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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 56241C433FE for ; Wed, 9 Dec 2020 22:33:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1F16523D20 for ; Wed, 9 Dec 2020 22:33:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388839AbgLIWdO (ORCPT ); Wed, 9 Dec 2020 17:33:14 -0500 Received: from mail.kernel.org ([198.145.29.99]:36720 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388604AbgLIWc5 (ORCPT ); Wed, 9 Dec 2020 17:32:57 -0500 Date: Wed, 9 Dec 2020 17:32:06 -0500 From: Steven Rostedt To: Christoph Hellwig Cc: Stanislaw Gruszka , Matthew Wilcox , Alexei Starovoitov , Michal Kubecek , Justin Forbes , bpf , Alex Shi , Andrew Morton , Souptick Joarder , Linux-MM , LKML , Alexei Starovoitov , Daniel Borkmann , Josef Bacik Subject: Re: [PATCH] mm/filemap: add static for function __add_to_page_cache_locked Message-ID: <20201209223206.GA1935@home.goodmis.org> References: <20201207081556.pwxmhgdxayzbofpi@lion.mk-sys.cz> <20201207225351.2liywqaxxtuezzw3@lion.mk-sys.cz> <20201209144628.GA3474@wp.pl> <20201209150826.GP7338@casper.infradead.org> <20201209155148.GA5552@wp.pl> <20201209180552.GA28692@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201209180552.GA28692@infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, Dec 09, 2020 at 06:05:52PM +0000, Christoph Hellwig wrote: > On Wed, Dec 09, 2020 at 04:51:48PM +0100, Stanislaw Gruszka wrote: > > On Wed, Dec 09, 2020 at 03:08:26PM +0000, Matthew Wilcox wrote: > > > On Wed, Dec 09, 2020 at 03:46:28PM +0100, Stanislaw Gruszka wrote: > > > > At this point of release cycle we should probably go with revert, > > > > but I think the main problem is that BPF and ERROR_INJECTION use > > > > function that is not intended to be used externally. For external users > > > > add_to_page_cache_lru() and add_to_page_cache_locked() are exported > > > > and I think those should be used (see the patch below). > > > > > > FWIW, I intend to do some consolidation/renaming in this area. I > > > trust that will not be a problem? > > > > If it does not break anything, it will be not a problem ;-) > > > > It's possible that __add_to_page_cache_locked() can be a global symbol > > with add_to_page_cache_lru() + add_to_page_cache_locked() being just > > static/inline wrappers around it. > > So what happens to BTF if we change this area entirely? Your IDs > sound like some kind of ABI to me, which is extremely scary. Is BTF becoming the new tracepoint? That is, random additions of things like: BTF_ID(func,__add_to_page_cache_locked) Like was done in commit 1e6c62a882155 ("bpf: Introduce sleepable BPF programs") without any notification to the maintainers of the __add_to_page_cache_locked code, will suddenly become an API? There's no mention in the change log to why __add_to_page_cache_locked was added. And interesting enough, __add_to_page_cache_locked is not in any header file, which is why it was switched to static. -- Steve