From 17bab407d54ba1320d71a45641ecffc33bd331c1 Mon Sep 17 00:00:00 2001 From: Stefan Richter Date: Tue, 3 Apr 2007 23:55:40 +0200 Subject: [PATCH] ieee1394: eth1394: allow MTU bigger than 1500 RFC 2734 says: "IP-capable nodes may operate with an MTU size larger than the default [1500 octets], but the means by which a larger MTU is configured are beyond the scope of this document." Allow users to set an MTU bigger than 1500. Signed-off-by: Stefan Richter --- drivers/ieee1394/eth1394.c | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-) diff --git a/drivers/ieee1394/eth1394.c b/drivers/ieee1394/eth1394.c index 8f19f5b..aee8292 100644 --- a/drivers/ieee1394/eth1394.c +++ b/drivers/ieee1394/eth1394.c @@ -136,9 +136,6 @@ static const int hdr_type_len[] = { sizeof(struct eth1394_sf_hdr) }; -/* For now, this needs to be 1500, so that XP works with us */ -#define ETH1394_DATA_LEN ETH_DATA_LEN - static const u16 eth1394_speedto_maxpayload[] = { /* S100, S200, S400, S800, S1600, S3200 */ 512, 1024, 2048, 4096, 4096, 4096 @@ -262,17 +259,27 @@ static void ether1394_tx_timeout(struct net_device *dev) ether1394_host_reset(host); } +static inline int ether1394_max_mtu(struct hpsb_host* host) +{ + return (1 << (host->csr.max_rec + 1)) + - sizeof(union eth1394_hdr) - ETHER1394_GASP_OVERHEAD; +} + static int ether1394_change_mtu(struct net_device *dev, int new_mtu) { - int max_rec = - ((struct eth1394_priv *)netdev_priv(dev))->host->csr.max_rec; + int max_mtu; - if (new_mtu < 68 || - new_mtu > ETH1394_DATA_LEN || - new_mtu > (1 << (max_rec + 1)) - sizeof(union eth1394_hdr) - - ETHER1394_GASP_OVERHEAD) + if (new_mtu < 68) return -EINVAL; + max_mtu = ether1394_max_mtu( + ((struct eth1394_priv *)netdev_priv(dev))->host); + if (new_mtu > max_mtu) { + ETH1394_PRINT(KERN_INFO, dev->name, + "Local node constrains MTU to %d\n", max_mtu); + return -ERANGE; + } + dev->mtu = new_mtu; return 0; } @@ -476,13 +483,10 @@ static void ether1394_reset_priv(struct net_device *dev, int set_mtu) max_speed = host->speed[i]; priv->bc_sspd = max_speed; - /* We'll use our maximum payload as the default MTU */ if (set_mtu) { - int max_payload = 1 << (host->csr.max_rec + 1); - - dev->mtu = min(ETH1394_DATA_LEN, - (int)(max_payload - sizeof(union eth1394_hdr) - - ETHER1394_GASP_OVERHEAD)); + /* Use the RFC 2734 default 1500 octets or the maximum payload + * as initial MTU */ + dev->mtu = min(1500, ether1394_max_mtu(host)); /* Set our hardware address while we're at it */ memcpy(dev->dev_addr, &guid, sizeof(u64)); -- 2.7.4