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=-2.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 E98AFC43381 for ; Tue, 26 Mar 2019 00:55:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B65152080F for ; Tue, 26 Mar 2019 00:55:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553561723; bh=YHd0EllFEA3WjOjR4Io1FeKzCEZ/Yp9iijFAELuKM4w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=TpF1mNLX+NKD/fuhBpSMSIV/ob8RDAqJ4uEbtkxiEgRpcEk/NhKJz3gdBgKku/oHo s7AF2VMFHemGL4Yr2PuHOnnk20Ow322EJd3m0FAC0l0ikUfrlSqSuV2k2i6Huv1Otu Q7Kx88F44vv2be3IV36y7dRIQbU676DLHkkEcQlA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730587AbfCZAzW (ORCPT ); Mon, 25 Mar 2019 20:55:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:38898 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727492AbfCZAzW (ORCPT ); Mon, 25 Mar 2019 20:55:22 -0400 Received: from localhost (li1825-44.members.linode.com [172.104.248.44]) (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 DCB4E2075D; Tue, 26 Mar 2019 00:55:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553561721; bh=YHd0EllFEA3WjOjR4Io1FeKzCEZ/Yp9iijFAELuKM4w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ybpkX2jBwDrR8PKRCzP+LHXdm0IYMrsZHqdRs6FYH/bmc1lZF1cZLN2IIwnU8p2Ac Em2nNXA368LnwMh0I424Gvo/Van+2FIZBDUGsHTq0tgQAuf1OPn8XPzyOhb92yeT3z FoZ92ahSLa+LG4hID8XX76hztf3vZ1bgeWW39wLU= Date: Tue, 26 Mar 2019 09:55:09 +0900 From: Greg Kroah-Hartman To: Brian Norris Cc: shuah , David Valleau , LKML , Linux USB Mailing List , Michael Grzeschik , Valentina Manea , Sasha Levin Subject: Re: [PATCH] tools: usb: usbip: adding support for older kernel versions Message-ID: <20190326005509.GA32180@kroah.com> References: <20190306214730.6545-1-valleau@chromium.org> <44e151af-b6c4-d0af-3ef1-a5632d079915@kernel.org> <23918a77-2694-fdae-4300-0882c7c940cf@kernel.org> <20190326001353.GA4315@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 25, 2019 at 05:49:07PM -0700, Brian Norris wrote: > > Not to say that this shouldn't be fixed if at all possible, but realize > > that this is not the "normal" case of "we do not break userspace" here, > > given the tool involved, and the apis being used. > > I think I sort of understand what you're going for here, but can you > elaborate so I don't have to assume? To be specific, tools at the "very low level" that are used to configure the kernel for userspace, or to interact with the kernel such that other programs work on top of things properly (like udev), we have broken apis such that we can fix issues with old mistakes and move on to more secure or "correct" apis. So we do change things at this layer at times, and normally no one notices as they have moved on to newer userspace programs in the past 3 years. Sometimes we do keep kernel support for really old userspace systems, until they die out, and then we can finally drop the kernel code. Again, udev has done this over the years as we worked to figure out a sane way to handle stuff. We have rolled back kernel changes until people finally killed their old Fedora 3 ppc32 systems for example :) To be honest, with the USB3 support added to usbip, no one noticed that things broke, and the fact that it took 4 years to notice implies that maybe it wasn't that big of a deal as no one used this. But, as you show, that assumption was not correct, so if we can fix things, we should. Did that help? thanks, greg k-h