Re: [PATCH -tip v3 0/3] tracepoint: Add signal events

[Oleg Nesterov <oleg at redhat dot com>]

On 11/23, Ingo Molnar wrote:
>
> * Masami Hiramatsu <mhiramat@redhat.com> wrote:
>
> > Hi,
> >
> > These patches add signal related tracepoints including
> > signal generation, delivery, and loss. First patch also
> > moves signal-sending tracepoint from events/sched.h to
> > events/signal.h.
> >
> > Changes in v3
> > - Add Docbook style comments
> >
> > Changes in v2
> > - Add siginfo arguments
> >
> > Thank you,
> >
> > ---
> >
> > Masami Hiramatsu (3):
> >       tracepoint: Add signal loss events
> >       tracepoint: Add signal deliver event
> >       tracepoint: Move signal sending tracepoint to events/signal.h
> >
> >
> >  Documentation/DocBook/tracepoint.tmpl |    5 +
> >  include/trace/events/sched.h          |   25 -----
> >  include/trace/events/signal.h         |  173 +++++++++++++++++++++++++++++++++
> >  kernel/signal.c                       |   27 ++++-
> >  4 files changed, 198 insertions(+), 32 deletions(-)
> >  create mode 100644 include/trace/events/signal.h
>
> Would be nice to have Roland's and Oleg's Acked-by tags in the patches -
> to show that this is a representative and useful looking set of signal
> events.

Sorry, I can't really comment these patches.

I mean, I do not know which info is useful and which is not.
For example, I am a bit surprized we report trace_signal_lose_info()
but please do not consider this as if I think we shouldn't. Just I
do not know.

OTOH, we do not report if __send_signal() fails just because the
legacy signal is already queued. We do not report who sends the signal,
we do not report if it was private or shared. zap_process, complete_signal
can "send" SIGKILL via sigaddset, this won't be noticed. But again, it is
not that I think this should be reported.

In short: I think any info may be useful, and these patches can help.
But I do not understand what exactly should be reported to userspace.

Oleg.