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Date:      Wed, 29 Feb 2012 15:25:07 +0200
From:      Konstantin Belousov <kostikbel@gmail.com>
To:        Mikolaj Golub <trociny@freebsd.org>
Cc:        src-committers@freebsd.org, Pawel Jakub Dawidek <pjd@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org, "Robert N. M. Watson" <rwatson@freebsd.org>, Konstantin Belousov <kostikbel@gmail.com>, Julian Elischer <julian@freebsd.org>
Subject:   Re: svn commit: r232181 - in head/sys: kern sys
Message-ID:  <20120229132507.GB55074@deviant.kiev.zoral.com.ua>
In-Reply-To: <86mx81byt6.fsf@in138.ua3>
References:  <201202261425.q1QEPm9g069102@svn.freebsd.org> <20120227082811.GC1363@garage.freebsd.pl> <864nucd5jc.fsf@in138.ua3> <20120227092951.GB55074@deviant.kiev.zoral.com.ua> <4F4C7571.7010407@freebsd.org> <86zkc3bell.fsf@in138.ua3> <4F4D6AA4.9040208@freebsd.org> <86vcmqaxij.fsf@in138.ua3> <9557FCA0-7428-4794-8A27-9888F42974CA@freebsd.org> <86mx81byt6.fsf@in138.ua3>

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On Wed, Feb 29, 2012 at 02:37:25PM +0200, Mikolaj Golub wrote:
>=20
> On Wed, 29 Feb 2012 12:03:00 +0000 Robert N. M. Watson wrote:
>=20
>  RNMW> I think the monitoring aspect of the patch is fine.
>=20
>  RNMW> The bit I was worried about was external umask changes. This can c=
ause
>  RNMW> race conditions for applications that manage their umask -- for
>  RNMW> example, bsdtar, if I recall correctly. It's one thing to use a
>  RNMW> debugger to force an application to change its umask -- the develo=
per
>  RNMW> needs to know they are changing application behaviour. But exposin=
g a
>  RNMW> feature that can lead to correct applications but incorrect result=
s is
>  RNMW> a risky thing to do, hence my objection.
>=20
>  RNMW> I think given the other objections, it would be wise to remove wri=
te
>  RNMW> access to process umasks, but retain read access for procstat (whi=
ch is
>  RNMW> quite useful, I agree).
>=20
> I still don't see why having a sysctl RW is worse than asking users to run
> something like in the attach when they need to change umask for another
> process, but ok, if people don't like RW I will remove it.
>=20
What is done is attach is much worse then the sysctl, just because
debugger attach often causes spurious EINTR, indeed seriously disrupting
applications, as opposed to some uncertain damage that could be done in
theory.

*shrug*

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