From: Roland McGrath <roland@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Project Archer <archer@sourceware.org>
Subject: Re: ptrace improvement: PTRACE_O_INHERIT
Date: Mon, 14 Feb 2011 19:31:00 -0000 [thread overview]
Message-ID: <20110214193052.3EC8D1814BA@magilla.sf.frob.com> (raw)
In-Reply-To: Oleg Nesterov's message of Saturday, 12 February 2011 20:02:53 +0100 <20110212190253.GA31866@redhat.com>
> > > I meant, we can intoduce the new W*** flag for do_wait(). If the new
> > > tracee was PTRACE_O_INHERIT'ed, do_wait() returns its pid.
> >
> > I still don't understand the proposal.
>
> To simplify the explanation, suppose we add task_struct->unknown_tracee
> boolean.
>
> if tracehook_finish_clone()->ptrace_init_task() does __ptrace_link()
> because of PTRACE_O_INHERIT, it also sets child->unknown_tracee and
> notifies the tracee via do_notify_parent_cldstop().
So the suggestion is to have the tracer see a wait report that simply says
"here is a new implicit tracee". I don't see how that is useful at all.
It supplies no new information, only mentions the tracee earlier. That
makes it a short race window in which it's possible for a tracer to have no
possible means of identifying the lineage of an implicit tracee. But it
does not solve the problem in the general case.
> > Tracing some threads but not all is really an artifact of the ptrace
> > interface and not something that any real userland debugger-like thing
> > ever wants to do.
>
> Off-topic note: I disagree very much, but this doesn't matter. I agree
> that ptrace nterface should not be per-thread, and gdb always traces all
> threads.
Then I don't understand at all what you are disagreeing with.
You think the interface should not be per-thread, but you don't agree
that a per-thread interface is not something debuggers really want?
Thanks,
Roland
next prev parent reply other threads:[~2011-02-14 19:31 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-03 22:39 ptrace improvement ideas Roland McGrath
2011-02-04 18:56 ` Oleg Nesterov
2011-02-04 18:58 ` Roland McGrath
2011-02-07 21:11 ` Jan Kratochvil
2011-02-08 1:58 ` Roland McGrath
2011-02-08 20:41 ` Jan Kratochvil
2011-02-09 2:48 ` Roland McGrath
2011-02-08 21:07 ` Oleg Nesterov
2011-02-08 23:18 ` hw_breakpoint userland interface Roland McGrath
2011-02-10 21:03 ` Oleg Nesterov
2011-02-10 21:14 ` Roland McGrath
2011-02-11 20:17 ` Oleg Nesterov
2011-02-10 20:00 ` ptrace improvement: PTRACE_O_INHERIT Oleg Nesterov
2011-02-11 19:24 ` Roland McGrath
2011-02-11 20:46 ` Oleg Nesterov
2011-02-12 0:59 ` Roland McGrath
2011-02-12 19:11 ` Oleg Nesterov
2011-02-14 19:31 ` Roland McGrath [this message]
2011-02-14 19:46 ` Oleg Nesterov
2011-02-15 0:36 ` Roland McGrath
2011-02-15 13:16 ` Oleg Nesterov
2011-02-15 21:43 ` Jan Kratochvil
2011-02-15 21:56 ` Roland McGrath
2011-02-16 19:42 ` Oleg Nesterov
2011-02-16 19:45 ` Roland McGrath
2011-02-16 20:09 ` Oleg Nesterov
2011-02-16 20:16 ` Roland McGrath
2011-02-19 19:48 ` Jan Kratochvil
2011-02-19 20:37 ` Oleg Nesterov
2011-02-20 8:18 ` Jan Kratochvil
2011-02-20 21:05 ` Oleg Nesterov
2011-02-21 19:54 ` Roland McGrath
2011-02-22 19:39 ` Oleg Nesterov
2011-02-22 20:49 ` Roland McGrath
2011-02-22 21:10 ` Oleg Nesterov
2011-02-22 22:16 ` Roland McGrath
2011-02-21 19:44 ` Roland McGrath
2011-02-15 22:02 ` Roland McGrath
2011-02-16 16:02 ` Jan Kratochvil
2011-02-16 18:28 ` Roland McGrath
2011-02-16 20:00 ` Oleg Nesterov
2011-02-16 20:07 ` Roland McGrath
2011-02-16 20:32 ` Oleg Nesterov
2011-02-16 19:48 ` Oleg Nesterov
2011-02-16 20:02 ` Roland McGrath
2011-02-16 20:15 ` Oleg Nesterov
2011-02-16 20:31 ` Roland McGrath
2011-02-16 21:04 ` Oleg Nesterov
2011-02-16 21:51 ` Roland McGrath
2011-02-16 19:38 ` Oleg Nesterov
2011-02-16 19:40 ` Roland McGrath
2011-02-15 22:17 ` Roland McGrath
2011-02-16 20:48 ` Oleg Nesterov
2011-02-16 11:31 ` ptrace improvement ideas (QPassSignals) Jan Kratochvil
2011-02-16 18:36 ` Roland McGrath
2011-02-16 20:21 ` Oleg Nesterov
2011-02-18 20:24 ` Oleg Nesterov
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