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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3821C25B08 for ; Wed, 17 Aug 2022 06:20:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231920AbiHQGUb (ORCPT ); Wed, 17 Aug 2022 02:20:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46666 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238898AbiHQGUX (ORCPT ); Wed, 17 Aug 2022 02:20:23 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B45E26CF74 for ; Tue, 16 Aug 2022 23:20:21 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 3175960B90 for ; Wed, 17 Aug 2022 06:20:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 47B59C433D6; Wed, 17 Aug 2022 06:20:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660717220; bh=noAyxvNgidBSDVmHlKRFgrezKarTi1dLXeyBzIIMOZ4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ehPk1Qh+BzrnB3BnX1MQ7O4RycQ22SGABtH9hcHeMfAYBinV3YBQkgm6J0JOxAB/d 1aJMD6CorRtL+YKf3y/tcUm/Hj3DJ5VukglJjGEHhJscvLAYr35pKbYAFRlswQyTlL EFjaszLS6GS9W0LPKGQhzij8yPvyIQyx6pm8TMV4= Date: Wed, 17 Aug 2022 08:20:15 +0200 From: Greg KH To: Arun Easi Cc: himanshu.madhani@oracle.com, martin.petersen@oracle.com, njavali@marvell.com, stable@vger.kernel.org Subject: Re: [EXT] Re: WTF: patch "[PATCH] scsi: qla2xxx: Fix response queue handler reading stale" was seriously submitted to be applied to the 5.19-stable tree? Message-ID: References: <166039743723771@kroah.com> <4ed36d0a-2f82-4fe6-1f8f-25870b9e05c6@marvell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4ed36d0a-2f82-4fe6-1f8f-25870b9e05c6@marvell.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Tue, Aug 16, 2022 at 11:17:39AM -0700, Arun Easi wrote: > On Tue, 16 Aug 2022, 2:30am, Greg KH wrote: > > > On Mon, Aug 15, 2022 at 03:35:09PM -0700, Arun Easi wrote: > > > Hi Greg, > > > > > > On Sat, 13 Aug 2022, 6:46am, Greg KH wrote: > > > > > > > > > > > ---------------------------------------------------------------------- > > > > On Sat, Aug 13, 2022 at 03:30:37PM +0200, gregkh@linuxfoundation.org wrote: > > > > > The patch below was submitted to be applied to the 5.19-stable tree. > > > > > > > > > > I fail to see how this patch meets the stable kernel rules as found at > > > > > Documentation/process/stable-kernel-rules.rst. > > > > > > > > > > I could be totally wrong, and if so, please respond to > > > > > and let me know why this patch should be > > > > > applied. Otherwise, it is now dropped from my patch queues, never to be > > > > > seen again. > > > > > > > > > > thanks, > > > > > > > > > > greg k-h > > > > > > > > > > ------------------ original commit in Linus's tree ------------------ > > > > > > > > > > >From b1f707146923335849fb70237eec27d4d1ae7d62 Mon Sep 17 00:00:00 2001 > > > > > From: Arun Easi > > > > > Date: Tue, 12 Jul 2022 22:20:39 -0700 > > > > > Subject: [PATCH] scsi: qla2xxx: Fix response queue handler reading stale > > > > > packets > > > > > > > > > > On some platforms, the current logic of relying on finding new packet > > > > > solely based on signature pattern can lead to driver reading stale > > > > > packets. Though this is a bug in those platforms, reduce such exposures by > > > > > limiting reading packets until the IN pointer. > > > > > > > > > > Two module parameters are introduced: > > > > > > > > > > ql2xrspq_follow_inptr: > > > > > > > > > > When set, on newer adapters that has queue pointer shadowing, look for > > > > > response packets only until response queue in pointer. > > > > > > > > > > When reset, response packets are read based on a signature pattern > > > > > logic (old way). > > > > > > > > > > ql2xrspq_follow_inptr_legacy: > > > > > > > > > > Like ql2xrspq_follow_inptr, but for those adapters where there is no > > > > > queue pointer shadowing. > > > > > > > > On a meta-note, this patch seems VERY wrong. You are adding a > > > > driver-wide module option for a device-specific action. That should be > > > > a device-specific functionality, not a module. > > > > > > > > Again, as I say many times, this isn't the 1990's, please never add new > > > > module parameters. Use the other interfaces we have in the kernel to > > > > configure individual devices properly, module parameters are not to be > > > > used for that at all for anything new. > > > > > > > > So, can you revert this commit and do it properly please? > > > > > > > > > > The reason I chose module parameter way was because of these primarily: > > > > > > 1 As this is a platform specific issue, this behavior does not require a > > > device granular level tuning. Either all the said adapters turns the > > > behavior on or off. > > > > What is going to allow a user to know to do this or not? Why is this > > needed at all, and why doesn't the driver automatically know what to do > > either based on the device id, or the platform, or the workload? > > The change is to err on the side of caution and make the logic > a bit conservative at the same time providing an option for those > platforms or architectures where the issue is not applicable, but the > logic is causing a reduction in performance. So this is a "enable the driver to work in a broken way" option? > > Forcing a user to pick something for "tuning" like this is horrible and > > messy and almost impossible to support properly over time. > > The option is intended for slightly advanced users, platform or os > vendors etc. When it comes to an end user, I agree it is challenging to > know if a change from default is needed or not. That's not ok, as a driver writer you need to make it "always work", don't force the user to choose "safe vs. unsafe" options, that's passing the blame. > > Just do it in the driver automatically and then there's no need for any > > options at all. > > The platform bug exhibited as driver accessing stale memory, so it is > tough to automatically tune the value automatically. That sounds like a real bug that you need to fix. Please revert this change and just fix the issue to always work properly. To have an option that allows a driver to work in a broken way is not acceptable. > > > If udev route is taken, I'd have to come up with a configuration file to > > > save tunable state, which could be a bit cumbersome and needs > > > documentation and be different (in terms of script location/submitting) > > > distro to distro. > > > > How is a module parameter saving any state anywhere? > > Since module parameter could be configured via modprobe.conf/equivalent, a > user could set the value of his choice in that file and have the value > persisted. Same for a udev rule, so this is not an issue. Do you want me to send a patch that reverts this, or will you? thanks, greg k-h