fix the program cannot be terminated through ctrl-c

[mozillazg]

No description provided.

[jschwinger233]

Thanks for your PR.

Basically I have no question in this change, just want to add a point:

I'm not sure how this change can fix the non-interrupting issue. If ctrl-c doesn't stop the process, there must be somewhere blocking for a long term so that process has no change to reach the "cancel point" to check <-ctx.Done(). As far as I can see, this can only happen on the bpf syscall LookupAndDelete or fs IO skbw.Write and pcapw.WritePacket, but none of these could be fixed by this PR, could it?

[mozillazg]

If ctrl-c doesn't stop the process, there must be somewhere blocking for a long term so that process has no change to reach the "cancel point" to check <-ctx.Done()

skbdump/main.go

Lines 109 to 119 in 105f01e

	for {
	if err := bpfObjs.DataQueue.LookupAndDelete(nil, &data); err == nil {
	break
	}
	select {
	case <-ctx.Done():
	return
	case <-time.After(time.Microsecond):
	continue
	}
	}

In most cases, line 111 will always be executed and there is no way to break the first for loop. for example:

skbdump -i eth0

I can not terminate this process through ctrl-c.

[jschwinger233]

Understood, you pointed out that the process can't reach ctx check point when two bpf syscalls keep succeeding fetching events.

You're correct.