[Maverick] [PATCH 1/1] x86, hwmon: Fix unsafe smp_processor_id() in thermal_throttle_add_dev

[Leann Ogasawara]

Hi All,

We'd applied a set of patches in Maverick [1] to provide Package Thermal
Status and Power Limit Notification which is a new feature for Intel's
Sandy Bridge processor.  The following patch is an upstream cherry-pick
to resolve "BUG: using smp_processor_id() in preemptible" errors
introduced by this patch set.  Proposing for Maverick.

Thanks,
Leann

[1] https://lists.ubuntu.com/archives/kernel-team/2010-August/012487.html

>From a2ba1e647812788c0e87965d717a54907912ceb1 Mon Sep 17 00:00:00 2001
From: Sergey Senozhatsky <sergey.senozhatsky at gmail.com>
Date: Fri, 20 Aug 2010 10:36:34 +0300
Subject: [PATCH] x86, hwmon: Fix unsafe smp_processor_id() in thermal_throttle_add_dev

BugLink: http://bugs.launchpad.net/bugs/601073

Fix BUG: using smp_processor_id() in preemptible thermal_throttle_add_dev.
We know the cpu number when calling thermal_throttle_add_dev, so we can
remove smp_processor_id call in thermal_throttle_add_dev by supplying
the cpu number as argument.

This should resolve kernel bugzilla 16615/16629.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky at gmail.com>
LKML-Reference: <20100820073634.GB5209 at swordfish.minsk.epam.com>
Cc: Fenghua Yu <fenghua.yu at intel.com>
Cc: Joerg Roedel <Joerg.Roedel at amd.com>
Cc: Maciej Rutecki <maciej.rutecki at gmail.com>
Signed-off-by: H. Peter Anvin <hpa at zytor.com>
(cherry picked from commit 51e3c1b558b31b11bf5fc66d3c6f5adacf3573f7)

Signed-off-by: Leann Ogasawara <leann.ogasawara at canonical.com>
---
 arch/x86/kernel/cpu/mcheck/therm_throt.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c
index c2a8b26..d9368ee 100644
--- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
+++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
@@ -202,10 +202,11 @@ static int therm_throt_process(bool new_event, int event, int level)
 
 #ifdef CONFIG_SYSFS
 /* Add/Remove thermal_throttle interface for CPU device: */
-static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev)
+static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev,
+				unsigned int cpu)
 {
 	int err;
-	struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
+	struct cpuinfo_x86 *c = &cpu_data(cpu);
 
 	err = sysfs_create_group(&sys_dev->kobj, &thermal_attr_group);
 	if (err)
@@ -251,7 +252,7 @@ thermal_throttle_cpu_callback(struct notifier_block *nfb,
 	case CPU_UP_PREPARE:
 	case CPU_UP_PREPARE_FROZEN:
 		mutex_lock(&therm_cpu_lock);
-		err = thermal_throttle_add_dev(sys_dev);
+		err = thermal_throttle_add_dev(sys_dev, cpu);
 		mutex_unlock(&therm_cpu_lock);
 		WARN_ON(err);
 		break;
@@ -287,7 +288,7 @@ static __init int thermal_throttle_init_device(void)
 #endif
 	/* connect live CPUs to sysfs */
 	for_each_online_cpu(cpu) {
-		err = thermal_throttle_add_dev(get_cpu_sysdev(cpu));
+		err = thermal_throttle_add_dev(get_cpu_sysdev(cpu), cpu);
 		WARN_ON(err);
 	}
 #ifdef CONFIG_HOTPLUG_CPU
-- 
1.7.1