Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751749AbdG0Q7o (ORCPT ); Thu, 27 Jul 2017 12:59:44 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:47777 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751575AbdG0Q7m (ORCPT ); Thu, 27 Jul 2017 12:59:42 -0400 Date: Thu, 27 Jul 2017 18:59:39 +0200 From: Peter Zijlstra To: Waiman Long Cc: Prateek Sood , mingo@redhat.com, sramana@codeaurora.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] rwsem: fix missed wakeup due to reordering of load Message-ID: <20170727165939.vomkrhpkyzvpxrbg@hirez.programming.kicks-ass.net> References: <1501100272-16338-1-git-send-email-prsood@codeaurora.org> <680a3f82-b36b-e09f-b1db-fa23d9f21fc2@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <680a3f82-b36b-e09f-b1db-fa23d9f21fc2@redhat.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 338 Lines: 10 On Thu, Jul 27, 2017 at 11:48:53AM -0400, Waiman Long wrote: > atomic_long_sub_return_release() is implmented. I've not had time to really thing about the problem at hand, but this I can answer: TSO (x86, s390, sparc): fully serialized PPC: lwsync; ll/sc (RCpc) ARM64: ll/sc-release (RCsc) other: smp_mb(); atomic_sub_return_relaxed();