[ofa-general] [PATCH] use scope from ipoib device link-level broadcast address in MGIDs

[Rolf Manderscheid]

An ipoib subnet on an IB fabric that spans multiple IB subnets can't use
link-local scope in multicast GIDs.  This patch takes the scope from the
link level broadcast address of the ipoib device when mapping to an IB
multicast address.

Signed-off-by: Rolf Manderscheid <rvm at obsidianresearch.com>

---

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 9ffb998..2fd1b30 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -2560,7 +2560,7 @@ static void cma_set_mgid(struct rdma_id_private *id_priv,
 		/* IPv6 address is an SA assigned MGID. */
 		memcpy(mgid, &sin6->sin6_addr, sizeof *mgid);
 	} else {
-		ip_ib_mc_map(sin->sin_addr.s_addr, mc_map);
+		ip_ib_mc_map(sin->sin_addr.s_addr, dev_addr->broadcast, mc_map);
 		if (id_priv->id.ps == RDMA_PS_UDP)
 			mc_map[7] = 0x01;	/* Use RDMA CM signature */
 		mc_map[8] = ib_addr_get_pkey(dev_addr) >> 8;
diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
index 3ec7d07..b636221 100644
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h
@@ -268,14 +268,17 @@ static inline void ipv6_arcnet_mc_map(const struct in6_addr *addr, char *buf)
 	buf[0] = 0x00;
 }
 
-static inline void ipv6_ib_mc_map(struct in6_addr *addr, char *buf)
+static inline void ipv6_ib_mc_map(const struct in6_addr *addr,
+				  const unsigned char *broadcast, char *buf)
 {
+	unsigned char scope = broadcast[5] & 0xF;
+
 	buf[0]  = 0;		/* Reserved */
 	buf[1]  = 0xff;		/* Multicast QPN */
 	buf[2]  = 0xff;
 	buf[3]  = 0xff;
 	buf[4]  = 0xff;
-	buf[5]  = 0x12;		/* link local scope */
+	buf[5]  = 0x10 | scope;	/* scope from broadcast address */
 	buf[6]  = 0x60;		/* IPv6 signature */
 	buf[7]  = 0x1b;
 	buf[8]  = 0;		/* P_Key */
diff --git a/include/net/ip.h b/include/net/ip.h
index abf2820..fbb4dd0 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -266,16 +266,18 @@ static inline void ip_eth_mc_map(__be32 naddr, char *buf)
  *	Leave P_Key as 0 to be filled in by driver.
  */
 
-static inline void ip_ib_mc_map(__be32 naddr, char *buf)
+static inline void ip_ib_mc_map(__be32 naddr, const unsigned char *broadcast, char *buf)
 {
 	__u32 addr;
+	unsigned char scope = broadcast[5] & 0xF;
+
 	buf[0]  = 0;		/* Reserved */
 	buf[1]  = 0xff;		/* Multicast QPN */
 	buf[2]  = 0xff;
 	buf[3]  = 0xff;
 	addr    = ntohl(naddr);
 	buf[4]  = 0xff;
-	buf[5]  = 0x12;		/* link local scope */
+	buf[5]  = 0x10 | scope;	/* scope from broadcast address */
 	buf[6]  = 0x40;		/* IPv4 signature */
 	buf[7]  = 0x1b;
 	buf[8]  = 0;		/* P_Key */
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 9ab9d53..feb643c 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -214,7 +214,7 @@ int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
 		ip_tr_mc_map(addr, haddr);
 		return 0;
 	case ARPHRD_INFINIBAND:
-		ip_ib_mc_map(addr, haddr);
+		ip_ib_mc_map(addr, dev->broadcast, haddr);
 		return 0;
 	default:
 		if (dir) {
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 0358e60..8275625 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -308,7 +308,7 @@ int ndisc_mc_map(struct in6_addr *addr, char *buf, struct net_device *dev, int d
 		ipv6_arcnet_mc_map(addr, buf);
 		return 0;
 	case ARPHRD_INFINIBAND:
-		ipv6_ib_mc_map(addr, buf);
+		ipv6_ib_mc_map(addr, dev->broadcast, buf);
 		return 0;
 	default:
 		if (dir) {