+/**
+ * Get kernel interface name from IB device path.
+ *
+ * @param[in] ibdev_path
+ * Pointer to IB device path.
+ * @param[out] ifname
+ * Interface name output buffer.
+ *
+ * @return
+ * 0 on success, a negative errno value otherwise and rte_errno is set.
+ */
+int
+mlx5_get_ifname_sysfs(const char *ibdev_path, char *ifname)
+{
+ DIR *dir;
+ struct dirent *dent;
+ unsigned int dev_type = 0;
+ unsigned int dev_port_prev = ~0u;
+ char match[IF_NAMESIZE] = "";
+
+ MLX5_ASSERT(ibdev_path);
+ {
+ MKSTR(path, "%s/device/net", ibdev_path);
+
+ dir = opendir(path);
+ if (dir == NULL) {
+ rte_errno = errno;
+ return -rte_errno;
+ }
+ }
+ while ((dent = readdir(dir)) != NULL) {
+ char *name = dent->d_name;
+ FILE *file;
+ unsigned int dev_port;
+ int r;
+
+ if ((name[0] == '.') &&
+ ((name[1] == '\0') ||
+ ((name[1] == '.') && (name[2] == '\0'))))
+ continue;
+
+ MKSTR(path, "%s/device/net/%s/%s",
+ ibdev_path, name,
+ (dev_type ? "dev_id" : "dev_port"));
+
+ file = fopen(path, "rb");
+ if (file == NULL) {
+ if (errno != ENOENT)
+ continue;
+ /*
+ * Switch to dev_id when dev_port does not exist as
+ * is the case with Linux kernel versions < 3.15.
+ */
+try_dev_id:
+ match[0] = '\0';
+ if (dev_type)
+ break;
+ dev_type = 1;
+ dev_port_prev = ~0u;
+ rewinddir(dir);
+ continue;
+ }
+ r = fscanf(file, (dev_type ? "%x" : "%u"), &dev_port);
+ fclose(file);
+ if (r != 1)
+ continue;
+ /*
+ * Switch to dev_id when dev_port returns the same value for
+ * all ports. May happen when using a MOFED release older than
+ * 3.0 with a Linux kernel >= 3.15.
+ */
+ if (dev_port == dev_port_prev)
+ goto try_dev_id;
+ dev_port_prev = dev_port;
+ if (dev_port == 0)
+ strlcpy(match, name, IF_NAMESIZE);
+ }
+ closedir(dir);
+ if (match[0] == '\0') {
+ rte_errno = ENOENT;
+ return -rte_errno;
+ }
+ strncpy(ifname, match, IF_NAMESIZE);
+ return 0;
+}
+