From: Eric Dumazet <edumazet@google.com>
Date: Mon, 13 Jan 2020 17:27:11 +0000 (-0800)
Subject: net: usb: lan78xx: limit size of local TSO packets
X-Git-Tag: baikal/mips/sdk5.9~14532^2~29
X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=336b228b90bfd245d9ce0366f70b289d855634c0;p=kernel.git

net: usb: lan78xx: limit size of local TSO packets

lan78xx_tx_bh() makes sure to not exceed MAX_SINGLE_PACKET_SIZE
bytes in the aggregated packets it builds, but does
nothing to prevent large GSO packets being submitted.

Pierre-Francois reported various hangs when/if TSO is enabled.

For localy generated packets, we can use netif_set_gso_max_size()
to limit the size of TSO packets.

Note that forwarded packets could still hit the issue,
so a complete fix might require implementing .ndo_features_check
for this driver, forcing a software segmentation if the size
of the TSO packet exceeds MAX_SINGLE_PACKET_SIZE.

Fixes: f98af78833e9 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: RENARD Pierre-Francois <pfrenard@gmail.com>
Tested-by: RENARD Pierre-Francois <pfrenard@gmail.com>
Cc: Stefan Wahren <stefan.wahren@i2se.com>
Cc: Woojung Huh <woojung.huh@microchip.com>
Cc: Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index fb4781080d6de..75bdfae5f3e20 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -3750,6 +3750,7 @@ static int lan78xx_probe(struct usb_interface *intf,
 
 	/* MTU range: 68 - 9000 */
 	netdev->max_mtu = MAX_SINGLE_PACKET_SIZE;
+	netif_set_gso_max_size(netdev, MAX_SINGLE_PACKET_SIZE - MAX_HEADER);
 
 	dev->ep_blkin = (intf->cur_altsetting)->endpoint + 0;
 	dev->ep_blkout = (intf->cur_altsetting)->endpoint + 1;