libibumad: exclude Ethernet ports from SMI/GSI pairs

umad_get_smi_gsi_pairs() processes every RDMA device returned by
umad_get_cas_names(). On a host with both RoCE and native InfiniBand
devices, an active Ethernet port without IsSMDisabled in its capability
mask is therefore assigned an SMI name and selected first. Opening its
UMAD device succeeds, but registering IB_SMI_CLASS fails with
EPROTONOSUPPORT instead of continuing to the usable InfiniBand port.

Skip non-InfiniBand link layers while counting port GUIDs and while
constructing SMI/GSI pairs. Applying the filter in both passes keeps
Ethernet devices from affecting planarized-port detection.

Fixes: be54b52e94be ("libibumad: Add new API to support SMI/GSI seperation")
Signed-off-by: Jonathan Süssemilch Poulain <jpoulain@coreweave.com>

libibumad/umad.c

diff --git a/libibumad/umad.c b/libibumad/umad.c
index 1618381..22e83bc 100644
--- a/libibumad/umad.c
+++ b/libibumad/umad.c
@@ -148,6 +148,12 @@
 	return (be32toh(port->capmask) & CAPMASK_IS_SM_DISABLED);
 }
 
+static bool is_ib_link_layer(const umad_port_t *port)
+{
+	return !strcmp(port->link_layer, "InfiniBand") ||
+	       !strcmp(port->link_layer, "IB");
+}
+
 static int release_port(umad_port_t * port)
 {
 	free(port->pkeys);
@@ -1453,7 +1459,7 @@
 			umad_port_t *p_port = curr_ca.ports[p_idx];
 			size_t count_idx = 0;
 
-			if (!p_port)
+			if (!p_port || !is_ib_link_layer(p_port))
 				continue;
 
 			if (find_port_guid_count(counts, max, p_port->port_guid, &count_idx)) {
@@ -1518,7 +1524,8 @@
 			umad_port_t *p_port = curr_ca.ports[p_idx];
 			uint8_t guid_count = 0;
 
-			if (!p_port || !p_port->port_guid)
+			if (!p_port || !p_port->port_guid ||
+			    !is_ib_link_layer(p_port))
 				continue;
 
 			guid_count = get_port_guid_count(curr_ca.ports[p_idx]->port_guid,