Message-ID: <1381870805.22110.37.camel@joe-AO722>
Subject: Re: [PATCH 2/3] core: Convert printk_once to use DO_ONCE
From: Joe Perches <joe@perches.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Liu Chuansheng <chuansheng.liu@intel.com>,
        Ingo Molnar <mingo@kernel.org>
Date: Tue, 15 Oct 2013 14:00:05 -0700
In-Reply-To: <1381870252-5430-3-git-send-email-fweisbec@gmail.com>
References: <1381870252-5430-1-git-send-email-fweisbec@gmail.com>
	 <1381870252-5430-3-git-send-email-fweisbec@gmail.com>
Content-Type: text/plain; charset="ISO-8859-1"
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 771
Lines: 26

On Tue, 2013-10-15 at 22:50 +0200, Frederic Weisbecker wrote:
[]
> diff --git a/include/linux/printk.h b/include/linux/printk.h
[]
> @@ -252,14 +253,7 @@ extern asmlinkage void dump_stack(void) __cold;
>  
>  #ifdef CONFIG_PRINTK
>  #define printk_once(fmt, ...)			\
> -({						\
> -	static bool __print_once;		\
> -						\
> -	if (!__print_once) {			\
> -		__print_once = true;		\
> -		printk(fmt, ##__VA_ARGS__);	\
> -	}					\
> -})
> +	DO_ONCE(printk(fmt, ##__VA_ARGS__));

It's hard to believe the overhead is worth it.


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