linux-kernel - Re: [PATCHSET] ptrace,signal: Improve ptrace and job control interaction

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Message-ID: <20110323183837.GA27680@redhat.com>
Date:	Wed, 23 Mar 2011 19:38:37 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	jan.kratochvil@...hat.com, vda.linux@...glemail.com,
	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, indan@....nu, roland@...k.frob.com
Subject: Re: [PATCHSET] ptrace,signal: Improve ptrace and job control
	interaction

On 03/23, Tejun Heo wrote:
>
> All patches have been reviewed and acked by Oleg and this will be the
> last repost of these patches.  They're being committed to a stable git
> tree (will eventually be managed by Oleg) and will be pulled into
> linux-next once -rc1 is released.

Thanks Tejun. The whole series is fine imho.

But of course we need more changes. In particular, there is still the
small problem with the CLD_CONTINUED notification.

__ptrace_unlink() does signal_wake_up() if it adds SIGNAL_STOP_STOPPED.
This is correct, but it should also add TIF_SIGPENDING if
(signal->flags & SIGNAL_CLD_MASK) != 0.

Otherwise, if the stopped tracee was PTRACE_CONT'ed and then SIGCONT
ends the group-stop, the real_parent won't be notified after detach.

Unfortunately, this means that recalc_sigpending_tsk() has to check
SIGNAL_CLD_MASK as well. Do you see another solution?

There is another case. SIGCONT can hit the stopped-but-running-task,
but I don't think we should try to set TIF_SIGPENDING in this case,
you are going to add the trap later.
There is another case. SIGCONT can hit the stopped-but-running-task,
but I don't think we should try to set TIF_SIGPENDING in this case,
you are going to add the trap later.

Oleg.

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