We see that IGMP timers are not properly deferred when hosts send IGMP
membership information. It looks as if the IPoIB layer does not properly
mark the multicast/broadcast packets with PACKET_MULTICAST or
PACKET_BROADCAST. As a results icmp_recv() ignores the IGMP membership
information from others. That in turn results in the IGMP timers
frequently expiring, thus the network becomes quite chatty.
The following is an untested patch: I am not sure how exact to access the
ipob Mac header. The IB header contains a special marker for IPoIB
multicast. So it should be simple to identify the multicast packets in the
receive path.
Subject: [IB] Make igmp processing work with IPOIB
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 <c...@linux.com>
---
drivers/infiniband/ulp/ipoib/ipoib.h | 13 +++++++++++++
drivers/infiniband/ulp/ipoib/ipoib_ib.c | 6 ++++--
2 files changed, 17 insertions(+), 2 deletions(-)
Index: linux-2.6/drivers/infiniband/ulp/ipoib/ipoib.h
===================================================================
--- linux-2.6.orig/drivers/infiniband/ulp/ipoib/ipoib.h 2010-08-20
19:44:13.000000000 -0500
+++ linux-2.6/drivers/infiniband/ulp/ipoib/ipoib.h 2010-08-20
19:58:21.000000000 -0500
@@ -114,6 +114,9 @@ enum {
#define IPOIB_OP_CM (0)
#endif
+#define IPOIB_MGID_IPV4_SIGNATURE 0x401B
+#define IPOIB_MGID_IPV6_SIGNATURE 0x601B
+
/* structs */
struct ipoib_header {
@@ -125,6 +128,16 @@ struct ipoib_pseudoheader {
u8 hwaddr[INFINIBAND_ALEN];
};
+int ipoib_is_ipv4_multicast(u8 *p)
+{
+ return *((u16 *)(p + 2)) == htonl(IPOIB_MGID_IPV4_SIGNATURE);
+}
+
+int ipoib_is_ipv6_multicast(u8 *p)
+{
+ return *((u16 *)(p + 2)) == htonl(IPOIB_MGID_IPV6_SIGNATURE);
+}
+
/* Used for all multicast joins (broadcast, IPv4 mcast and IPv6 mcast) */
struct ipoib_mcast {
struct ib_sa_mcmember_rec mcmember;
Index: linux-2.6/drivers/infiniband/ulp/ipoib/ipoib_ib.c
===================================================================
--- linux-2.6.orig/drivers/infiniband/ulp/ipoib/ipoib_ib.c 2010-08-20
18:43:44.000000000 -0500
+++ linux-2.6/drivers/infiniband/ulp/ipoib/ipoib_ib.c 2010-08-20
19:58:34.000000000 -0500
@@ -281,8 +281,10 @@ 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 (ipoib_is_ipv4_multicast(skb_mac_header(skb)))
+ skb->pkt_type = PACKET_MULTICAST;
+ else
+ skb->pkt_type = PACKET_HOST;
if (test_bit(IPOIB_FLAG_CSUM, &priv->flags) && likely(wc->csum_ok))
skb->ip_summed = CHECKSUM_UNNECESSARY;
--
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