Date: Wed, 29 Feb 2012 17:33:28 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: src-committers@freebsd.org, Pawel Jakub Dawidek <pjd@freebsd.org>, svn-src-all@freebsd.org, Mikolaj Golub <trociny@freebsd.org>, "Robert N. M. Watson" <rwatson@freebsd.org>, svn-src-head@freebsd.org, Julian Elischer <julian@freebsd.org> Subject: Re: svn commit: r232181 - in head/sys: kern sys Message-ID: <20120229153328.GG55074@deviant.kiev.zoral.com.ua> In-Reply-To: <201202290936.02309.jhb@freebsd.org> References: <201202261425.q1QEPm9g069102@svn.freebsd.org> <86mx81byt6.fsf@in138.ua3> <20120229132507.GB55074@deviant.kiev.zoral.com.ua> <201202290936.02309.jhb@freebsd.org>
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--cl8+tZBacEYae1bh Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Feb 29, 2012 at 09:36:02AM -0500, John Baldwin wrote: > On Wednesday, February 29, 2012 8:25:07 am Konstantin Belousov wrote: > > 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 c= an cause > > > 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 de= veloper > > > RNMW> needs to know they are changing application behaviour. But exp= osing a > > > RNMW> feature that can lead to correct applications but incorrect re= sults is > > > RNMW> a risky thing to do, hence my objection. > > >=20 > > > RNMW> I think given the other objections, it would be wise to remove= write > > > RNMW> access to process umasks, but retain read access for procstat = (which is > > > RNMW> quite useful, I agree). > > >=20 > > > I still don't see why having a sysctl RW is worse than asking users t= o run > > > something like in the attach when they need to change umask for anoth= er > > > 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. >=20 > kgdb doesn't though, and presumably for umask you would change it via kgd= b, so > from the running process' perspective it would look the same as changing = it via > sysctl. Right, but an idea of the change was to allow to do this for somebody who does not know how to perform it in kgdb. Not to mention that kgdb -w is risky, e.g. because filedesc might have changed under kgdb, so you would write over freed memory. --cl8+tZBacEYae1bh Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (FreeBSD) iEYEARECAAYFAk9ORUgACgkQC3+MBN1Mb4hkgQCg4eZSfK8M8FK2ywsijJ7pD58F kQAAoOUtORWe6fX3d8qK10JBlXRHZUG9 =NiSX -----END PGP SIGNATURE----- --cl8+tZBacEYae1bh--
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