From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org, linux1394-devel@lists.sourceforge.net,
Jarod Wilson <jarod@redhat.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH net-next 2/2] firewire: net: set initial MTU = 1500 unconditionally, fix IPv6 on some CardBus cards
Date: Sun, 23 Oct 2016 16:30:56 +0200 [thread overview]
Message-ID: <20161023163056.6bc38610@kant> (raw)
In-Reply-To: <20161023162903.4166a35d@kant>
firewire-net, like the older eth1394 driver, reduced the initial MTU to
less than 1500 octets if the local link layer controller's asynchronous
packet reception limit was lower.
This is bogus, since this reception limit does not have anything to do
with the transmission limit. Neither did this reduction affect the TX
path positively, nor could it prevent link fragmentation at the RX path.
Many FireWire CardBus cards have a max_rec of 9, causing an initial MTU
of 1024 - 16 = 1008. RFC 2734 and RFC 3146 allow a minimum max_rec = 8,
which would result in an initial MTU of 512 - 16 = 496. On such cards,
IPv6 could only be employed if the MTU was manually increased to 1280 or
more, i.e. IPv6 would not work without intervention from userland.
We now always initialize the MTU to 1500, which is the default according
to RFC 2734 and RFC 3146.
On a VIA VT6316 based CardBus card which was affected by this, changing
the MTU from 1008 to 1500 also increases TX bandwidth by 6 %.
RX remains unaffected.
CC: netdev@vger.kernel.org
CC: linux1394-devel@lists.sourceforge.net
CC: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
drivers/firewire/net.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/drivers/firewire/net.c b/drivers/firewire/net.c
index 99379542b263..03715e7d9d92 100644
--- a/drivers/firewire/net.c
+++ b/drivers/firewire/net.c
@@ -1463,13 +1463,7 @@ static int fwnet_probe(struct fw_unit *unit,
goto out;
dev->local_fifo = dev->handler.offset;
- /*
- * Use the RFC 2734 default 1500 octets or the maximum payload
- * as initial MTU
- */
- net->mtu = min(1500U,
- (1U << (card->max_receive + 1))
- - RFC2374_FRAG_HDR_SIZE - IEEE1394_GASP_HDR_SIZE);
+ net->mtu = 1500U;
net->min_mtu = ETH_MIN_MTU;
net->max_mtu = ETH_MAX_MTU;
--
Stefan Richter
-======----- =-=- =-===
http://arcgraph.de/sr/
next prev parent reply other threads:[~2016-10-23 14:31 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-19 2:33 [PATCH net-next 0/6] net: use core MTU range checking everywhere Jarod Wilson
2016-10-19 2:33 ` [PATCH net-next 1/6] net: use core MTU range checking in USB NIC drivers Jarod Wilson
2016-10-19 2:33 ` [PATCH net-next 2/6] net: use core MTU range checking in wireless drivers Jarod Wilson
2016-10-19 7:38 ` Johannes Berg
2016-10-19 14:27 ` Jarod Wilson
2016-10-19 14:28 ` Johannes Berg
2016-10-19 2:33 ` [PATCH net-next 3/6] net: use core MTU range checking in WAN drivers Jarod Wilson
2016-10-21 12:04 ` Krzysztof Hałasa
2016-10-19 2:33 ` [PATCH net-next 4/6] net: use core MTU range checking in core net infra Jarod Wilson
2016-10-19 12:17 ` Jiri Benc
2016-10-19 14:51 ` Jarod Wilson
2016-10-19 13:55 ` Sabrina Dubroca
2016-10-19 14:40 ` Jarod Wilson
2016-10-19 15:28 ` Sabrina Dubroca
2016-10-19 15:46 ` Jarod Wilson
