quoted

Allow kprobe tracepoint events creation through legacy interface, as the
kprobe dynamic PMUs support, used by default, was only created in v4.17.

After commit "bpf: implement minimal BPF perf link", it was allowed that
some extra - to the link - information is accessed through container_of
struct bpf_link. This allows the tracing perf event legacy name, and
information whether it is a retprobe, to be saved outside bpf_link
structure, which would not be optimal.

This enables CO-RE support for older kernels.

Cc: Andrii Nakryiko <redacted>
Signed-off-by: Rafael David Tinoco <redacted>
---

I've adjusted the commit message a bit (this has nothing to do with
CO-RE per se, so I dropped that, for example). Also see my comments
below, I've applied all that to your patch while applying, please
check them out.

Thanks. I'm assuming you don't need a v6 based on your adjustment comments, let me know if you do please.

...

quoted

-       if (ioctl(perf_link->perf_event_fd, PERF_EVENT_IOC_DISABLE, 0) < 0)
-               err = -errno;
+       ioctl(perf_link->perf_event_fd, PERF_EVENT_IOC_DISABLE, 0);

what's the reason for dropping the error check? I kept it, but please
let me know if there is any reason to drop it

From: _perf_ioctl() -> case PERF_EVENT_IOC_DISABLE: func = _perf_event_disable;

_perf_ioctl() will always return 0 and func is void (*func)(struct perf_event *).