kern/148698: commit references a PR

dfilter service dfilter at FreeBSD.ORG
Mon Aug 9 00:30:11 UTC 2010

The following reply was made to PR kern/148698; it has been noted by GNATS.

From: dfilter at FreeBSD.ORG (dfilter service)
To: bug-followup at
Subject: Re: kern/148698: commit references a PR
Date: Mon,  9 Aug 2010 00:24:11 +0000 (UTC)

 Author: attilio
 Date: Mon Aug  9 00:23:57 2010
 New Revision: 211087
   The r208165 fixed a bug related to unsigned integer overflowing for the
   number of CPUs detection.
   However, that was not mention at all, the problem was not reported, the
   patch has not been MFCed and the fix is mostly improper.
   Fix the original overflow (caused when 32 CPUs must be detected) by
   just using a different mathematical computation (it also makes more
   explicit the size of operands involved, which is good in the moment
   waiting for a more complete support for a large number of CPUs).
   PR:		kern/148698
   Submitted by:	Joe Landers <jlanders at vmware dot com>
   Tested by:	gianni
   MFC after:	10 days
 Modified: head/sys/kern/subr_smp.c
 --- head/sys/kern/subr_smp.c	Sun Aug  8 23:24:23 2010	(r211086)
 +++ head/sys/kern/subr_smp.c	Mon Aug  9 00:23:57 2010	(r211087)
 @@ -504,10 +504,7 @@ smp_topo_none(void)
  	top = &group[0];
  	top->cg_parent = NULL;
  	top->cg_child = NULL;
 -	if (mp_ncpus == sizeof(top->cg_mask) * 8)
 -		top->cg_mask = -1;
 -	else
 -		top->cg_mask = (1 << mp_ncpus) - 1;
 +	top->cg_mask = ~0U >> (32 - mp_ncpus);
  	top->cg_count = mp_ncpus;
  	top->cg_children = 0;
  	top->cg_level = CG_SHARE_NONE;
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