From: Jan Kratochvil <jan.kratochvil@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Pedro Alves <palves@redhat.com>,
Cyrill Gorcunov <gorcunov@openvz.org>,
Pavel Emelyanov <xemul@parallels.com>, Tejun Heo <tj@kernel.org>,
Andrew Vagin <avagin@openvz.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ptrace: add ability to get clear_tid_address
Date: Wed, 8 Feb 2012 20:21:26 +0100 [thread overview]
Message-ID: <20120208192126.GA15599@host2.jankratochvil.net> (raw)
In-Reply-To: <20120208190250.GA23163@redhat.com>
On Wed, 08 Feb 2012 20:02:50 +0100, Oleg Nesterov wrote:
> If only I understood why do we need CLONE_CHILD_SETTID... at least
> I certainly do not understand why glibc translates fork() into
> clone(CLONE_CHILD_SETTID) on my system. The child write into its
> memory, the parent can't see this change. IIRC, initially
> CLONE_CHILD_SETTID wrote child->pid into the parent's memory, and
> even before the child was actually created.
IIUC your question correctly it is because if you PTRACE_SYSCALL SYS_fork
(therefore you PTRACE_SYSCALL SYS_clone) twice (therefore you stop on the
fork/clone syscall exit) you should have struct pthread contents valid for
iterating and examinating the thread structures via libthread_db.
This cannot be achieved by any userland code.
Regards,
Jan
next prev parent reply other threads:[~2012-02-08 19:21 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-03 11:11 Andrew Vagin
2012-02-03 16:25 ` Tejun Heo
2012-02-03 16:30 ` Cyrill Gorcunov
2012-02-03 16:41 ` Oleg Nesterov
2012-02-03 16:54 ` Cyrill Gorcunov
2012-02-03 16:45 ` Pavel Emelyanov
2012-02-03 16:51 ` Oleg Nesterov
2012-02-07 20:07 ` Pedro Alves
2012-02-07 20:56 ` Cyrill Gorcunov
2012-02-07 21:15 ` Pedro Alves
2012-02-07 21:51 ` Cyrill Gorcunov
2012-02-08 12:30 ` Pedro Alves
2012-02-08 12:42 ` Cyrill Gorcunov
2012-02-08 17:31 ` Oleg Nesterov
2012-02-08 18:04 ` Pedro Alves
2012-02-08 19:02 ` Oleg Nesterov
2012-02-08 19:20 ` Cyrill Gorcunov
2012-02-08 19:21 ` Jan Kratochvil [this message]
2012-02-08 19:42 ` Pedro Alves
2012-02-08 13:41 ` Andrew Vagin
2012-02-08 18:12 ` Jan Kratochvil
2012-02-10 3:02 ` Jamie Lokier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120208192126.GA15599@host2.jankratochvil.net \
--to=jan.kratochvil@redhat.com \
--cc=avagin@openvz.org \
--cc=gorcunov@openvz.org \
--cc=linux-kernel@vger.kernel.org \
--cc=oleg@redhat.com \
--cc=palves@redhat.com \
--cc=tj@kernel.org \
--cc=xemul@parallels.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome