From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Graf Subject: Re: rhashtable: Remove unnecessary wmb for future_tbl Date: Wed, 9 Dec 2015 03:52:12 +0100 Message-ID: <20151209025212.GB20213@pox.localdomain> References: <20151208090904.GA17605@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "David S. Miller" , Eric Dumazet , Josh Triplett , "Paul E. McKenney" , netdev@vger.kernel.org To: Herbert Xu Return-path: Received: from mail-wm0-f52.google.com ([74.125.82.52]:34309 "EHLO mail-wm0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751187AbbLICwP (ORCPT ); Tue, 8 Dec 2015 21:52:15 -0500 Received: by wmvv187 with SMTP id v187so240542176wmv.1 for ; Tue, 08 Dec 2015 18:52:14 -0800 (PST) Content-Disposition: inline In-Reply-To: <20151208090904.GA17605@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: On 12/08/15 at 05:09pm, Herbert Xu wrote: > The patch 9497df88ab5567daa001829051c5f87161a81ff0 ("rhashtable: > Fix reader/rehash race") added a pair of barriers. In fact the > wmb is superfluous because every subsequent write to the old or > new hash table uses rcu_assign_pointer, which itself carriers a > full barrier prior to the assignment. > > Therefore we may remove the explicit wmb. > > Signed-off-by: Herbert Xu The RELEASE which is now in place afterwards act as a wmb as well, we are well protected ;-) Acked-by: Thomas Graf