TRACEFS_DIR
root = tracefs_create_dir(TRACEFS_DIR, NULL);
pr_err("Failed to create tracefs dir "TRACEFS_DIR"\n");
pr_err("Failed to create tracefs dir "TRACEFS_DIR"%s/\n", name);
pr_err("Failed to create tracefs dir "TRACEFS_DIR"%s/per_cpu/\n", name);
pr_err("Failed to create tracefs dir "TRACEFS_DIR"%s/percpu/cpu%d\n",