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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,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 BDCFDC43387 for ; Thu, 17 Jan 2019 15:31:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F272120652 for ; Thu, 17 Jan 2019 15:31:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amarulasolutions.com header.i=@amarulasolutions.com header.b="O6Mqytgk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727634AbfAQPbl (ORCPT ); Thu, 17 Jan 2019 10:31:41 -0500 Received: from mail-ed1-f67.google.com ([209.85.208.67]:35166 "EHLO mail-ed1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727291AbfAQPbl (ORCPT ); Thu, 17 Jan 2019 10:31:41 -0500 Received: by mail-ed1-f67.google.com with SMTP id x30so8706642edx.2 for ; Thu, 17 Jan 2019 07:31:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amarulasolutions.com; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=g5nQozMppk8DZZa/5as2q1ELxnw4VUfa1KmQAedy0yk=; b=O6Mqytgky/RfbwIcMG4yXQUjH3BOLGz94nRWIQc4zvqoLXMdmqPnEoloP4yGNjA9lT ULZZr3J4ayw1EpOtaK9r6WYwKhhfWEJKTZ372Hu3eWH0xLCD8d/VgABwMGq05uYAzLdv yCyERVhswS0REKUH2qF8vj7wVrLWGLc8D+po0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=g5nQozMppk8DZZa/5as2q1ELxnw4VUfa1KmQAedy0yk=; b=YkQUnhTqAY1key2+pafLdoCXt0y4FyePxd3uOKPCt+I1F+bNyLc/Ii04NjRPIBwbRw Nk676WZDavRxpJGYpojgtPA0bM5+RHZpzn2Li9NEYkxW8rO9/M26N3C1qWUmyO2UoOZ5 341lRMUcM5Tcq/N30iEy8tk4Ag4ICROyFYS2DCUMzqXPpsuhJZsM7Tw78Z9x6nHaCPdn RSlxe19bb5g0/nsOAaRkbG5ZPD4c0Q5ErsbTZuVZ7xd2U2dk4Z9MoF9zcXDwpQQQaIps 0OQik02NY+Jyz9enWOXB3rVFgcr2fxcqQBYXtgomWlxOZTGOCXYQbC34WIyKOTWejtFU velw== X-Gm-Message-State: AJcUukevpNrQRgF6qyIKl5r4WzgCqpSX8u9891XKsqMFZV3B856oQF6W 77rtiv0RYIbx1ZK1qhKpNdlqgA== X-Google-Smtp-Source: ALg8bN7e+nlzm2+2MsxDFCruli4t9nzBpnV9NiCRw238gEdbOwM2SIjGICvPC0FlwsFxk07et/d+0g== X-Received: by 2002:a50:903c:: with SMTP id b57mr12377573eda.161.1547739099271; Thu, 17 Jan 2019 07:31:39 -0800 (PST) Received: from andrea (85.100.broadband17.iol.cz. [109.80.100.85]) by smtp.gmail.com with ESMTPSA id v14sm6030650edq.74.2019.01.17.07.31.38 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 17 Jan 2019 07:31:38 -0800 (PST) Date: Thu, 17 Jan 2019 16:31:32 +0100 From: Andrea Parri To: David Howells Cc: linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] afs: Add missing memory barriers in afs_manage_cell() Message-ID: <20190117153132.GA10932@andrea> References: <20181126164412.11184-1-andrea.parri@amarulasolutions.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181126164412.11184-1-andrea.parri@amarulasolutions.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 26, 2018 at 05:44:12PM +0100, Andrea Parri wrote: > As the comments for wake_up_bit() and waitqueue_active() point out, > the barriers are needed to order the clearing of the _FL_NOT_READY > bit and the waitqueue_active() load; match the implicit barrier in > prepare_to_wait(). > > Signed-off-by: Andrea Parri Hi David, do you have any feedback on this? Andrea > --- > fs/afs/cell.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/afs/cell.c b/fs/afs/cell.c > index cf445dbd5f2e0..a9488abe56029 100644 > --- a/fs/afs/cell.c > +++ b/fs/afs/cell.c > @@ -637,6 +637,7 @@ static void afs_manage_cell(struct work_struct *work) > cell->state = AFS_CELL_ACTIVE; > smp_wmb(); > clear_bit(AFS_CELL_FL_NOT_READY, &cell->flags); > + smp_mb__after_atomic(); /* see comment for wake_up_bit() */ > wake_up_bit(&cell->flags, AFS_CELL_FL_NOT_READY); > goto again; > > @@ -678,6 +679,7 @@ static void afs_manage_cell(struct work_struct *work) > cell->state = AFS_CELL_ACTIVE; > smp_wmb(); > clear_bit(AFS_CELL_FL_NOT_READY, &cell->flags); > + smp_mb__after_atomic(); /* see comment for wake_up_bit() */ > wake_up_bit(&cell->flags, AFS_CELL_FL_NOT_READY); > _leave(" [deact->act]"); > return; > -- > 2.17.1 >