On Mon, 23 Aug 2010, Yossi Etigin wrote:
> >
> > Simplest then is to check if byte 24 of the packet is 0xff.
> > (ie IN6_IS_ADDR_MULTICAST)
> >
> > No need to worry about if it is properly formed or anything, if it is
> > a multicast DGID then it is a multicast packet at the link level.
> >
>
> Sounds good to me
Therefore this patch?
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_ib.c | 7 +++++--
include/linux/in6.h | 3 +++
2 files changed, 8 insertions(+), 2 deletions(-)
Index: linux-2.6/drivers/infiniband/ulp/ipoib/ipoib_ib.c
===================================================================
--- linux-2.6.orig/drivers/infiniband/ulp/ipoib/ipoib_ib.c 2010-08-23
16:04:38.000000000 -0500
+++ linux-2.6/drivers/infiniband/ulp/ipoib/ipoib_ib.c 2010-08-25
09:43:01.000000000 -0500
@@ -281,8 +281,11 @@ 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 (IN6_IS_ADDR_MULTICAST(skb->head + 24))
+
+ 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;
Index: linux-2.6/include/linux/in6.h
===================================================================
--- linux-2.6.orig/include/linux/in6.h 2010-08-25 09:39:40.000000000 -0500
+++ linux-2.6/include/linux/in6.h 2010-08-25 09:40:22.000000000 -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) (((const __u8 *) (a))[0] == 0xff)
+
#endif
struct sockaddr_in6 {
--
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