Re: [PATCH v5 1/2] kernel/signal: Signal-based pre-coredump notification

[Oleg Nesterov]

On 12/04, Andrew Morton wrote:
>
> I'm not sure what to make of this patchset, really.  Oleg sounds
> unhappy and that's always a bad sign.  And signals are rather ugly
> things.  Oleg, can you please expand on your concerns?

I don't really know what can I say...

Yes the signals are ugly things, this is one reason. Worse, you need to
use real-time predump_signal if parent has 2 or more children.

And when it comes to child-parent notifications we already have do_wait().
So probably it would be better to implement WCOREDUMP so that the parent
could rely on SIGCHLD + waitpid(WCOREDUMP). Not that I think this is a
good idea and this is much more complex especially if we want to report
this event to ptracer too, while this patch is very simple.

In fact I think that we need something more generic, but I can't suggest
any good idea :/

May be we could simply add a tracepoint or perf_event_coredump, I dunno.
Sure, the usage of perf events is not that simple...

Oleg.