svn commit: r211087 - head/sys/kern

[Attilio Rao]

Author: attilio
Date: Mon Aug  9 00:23:57 2010
New Revision: 211087
URL: http://svn.freebsd.org/changeset/base/211087

Log:
  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

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;