[PATCHv4 net-next 3/3] sunvnet: generate ICMP PTMUD messages for smaller port MTUs
From: David L Stevens <hidden>
Date: 2014-09-16 00:35:48
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
This patch sends ICMP and ICMPv6 messages for Path MTU Discovery when a remote port MTU is smaller than the device MTU. This allows mixing newer VIO protocol devices that support MTU negotiation with older devices that do not on the same vswitch. It also allows Linux-Linux LDOMs to use 64K-1 data packets even though Solaris vswitch is limited to <16K MTU. Signed-off-by: David L Stevens <redacted> --- drivers/net/ethernet/sun/sunvnet.c | 37 +++++++++++++++++++++++++++++++++++- 1 files changed, 36 insertions(+), 1 deletions(-)
diff --git a/drivers/net/ethernet/sun/sunvnet.c b/drivers/net/ethernet/sun/sunvnet.c
index 5619798..5ac2b0c 100644
--- a/drivers/net/ethernet/sun/sunvnet.c
+++ b/drivers/net/ethernet/sun/sunvnet.c@@ -17,6 +17,13 @@ #include <linux/mutex.h> #include <linux/if_vlan.h> +#if IS_ENABLED(CONFIG_IPV6) +#include <linux/icmpv6.h> +#endif + +#include <net/icmp.h> +#include <net/route.h> + #include <asm/vio.h> #include <asm/ldc.h>
@@ -791,8 +798,36 @@ static int vnet_start_xmit(struct sk_buff *skb, struct net_device *dev) if (unlikely(!port)) goto out_dropped; - if (skb->len > port->rmtu) + if (skb->len > port->rmtu) { + unsigned long localmtu = port->rmtu - ETH_HLEN; + + if (vio_version_after_eq(&port->vio, 1, 3)) + localmtu -= VLAN_HLEN; + + if (skb->protocol == htons(ETH_P_IP)) { + struct flowi4 fl4; + struct rtable *rt = NULL; + + memset(&fl4, 0, sizeof(fl4)); + fl4.flowi4_oif = dev->ifindex; + fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); + fl4.daddr = ip_hdr(skb)->daddr; + fl4.saddr = ip_hdr(skb)->saddr; + + rt = ip_route_output_key(dev_net(dev), &fl4); + if (!IS_ERR(rt)) { + skb_dst_set(skb, &rt->dst); + icmp_send(skb, ICMP_DEST_UNREACH, + ICMP_FRAG_NEEDED, + htonl(localmtu)); + } + } +#if IS_ENABLED(CONFIG_IPV6) + else if (skb->protocol == htons(ETH_P_IPV6)) + icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, localmtu); +#endif goto out_dropped; + } spin_lock_irqsave(&port->vio.lock, flags);
--
1.7.1