DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=sender:date:from:to:cc:subject:message-id:references:mime-version
         :content-type:content-disposition:in-reply-to:user-agent;
        b=hD1cNhdBJJ8yF+a5P+kRw2GMtrErTo1qRkNwGVqtDcsH8mByo7WlIlf3JUgV7BQLHh
         5ld6R70WfudPo6JqfVAap+Wzg8mty1QrhGO6yXXylycCVXwaljP9bqZEwuRgTGWlkGrf
         EXKkRCcO2SuHziRXO/Zv03JiRx+G/1dSnQSXs=
Date: Wed, 13 Apr 2011 04:02:51 +0900
From: Tejun Heo <tj@kernel.org>
To: Shaohua Li <shaohua.li@intel.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>, cl@linux.com
Subject: Re: [PATCH 3/4]percpu_counter: fix code for 32bit systems
Message-ID: <20110412190251.GD16342@mtj.dyndns.org>
References: <1302595444.3981.129.camel@sli10-conroe>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1302595444.3981.129.camel@sli10-conroe>
User-Agent: Mutt/1.5.20 (2009-06-14)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 790
Lines: 26

On Tue, Apr 12, 2011 at 04:04:04PM +0800, Shaohua Li wrote:
>  static inline s64 percpu_counter_read(struct percpu_counter *fbc)
>  {
> +#if BITS_PER_LONG == 32
> +	s64 count;
> +	spin_lock(&fbc->lock);
> +	count = fbc->count;
> +	spin_unlock(&fbc->lock);
> +	return count;
> +#else
>  	return fbc->count;
> +#endif

I don't know.  Is there any problem caused by this?  The interface is
known to be unreliable and already being used in speculative manner.
I think it's more beneficial to avoid using locks on fast read path.

Thanks.

-- 
tejun
--
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/