From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754814AbcEBSAA (ORCPT <rfc822;w@1wt.eu>);
	Mon, 2 May 2016 14:00:00 -0400
Received: from bombadil.infradead.org ([198.137.202.9]:44533 "EHLO
	bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1753818AbcEBR7w (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Mon, 2 May 2016 13:59:52 -0400
Date: Mon, 2 May 2016 10:59:50 -0700
From: Christoph Hellwig <hch@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>,
        Muhammad Falak R Wani <falakreyaz@gmail.com>,
        "Nicholas A. Bellinger" <nab@linux-iscsi.org>,
        target-devel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] target: use RCU_INIT_POINTER() when NULLing.
Message-ID: <20160502175950.GA16580@infradead.org>
References: <1462107122-9562-1-git-send-email-falakreyaz@gmail.com>
 <20160501170120.GA15010@infradead.org>
 <20160501195313.GL3686@linux.vnet.ibm.com>
 <20160502141023.GA1187@linux.vnet.ibm.com>
 <20160502175738.GA24455@linux.vnet.ibm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20160502175738.GA24455@linux.vnet.ibm.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
X-SRS-Rewrite: SMTP reverse-path rewritten from <hch@infradead.org> by bombadil.infradead.org. See http://www.infradead.org/rpr.html
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, May 02, 2016 at 10:57:38AM -0700, Paul E. McKenney wrote:
> -#define rcu_assign_pointer(p, v) smp_store_release(&p, RCU_INITIALIZER(v))
> +#define rcu_assign_pointer(p, v) \
> +({ \
> +	uintptr_t _r_a_p__v = (uintptr_t)(v); \
> +	\
> +	if (__builtin_constant_p(v) && (_r_a_p__v) == (uintptr_t)NULL) \
> +		WRITE_ONCE((p), (typeof(p))(_r_a_p__v)); \
> +	else \
> +		smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \
> +	_r_a_p__v; \
> +})

Can't we turn it into an inline (would need different calling
conventions for p, though).