ath9k: Fix bug in paprd

It is possbile that the transmission of paprd test frame
might not get completed in 100ms if tx is stuck. Freeing
this skb upon timeout in ath_paprd_calibrate() will result
in accessing already freed memory when the associated pending
buffer is drained in txq. This patch fixes this issue.

Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/ath9k.h

@@ -226,6 +226,7 @@ struct ath_buf_state {
 	int bfs_retries;
 	u8 bf_type;
 	u8 bfs_paprd;
+	unsigned long bfs_paprd_timestamp;
 	u32 bfs_keyix;
 	enum ath9k_key_type bfs_keytype;
 };
@@ -425,6 +426,8 @@ int ath_beaconq_config(struct ath_softc *sc);
 #define ATH_LONG_CALINTERVAL      30000   /* 30 seconds */
 #define ATH_RESTART_CALINTERVAL   1200000 /* 20 minutes */
 
+#define ATH_PAPRD_TIMEOUT	100 /* msecs */
+
 void ath_paprd_calibrate(struct work_struct *work);
 void ath_ani_calibrate(unsigned long data);
 

drivers/net/wireless/ath/ath9k/main.c

@@ -310,13 +310,13 @@ void ath_paprd_calibrate(struct work_struct *work)
 			break;
 
 		time_left = wait_for_completion_timeout(&sc->paprd_complete,
-							100);
+				msecs_to_jiffies(ATH_PAPRD_TIMEOUT));
 		if (!time_left) {
 			ath_print(ath9k_hw_common(ah), ATH_DBG_CALIBRATE,
 				  "Timeout waiting for paprd training on "
 				  "TX chain %d\n",
 				  chain);
-			break;
+			goto fail_paprd;
 		}
 
 		if (!ar9003_paprd_is_done(ah))
@@ -334,6 +334,7 @@ void ath_paprd_calibrate(struct work_struct *work)
 		ath_paprd_activate(sc);
 	}
 
+fail_paprd:
 	ath9k_ps_restore(sc);
 }
 

drivers/net/wireless/ath/ath9k/xmit.c

@@ -1644,6 +1644,8 @@ static int ath_tx_setup_buffer(struct ieee80211_hw *hw, struct ath_buf *bf,
 	}
 
 	bf->bf_state.bfs_paprd = txctl->paprd;
+	if (txctl->paprd)
+		bf->bf_state.bfs_paprd_timestamp = jiffies;
 	bf->bf_flags = setup_tx_flags(skb, use_ldpc);
 
 	bf->bf_keytype = get_hw_crypto_keytype(skb);
@@ -1944,8 +1946,14 @@ static void ath_tx_complete_buf(struct ath_softc *sc, struct ath_buf *bf,
 	dma_unmap_single(sc->dev, bf->bf_dmacontext, skb->len, DMA_TO_DEVICE);
 
 	if (bf->bf_state.bfs_paprd) {
-		sc->paprd_txok = txok;
-		complete(&sc->paprd_complete);
+		if (time_after(jiffies,
+			       bf->bf_state.bfs_paprd_timestamp +
+			       msecs_to_jiffies(ATH_PAPRD_TIMEOUT))) {
+			dev_kfree_skb_any(skb);
+		} else {
+			sc->paprd_txok = txok;
+			complete(&sc->paprd_complete);
+		}
 	} else {
 		ath_tx_complete(sc, skb, bf->aphy, tx_flags);
 		ath_debug_stat_tx(sc, txq, bf, ts);