Re: [PATCH] rv: Add signal reactor

[Thomas Weißschuh]

On Mon, Oct 06, 2025 at 05:19:24PM +0200, Gabriele Monaco wrote:
> On Mon, 2025-10-06 at 12:10 +0200, Thomas Weißschuh wrote:

(...)

> > > For instance, what's the exact use case of the signal reactor? Isn't it
> > > simpler
> > > to do everything in BPF? Is the signal needed at all or something else (e.g.
> > > perf) would do the job?
> > 
> > The signal reactor is convenient to write automated tests. It can be used to
> > validate the monitors by triggering known-bad systemcalls from a test
> > executable and expect it to be killed with the reactor signal, see below for
> > an example.
> > On the other hand it can be used to validate that the kernel itself does not
> > regress with respect to RV-validated properties. For example the test program
> > can enable the rtapp monitor and run an example RT application using all kinds
> > of known-good IPC mechanisms without it being killed.
> > 
> 
> Yeah, what I meant is: having a signal isn't your goal. Easily understand if
> there was a reaction is.
> You could even restructure your test using tracepoints without any signal.

Agreed.

> So if I get it correctly, you are both "voting" for removing reactors in favour
> of tracepoint-only error reporting.
> Am I getting this right?

No, it is a suggestion for a cleanup/optimization where reactors are not
directly called from the monitors but instead from a tracepoint which is
triggered from the monitors. It would decouple the monitor and reactor
subsystems.


Thomas