From 0bf97ae271ef54efd04d20668ed657d3b380c6d0 Mon Sep 17 00:00:00 2001
From: Andrew Thompson <thompsa@FreeBSD.org>
Date: Wed, 22 Feb 2012 22:01:30 +0000
Subject: [PATCH] Using the flowid in the mbuf assumes the network card is
 giving a good hash for the traffic flow, this may not be the case giving poor
 traffic distribution. Add a sysctl which allows us to fall back to our own
 flow hash code.

PR:		kern/164901
Submitted by:	Eugene Grosbein
MFC after:	1 week
---
 sys/net/ieee8023ad_lacp.c |  2 +-
 sys/net/if_lagg.c         | 14 +++++++++++++-
 sys/net/if_lagg.h         |  4 ++++
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/sys/net/ieee8023ad_lacp.c b/sys/net/ieee8023ad_lacp.c
index 2284ce2486e6..ea838669e863 100644
--- a/sys/net/ieee8023ad_lacp.c
+++ b/sys/net/ieee8023ad_lacp.c
@@ -812,7 +812,7 @@ lacp_select_tx_port(struct lagg_softc *sc, struct mbuf *m)
 		return (NULL);
 	}
 
-	if (m->m_flags & M_FLOWID)
+	if (sc->use_flowid && (m->m_flags & M_FLOWID))
 		hash = m->m_pkthdr.flowid;
 	else
 		hash = lagg_hashmbuf(m, lsc->lsc_hashkey);
diff --git a/sys/net/if_lagg.c b/sys/net/if_lagg.c
index 730047fa0733..488dca3e257f 100644
--- a/sys/net/if_lagg.c
+++ b/sys/net/if_lagg.c
@@ -262,6 +262,8 @@ lagg_clone_create(struct if_clone *ifc, int unit, caddr_t params)
 	struct ifnet *ifp;
 	int i, error = 0;
 	static const u_char eaddr[6];	/* 00:00:00:00:00:00 */
+	struct sysctl_oid *oid;
+	char num[14];			/* sufficient for 32 bits */
 
 	sc = malloc(sizeof(*sc), M_DEVBUF, M_WAITOK|M_ZERO);
 	ifp = sc->sc_ifp = if_alloc(IFT_ETHER);
@@ -270,6 +272,15 @@ lagg_clone_create(struct if_clone *ifc, int unit, caddr_t params)
 		return (ENOSPC);
 	}
 
+	sysctl_ctx_init(&sc->ctx);
+	snprintf(num, sizeof(num), "%u", unit);
+	sc->use_flowid = 1;
+	oid = SYSCTL_ADD_NODE(&sc->ctx, &SYSCTL_NODE_CHILDREN(_net_link, lagg),
+		OID_AUTO, num, CTLFLAG_RD, NULL, "");
+	SYSCTL_ADD_INT(&sc->ctx, SYSCTL_CHILDREN(oid), OID_AUTO,
+		"use_flowid", CTLTYPE_INT|CTLFLAG_RW, &sc->use_flowid, sc->use_flowid,
+		"Use flow id for load sharing");
+
 	sc->sc_proto = LAGG_PROTO_NONE;
 	for (i = 0; lagg_protos[i].ti_proto != LAGG_PROTO_NONE; i++) {
 		if (lagg_protos[i].ti_proto == LAGG_PROTO_DEFAULT) {
@@ -349,6 +360,7 @@ lagg_clone_destroy(struct ifnet *ifp)
 
 	LAGG_WUNLOCK(sc);
 
+	sysctl_ctx_free(&sc->ctx);
 	ifmedia_removeall(&sc->sc_media);
 	ether_ifdetach(ifp);
 	if_free(ifp);
@@ -1676,7 +1688,7 @@ lagg_lb_start(struct lagg_softc *sc, struct mbuf *m)
 	struct lagg_port *lp = NULL;
 	uint32_t p = 0;
 
-	if (m->m_flags & M_FLOWID)
+	if (sc->use_flowid && (m->m_flags & M_FLOWID))
 		p = m->m_pkthdr.flowid;
 	else
 		p = lagg_hashmbuf(m, lb->lb_key);
diff --git a/sys/net/if_lagg.h b/sys/net/if_lagg.h
index 0034c61799b1..823176449645 100644
--- a/sys/net/if_lagg.h
+++ b/sys/net/if_lagg.h
@@ -21,6 +21,8 @@
 #ifndef _NET_LAGG_H
 #define _NET_LAGG_H
 
+#include <sys/sysctl.h>
+
 /*
  * Global definitions
  */
@@ -202,6 +204,8 @@ struct lagg_softc {
 	eventhandler_tag vlan_attach;
 	eventhandler_tag vlan_detach;
 #endif
+	struct sysctl_ctx_list		ctx;		/* sysctl variables */
+	int				use_flowid;	/* use M_FLOWID */
 };
 
 struct lagg_port {