svn commit: r232181 - in head/sys: kern sys
John Baldwin
jhb at freebsd.org
Wed Feb 29 15:21:51 UTC 2012
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:
> >
> > On Wed, 29 Feb 2012 12:03:00 +0000 Robert N. M. Watson wrote:
> >
> > RNMW> I think the monitoring aspect of the patch is fine.
> >
> > RNMW> The bit I was worried about was external umask changes. This can 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 developer
> > RNMW> needs to know they are changing application behaviour. But exposing a
> > RNMW> feature that can lead to correct applications but incorrect results is
> > RNMW> a risky thing to do, hence my objection.
> >
> > 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).
> >
> > 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.
> >
> 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.
kgdb doesn't though, and presumably for umask you would change it via kgdb, so
from the running process' perspective it would look the same as changing it via
sysctl.
--
John Baldwin
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