normal users calling setpriority(2)

[Marc Olzheim]

On Tue, Apr 08, 2008 at 10:02:03AM -0700, LI Xin wrote:
> Aryeh M. Friedman wrote:
> >Is it possible via sysctl or some other method to allow non-superusers 
> >to set any priority they want.   The specific question is I often want 
> >to set idprio 31 on stuff but don't want to switch to root to do it (I 
> >am the only user on the machine).
> 
> No if nobody implement PRIV_SCHED_SETPRIORTY support for non-root.

It's intentionally disabled to prevent deadlocks, see about line 330 of
/usr/src/sys/kern/kern_resource.c:

 * Realtime priority has to be restricted for reasons which should be
 * obvious.  However, for idle priority, there is a potential for
 * system deadlock if an idleprio process gains a lock on a resource
 * that other processes need (and the idleprio process can't run
 * due to a CPU-bound normal process).  Fix me!  XXX

If you want to allow it (we've done so for years without any real
trouble), simply change it to like:

#if 1
	if (RTP_PRIO_IS_REALTIME(rtp.type))
#else
	if (rtp.type != RTP_PRIO_NORMAL)
#endif
	{

Marc
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