From b6af0abdc4c53aa47b2efd006d9ce9134971fafa Mon Sep 17 00:00:00 2001
From: Andrew Gallatin <gallatin@FreeBSD.org>
Date: Mon, 11 Jun 2007 14:59:56 +0000
Subject: [PATCH] Allow drivers, such as cxgb and mxge, which support LRO to
 bypass the MTU check in ether_input() on LRO merged frames.

Discussed with: kmacy
---
 sys/dev/mxge/mxge_lro.c | 1 +
 sys/net/if_ethersubr.c  | 3 ++-
 sys/sys/mbuf.h          | 3 ++-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/sys/dev/mxge/mxge_lro.c b/sys/dev/mxge/mxge_lro.c
index 7080588b396c..78e12202e2ad 100644
--- a/sys/dev/mxge/mxge_lro.c
+++ b/sys/dev/mxge/mxge_lro.c
@@ -99,6 +99,7 @@ mxge_lro_flush(mxge_softc_t *mgp, struct lro_entry *lro)
 			CSUM_IP_VALID | CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
 		lro->m_head->m_pkthdr.csum_data = 0xffff;
 		lro->m_head->m_pkthdr.len = lro->len;
+		lro->m_head->m_flags |= M_LRO;
 
 		/* incorporate the latest ack into the tcp header */
 		tcp = (struct tcphdr *) (ip + 1);
diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
index 1fabaca614dc..41a24674c966 100644
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -542,7 +542,8 @@ ether_input(struct ifnet *ifp, struct mbuf *m)
 	}
 	eh = mtod(m, struct ether_header *);
 	etype = ntohs(eh->ether_type);
-	if (m->m_pkthdr.len >
+	if ((m->m_flags & M_LRO) == 0 &&
+	    m->m_pkthdr.len >
 	    ETHER_MAX_FRAME(ifp, etype, m->m_flags & M_HASFCS)) {
 		if_printf(ifp, "discard oversize frame "
 				"(ether type %x flags %x len %u > max %lu)\n",
diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index 10e7915309a1..345e9d3debb1 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -192,6 +192,7 @@ struct mbuf {
 #define	M_LASTFRAG	0x2000	/* packet is last fragment */
 #define	M_VLANTAG	0x10000	/* ether_vtag is valid */
 #define	M_PROMISC	0x20000	/* packet was not for us */
+#define	M_LRO		0x40000	/* packet is LRO merged and may exceed mtu */
 
 /*
  * External buffer types: identify ext_buf type.
@@ -214,7 +215,7 @@ struct mbuf {
 #define	M_COPYFLAGS	(M_PKTHDR|M_EOR|M_RDONLY|M_PROTO1|M_PROTO1|M_PROTO2|\
 			    M_PROTO3|M_PROTO4|M_PROTO5|M_SKIP_FIREWALL|\
 			    M_BCAST|M_MCAST|M_FRAG|M_FIRSTFRAG|M_LASTFRAG|\
-			    M_VLANTAG|M_PROMISC)
+			    M_VLANTAG|M_PROMISC|M_LRO)
 
 /*
  * Flags to purge when crossing layers.