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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=no 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 AD092C76188 for ; Mon, 22 Jul 2019 14:40:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A36921901 for ; Mon, 22 Jul 2019 14:40:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726343AbfGVOkx (ORCPT ); Mon, 22 Jul 2019 10:40:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:60274 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725795AbfGVOkw (ORCPT ); Mon, 22 Jul 2019 10:40:52 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A5BD32190D; Mon, 22 Jul 2019 14:40:49 +0000 (UTC) Date: Mon, 22 Jul 2019 10:40:48 -0400 From: Steven Rostedt To: Amir Goldstein Cc: Gao Xiang , Alexander Viro , Greg Kroah-Hartman , Andrew Morton , Stephen Rothwell , "Theodore Ts'o" , Linus Torvalds , linux-fsdevel , devel@driverdev.osuosl.org, LKML , linux-erofs@lists.ozlabs.org, Chao Yu , Miao Xie , Li Guifu , Fang Wei , Ingo Molnar , Matthew Wilcox , Will Deacon , Peter Zijlstra Subject: Re: [PATCH v3 12/24] erofs: introduce tagged pointer Message-ID: <20190722104048.463397a0@gandalf.local.home> In-Reply-To: References: <20190722025043.166344-1-gaoxiang25@huawei.com> <20190722025043.166344-13-gaoxiang25@huawei.com> <39fad3ab-c295-5f6f-0a18-324acab2f69e@huawei.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 22 Jul 2019 09:16:22 +0300 Amir Goldstein wrote: > CC kernel/trace maintainers for RB_PAGE_HEAD/RB_PAGE_UPDATE > and kernel/locking maintainers for RT_MUTEX_HAS_WAITERS Interesting. > > > (Is there some use scenerios in overlayfs and fanotify?...) > > We had one in overlayfs once. It is gone now. > > > > > and I'm not sure Al could accept __fdget conversion (I just wanted to give a example then...) > > > > Therefore, I tend to keep silence and just promote EROFS... some better ideas?... > > > > Writing example conversion patches to demonstrate cleaner code > and perhaps reduce LOC seems the best way. Yes, I would be more interested in seeing patches that clean up the code than just talking about it. > > Also pointing out that fixing potential bugs in one implementation is preferred > to having to patch all copied implementations. > > I wonder if tagptr_unfold_tags() doesn't need READ_ONCE() as per: > 1be5d4fa0af3 locking/rtmutex: Use READ_ONCE() in rt_mutex_owner() > > rb_list_head() doesn't have READ_ONCE() Hmm, even if the compiler decided to reread the data, it would still need to clear the extra bits wouldn't it? Or am I missing something? -- Steve > Nor does hlist_bl_first() and BPF_MAP_PTR(). > > Are those all safe due to safe call sites? or potentially broken?