svn commit: r232181 - in head/sys: kern sys

[John Baldwin]

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