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Date: Sun, 19 Jan 2014 18:35:24 -0800
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
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Subject: Re: [PATCH v7 6/6] MCS Lock: add Kconfig entries to allow
 arch-specific hooks
Message-ID: <20140120023524.GN10038@linux.vnet.ibm.com>
Reply-To: paulmck@linux.vnet.ibm.com
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On Thu, Jan 16, 2014 at 04:08:36PM -0800, Tim Chen wrote:
> This patch adds Kconfig entries to allow architectures to hook into the
> MCS lock/unlock functions in the contended case.
> 
> From: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Will Deacon <will.deacon@arm.com>

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

> ---
>  arch/Kconfig                 | 3 +++
>  include/linux/mcs_spinlock.h | 8 ++++++++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 80bbb8c..8a2a056 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -303,6 +303,9 @@ config HAVE_CMPXCHG_LOCAL
>  config HAVE_CMPXCHG_DOUBLE
>  	bool
> 
> +config HAVE_ARCH_MCS_LOCK
> +	bool
> +
>  config ARCH_WANT_IPC_PARSE_VERSION
>  	bool
> 
> diff --git a/include/linux/mcs_spinlock.h b/include/linux/mcs_spinlock.h
> index d54bb23..d2c02ad 100644
> --- a/include/linux/mcs_spinlock.h
> +++ b/include/linux/mcs_spinlock.h
> @@ -12,6 +12,14 @@
>  #ifndef __LINUX_MCS_SPINLOCK_H
>  #define __LINUX_MCS_SPINLOCK_H
> 
> +/*
> + * An architecture may provide its own lock/unlock functions for the
> + * contended case.
> + */
> +#ifdef CONFIG_HAVE_ARCH_MCS_LOCK
> +#include <asm/mcs_spinlock.h>
> +#endif
> +
>  struct mcs_spinlock {
>  	struct mcs_spinlock *next;
>  	int locked; /* 1 if lock acquired */
> -- 
> 1.7.11.7
> 
>