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Date: Mon, 19 Mar 2012 20:55:34 +0400
From: Cyrill Gorcunov <gorcunov@openvz.org>
To: Kees Cook <keescook@chromium.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Pavel Emelyanov <xemul@parallels.com>, Tejun Heo <tj@kernel.org>,
        Matt Helsley <matthltc@us.ibm.com>, Andrew Vagin <avagin@openvz.org>,
        Pedro Alves <palves@redhat.com>
Subject: Re: [patch 2/2] c/r: prctl: Add ability to get clear_tid_address
Message-ID: <20120319165534.GI19594@moon>
References: <20120316205556.595309230@openvz.org>
 <20120316210343.993662395@openvz.org>
 <CAGXu5jJq5yQDadMpRasXNOV3=auRF5WbyyEf3bodf42veg9F0g@mail.gmail.com>
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On Mon, Mar 19, 2012 at 09:51:36AM -0700, Kees Cook wrote:
> On Fri, Mar 16, 2012 at 1:55 PM, Cyrill Gorcunov <gorcunov@openvz.org> wrote:
> > Zero is written at clear_tid_address, when
> > the process exits. This functionality is used
> > by pthread_join().
> >
> > We already have sys_set_tid_address() to change this
> > address for current task but there is no way to obtain
> > it from a user space.
> 
> Is it worth introducing a syscall for this just for symmetry? I
> suspect not, in which case:
> 
> Acked-by: Kees Cook <keescook@chromium.org>
> 

Thanks Kees! syscall was considered as "no-no" in previous
convesation about this patch, so we switched to prctl.

	Cyrill