From: Oleg Nesterov <oleg@redhat.com>
To: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Roland McGrath <roland@redhat.com>,
Project Archer <archer@sourceware.org>
Subject: Re: ptrace improvement: PTRACE_O_INHERIT
Date: Sat, 19 Feb 2011 20:37:00 -0000 [thread overview]
Message-ID: <20110219202921.GA12280@redhat.com> (raw)
In-Reply-To: <20110219194758.GA8994@host1.dyn.jankratochvil.net>
On 02/19, Jan Kratochvil wrote:
>
> On Wed, 16 Feb 2011 21:01:10 +0100, Oleg Nesterov wrote:
> > On 02/16, Roland McGrath wrote:
> > > If the process-wide PID (tgid) is not reused
> > > ...
> > > then tgkill does protect completely against TID reuse.
> >
> > How? sooner or later the process which creates/destroys a thread
> > in a loop will reuse some pid number.
>
> (a) GDB tracks separately threads (libpthread-managed) and LWPs (TIDs).
> (So the libthread_db TD_DEATH notification is offtopic for this mail.)
>
> (b) For LWPs it does not use PTRACE_O_TRACEEXIT.
> /* Do not enable PTRACE_O_TRACEEXIT until GDB is more prepared to support
> read-only process state. */
> (I do not know more regarding this comment.)
>
> Therefore it occasionally uses tkill (TID, 0) instead of PTRACE_O_TRACEEXIT.
Cough. I still can't understand why gdb needs tkill(TID, 0). Please
ignore, I know nothing about gdb implementation.
However. With or without PTRACE_O_TRACEEXIT, the thread can't go away
until ptracer does do_wait(WEXITED). And until it does do_wait() tkill()
succeeds even if the tracee is dead/zombie.
Oleg.
next prev parent reply other threads:[~2011-02-19 20:37 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
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 [this message]
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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