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=-5.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, 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 91551C282D7 for ; Wed, 30 Jan 2019 14:21:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 57FF220855 for ; Wed, 30 Jan 2019 14:21:56 +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="GHkpfBoK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729748AbfA3OVz (ORCPT ); Wed, 30 Jan 2019 09:21:55 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:60704 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725803AbfA3OVy (ORCPT ); Wed, 30 Jan 2019 09:21:54 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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=tdEG+MKzTG+afEyamSwnqbIz4Gr3gzvattFq+YOW3xg=; b=GHkpfBoK7F+3EI4b0I3os8+Pw tNgrFs039sCghNUrQgSFQp1PLPBoDOQn+N0B89hD/3GL2GgvzdfZx/fKvxuV5FFWE2JQdJrHKIzJm ytJ2HkQgLW03jaTyRBCD0Wv7hbY05WbEEddfj4DU3my+vwvNy4f2QJKUsxEv4H8KLGTIVjFcc/30S sLXUBiqX7v5ZdCZK/SsWYHAfIqSj1ZUt3t0bktHZOxohbsxiwMi3phn7Ps3W/1gVad3qxIB/B6irJ LF6aR0+vHf7bBvitq+HAvOA5w0vwf6Hvr/1KFhFuVLuoHFXSb1M0HwbwkeQDhql3Kk+tiIJ/tH0/1 30uQSkpvw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1goqkP-0004O1-Kt; Wed, 30 Jan 2019 14:21:49 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id F093220160355; Wed, 30 Jan 2019 15:21:47 +0100 (CET) Date: Wed, 30 Jan 2019 15:21:47 +0100 From: Peter Zijlstra To: Andrea Parri Cc: Elena Reshetova , linux-kernel@vger.kernel.org, dvyukov@google.com, stern@rowland.harvard.edu, keescook@chromium.org Subject: Re: [PATCH] refcount_t: add ACQUIRE ordering on success for dec(sub)_and_test variants Message-ID: <20190130142147.GD2296@hirez.programming.kicks-ass.net> References: <1548847131-27854-1-git-send-email-elena.reshetova@intel.com> <1548847131-27854-2-git-send-email-elena.reshetova@intel.com> <20190130123131.GA20517@andrea> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190130123131.GA20517@andrea> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 30, 2019 at 01:31:31PM +0100, Andrea Parri wrote: > On Wed, Jan 30, 2019 at 01:18:51PM +0200, Elena Reshetova wrote: > > This adds an smp_acquire__after_ctrl_dep() barrier on successful > > decrease of refcounter value from 1 to 0 for refcount_dec(sub)_and_test > > variants and therefore gives stronger memory ordering guarantees than > > prior versions of these functions. > > > > Co-developed-by: Peter Zijlstra (Intel) > > Signed-off-by: Elena Reshetova > > Reviewed-by: Andrea Parri Thanks, got it queued now.