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Date:      Thu, 30 Apr 2009 22:10:04 +0000 (UTC)
From:      Jung-uk Kim <jkim@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r191708 - in head/sys: amd64/amd64 i386/i386
Message-ID:  <200904302210.n3UMA4Zq024212@svn.freebsd.org>
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Author: jkim
Date: Thu Apr 30 22:10:04 2009
New Revision: 191708
URL: http://svn.freebsd.org/changeset/base/191708

Log:
  - Fix divide-by-zero panic when SMP kernel is used on UP system[1].
  - Avoid possible divide-by-zero panic on SMP system when the CPUID is
  disabled, unsupported, or buggy.
  
  Submitted by:	pluknet (pluknet at gmail dot com)[1]

Modified:
  head/sys/amd64/amd64/mp_machdep.c
  head/sys/i386/i386/mp_machdep.c

Modified: head/sys/amd64/amd64/mp_machdep.c
==============================================================================
--- head/sys/amd64/amd64/mp_machdep.c	Thu Apr 30 21:48:31 2009	(r191707)
+++ head/sys/amd64/amd64/mp_machdep.c	Thu Apr 30 22:10:04 2009	(r191708)
@@ -292,6 +292,10 @@ topo_probe_0x4(void)
 static void
 topo_probe(void)
 {
+	static int cpu_topo_probed = 0;
+
+	if (cpu_topo_probed)
+		return;
 
 	logical_cpus = logical_cpus_mask = 0;
 	if (cpu_high >= 0xb)
@@ -299,9 +303,10 @@ topo_probe(void)
 	else if (cpu_high)
 		topo_probe_0x4();
 	if (cpu_cores == 0)
-		cpu_cores = mp_ncpus;
+		cpu_cores = mp_ncpus > 0 ? mp_ncpus : 1;
 	if (cpu_logical == 0)
 		cpu_logical = 1;
+	cpu_topo_probed = 1;
 }
 
 struct cpu_group *
@@ -313,6 +318,7 @@ cpu_topo(void)
 	 * Determine whether any threading flags are
 	 * necessry.
 	 */
+	topo_probe();
 	if (cpu_logical > 1 && hyperthreading_cpus)
 		cg_flags = CG_FLAG_HTT;
 	else if (cpu_logical > 1)

Modified: head/sys/i386/i386/mp_machdep.c
==============================================================================
--- head/sys/i386/i386/mp_machdep.c	Thu Apr 30 21:48:31 2009	(r191707)
+++ head/sys/i386/i386/mp_machdep.c	Thu Apr 30 22:10:04 2009	(r191708)
@@ -345,6 +345,10 @@ topo_probe_0x4(void)
 static void
 topo_probe(void)
 {
+	static int cpu_topo_probed = 0;
+
+	if (cpu_topo_probed)
+		return;
 
 	logical_cpus = logical_cpus_mask = 0;
 	if (cpu_high >= 0xb)
@@ -352,9 +356,10 @@ topo_probe(void)
 	else if (cpu_high)
 		topo_probe_0x4();
 	if (cpu_cores == 0)
-		cpu_cores = mp_ncpus;
+		cpu_cores = mp_ncpus > 0 ? mp_ncpus : 1;
 	if (cpu_logical == 0)
 		cpu_logical = 1;
+	cpu_topo_probed = 1;
 }
 
 struct cpu_group *
@@ -366,6 +371,7 @@ cpu_topo(void)
 	 * Determine whether any threading flags are
 	 * necessry.
 	 */
+	topo_probe();
 	if (cpu_logical > 1 && hyperthreading_cpus)
 		cg_flags = CG_FLAG_HTT;
 	else if (cpu_logical > 1)

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