Date: Wed, 1 Jun 2011 21:01:17 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: vda.linux@googlemail.com, jan.kratochvil@redhat.com,
        linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
        akpm@linux-foundation.org, indan@nul.nu, bdonlan@gmail.com,
        pedro@codesourcery.com
Subject: Re: [PATCH 11/17] ptrace: implement PTRACE_SEIZE
Message-ID: <20110601190117.GB6504@redhat.com>
References: <1306710760-16440-1-git-send-email-tj@kernel.org> <1306710760-16440-12-git-send-email-tj@kernel.org>
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On 05/30, Tejun Heo wrote:
>
> implements a new ptrace request PTRACE_SEIZE which attaches and traps
> tracee

it doesn't trap the tracee ;)

> * PTRACE_SEIZE, unlike ATTACH, doesn't force tracee to trap.  After
>   attaching tracee continues to run unless a trap condition occurs.

OK.

Just to remind, tracehook_report_clone() shouldn't send SIGSTOP if
the auto-attached tracee is PT_SEIZED.

> * If PTRACE_SEIZE'd, group stop uses PTRACE_EVENT_STOP trap which uses
>   exit_code of (SIGTRAP | PTRACE_EVENT_STOP << 8) instead of the
>   stopping signal number

Hmm. May be it would be better to report stopping_signal | PTRACE_EVENT_STOP
instead... I am not sure yet, but it seems this way we can avoid the
PTRACE_GETSIGINFO changes. I'll try to explain later, when I finsh the
reading.

Oleg.

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