e1000e: Disable TSO for buffer overrun workaround

Commit b10effb92e27 ("e1000e: fix buffer overrun while the I219 is
processing DMA transactions") imposes roughly 30% performance penalty.

The commit log states that "Disabling TSO eliminates performance loss
for TCP traffic without a noticeable impact on CPU performance", so
let's disable TSO by default to regain the loss.

CC: stable <stable@vger.kernel.org>
Fixes: b10effb92e27 ("e1000e: fix buffer overrun while the I219 is processing DMA transactions")
BugLink: https://bugs.launchpad.net/bugs/1802691
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index e0b0748..66609cf 100644 (file)
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -5294,6 +5294,10 @@ static void e1000_watchdog_task(struct work_struct *work)
                                        /* oops */
                                        break;
                                }
+                               if (hw->mac.type == e1000_pch_spt) {
+                                       netdev->features &= ~NETIF_F_TSO;
+                                       netdev->features &= ~NETIF_F_TSO6;
+                               }
                        }
 
                        /* enable transmits in the hardware, need to do this