e1000e: Avoid wrong check on TX hang

BugLink: http://bugs.launchpad.net/bugs/971808

commit 09357b00255c233705b1cf6d76a8d147340545b8 upstream.

Based on the original patch submitted my Michael Wang
<wangyun@linux.vnet.ibm.com>.
Descriptors may not be write-back while checking TX hang with flag
FLAG2_DMA_BURST on.
So when we detect hang, we just flush the descriptor and detect
again for once.

-v2 change 1 to true and 0 to false and remove extra ()

CC: Michael Wang <wangyun@linux.vnet.ibm.com>
CC: Flavio Leitner <fbl@redhat.com>
Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 21 insertions, 3 deletions

diff --git a/drivers/net/e1000e/e1000.h b/drivers/net/e1000e/e1000.h
index 9549879e66a..8a265f3528d 100644
--- a/drivers/net/e1000e/e1000.h
+++ b/drivers/net/e1000e/e1000.h
@@ -311,6 +311,7 @@ struct e1000_adapter {
         u32 txd_cmd;
 
         bool detect_tx_hung;
+        bool tx_hang_recheck;
         u8 tx_timeout_factor;
 
         u32 tx_int_delay;
diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
index 3310c3d477d..5430a9a4a28 100644
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -930,6 +930,7 @@ static void e1000_print_hw_hang(struct work_struct *work)
         struct e1000_adapter *adapter = container_of(work,
                                                      struct e1000_adapter,
                                                      print_hang_task);
+        struct net_device *netdev = adapter->netdev;
         struct e1000_ring *tx_ring = adapter->tx_ring;
         unsigned int i = tx_ring->next_to_clean;
         unsigned int eop = tx_ring->buffer_info[i].next_to_watch;
@@ -941,6 +942,21 @@ static void e1000_print_hw_hang(struct work_struct *work)
         if (test_bit(__E1000_DOWN, &adapter->state))
                 return;
 
+        if (!adapter->tx_hang_recheck &&
+            (adapter->flags2 & FLAG2_DMA_BURST)) {
+                /* May be block on write-back, flush and detect again
+                 * flush pending descriptor writebacks to memory
+                 */
+                ew32(TIDV, adapter->tx_int_delay | E1000_TIDV_FPD);
+                /* execute the writes immediately */
+                e1e_flush();
+                adapter->tx_hang_recheck = true;
+                return;
+        }
+        /* Real hang detected */
+        adapter->tx_hang_recheck = false;
+        netif_stop_queue(netdev);
+
         e1e_rphy(hw, PHY_STATUS, &phy_status);
         e1e_rphy(hw, PHY_1000T_STATUS, &phy_1000t_status);
         e1e_rphy(hw, PHY_EXT_STATUS, &phy_ext_status);
@@ -1054,10 +1070,10 @@ static bool e1000_clean_tx_irq(struct e1000_adapter *adapter)
                 if (tx_ring->buffer_info[i].time_stamp &&
                     time_after(jiffies, tx_ring->buffer_info[i].time_stamp
                                + (adapter->tx_timeout_factor * HZ)) &&
-                    !(er32(STATUS) & E1000_STATUS_TXOFF)) {
+                    !(er32(STATUS) & E1000_STATUS_TXOFF))
                         schedule_work(&adapter->print_hang_task);
-                        netif_stop_queue(netdev);
-                }
+                else
+                        adapter->tx_hang_recheck = false;
         }
         adapter->total_tx_bytes += total_tx_bytes;
         adapter->total_tx_packets += total_tx_packets;
@@ -3678,6 +3694,7 @@ static int e1000_open(struct net_device *netdev)
 
         e1000_irq_enable(adapter);
 
+        adapter->tx_hang_recheck = false;
         netif_start_queue(netdev);
 
         adapter->idle_check = true;