From: Oleg Nesterov <oleg@redhat.com>
To: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Tejun Heo <tj@kernel.org>,
roland@redhat.com, linux-kernel@vger.kernel.org, rjw@sisk.pl
Subject: Re: [PATCH 1/4] signal: fix SIGCONT notification code
Date: Thu, 13 Jan 2011 15:40:11 +0100 [thread overview]
Message-ID: <20110113144011.GA28678@redhat.com> (raw)
In-Reply-To: <20110112204136.GB13830@host1.dyn.jankratochvil.net>
On 01/12, Jan Kratochvil wrote:
>
> On Wed, 22 Dec 2010 12:13:15 +0100, Tejun Heo wrote:
> > If SIGCONT is received while the child process is stopped, the code should
> > be CLD_CONTINUED. If SIGCONT is recieved while the child process is in the
> > process of being stopped, it should be CLD_STOPPED.
>
> If a process does
> kill (PID, SIGSTOP);
> <varying delay, possibly even from a different process>
> kill (PID, SIGCONT);
>
> does it mean the PID's parent may get different waitid() results?
No. The only problem is that SIGCHLD can come with the wrong
info.si_code/si_status
> Or even that PID will finally remain still `T (stopped)'?
No.
> I do not see it has any userland impact,
Yes, the problem is minor.
Still, this is the clear bug due to
SIGNAL_CLD_CONTINUED/SIGNAL_STOP_CONTINUED typo. And damn, it was
introduced by me ;)
> the
> PTRACE_ATTACH-to-T(stopped)-process is already racy for different reasons.
Please note that this bug affects !ptrace case too.
Oleg.
next prev parent reply other threads:[~2011-01-13 14:47 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-22 11:13 [PATCHSET] ptrace,signal: cleanups and fixes Tejun Heo
2010-12-22 11:13 ` [PATCH 1/4] signal: fix SIGCONT notification code Tejun Heo
2011-01-12 20:41 ` Jan Kratochvil
2011-01-13 11:27 ` Tejun Heo
2011-01-13 14:40 ` Oleg Nesterov [this message]
2010-12-22 11:13 ` [PATCH 2/4] ptrace: remove the extra wake_up_process() from ptrace_detach() Tejun Heo
2011-01-17 22:13 ` Roland McGrath
2011-01-27 13:34 ` Tejun Heo
2011-01-28 7:02 ` Roland McGrath
2011-01-28 10:59 ` Tejun Heo
2010-12-22 11:13 ` [PATCH 3/4] signal: remove superflous try_to_freeze() loop in do_signal_stop() Tejun Heo
2011-01-17 22:10 ` Roland McGrath
2010-12-22 11:13 ` [PATCH 4/4] ptrace: kill tracehook_notify_jctl() Tejun Heo
2011-01-17 22:14 ` Roland McGrath
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