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 fb4781080d6dec2af22f41c5e064350ea74130b3..75bdfae5f3e20afef3d2880171c7c6e8511546c5 100644 (file)
--- 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;