From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932349AbbJ1AK5 (ORCPT ); Tue, 27 Oct 2015 20:10:57 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:52232 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754705AbbJ1AKt (ORCPT ); Tue, 27 Oct 2015 20:10:49 -0400 Date: Tue, 27 Oct 2015 19:40:20 +0100 From: Peter Zijlstra To: Will Deacon Cc: Catalin Marinas , Ingo Molnar , "Paul E. McKenney" , Linux Kernel Mailing List , Oleg Nesterov , Linus Torvalds , Andrew Morton Subject: Re: Q: schedule() and implied barriers on arm64 Message-ID: <20151027184020.GB3201@worktop.amr.corp.intel.com> References: <20151016151830.GZ3816@twins.programming.kicks-ass.net> <20151016160422.GQ3910@linux.vnet.ibm.com> <20151016161608.GA3816@twins.programming.kicks-ass.net> <20151016190648.GC3816@twins.programming.kicks-ass.net> <20151019070604.GA17855@gmail.com> <20151019152108.GC11226@e104818-lin.cambridge.arm.com> <20151019162423.GP3816@twins.programming.kicks-ass.net> <20151027161948.GE20208@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151027161948.GE20208@arm.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 27, 2015 at 04:19:48PM +0000, Will Deacon wrote: > ... and the 'normal' code will have a control hazard somewhere, followed > by the implicit ISB in exception return, so there's a barrier of sorts > there too. Which exception return? > The problem is that people say "full barrier" without defining what it > really means, and we end up going round the houses on things like > transitivity (which ctrl + isb doesn't always give you). I pretty much meant smp_mb() here :-)