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=-2.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,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 A81BEC43219 for ; Mon, 29 Apr 2019 09:24:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 73BFB20652 for ; Mon, 29 Apr 2019 09:24:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556529874; bh=q3YiTWs50dMDTd8JeYCZknpgHRHn8ZwgqhXR1mTJh2M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=KmX2OWvfc0whoeP+ULxK5U/Ki+PmN0mZld2TKBtvSOS8s3RPXIU7J/QgCLI0wWXpr FCZCuAdWWBTJB8bx6r3bylHM2e3uKun4AAc/mMtBh9DNFD6JM5lX3mfbK4T2KjK77j sJCEAHRJ1HAa0IspZNURiHKFuy0C65bh4x7NCAeI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727673AbfD2JYd (ORCPT ); Mon, 29 Apr 2019 05:24:33 -0400 Received: from mail-lj1-f196.google.com ([209.85.208.196]:41614 "EHLO mail-lj1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727072AbfD2JYc (ORCPT ); Mon, 29 Apr 2019 05:24:32 -0400 Received: by mail-lj1-f196.google.com with SMTP id k8so8665765lja.8 for ; Mon, 29 Apr 2019 02:24:31 -0700 (PDT) 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=PEJdVdZWdwXAxOfDG1xY+PigwDXCpbRA1Hg7zPvHQ6o=; b=GfK54Lv/zee/iL/t0fBaNmTn1PaER5zOFF3h0Rm87LybGU/LKBCEUkaTuNLGalSbvH 4mXPPxkhm9xleq3lbC+2H5hJgOdVjncpv3BzCzkSvC+omW2zCYZHcAW7J/TLj2EfU4S+ fxPe0Z10WvsI6TLlWoOKOQAWtpZ4f9qAqt7KPQL0pN/jhKBCviCCVkwB3S8+KneUhH4T AjBOJKL1odaHVroPx7VPIXkm0c/J7TyhCoUrGRw1DHXKzGTZ1xxiob0zcRBvKVO+wFlZ gxoFjNmM24u+MEclGj8xj0YxPiOmgP6zMIcwmBHFwPYU6i0ttMlGFYO4Fndlt5aUvK/i haEQ== X-Gm-Message-State: APjAAAXKDl2ZA7+sYvx3gTaZLgz2GajB2Mmhzqdkob1zyELSIaTi+nwD 6qnbDymhg5peYzYuEydbQ5A= X-Google-Smtp-Source: APXvYqzsqbzql/ON6mGxvxLdcdKbXtmXtfv8yW22ez3OOAx0jNgFhKSpru3mC40b/etESjF56kkX1g== X-Received: by 2002:a2e:3815:: with SMTP id f21mr9029618lja.25.1556529870868; Mon, 29 Apr 2019 02:24:30 -0700 (PDT) Received: from xi.terra (c-74bee655.07-184-6d6c6d4.bbcust.telenor.se. [85.230.190.116]) by smtp.gmail.com with ESMTPSA id m28sm7242040lfc.71.2019.04.29.02.24.29 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 29 Apr 2019 02:24:29 -0700 (PDT) Received: from johan by xi.terra with local (Exim 4.91) (envelope-from ) id 1hL2WU-0002zz-Pi; Mon, 29 Apr 2019 11:24:30 +0200 Date: Mon, 29 Apr 2019 11:24:30 +0200 From: Johan Hovold To: "Paul E. McKenney" Cc: Peter Zijlstra , Nicholas Piggin , LKMM Maintainers -- Akira Yokosawa , Andrea Parri , Boqun Feng , David Howells , Daniel Lustig , Jade Alglave , Kernel development list , Luc Maranget , Alan Stern , Will Deacon Subject: Re: [PATCH] Documentation: atomic_t.txt: Explain ordering provided by smp_mb__{before,after}_atomic() Message-ID: <20190429092430.GF26546@localhost> References: <20190419180017.GP4038@hirez.programming.kicks-ass.net> <20190419182620.GF14111@linux.ibm.com> <1555719429.t9n8gkf70y.astroid@bobo.none> <20190420085440.GK14111@linux.ibm.com> <20190423123209.GR4038@hirez.programming.kicks-ass.net> <20190423133010.GK3923@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190423133010.GK3923@linux.ibm.com> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 23, 2019 at 06:30:10AM -0700, Paul E. McKenney wrote: > On Tue, Apr 23, 2019 at 02:32:09PM +0200, Peter Zijlstra wrote: > > On Sat, Apr 20, 2019 at 01:54:40AM -0700, Paul E. McKenney wrote: > > > And lock acquisition??? acm_read_bulk_callback(). > > > > I think it goes with the set_bit() earlier, but what do I know. > > Quite possibly! In that case it should be smp_mb__after_atomic(), > and it would be nice if it immediately followed the set_bit(). I noticed this one last week as well. The set_bit() had been incorrectly moved and without noticing the smp_mb__before_atomic(). I've submitted a patch to restore it and to fix a related issue to due missing barriers: https://lkml.kernel.org/r/20190425160540.10036-5-johan@kernel.org Johan