From: Denys Vlasenko <vda.linux@googlemail.com>
To: "Indan Zupancic" <indan@nul.nu>
Cc: "Oleg Nesterov" <oleg@redhat.com>, "Tejun Heo" <tj@kernel.org>,
"Denys Vlasenko" <dvlasenk@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: Why I want PTRACE_O_TRACESTOP option
Date: Sat, 10 Sep 2011 03:17:03 +0200 [thread overview]
Message-ID: <201109100317.03979.vda.linux@googlemail.com> (raw)
In-Reply-To: <e7392891fba13321668f533c6a0d637b.squirrel@webmail.greenhost.nl>
On Saturday 10 September 2011 01:09, Indan Zupancic wrote:
> On Fri, September 9, 2011 18:26, Oleg Nesterov wrote:
> > On 09/09, Indan Zupancic wrote:
> >>
> >> It is very useful to set options atomically at SEIZE time.
> >
> > Nobody argues with this.
> >
> >> Another important reason to make PTRACE_O_TRACESTOP an option is
> >> because not everyone uses SEIZE: Users using PTRACE_TRACEME can't
> >> set this option at all.
> >
> > Yes. This was already discussed, PTRACE_TRACEME obviously doesn't
> > work if you need the new features. So far it was decided TRACEME
> > should be avoided,
>
> How do you want to attach/seize a just forked child without races
> in a less ugly way than with TRACEME?
I needed to do it when I was adding usage of SEIZE to strace.
It goes like this:
- fork
- child: raise(SIGSTOP)
- parent: waits until it sees child stopping
- parent: seizes the child
- parent: kill(child, SIGCONT)
--
vda
next prev parent reply other threads:[~2011-09-10 1:17 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-08 16:50 Why I want PTRACE_O_TRACESTOP option Denys Vlasenko
2011-09-09 0:18 ` Tejun Heo
2011-09-09 5:45 ` Denys Vlasenko
2011-09-09 16:00 ` Oleg Nesterov
2011-09-10 23:43 ` Tejun Heo
2011-09-09 5:54 ` Denys Vlasenko
2011-09-09 12:26 ` Indan Zupancic
2011-09-09 13:01 ` Indan Zupancic
2011-09-09 16:46 ` Denys Vlasenko
2011-09-09 16:26 ` Oleg Nesterov
2011-09-09 23:09 ` Indan Zupancic
2011-09-10 1:17 ` Denys Vlasenko [this message]
2011-09-10 11:20 ` Pedro Alves
2011-09-11 0:58 ` Tejun Heo
2011-09-09 16:14 ` Oleg Nesterov
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