cvs commit: src/sys/kern kern_exit.c kern_resource.c

[John Baldwin]

On Monday 23 January 2006 14:15, Stephan Uphoff wrote:
> ups         2006-01-23 19:15:13 UTC
>
>   FreeBSD src repository
>
>   Modified files:
>     sys/kern             kern_exit.c kern_resource.c
>   Log:
>   Hopefully fix the "calcru: runtime went backwards from ..." problem by
>   keeping the resource values locked (where needed) while we use them
>   for calculations.
>
>   MFC after:      3 days

Why expand the locking in calcru()?  calcru1() is working with a static 
rusage_ext on calcru()'s stack, not the one for process p that is generated 
while sched_lock is held.  The 'p' for calcru1() is only used for printfs, no 
actual data is taken from p.  I think the ruadd() change might be the only 
fix needed, though I think the updating of p->p_stats->p_ru.ru_nvcsw and 
p->p_ru needs to be deferred as well since the race you seem to be fixing is 
the case where exit1() is preempted, but with the current change you'd still 
have stale data in p->p_ru (since it is a copy of p->p_stats->p_ru, not a 
pointer) unless you move the updating of p->p_ru down to just before the 
ruadd() as it was previously.

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org