+/* Modifies the 'flag' bit in ethtool's flags field for 'netdev'. If
+ * 'enable' is true, the bit is set. Otherwise, it is cleared. */
+int
+netdev_linux_ethtool_set_flag(struct netdev *netdev, uint32_t flag,
+ const char *flag_name, bool enable)
+{
+ const char *netdev_name = netdev_get_name(netdev);
+ struct ethtool_value evalue;
+ uint32_t new_flags;
+ int error;
+
+ memset(&evalue, 0, sizeof evalue);
+ error = netdev_linux_do_ethtool(netdev_name,
+ (struct ethtool_cmd *)&evalue,
+ ETHTOOL_GFLAGS, "ETHTOOL_GFLAGS");
+ if (error) {
+ return error;
+ }
+
+ evalue.data = new_flags = (evalue.data & ~flag) | (enable ? flag : 0);
+ error = netdev_linux_do_ethtool(netdev_name,
+ (struct ethtool_cmd *)&evalue,
+ ETHTOOL_SFLAGS, "ETHTOOL_SFLAGS");
+ if (error) {
+ return error;
+ }
+
+ memset(&evalue, 0, sizeof evalue);
+ error = netdev_linux_do_ethtool(netdev_name,
+ (struct ethtool_cmd *)&evalue,
+ ETHTOOL_GFLAGS, "ETHTOOL_GFLAGS");
+ if (error) {
+ return error;
+ }
+
+ if (new_flags != evalue.data) {
+ VLOG_WARN_RL(&rl, "attempt to %s ethtool %s flag on network "
+ "device %s failed", enable ? "enable" : "disable",
+ flag_name, netdev_name);
+ return EOPNOTSUPP;
+ }
+
+ return 0;
+}
+