ath9k: fix a stale bf->bf_next pointer, potentially leading to double-free errors and "Failed to stop Tx DMA" errors

SVN-Revision: 33938

package/mac80211/patches/568-ath9k_fix_stale_pointer.patch

@@ -0,0 +1,18 @@
+--- a/drivers/net/wireless/ath/ath9k/xmit.c
++++ b/drivers/net/wireless/ath/ath9k/xmit.c
+@@ -312,6 +312,7 @@ static struct ath_buf *ath_tx_get_buffer
+ 	}
+ 
+ 	bf = list_first_entry(&sc->tx.txbuf, struct ath_buf, list);
++	bf->bf_next = NULL;
+ 	list_del(&bf->list);
+ 
+ 	spin_unlock_bh(&sc->tx.txbuflock);
+@@ -1774,6 +1775,7 @@ static void ath_tx_send_normal(struct at
+ 	list_add_tail(&bf->list, &bf_head);
+ 	bf->bf_state.bf_type = 0;
+ 
++	bf->bf_next = NULL;
+ 	bf->bf_lastbf = bf;
+ 	ath_tx_fill_desc(sc, bf, txq, fi->framelen);
+ 	ath_tx_txqaddbuf(sc, txq, &bf_head, false);