Re: kprobe not always triggering

[Daniel Wagner <dwagner@suse.de>]

On Wed, Jan 15, 2025 at 10:17:15AM -0500, Steven Rostedt wrote:
> [ Adding Masami ]
> Is it consistently the same locations being dropped?

Yes, it is very consistent.

> There's been cases of a compiler inlining some functions for the code
> called in the same file. If that happened, then those will likely be
> dropped. That can be tested by adding:
> 
> bool noinline nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
>                 enum nvme_ctrl_state new_state) 
> 
> You would think it shouldn't inline it, but there's nothing in the spec
> that says it can't do so.

This did the trick, now I see the missing state transitions.

> > The system is idle, so I hope it's not just a dropped event. Any ideas
> > what I am doing wrong?
> 
> I don't think it's a dropped event. It's not busy enough. But the compiler
> making a copy of the function (by inlining or what not) can cause something
> like this to happen.

I didn't expect that the compiler does inlining and not inlining at the
same time. Again what learned :)

Thanks,
Daniel