From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1897FC43144 for ; Tue, 26 Jun 2018 17:15:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C7BB925FDC for ; Tue, 26 Jun 2018 17:15:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="gos1pJ8Y" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C7BB925FDC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933346AbeFZRPR (ORCPT ); Tue, 26 Jun 2018 13:15:17 -0400 Received: from merlin.infradead.org ([205.233.59.134]:52104 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932748AbeFZRPO (ORCPT ); Tue, 26 Jun 2018 13:15:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=0kVTeRiDGxhCHeHvIPmEOBC2dL/4FLEoN/JCukkEVoc=; b=gos1pJ8Yoon67yOjTVIR/Byxl /cQ44l1WSCh6u/FjUxazizMDyx1tsPD1xFkafp5IqM6GkVFX4QSlK4u7KbWNu4VJGcCxaJxBsrfHx ML18EvVcKijz4ouF3J7TdC6WPiV6ztTGvuq6NmGMS1anFZ4jgnXM279JlMuMi+27NGgbOZ2vNQvpr Y/DCYor7RsahB5ZK8Dsjrqigijbl8PlbvtchNO0ojhwiGpblahAb8EPIbSefQyH7KQK0HTipli7y0 S6nztOdmmgD+82wje0G5wZbrQSJ62mDZstGANc6K2um0zGqWhAbGWkAGr2vYs7ZR9VT5M1ClQiyc2 i3QH3KTjw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fXrYP-0004Bj-B1; Tue, 26 Jun 2018 17:14:57 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C10072029F1D7; Tue, 26 Jun 2018 19:14:54 +0200 (CEST) Date: Tue, 26 Jun 2018 19:14:54 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org Subject: Re: [PATCH tip/core/rcu 16/27] rcu: Add comment documenting how rcu_seq_snap works Message-ID: <20180626171454.GI2494@hirez.programming.kicks-ass.net> References: <20180626003448.GA26209@linux.vnet.ibm.com> <20180626003513.27812-16-paulmck@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180626003513.27812-16-paulmck@linux.vnet.ibm.com> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 25, 2018 at 05:35:02PM -0700, Paul E. McKenney wrote: > From: "Joel Fernandes (Google)" > > rcu_seq_snap may be tricky to decipher. Lets document how it works with > an example to make it easier. Since you had me looking at them functions; why isn't rcu_seq_snap() using smp_load_acquire() and rcu_seq_end() using smp_store_release() ? Their respective comments seem to suggest that would be sufficent.