samples/bpf/trace_event_user.c

141 	int i, pmu_fd, error = 1;
153 		pmu_fd = sys_perf_event_open(attr, -1, i, -1, 0);
154 		if (pmu_fd < 0) {
158 		links[i] = bpf_program__attach_perf_event(prog, pmu_fd);
162 			close(pmu_fd);
184 	int pmu_fd, error = 1;
192 	pmu_fd = sys_perf_event_open(attr, 0, -1, -1, 0);
193 	if (pmu_fd < 0) {
197 	link = bpf_program__attach_perf_event(prog, pmu_fd);
201 		close(pmu_fd);