Date: Mon, 20 Jan 2014 16:03:16 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <Waiman.Long@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Arnd Bergmann <arnd@arndb.de>,
        linux-arch@vger.kernel.org, x86@kernel.org,
        linux-kernel@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Michel Lespinasse <walken@google.com>,
        Andi Kleen <andi@firstfloor.org>, Rik van Riel <riel@redhat.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
        George Spelvin <linux@horizon.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        "Aswin Chandramouleeswaran\"" <aswin@hp.com>,
        Scott J Norton <scott.norton@hp.com>
Subject: Re: [PATCH v9 3/5] qrwlock, x86 - Treat all data type not bigger
 than long as atomic in x86
Message-ID: <20140120150316.GG30183@twins.programming.kicks-ass.net>
References: <1389761047-47566-1-git-send-email-Waiman.Long@hp.com>
 <1389761047-47566-4-git-send-email-Waiman.Long@hp.com>
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On Tue, Jan 14, 2014 at 11:44:05PM -0500, Waiman Long wrote:
> The generic __native_word() macro defined in include/linux/compiler.h
> only allows "int" and "long" data types to be treated as native and
> atomic. The x86 architecture, however, allow the use of char and short
> data types as atomic as well.
> 
> This patch extends the data type allowed in the __native_word() macro to
> allow the use of char and short.
> 
> Signed-off-by: Waiman Long <Waiman.Long@hp.com>
> ---
>  arch/x86/include/asm/barrier.h |    8 ++++++++
>  1 files changed, 8 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
> index 04a4890..4d3e30a 100644
> --- a/arch/x86/include/asm/barrier.h
> +++ b/arch/x86/include/asm/barrier.h
> @@ -24,6 +24,14 @@
>  #define wmb()	asm volatile("sfence" ::: "memory")
>  #endif
>  
> +/*
> + * All data types <= long are atomic in x86
> + */
> +#ifdef __native_word
> +#undef __native_word
> +#endif
> +#define __native_word(t)	(sizeof(t) <= sizeof(long))

Yeah, not going to happen.
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