Commit 357f4aae authored Oct 29, 2016 by Stefan Richter Committed by David S. Miller Oct 29, 2016

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: 5d48f00d('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>

parent 0e82c763

drivers/firewire/net.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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;