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=-17.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 211F4C432BE for ; Thu, 26 Aug 2021 18:10:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EBD3E60F4A for ; Thu, 26 Aug 2021 18:10:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243252AbhHZSLd (ORCPT ); Thu, 26 Aug 2021 14:11:33 -0400 Received: from smtprelay04.ispgateway.de ([80.67.18.16]:36013 "EHLO smtprelay04.ispgateway.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230525AbhHZSLc (ORCPT ); Thu, 26 Aug 2021 14:11:32 -0400 X-Greylist: delayed 490 seconds by postgrey-1.27 at vger.kernel.org; Thu, 26 Aug 2021 14:11:32 EDT Received: from [87.92.210.171] (helo=[192.168.0.111]) by smtprelay04.ispgateway.de with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1mJJex-00012i-LY; Thu, 26 Aug 2021 19:59:27 +0200 Subject: Re: [PATCH] drivers/cdrom: improved ioctl for media change detection To: axboe@kernel.dk Cc: linux-kernel@vger.kernel.org References: <20210805194417.12439-1-lumip@lumip.de> From: Lukas Prediger Message-ID: Date: Thu, 26 Aug 2021 21:01:19 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210805194417.12439-1-lumip@lumip.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Df-Sender: bHVrYXMucHJlZGlnZXJAbHVtaXAuZGU= Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05.08.21 22:44, Lukas Prediger wrote: > The current implementation of the CDROM_MEDIA_CHANGED ioctl relies on > global state, meaning that only one process can detect a disc change > while the ioctl call will return 0 for other calling processes afterwards > (see bug 213267 ). > > This introduces a new cdrom ioctl, CDROM_TIMED_MEDIA_CHANGE, that > works by maintaining a timestamp of the last detected disc change instead > of a boolean flag: Processes calling this ioctl command can provide > a timestamp of the last disc change known to them and receive > an indication whether the disc was changed since then and the updated > timestamp. > > I considered fixing the buggy behavior in the original > CDROM_MEDIA_CHANGED ioctl but that would require maintaining state > for each calling process in the kernel, which seems like a worse > solution than introducing this new ioctl. > > Signed-off-by: Lukas Prediger > --- > This is my first patch sent to the kernel and I followed the recommended > process as closely as I could. If I misstepped somewhere, please let me know. > I also tried to find a mailing list more specific to the problem but was unable, > please inform me if there is one where this should be sent instead. > > Finally, I wasn't sure whether/how to add my name to the updated docs > and if I should update the date on them (there have been some recent commits > that did not result in credits given to the commit author or updating > the dates in the docs, but those did not add any new content either), so > info in the most appropriate way would be welcome. > > Looking forward to your feedback. > --- > Documentation/cdrom/cdrom-standard.rst | 14 +++++- > Documentation/userspace-api/ioctl/cdrom.rst | 6 ++- > drivers/cdrom/cdrom.c | 56 +++++++++++++++++++-- > include/linux/cdrom.h | 1 + > include/uapi/linux/cdrom.h | 15 ++++++ > 5 files changed, 86 insertions(+), 6 deletions(-) As it has been several weeks and I haven't heard anything at all in response to this, I'd like to bring this to your attention once more. If something is wrong with it, please let me know so I can fix it. - Lukas