| From b34a93b528f08401835259c477ade49730fc1baf Mon Sep 17 00:00:00 2001 |
| From: Dave Stevenson <dave.stevenson@raspberrypi.org> |
| Date: Wed, 13 Jun 2018 15:21:10 +0100 |
| Subject: [PATCH] net: lan78xx: Disable TCP Segmentation Offload (TSO) |
| |
| 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 <dave.stevenson@raspberrypi.org> |
| --- |
| drivers/net/usb/lan78xx.c | 19 +++++++++++++++++-- |
| 1 file changed, 17 insertions(+), 2 deletions(-) |
| |
| --- a/drivers/net/usb/lan78xx.c |
| +++ b/drivers/net/usb/lan78xx.c |
| @@ -427,6 +427,15 @@ 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); |
| @@ -2899,8 +2908,14 @@ static int lan78xx_bind(struct lan78xx_n |
| 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; |