netdev - [IPoIB] Identify multicast packets and fix IGMP breakage V2

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Date:	Thu, 26 Aug 2010 16:31:14 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	Roland Dreier <rdreier@...co.com>
cc:	linux-rdma@...r.kernel.org, Or Gerlitz <ogerlitz@...taire.com>,
	Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
	Yossi Etigin <yosefe@...taire.com>, netdev@...r.kernel.org
Subject: [IPoIB] Identify multicast packets and fix IGMP breakage V2

Is this better?


Subject: [IPoIB] Identify Multicast packets and fix IGMP breakage V2

IGMP processing is broken because the IPOIB does not set the
skb->pkt_type the right way for Multicast traffic. All incoming
packets are set to PACKET_HOST which means that the igmp_recv()
function will ignore the IGMP broadcasts/multicasts.

This in turn means that the IGMP timers are firing and are sending
information about multicast subscriptions unnecessarily. In a large
private network this can cause traffic spikes.

Signed-off-by: Christoph Lameter <cl@...ux.com>

---
 drivers/infiniband/ulp/ipoib/ipoib_ib.c |   10 +++++++---
 include/linux/in6.h                     |    3 +++
 2 files changed, 10 insertions(+), 3 deletions(-)

Index: linux-2.6/drivers/infiniband/ulp/ipoib/ipoib_ib.c
===================================================================
--- linux-2.6.orig/drivers/infiniband/ulp/ipoib/ipoib_ib.c	2010-08-26 15:11:34.000000000 -0500
+++ linux-2.6/drivers/infiniband/ulp/ipoib/ipoib_ib.c	2010-08-26 16:29:19.000000000 -0500
@@ -271,6 +271,13 @@ static void ipoib_ib_handle_rx_wc(struct
 	ipoib_ud_dma_unmap_rx(priv, mapping);
 	ipoib_ud_skb_put_frags(priv, skb, wc->byte_len);

+	if ((wc->wc_flags & IB_WC_GRH) &&
+		IN6_IS_ADDR_MULTICAST(&((struct ipv6hdr *)skb->data)->daddr))
+
+		skb->pkt_type = PACKET_MULTICAST;
+	else
+		skb->pkt_type = PACKET_HOST;
+
 	skb_pull(skb, IB_GRH_BYTES);

 	skb->protocol = ((struct ipoib_header *) skb->data)->proto;
@@ -281,9 +288,6 @@ static void ipoib_ib_handle_rx_wc(struct
 	dev->stats.rx_bytes += skb->len;

 	skb->dev = dev;
-	/* XXX get correct PACKET_ type here */
-	skb->pkt_type = PACKET_HOST;
-
 	if (test_bit(IPOIB_FLAG_CSUM, &priv->flags) && likely(wc->csum_ok))
 		skb->ip_summed = CHECKSUM_UNNECESSARY;

Index: linux-2.6/include/linux/in6.h
===================================================================
--- linux-2.6.orig/include/linux/in6.h	2010-08-26 15:11:34.000000000 -0500
+++ linux-2.6/include/linux/in6.h	2010-08-26 16:27:08.000000000 -0500
@@ -53,6 +53,9 @@ extern const struct in6_addr in6addr_lin
 extern const struct in6_addr in6addr_linklocal_allrouters;
 #define IN6ADDR_LINKLOCAL_ALLROUTERS_INIT \
 		{ { { 0xff,2,0,0,0,0,0,0,0,0,0,0,0,0,0,2 } } }
+
+#define IN6_IS_ADDR_MULTICAST(a) ((a)->in6_u.u6_addr8[0] == 0xff)
+
 #endif

 struct sockaddr_in6 {
--
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