firewire: net: really fix maximum possible MTU
The maximum unicast datagram size /without/ link fragmentation is
4096 - 4 = 4092 (max IEEE 1394 async payload size at >= S800 bus speed,
minus unfragmented encapssulation header). Max broadcast datagram size
without fragmentation is 8 bytes less than that (due to GASP header).
The maximum datagram size /with/ link fragmentation is 0xfff = 4095
for unicast and broadcast. This is because the RFC 2734 fragment
encapsulation header field for datagram size is only 12 bits wide.
Fixes: 5d48f00d836a('firewire: net: fix maximum possible MTU')
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/firewire/net.c b/drivers/firewire/net.c
index 03715e7..363fc5e 100644
--- a/drivers/firewire/net.c
+++ b/drivers/firewire/net.c
@@ -1465,7 +1465,7 @@ static int fwnet_probe(struct fw_unit *unit,
net->mtu = 1500U;
net->min_mtu = ETH_MIN_MTU;
- net->max_mtu = ETH_MAX_MTU;
+ net->max_mtu = 0xfff;
/* Set our hardware address while we're at it */
ha = (union fwnet_hwaddr *)net->dev_addr;