3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jeff Kirsher <[email protected]>

commit 09357b00255c233705b1cf6d76a8d147340545b8 upstream.

Based on the original patch submitted my Michael Wang
<[email protected]>.
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 <[email protected]>
CC: Flavio Leitner <[email protected]>
Acked-by: Jesse Brandeburg <[email protected]>
Tested-by: Aaron Brown <[email protected]>
Signed-off-by: Jeff Kirsher <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 drivers/net/e1000e/e1000.h  |    1 +
 drivers/net/e1000e/netdev.c |   23 ++++++++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)

--- 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;
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -930,6 +930,7 @@ static void e1000_print_hw_hang(struct w
        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 w
        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 e1
                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
 
        e1000_irq_enable(adapter);
 
+       adapter->tx_hang_recheck = false;
        netif_start_queue(netdev);
 
        adapter->idle_check = true;


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