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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 D99B3C10F13 for ; Tue, 16 Apr 2019 14:47:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A1544206BA for ; Tue, 16 Apr 2019 14:47:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555426056; bh=Z4GWK4zt9/mb999OoqGoRlZSSvxM3Al0ieaQI3Id3P4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=nZcqIJft5YbL+AnDUeIZ06z1ZmkZHZEJMQGKShckieOvJ3I9ebq46bOeJ2S3YmEMQ ocOAvs6eWr2hDQf+6mjWb2UXVsr2rwtG8il14ksZ8DvHER1Wlb0hMtL5t9V/wjKrnm XPG6n7uhizrqGit+Ci2/MSx1sPfz7oGJzP5AmPZI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729211AbfDPOrf (ORCPT ); Tue, 16 Apr 2019 10:47:35 -0400 Received: from mail-qk1-f195.google.com ([209.85.222.195]:36523 "EHLO mail-qk1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725796AbfDPOre (ORCPT ); Tue, 16 Apr 2019 10:47:34 -0400 Received: by mail-qk1-f195.google.com with SMTP id k130so12306964qke.3 for ; Tue, 16 Apr 2019 07:47:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=0+l6FTGfnWimBOLodz1v2xMz2DpyjOFmTOvNncQbzjY=; b=poELPxgVPbPuCAlPCYM26IozQ75Zw3Ch/UM9jw9h8xeQWc9VJdftv0tl8P4rTMCIWV Bj65bpXeJQchx2RJHEyqAI6ALa9/SfWsRR/IyZnMNBAdRGpYaoL8yzwcBIDm26N1vfha NWRMvBC4Sg6wataQni3qdy9hv/sfAuuDdRRp7WKK9cftAMrRlRnmbo4jhWlZxScinRix Cp2fvgZm0nERtmIYPajLkq7lrrmcAupWB7b6gJGxCnOV6HE9/ZONHkp4wHYb7Hgff08Y 9G1U/DJxNQhteFgYiYpNURVmmFqNjibk93wx8/MV6whqp/lu+RTJsoLlkLEM7AhDOXS3 XrMg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=0+l6FTGfnWimBOLodz1v2xMz2DpyjOFmTOvNncQbzjY=; b=VpcnB4+6GUBKmxxBq5nF3hF1vYDv86/D8v2x1DgoVkqsxbF8UJcO2MARo0Y2UNaHFo MW42zO1d67iVwYFtXSG6+G5lXXgfT8bMqD1lZr+p39oWfXviuPFNBWm6iXRuRcMLyvn8 mngXSeqP90W2gM/IlxRzhEyHITfcF2H3SkmCV9YD8X/twUPyWeH7P7VhjGzNxlrxv0kp GKYyqV4N7MDmkeirD8eYzbzqZP8WYvPCI1/QrSMimckDfK0CIlPPs1SG5goBdySkWNRa JveYPNPlU09FgUxgiaI1M/ISZUgMg662I9NuznOsNbJGyZ4V0Tn2Y592+G49FRWtgKls Dv3Q== X-Gm-Message-State: APjAAAVKa1FqMaEdxx8jOB9n5QJA6Ij3hOa+R6Z5GUYdd/6TDuRzc5pt Gc3bwgImRY6x0vnIJL+DauA= X-Google-Smtp-Source: APXvYqw/wj/5juWRznW6fHEokbDAMM9Ov94hixd8y3cn6F0Gk5DEyunCKC7YQ4/xnAzde8HWKSkTnA== X-Received: by 2002:a37:8bc7:: with SMTP id n190mr60402363qkd.108.1555426053539; Tue, 16 Apr 2019 07:47:33 -0700 (PDT) Received: from localhost ([2620:10d:c091:200::c7e0]) by smtp.gmail.com with ESMTPSA id j93sm32285151qtd.82.2019.04.16.07.47.32 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 16 Apr 2019 07:47:32 -0700 (PDT) Date: Tue, 16 Apr 2019 07:47:30 -0700 From: Tejun Heo To: Andrea Parri Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org Subject: Re: [PATCH] kernfs: fix barrier usage in __kernfs_new_node() Message-ID: <20190416144617.GA349476@devbig004.ftw2.facebook.com> References: <1555417031-27356-1-git-send-email-andrea.parri@amarulasolutions.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1555417031-27356-1-git-send-email-andrea.parri@amarulasolutions.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 16, 2019 at 02:17:11PM +0200, Andrea Parri wrote: > smp_mb__before_atomic() can not be applied to atomic_set(). Remove the > barrier and rely on RELEASE synchronization. > > Fixes: ba16b2846a8c6 ("kernfs: add an API to get kernfs node from inode number") > Cc: stable@vger.kernel.org > Signed-off-by: Andrea Parri > --- > fs/kernfs/dir.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c > index b84d635567d38..1e7a74b8e0647 100644 > --- a/fs/kernfs/dir.c > +++ b/fs/kernfs/dir.c > @@ -650,11 +650,10 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, > kn->id.generation = gen; > > /* > - * set ino first. This barrier is paired with atomic_inc_not_zero in > + * set ino first. This RELEASE is paired with atomic_inc_not_zero in > * kernfs_find_and_get_node_by_ino > */ > - smp_mb__before_atomic(); > - atomic_set(&kn->count, 1); > + atomic_set_release(&kn->count, 1); Acked-by: Tejun Heo Thanks. -- tejun