linux-kernel - Re: fix BUG: using smp_processor_id() in preemptible code (resend)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 19 Aug 2010 19:03:59 +0200
From:	"Roedel, Joerg" <Joerg.Roedel@....com>
To:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"x86@...nel.org" <x86@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: fix BUG: using smp_processor_id() in preemptible code (resend)

On Wed, Aug 18, 2010 at 05:11:58AM -0400, Sergey Senozhatsky wrote:
> Should we call smp_processor_id/get_cpu in thermal_throttle_add_dev?
> We know the cpu when calling thermal_throttle_add_dev (in thermal_throttle_cpu_callback and
> thermal_throttle_init_device) so we can pass the cpu number when calling it.
> 
> My second solution is:
> 
> diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c
> index c2a8b26..bcd8499 100644
> --- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
> +++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
> @@ -202,11 +202,12 @@ 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)
>  		return 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

The notifier is preemtible so it can run on another CPU. So using the
supplied cpu arguemnt in the path looks like the right solution to me.

	Joerg

-- 
AMD Operating System Research Center

Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach
General Managers: Alberto Bozzo, Andrew Bowd
Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/