->nodes_lock);
+	an->sta = sta;
+#endif
 	if ((ah->caps.hw_caps) & ATH9K_HW_CAP_APM)
 		sc->sc_flags |= SC_OP_ENABLE_APM;
 
@@ -563,6 +569,13 @@
 {
 	struct ath_node *an = (struct ath_node *)sta->drv_priv;
 
+#ifdef CONFIG_ATH9K_DEBUGFS
+	spin_lock(&sc->nodes_lock);
+	list_del(&an->list);
+	spin_unlock(&sc->nodes_lock);
+	an->sta = NULL;
+#endif
+
 	if (sc->sc_flags & SC_OP_TXAGGR)
 		ath_tx_node_cleanup(sc, an);
 }