BR_STP_PROG
char *argv[] = { BR_STP_PROG, br->dev->name, arg, NULL };
rc = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
br_debug(br, BR_STP_PROG " received signal %d\n",
br_debug(br, BR_STP_PROG " exited with code %d\n",