rt2x00: Introduce extra queue entry sanity flag

Add a queue entry flag ENTRY_DATA_STATUS_PENDING,
which can be used to indicate a queue entry has
returned from the hardware and is waiting for
status processing. Using this flag we can add
some extra sanity checks to prevent queue corruption.
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Acked-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2x00dev.c

@@ -235,6 +235,7 @@ EXPORT_SYMBOL_GPL(rt2x00lib_dmastart);
 
 void rt2x00lib_dmadone(struct queue_entry *entry)
 {
+	set_bit(ENTRY_DATA_STATUS_PENDING, &entry->flags);
 	clear_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags);
 	rt2x00queue_index_inc(entry->queue, Q_INDEX_DMA_DONE);
 }

drivers/net/wireless/rt2x00/rt2x00queue.h

@@ -340,12 +340,16 @@ struct txentry_desc {
  * @ENTRY_DATA_IO_FAILED: Hardware indicated that an IO error occured
  *	while transfering the data to the hardware. No TX status report will
  *	be expected from the hardware.
+ * @ENTRY_DATA_STATUS_PENDING: The entry has been send to the device and
+ *	returned. It is now waiting for the status reporting before the
+ *	entry can be reused again.
  */
 enum queue_entry_flags {
 	ENTRY_BCN_ASSIGNED,
 	ENTRY_OWNER_DEVICE_DATA,
 	ENTRY_DATA_PENDING,
-	ENTRY_DATA_IO_FAILED
+	ENTRY_DATA_IO_FAILED,
+	ENTRY_DATA_STATUS_PENDING,
 };
 
 /**

drivers/net/wireless/rt2x00/rt2x00usb.c

@@ -195,7 +195,8 @@ static void rt2x00usb_work_txdone(struct work_struct *work)
 		while (!rt2x00queue_empty(queue)) {
 			entry = rt2x00queue_get_entry(queue, Q_INDEX_DONE);
 
-			if (test_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags))
+			if (test_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags) ||
+			    !test_bit(ENTRY_DATA_STATUS_PENDING, &entry->flags))
 				break;
 
 			rt2x00usb_work_txdone_entry(entry);
@@ -237,7 +238,8 @@ static void rt2x00usb_kick_tx_entry(struct queue_entry *entry)
 	u32 length;
 	int status;
 
-	if (!test_and_clear_bit(ENTRY_DATA_PENDING, &entry->flags))
+	if (!test_and_clear_bit(ENTRY_DATA_PENDING, &entry->flags) ||
+	    test_bit(ENTRY_DATA_STATUS_PENDING, &entry->flags))
 		return;
 
 	/*
@@ -275,7 +277,8 @@ static void rt2x00usb_work_rxdone(struct work_struct *work)
 	while (!rt2x00queue_empty(rt2x00dev->rx)) {
 		entry = rt2x00queue_get_entry(rt2x00dev->rx, Q_INDEX_DONE);
 
-		if (test_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags))
+		if (test_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags) ||
+		    !test_bit(ENTRY_DATA_STATUS_PENDING, &entry->flags))
 			break;
 
 		/*
@@ -327,7 +330,8 @@ static void rt2x00usb_kick_rx_entry(struct queue_entry *entry)
 	struct queue_entry_priv_usb *entry_priv = entry->priv_data;
 	int status;
 
-	if (test_and_set_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags))
+	if (test_and_set_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags) ||
+	    test_bit(ENTRY_DATA_STATUS_PENDING, &entry->flags))
 		return;
 
 	rt2x00lib_dmastart(entry);