ixgbevf: Check if EOP has changed before using it

There is a chance that between the time EOP is read and the time it is
used another transmit on a different CPU could have run and completed,
thus leaving EOP in a bad state.

Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
index b1e1c2daf5f9a7d935dc3ad7b8b0f9efe3f9af9f..936532fa42ad0b10dca5afcc7326022199e5f9a4 100644 (file)
--- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
+++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
@@ -203,6 +203,9 @@ static bool ixgbevf_clean_tx_irq(struct ixgbevf_adapter *adapter,
               (count < tx_ring->work_limit)) {
                bool cleaned = false;
                rmb(); /* read buffer_info after eop_desc */
+               /* eop could change between read and DD-check */
+               if (unlikely(eop != tx_ring->tx_buffer_info[i].next_to_watch))
+                       goto cont_loop;
                for ( ; !cleaned; count++) {
                        struct sk_buff *skb;
                        tx_desc = IXGBE_TX_DESC_ADV(*tx_ring, i);
@@ -232,6 +235,7 @@ static bool ixgbevf_clean_tx_irq(struct ixgbevf_adapter *adapter,
                                i = 0;
                }
 
+cont_loop:
                eop = tx_ring->tx_buffer_info[i].next_to_watch;
                eop_desc = IXGBE_TX_DESC_ADV(*tx_ring, eop);
        }