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=-7.0 required=3.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS 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 C09E4C282C4 for ; Tue, 12 Feb 2019 15:41:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8F5702186A for ; Tue, 12 Feb 2019 15:41:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729695AbfBLPlt (ORCPT ); Tue, 12 Feb 2019 10:41:49 -0500 Received: from mout.gmx.net ([212.227.17.21]:44971 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729313AbfBLPlt (ORCPT ); Tue, 12 Feb 2019 10:41:49 -0500 Received: from [10.0.0.4] ([113.116.50.220]) by mail.gmx.com (mrgmx101 [212.227.17.174]) with ESMTPSA (Nemesis) id 0Ld4xA-1hJoFt0Xs8-00iEgi; Tue, 12 Feb 2019 16:41:47 +0100 Subject: Re: [PATCH 2/2] chardev: showing minor range for chardev in the output of /proc/devices To: Greg KH Cc: viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20190212084739.27602-1-cgxu519@gmx.com> <20190212084739.27602-2-cgxu519@gmx.com> <20190212090212.GE31657@kroah.com> <20190212152053.GA25804@kroah.com> From: cgxu519 Message-ID: Date: Tue, 12 Feb 2019 23:41:35 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190212152053.GA25804@kroah.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Provags-ID: V03:K1:NWE2M9a/8IrjrA+KnVD99ve1MX9xqU+wv0r7u1G+zfgRvPXWR4r toEpXey4m1ep+ySthOpvWRk3UpNWa5iKgjDJ8YwV5PuKf5XEKPU0L0Ps5WSZtLYBwMq3/Od +L4tq14Zwa+03sgp/wWb3qNJLAJATs/Y8VjBnFxB8KAqZz+0Bv56NXal2t7QBhaEUTUOT3K zubL7EGenPppWQecQE1QQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:kthetnN4f2g=:fLieYvO6rvzC2nx9HkjZwA WdkPPOvir3lP9ezruBZevRXLuJnXE8+8eDtTYEGiinQ6wLWalnIaLyvFDDQOFuBAJYNPzPcUa jmog0xwxUQNhcRM8BDsyJ7xVEDJoa9TPiJuG9jFl5+5k3Yd8ZB9UWqKrO4Ri25rpY7+TCq8Bx wrF7KpFreJQERw8uTSdKhyIfWf7x/hQvINsKjlmqKoLucCgThFozj9eyuTSC6M2Igr+WngOrK /JX0CDjHwEJuvcT5whN4FAT00cAH2YW3XjBC3n8TkbHPhW+SSRKSNrUQ5b9oqkqitGdgmLMO8 XQi6VMa6F2gdWCYeSCVtCcdpt3FphYdueC+rByDhXwd/Zsp6BmYcoWWYTAtSjp+rPuVG681Fd +wtCVZctDDWY6n0GJcGuTGJpUtPb53nT0zI21wdRYe4/qx8lynK9wF3sgh9VxVVii97eB6gzw ruLEJfsmeGcDMRwMJbDKCYs69qu6r+sZ6zZFmL0IoOalWh+nJxSv1vs97z7uxOiHIfjIqcHBz druCRqKquSOJQXj+h5OPFCi83o07e7c2FsbduopJ1L180LMNiKCbRXVpZ6U/Qe1H9BlHgGIlM 2yXxv2C211FIZ3KHlTPzyyPonxYloGyJl4KryeBybAbLZ2Vyg9BfDPLxzOs8+RJR6ZcF7Lgpp 8vEjKZnD6joYjqZWgbhFDex6ih+aaoePzu7YTnbk3R4iR5u0kol6pzCOa4oUm5UnDTdJGRIaQ 8AVhs5GWM65WnVOYy6tHqv68hBj+OXnqT92vAjeYfkURfq1a+g7Xpn0mGB5a5zakb5KXiBkOQ VKMLjSwHAcqHTO/uQLbiMbau3+Smir9YIe0eoxVruCZ1bgRC1bYij409oj3NA25q/Y7biwBFW kNbErdUt8AbMZZQ/LvCW7NCoI85CSN88QgHoXf3bz7xOp+ysRponIGS8MDY2XHdWvnESA0Q4p w5p8aTfShn0FN8lVpO5DYCc+Ht/1UCBJyjgSoT/cLYUTeacj0iO/72ZrKHzTvfa9BB65Gpxza kKsqd6f2St4W/tUQC/07qXw/0lcgy25MNVZSCHMu2w2GnQaXZKn6MFA/us4dELTZu5pdIn/2K PjczuW1fdvEhKwM6UBf8eK6zOYERU/4aOi2 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On 2/12/19 11:20 PM, Greg KH wrote: > On Tue, Feb 12, 2019 at 11:18:22PM +0800, cgxu519 wrote: >> On 2/12/19 5:02 PM, Greg KH wrote: >>> On Tue, Feb 12, 2019 at 04:47:39PM +0800, Chengguang Xu wrote: >>>> Currently chardev allows to share major, showing >>>> major with minor range for chardev will be more >>>> helpful. >>>> >>>> Signed-off-by: Chengguang Xu >>>> --- >>>> fs/char_dev.c | 4 +++- >>>> 1 file changed, 3 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/fs/char_dev.c b/fs/char_dev.c >>>> index b25b1da097d5..6f00acdeb308 100644 >>>> --- a/fs/char_dev.c >>>> +++ b/fs/char_dev.c >>>> @@ -55,7 +55,9 @@ void chrdev_show(struct seq_file *f, off_t offset) >>>> mutex_lock(&chrdevs_lock); >>>> for (cd = chrdevs[major_to_index(offset)]; cd; cd = cd->next) { >>>> if (cd->major == offset) >>>> - seq_printf(f, "%3d %s\n", cd->major, cd->name); >>>> + seq_printf(f, "%3d %s (%u-%u)\n", cd->major, cd->name, >>>> + cd->baseminor, >>>> + cd->baseminor + cd->minorct - 1); >>> You are changing the format of a userspace file, what tools are going to >>> break when you do this? >> I'll remove this part in V2. Do you have any idea how to get the minor >> range info for particular major? Or adding a similar file to somewhere >> under /sys is acceptable? > Why do you need to know the minor range? What can userspace do with > this that actually matters? Assume that when we try to load a driver module and fail with -EBUSY because of minor range overlapping, then what can we do for this case? we even don't know what range has occupied and what range is available. Also, I think we can obviously notice range overlapping bugs by showing all registered minor ranges. Thanks, Chengguang.