linuxio: ude dev_port in favor of dev_id when available in net device sysfs directories

dev_id is somehow deprecated for exposing the port number.
Mostly matters for IB devices.

Thanks to Thomas Gruber for the report.

Signed-off-by: Brice Goglin <[email protected]>

Author: bgoglin

hwloc/topology-linux.c

@@ -5947,6 +5947,7 @@ hwloc_linuxfs_net_class_fillinfos(int root_fd,
   struct stat st;
   char path[296]; /* osdevpath <= 256 */
   char address[128];
+  int err;
   snprintf(path, sizeof(path), "%s/address", osdevpath);
   if (!hwloc_read_path_by_length(path, address, sizeof(address), root_fd)) {
     char *eol = strchr(address, '\n');
@@ -5957,8 +5958,14 @@ hwloc_linuxfs_net_class_fillinfos(int root_fd,
   snprintf(path, sizeof(path), "%s/device/infiniband", osdevpath);
   if (!hwloc_stat(path, &st, root_fd)) {
     char hexid[16];
-    snprintf(path, sizeof(path), "%s/dev_id", osdevpath);
-    if (!hwloc_read_path_by_length(path, hexid, sizeof(hexid), root_fd)) {
+    snprintf(path, sizeof(path), "%s/dev_port", osdevpath);
+    err = hwloc_read_path_by_length(path, hexid, sizeof(hexid), root_fd);
+    if (err < 0) {
+      /* fallback t dev_id for old kernels/drivers */
+      snprintf(path, sizeof(path), "%s/dev_id", osdevpath);
+      err = hwloc_read_path_by_length(path, hexid, sizeof(hexid), root_fd);
+    }
+    if (!err) {
       char *eoid;
       unsigned long port;
       port = strtoul(hexid, &eoid, 0);