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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 2C80BC17441 for ; Mon, 11 Nov 2019 09:36:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0110520818 for ; Mon, 11 Nov 2019 09:36:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573465004; bh=10fPEu9FZrhk6J1j7t879mqhJ3XB2/xSo4oLnUX/mUw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=y71PKivV2Qi6D9Pv9JiOZtyxgE42FKO8WhHeqrZ1+TY4ImaVgracqbLYDz/5D316t pOAJPvD7uDL1G7ZpfbxwrE/mfTTgHHYmA6HVZ4Vlt/uZOV8AMl/9rd3rrv7S3oDszM 2RekIF06xRH4ktxcDipXL0KBSsfdJGFrmAj22+0A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726903AbfKKJgn (ORCPT ); Mon, 11 Nov 2019 04:36:43 -0500 Received: from mail.kernel.org ([198.145.29.99]:53602 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726768AbfKKJgm (ORCPT ); Mon, 11 Nov 2019 04:36:42 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 4A8502075B; Mon, 11 Nov 2019 09:36:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573465001; bh=10fPEu9FZrhk6J1j7t879mqhJ3XB2/xSo4oLnUX/mUw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cIXR3fs4XsjhXq1ExFdK/YS942Ly/v7iv6y3lZoG2sCdymoknCYpZodIN9yBO8sct n86fPGr6jHtPg5rt4BrMUoth0beZsKKi8leZs2pHOQi1NRoY29PB8hgv5jQ2DBBetL UsGekVUimWIBOrYqHjF7nJjxcGDxvm7GoPxs0sJU= Date: Mon, 11 Nov 2019 10:36:38 +0100 From: Greg Kroah-Hartman To: Alan Stern Cc: Oliver Neukum , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Christoph Hellwig Subject: Re: [PATCH 4.19 114/149] UAS: Revert commit 3ae62a42090f ("UAS: fix alignment of scatter/gather segments") Message-ID: <20191111093638.GD4139389@kroah.com> References: <1573396023.2662.4.camel@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Nov 10, 2019 at 10:34:02AM -0500, Alan Stern wrote: > On Sun, 10 Nov 2019, Oliver Neukum wrote: > > > Am Freitag, den 08.11.2019, 10:35 -0500 schrieb Alan Stern: > > > On Fri, 8 Nov 2019, Greg Kroah-Hartman wrote: > > > > > > > On Thu, Nov 07, 2019 at 12:32:45PM +0100, Oliver Neukum wrote: > > > > > Am Dienstag, den 05.11.2019, 17:38 +0100 schrieb Greg Kroah-Hartman: > > > > > > > > Given this information, perhaps you will decide that the revert is > > > > > > > > worthwhile. > > > > > > > > > > > > > > Damned if I do, damned if I do not. > > > > > > > Check for usbip and special case it? > > > > > > > > > > > > We should be able to do that in the host controller driver for usbip, > > > > > > right? What is the symptom if you use a UAS device with usbip and this > > > > > > commit? > > > > > > > > > > Yes, that patch should then also be applied. Then it will work. > > > > > Without it, commands will fail, as transfers will end prematurely. > > > > > > > > Ok, I'm confused now. I just checked, and I really have no idea what > > > > needs to be backported anymore. 3ae62a42090f ("UAS: fix alignment of > > > > scatter/gather segments") was backported to all of the stable kernels, > > > > and now we reverted it. > > > > > > > > So what else needs to be done here? > > > > > > In one sense, nothing needs to be done. 3ae62a42090f was intended to > > > fix a long-standing problem with USBIP, but people reported a > > > > OK, now I am a bit confused. AFAICT 3ae62a42090f actually did fix the > > issue. So if you simply revert it, the issue will reappear. > > Correct. I think. > > > > regression in performance. (Admittedly, the report was about the > > > correponding change to usb-storage, not the change to uas, but it's > > > reasonable to think the effect would be the same.) So in line with the > > > > Yes. > > > > > no-regressions policy, we only need to revert the commit -- which you > > > have already done. > > > > But that breaks UAS over USBIP, doesn't it? > > It was already broken to start with. The attempted fix caused a > regression, so the fix must be reverted. > > > > On the other hand, the long-standing problem in USBIP can be fixed by > > > back-porting commit ea44d190764b. But since that commit isn't a > > > bug-fix (and since it's rather large), you may question whether it is > > > appropriate for the -stable kernel series. > > > > It certainly is large. But without it UAS won't work over USBIP, will > > it? I think that is the central question we need to answer here. > > You are right. If Greg is okay with porting ea44d190764b to the stable > kernels, I won't object. Ok, I've backported this to 4.14.y, 4.19.y, and 5.3.y. As superspeed support was not added to vhci until the 4.13 release, I don't think that UAS will be an issue on those older kernels. thanks, greg k-h