e1000e: Disable TSO for buffer overrun workaround

khfeng · Jeff Kirsher · commit f29801030ac6 · 2020-05-22T18:21:52.000-07:00
Commit b10effb ("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: b10effb ("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
@@ -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

Original file line number	Diff line number	Diff line change
`@@ -5294,6 +5294,10 @@ static void e1000_watchdog_task(struct work_struct *work)`
`5294`	`5294`	`/* oops */`
`5295`	`5295`	`break;`
`5296`	`5296`	`}`
	`5297`	`+ if (hw->mac.type == e1000_pch_spt) {`
	`5298`	`+ netdev->features &= ~NETIF_F_TSO;`
	`5299`	`+ netdev->features &= ~NETIF_F_TSO6;`
	`5300`	`+ }`
`5297`	`5301`	`}`
`5298`	`5302`
`5299`	`5303`	`/* enable transmits in the hardware, need to do this`