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=-5.3 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 35879C433B4 for ; Thu, 6 May 2021 18:32:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EBC92610FB for ; Thu, 6 May 2021 18:32:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234650AbhEFSdR (ORCPT ); Thu, 6 May 2021 14:33:17 -0400 Received: from netrider.rowland.org ([192.131.102.5]:36961 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S234481AbhEFSdN (ORCPT ); Thu, 6 May 2021 14:33:13 -0400 Received: (qmail 748263 invoked by uid 1000); 6 May 2021 14:32:14 -0400 Date: Thu, 6 May 2021 14:32:13 -0400 From: Alan Stern To: Guido Kiener Cc: Dmitry Vyukov , syzbot , Greg Kroah-Hartman , "dpenkler@gmail.com" , "lee.jones@linaro.org" , USB list , "bp@alien8.de" , "dwmw@amazon.co.uk" , "hpa@zytor.com" , "linux-kernel@vger.kernel.org" , "luto@kernel.org" , "mingo@redhat.com" , "syzkaller-bugs@googlegroups.com" , "tglx@linutronix.de" , "x86@kernel.org" Subject: Re: Re: Re: Re: [syzbot] INFO: rcu detected stall in tx Message-ID: <20210506183213.GA748114@rowland.harvard.edu> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 06, 2021 at 05:44:55PM +0000, Guido Kiener wrote: > > -----Original Message----- > > From: Alan Stern > > Sent: Thursday, May 6, 2021 3:49 PM > > To: Kiener Guido 14DS1 > > > > > > Thanks for your assessment. I agree with the general feeling. I > > > counted about hundred specific usb drivers, so wouldn't it be better to fix the > > problem in some of the host drivers (e.g. urb.c)? > > > We could return an error when calling usb_submit_urb() on an erroneous pipe. > > > I cannot estimate the side effects and we need to check all drivers > > > again how they deal with the error situation. Maybe there are some special driver > > that need a specialized error handling. > > > In this case these drivers could reset the (new?) error flag to allow > > > calling usb_submit_urb() again without error. This could work, isn't it? > > > > That is feasible, although it would be an awkward approach. As you said, the side > > effects aren't clear. But it might work. > > Otherwise I see only the other approach to change hundred drivers and add the > cases EPROTO, EILSEQ and ETIME in each callback handler. The usbtmc driver > already respects the EILSEQ and ETIME, and only EPROTO is missing. > The rest should be more a management task. > BTW do you assume it is only a problem for INT pipes or is it also a problem > for isochronous and bulk transfers? All of them. Control too. > > Will you be able to test patches? > > I only can test the USBTMC function in some different PCs. I do not have automated > regression tests for USB drivers or Linux kernels. > Maybe there is company who could do that. Well then, if I do find time to write a patch, I'll ask you to try it out with the usbtmc driver. Alan Stern