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

[Tim Gardner]

On 09/14/2010 12:36 PM, Leann Ogasawara wrote:
> 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

Acked-by: Tim Gardner <tim.gardner at canonical.com>

-- 
Tim Gardner tim.gardner at canonical.com