linux-kernel - Re: [PATCH 3/4] hotplug, x86: Disable ARCH_CPU_PROBE

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 for Android: free password hash cracker in your pocket

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

Message-ID: <2917026.KqRDPssAuo@vostro.rjw.lan>
Date:	Sun, 18 Aug 2013 03:00:45 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Toshi Kani <toshi.kani@...com>
Cc:	mingo@...hat.com, hpa@...ux.intel.com, tglx@...utronix.de,
	gregkh@...uxfoundation.org, benh@...nel.crashing.org,
	x86@...nel.org, linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org, fenghua.yu@...el.com, bp@...e.de,
	srivatsa.bhat@...ux.vnet.ibm.com, isimatu.yasuaki@...fujitsu.com
Subject: Re: [PATCH 3/4] hotplug, x86: Disable ARCH_CPU_PROBE_RELEASE on x86

On Saturday, August 17, 2013 01:46:58 PM Toshi Kani wrote:
> Commit d7c53c9e enabled ARCH_CPU_PROBE_RELEASE on x86 in order to
> serialize CPU online/offline operations.  Although it is the config
> option to enable CPU hotplug test interfaces, probe & release, it is
> also the option to enable cpu_hotplug_driver_lock() as well.  Therefore,
> this option had to be enabled on x86 with dummy arch_cpu_probe() and
> arch_cpu_release().
> 
> Since then, lock_device_hotplug() was introduced to serialize CPU
> online/offline & hotplug operations.  Therefore, this config option
> is no longer required for the serialization.  This patch disables
> this config option on x86 and revert the changes made by commit
> d7c53c9e.
> 
> Signed-off-by: Toshi Kani <toshi.kani@...com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
>  arch/x86/Kconfig          |    4 ----
>  arch/x86/kernel/smpboot.c |   21 ---------------------
>  2 files changed, 25 deletions(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index b32ebf9..c87e49a 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -255,10 +255,6 @@ config ARCH_HWEIGHT_CFLAGS
>  	default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
>  	default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" if X86_64
>  
> -config ARCH_CPU_PROBE_RELEASE
> -	def_bool y
> -	depends on HOTPLUG_CPU
> -
>  config ARCH_SUPPORTS_UPROBES
>  	def_bool y
>  
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index aecc98a..5b24a9d 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -82,27 +82,6 @@
>  /* State of each CPU */
>  DEFINE_PER_CPU(int, cpu_state) = { 0 };
>  
> -#ifdef CONFIG_HOTPLUG_CPU
> -/*
> - * We need this for trampoline_base protection from concurrent accesses when
> - * off- and onlining cores wildly.
> - */
> -static DEFINE_MUTEX(x86_cpu_hotplug_driver_mutex);
> -
> -void cpu_hotplug_driver_lock(void)
> -{
> -	mutex_lock(&x86_cpu_hotplug_driver_mutex);
> -}
> -
> -void cpu_hotplug_driver_unlock(void)
> -{
> -	mutex_unlock(&x86_cpu_hotplug_driver_mutex);
> -}
> -
> -ssize_t arch_cpu_probe(const char *buf, size_t count) { return -1; }
> -ssize_t arch_cpu_release(const char *buf, size_t count) { return -1; }
> -#endif
> -
>  /* Number of siblings per CPU package */
>  int smp_num_siblings = 1;
>  EXPORT_SYMBOL(smp_num_siblings);
> --
> 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/
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
--
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/