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>

3 files changed, 14 insertions, 5 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c
index 3d4c61fcf06f..fa74acdd271f 100644
--- a/drivers/net/wireless/rt2x00/rt2x00dev.c
+++ b/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);
 }
diff --git a/drivers/net/wireless/rt2x00/rt2x00queue.h b/drivers/net/wireless/rt2x00/rt2x00queue.h
index baa39b75430c..47659346070b 100644
--- a/drivers/net/wireless/rt2x00/rt2x00queue.h
+++ b/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,
 };
 
 /**
diff --git a/drivers/net/wireless/rt2x00/rt2x00usb.c b/drivers/net/wireless/rt2x00/rt2x00usb.c
index cd29ebc8a37b..8a16b5106a33 100644
--- a/drivers/net/wireless/rt2x00/rt2x00usb.c
+++ b/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);