2016-10-19 2:33 ` [PATCH net-next 5/6] net: use core MTU range checking in virt drivers Jarod Wilson
2016-10-19 13:06 ` Aaron Conole
2016-10-19 13:59 ` Michael S. Tsirkin
2016-10-19 14:03 ` Michael S. Tsirkin
2016-10-19 14:17 ` Jarod Wilson
2016-10-19 14:15 ` Jarod Wilson
2016-10-19 14:07 ` Haiyang Zhang
2016-10-19 14:23 ` Jarod Wilson
2016-10-19 22:21 ` Shrikrishna Khare
2016-10-19 2:33 ` [PATCH net-next 6/6] net: use core MTU range checking in misc drivers Jarod Wilson
2016-10-19 14:37 ` Robin Holt
2016-10-19 16:05 ` Sabrina Dubroca
2016-10-19 22:38 ` Stefan Richter
2016-10-20 3:16 ` Jarod Wilson
2016-10-22 9:36 ` Stefan Richter
2016-10-22 18:51 ` Stefan Richter
2016-10-19 19:10 ` [PATCH net-next 0/6] net: use core MTU range checking everywhere David Miller
2016-10-19 19:29 ` Jarod Wilson
2016-10-20 17:55 ` [PATCH net-next v2 0/9] " Jarod Wilson
2016-10-20 17:55 ` [PATCH net-next v2 1/9] ethernet: use net core MTU range checking in more drivers Jarod Wilson
2016-10-20 17:55 ` [PATCH net-next v2 2/9] net: use core MTU range checking in USB NIC drivers Jarod Wilson
2016-10-20 17:55 ` [PATCH net-next v2 3/9] net: use core MTU range checking in wireless drivers Jarod Wilson
2016-10-20 18:22 ` Johannes Berg
2016-10-20 18:38 ` David Miller
2016-10-20 17:55 ` [PATCH net-next v2 4/9] net: use core MTU range checking in WAN drivers Jarod Wilson
2016-10-20 17:55 ` [PATCH net-next v2 5/9] net: use core MTU range checking in core net infra Jarod Wilson
2016-10-20 17:55 ` [PATCH net-next v2 6/9] net: use core MTU range checking in virt drivers Jarod Wilson
2016-10-20 18:05 ` Haiyang Zhang
2016-10-20 20:12 ` Kershner, David A
2016-10-20 20:23 ` Michael S. Tsirkin
2016-10-21 2:37 ` Jarod Wilson
2016-10-21 3:36 ` Michael S. Tsirkin
2016-10-21 13:24 ` Aaron Conole
2016-10-21 10:09 ` Wei Liu
2016-10-20 17:55 ` [PATCH net-next v2 7/9] net: use core MTU range checking in misc drivers Jarod Wilson
2016-10-21 6:52 ` Rémi Denis-Courmont
2016-10-21 16:22 ` Sebastian Reichel
2016-10-22 7:17 ` [net-next,v2,7/9] " Sven Eckelmann
2016-10-22 19:16 ` [PATCH net-next v2 7/9] " Stefan Richter
2016-10-22 19:27 ` Stefan Richter
2016-10-23 1:18 ` Jarod Wilson
2016-10-23 14:29 ` [PATCH net-next 1/2] firewire: net: fix maximum possible MTU Stefan Richter
2016-10-23 14:30 ` Stefan Richter [this message]
2016-10-24 1:50 ` [PATCH net-next 2/2] firewire: net: set initial MTU = 1500 unconditionally, fix IPv6 on some CardBus cards Jarod Wilson
2016-10-24 12:26 ` [PATCH net-next 2/2 v2] " Stefan Richter
2016-10-25 3:05 ` Jarod Wilson
2016-10-26 21:29 ` [PATCH net-next 2/2] " David Miller
2016-10-29 20:16 ` [PATCH net-next] firewire: net: really fix maximum possible MTU Stefan Richter
2016-10-30 3:01 ` David Miller
2016-10-24 1:50 ` [PATCH net-next 1/2] firewire: net: " Jarod Wilson
2016-10-26 21:29 ` David Miller
2016-10-20 17:55 ` [PATCH net-next v2 8/9] s390/net: use net core MTU range checking Jarod Wilson
2016-10-20 17:55 ` [PATCH net-next v2 9/9] ipv4/6: use core net " Jarod Wilson
2016-10-20 18:53 ` [PATCH net-next v2 0/9] net: use core MTU range checking everywhere David Miller
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