From: Jarod Wilson <jarod@redhat.com>
To: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: "David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org, linux1394-devel@lists.sourceforge.net,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 2/2] firewire: net: set initial MTU = 1500 unconditionally, fix IPv6 on some CardBus cards
Date: Sun, 23 Oct 2016 21:50:13 -0400 [thread overview]
Message-ID: <20161024015013.GB42084@redhat.com> (raw)
In-Reply-To: <20161023163056.6bc38610@kant>
On Sun, Oct 23, 2016 at 04:30:56PM +0200, Stefan Richter wrote:
> 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;
Should be able to do just net->mtu = ETH_DATA_LEN;
--
Jarod Wilson
jarod@redhat.com
next prev parent reply other threads:[~2016-10-24 1:50 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 via Virtualization
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
[not found] ` <20161020031641.GJ18569-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
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
[not found] ` <20161020175524.6184-8-jarod-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
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 ` [PATCH net-next 2/2] firewire: net: set initial MTU = 1500 unconditionally, fix IPv6 on some CardBus cards Stefan Richter
2016-10-24 1:50 ` Jarod Wilson [this message]
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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