e1000e: stop cleaning when we reach tx_ring->next_to_use

Tx ring buffers after tx_ring->next_to_use are volatile and could
change, possibly causing a crash.  Stop cleaning when we hit
tx_ring->next_to_use.

Signed-off-by: Terry Loftin <terry.loftin@hp.com>
Acked-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
index cfd09cea7214..73d43c53015a 100644
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -661,6 +661,8 @@ static bool e1000_clean_tx_irq(struct e1000_adapter *adapter)
                                 i = 0;
                 }
 
+                if (i == tx_ring->next_to_use)
+                        break;
                 eop = tx_ring->buffer_info[i].next_to_watch;
                 eop_desc = E1000_TX_DESC(*tx_ring, eop);
         }