RDMA/cma: Consider scope_id while binding to ipv6 ll address

When two netdev have same link local addresses (such as vlan and non
vlan), two rdma cm listen id should be able to bind to following different
addresses.

listener-1: addr=lla, scope_id=A, port=X
listener-2: addr=lla, scope_id=B, port=X

However while comparing the addresses only addr and port are considered,
due to which 2nd listener fails to listen.

In below example of two listeners, 2nd listener is failing with address in
use error.

$ rping -sv -a fe80::268a:7ff:feb3:d113%ens2f1 -p 4545&

$ rping -sv -a fe80::268a:7ff:feb3:d113%ens2f1.200 -p 4545
rdma_bind_addr: Address already in use

To overcome this, consider the scope_ids as well which forms the accurate
IPv6 link local address.
Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/cma.c

@@ -1177,18 +1177,31 @@ static inline bool cma_any_addr(const struct sockaddr *addr)
 	return cma_zero_addr(addr) || cma_loopback_addr(addr);
 }
 
-static int cma_addr_cmp(struct sockaddr *src, struct sockaddr *dst)
+static int cma_addr_cmp(const struct sockaddr *src, const struct sockaddr *dst)
 {
 	if (src->sa_family != dst->sa_family)
 		return -1;
 
 	switch (src->sa_family) {
 	case AF_INET:
-		return ((struct sockaddr_in *) src)->sin_addr.s_addr !=
-		       ((struct sockaddr_in *) dst)->sin_addr.s_addr;
-	case AF_INET6:
-		return ipv6_addr_cmp(&((struct sockaddr_in6 *) src)->sin6_addr,
-				     &((struct sockaddr_in6 *) dst)->sin6_addr);
+		return ((struct sockaddr_in *)src)->sin_addr.s_addr !=
+		       ((struct sockaddr_in *)dst)->sin_addr.s_addr;
+	case AF_INET6: {
+		struct sockaddr_in6 *src_addr6 = (struct sockaddr_in6 *)src;
+		struct sockaddr_in6 *dst_addr6 = (struct sockaddr_in6 *)dst;
+		bool link_local;
+
+		if (ipv6_addr_cmp(&src_addr6->sin6_addr,
+					  &dst_addr6->sin6_addr))
+			return 1;
+		link_local = ipv6_addr_type(&dst_addr6->sin6_addr) &
+			     IPV6_ADDR_LINKLOCAL;
+		/* Link local must match their scope_ids */
+		return link_local ? (src_addr6->sin6_scope_id !=
+				     dst_addr6->sin6_scope_id) :
+				    0;
+	}
+
 	default:
 		return ib_addr_cmp(&((struct sockaddr_ib *) src)->sib_addr,
 				   &((struct sockaddr_ib *) dst)->sib_addr);