On Wed, Jul 03, 2019 at 08:14:30PM -0700, Kris Van Hees wrote:
> +int dt_bpf_attach(int event_id, int bpf_fd)
> +{
> + int event_fd;
> + int rc;
> + struct perf_event_attr attr = {};
> +
> + attr.type = PERF_TYPE_TRACEPOINT;
> + attr.sample_type = PERF_SAMPLE_RAW;
> + attr.sample_period = 1;
> + attr.wakeup_events = 1;
> + attr.config = event_id;
> +
> + /* Register the event (based on its id), and obtain a fd. */
> + event_fd = perf_event_open(&attr, -1, 0, -1, 0);
> + if (event_fd < 0) {
> + perror("sys_perf_event_open");
> + return -1;
> + }
> +
> + /* Enable the probe. */
> + rc = ioctl(event_fd, PERF_EVENT_IOC_ENABLE, 0);
AFAICT you didn't use attr.disabled = 1, so this IOC_ENABLE is
completely superfluous.
> + if (rc < 0) {
> + perror("PERF_EVENT_IOC_ENABLE");
> + return -1;
> + }
> +
> + /* Associate the BPF program with the event. */
> + rc = ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, bpf_fd);
> + if (rc < 0) {
> + perror("PERF_EVENT_IOC_SET_BPF");
> + return -1;
> + }
> +
> + return 0;
> +}
