From 1a37809d6e0d01154a7d518f4d9b50214ae53076 Mon Sep 17 00:00:00 2001 From: Dave Stevenson Date: Wed, 13 Jun 2018 15:21:10 +0100 Subject: [PATCH] net: lan78xx: Disable TCP Segmentation Offload (TSO) raspberrypi inclusion category: feature bugzilla: 50432 -------------------------------- TSO seems to be having issues when packets are dropped and the remote end uses Selective Acknowledge (SACK) to denote that data is missing. The missing data is never resent, so the connection eventually stalls. There is a module parameter of enable_tso added to allow further debugging without forcing a rebuild of the kernel. https://github.com/raspberrypi/linux/issues/2449 https://github.com/raspberrypi/linux/issues/2482 Signed-off-by: Dave Stevenson Signed-off-by: Fang Yafen Signed-off-by: Zheng Zengkai --- drivers/net/usb/lan78xx.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c index 8e234a7c84ef..681a6b949140 100644 --- a/drivers/net/usb/lan78xx.c +++ b/drivers/net/usb/lan78xx.c @@ -425,6 +425,15 @@ static int msg_level = -1; module_param(msg_level, int, 0); MODULE_PARM_DESC(msg_level, "Override default message level"); +/* TSO seems to be having some issue with Selective Acknowledge (SACK) that + * results in lost data never being retransmitted. + * Disable it by default now, but adds a module parameter to enable it for + * debug purposes (the full cause is not currently understood). + */ +static bool enable_tso; +module_param(enable_tso, bool, 0644); +MODULE_PARM_DESC(enable_tso, "Enables TCP segmentation offload"); + static int lan78xx_read_reg(struct lan78xx_net *dev, u32 index, u32 *data) { u32 *buf = kmalloc(sizeof(u32), GFP_KERNEL); @@ -2917,8 +2926,14 @@ static int lan78xx_bind(struct lan78xx_net *dev, struct usb_interface *intf) if (DEFAULT_RX_CSUM_ENABLE) dev->net->features |= NETIF_F_RXCSUM; - if (DEFAULT_TSO_CSUM_ENABLE) - dev->net->features |= NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_SG; + if (DEFAULT_TSO_CSUM_ENABLE) { + dev->net->features |= NETIF_F_SG; + /* Use module parameter to control TCP segmentation offload as + * it appears to cause issues. + */ + if (enable_tso) + dev->net->features |= NETIF_F_TSO | NETIF_F_TSO6; + } if (DEFAULT_VLAN_RX_OFFLOAD) dev->net->features |= NETIF_F_HW_VLAN_CTAG_RX; -- GitLab