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=-7.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS 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 2F15FC64E7B for ; Mon, 30 Nov 2020 19:03:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C748B206CB for ; Mon, 30 Nov 2020 19:03:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="O10VOEVX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388038AbgK3TCv (ORCPT ); Mon, 30 Nov 2020 14:02:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33930 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726026AbgK3TCu (ORCPT ); Mon, 30 Nov 2020 14:02:50 -0500 Received: from mail-ej1-x644.google.com (mail-ej1-x644.google.com [IPv6:2a00:1450:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 54642C0613D3; Mon, 30 Nov 2020 11:02:10 -0800 (PST) Received: by mail-ej1-x644.google.com with SMTP id f23so23924171ejk.2; Mon, 30 Nov 2020 11:02:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=v4/QIctrXLZuVGTfw6POOs0tQ2zR3ltEGhnHc4d6oJE=; b=O10VOEVXfmXkEILqKQALml9aAfJz6EnjEpbfKhPiRySHeclSkV/wGfC8b0e9oWzOYW K4BDDsuc58bvppvDgT+GwJli0EWJNXWA0i+H6MTk9GQYZe1DmT4VzxzwPHjUvnXdFRcY 2doSVHtPDmNgpm2G7ZWDwpFN7ltKZkGcMe3ad9qZvrdpnyz4cLYusJSNuo/g/nVL6hbI BkXCYF90PlrkVlXgTkcYzP6tXR1InkcCsTEQStaTJ4vNqniITulXww6ZGt8gR/RhCb4B e2KCV0npfYcC2nRXMoWQNFEnP5x+cmK2P9JEbufxg41WnRhGu4g4OT55tF2qh7TXkquJ hO8A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=v4/QIctrXLZuVGTfw6POOs0tQ2zR3ltEGhnHc4d6oJE=; b=WvwfT2GWu1/U2AGqr0X5ZuueXuOeeEw8zuydTEfTTYUbxKlFMTkz4SxYZcIG2C0FK8 p+XBIDnW9zk5j9XcL8tbgrZzwPxlkT7QuoHkENMR60tu+PPYNguuMzmtNOfYK9AnfH3U A4URs7E3mvZxUQQk74Tm7vihREjLWW/u3LZHhijvZUpHJXpwXGMf+30XArFEzkIpn/9Q y7kEgna4+TK0GqNF6J1H4dtoOgFe2vsuur047yZXkF2VNx3gXZo+n8rjuilN5EJ9jpjn Rj/0hUiV+U+352drvTUkctIC+oWfkbSQYVORCFurxob6/CveyLNXWMpSr3C+O80DHaQM /UBw== X-Gm-Message-State: AOAM53271n3JR/4X8WmjaJZjIYjvzX1ntpKK4FqL43x29o9ajDDI4N28 uCYkFbt/3p7CcG1FMYMzBckuALvipvAAEIuBGvA= X-Google-Smtp-Source: ABdhPJz4KuzGJhb1+vLgjIvU2MC2gadiZChQVU7Nl0bodKE6nGqNgVjhjEHiK7FjlDLwqWlqRJV7zN82R2Yo0POBeZ8= X-Received: by 2002:a17:906:c046:: with SMTP id bm6mr3658460ejb.436.1606762928897; Mon, 30 Nov 2020 11:02:08 -0800 (PST) MIME-Version: 1.0 References: <09992cec-65e4-2757-aae6-8fb02a42f961@redhat.com> <20201128154849.3193-1-tom.ty89@gmail.com> <20201128154849.3193-2-tom.ty89@gmail.com> <5e62c383-22ea-6df6-5acc-5e9f381d4632@redhat.com> <186eb035-4bc4-ff72-ee41-aeb6d81888e3@redhat.com> <20201130172004.GA966032@rowland.harvard.edu> In-Reply-To: From: Tom Yan Date: Tue, 1 Dec 2020 03:01:56 +0800 Message-ID: Subject: Re: [PATCH 2/2] usb-storage: revert from scsi_add_host_with_dma() to scsi_add_host() To: Hans de Goede Cc: Alan Stern , Greg KH , Christoph Hellwig , linux-usb , Mathias Nyman , Linux Kernel Mailing List , linux-pci@vger.kernel.org, Lu Baolu Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org For the record, https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/scsi/scsi_host.h?h=v5.10-rc6#n753 On Tue, 1 Dec 2020 at 02:57, Tom Yan wrote: > > This maybe? https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/scsi/scsi_lib.c?h=v5.10-rc6#n1816 > > UAS: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/storage/uas.c?h=v5.10-rc6#n918 > BOT (AFAICT): > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/scsi/hosts.c?h=v5.10-rc6#n466 > > It would explain why the issue is only triggered with UAS drives. > > The questions (from me) are: > 1. From the scsi layer POV (as per what __scsi_init_queue() does), > what/which should we use as dma_dev? > 2. Do we really need to set dma_boundary in the UAS host template (to > PAGE_SIZE - 1)? > 3. Kind of the same question as #1: when we clamp hw_max_sectors to > dma max mapping size, should the size actually be "the smaller one > among dev and sysdev"? Or is one of the two sizes *always* the smaller > one? > > > On Tue, 1 Dec 2020 at 02:19, Hans de Goede wrote: > > > > Hi, > > > > On 11/30/20 6:20 PM, Alan Stern wrote: > > > On Mon, Nov 30, 2020 at 02:36:38PM +0100, Hans de Goede wrote: > > >> Hi, > > >> > > >> On 11/30/20 2:30 PM, Greg KH wrote: > > >>> On Mon, Nov 30, 2020 at 02:23:48PM +0100, Hans de Goede wrote: > > >>>> Hi, > > >>>> > > >>>> On 11/30/20 1:58 PM, Tom Yan wrote: > > >>>>> It's merely a moving of comment moving for/and a no-behavioral-change > > >>>>> adaptation for the reversion.> > > >>>> > > >>>> IMHO the revert of the troublesome commit and the other/new changes really > > >>>> should be 2 separate commits. But I will let Alan and Greg have the final > > >>>> verdict on this. > > >>> > > >>> I would prefer to just revert the commits and not do anything > > >>> different/special here so late in the release cycle. > > >>> > > >>> So, if Alan agrees, I'll be glad to do them on my end, I just need the > > >>> commit ids for them. > > >> > > >> The troublesome commit are (in reverse, so revert, order): > > >> > > >> 5df7ef7d32fe ("uas: bump hw_max_sectors to 2048 blocks for SS or faster drives") > > >> 558033c2828f ("uas: fix sdev->host->dma_dev") > > >> 0154012f8018 ("usb-storage: fix sdev->host->dma_dev") > > >> > > >> Alan, the reason for reverting these is that using scsi_add_host_with_dma() as the > > >> last 2 patches do, with the dmadev argument of that call pointing to the device > > >> for the XHCI controller is causing changes to the DMA settings of the XHCI controller > > >> itself which is causing regressions in 5.10, see this email thread: > > >> > > >> https://lore.kernel.org/linux-usb/fde7e11f-5dfc-8348-c134-a21cb1116285@redhat.com/T/#t > > > > > > It's hard to go wrong with reverting, so it's okay with me. > > > > > > Still, Hans, have you checked out the difference between the > > > scsi_add_host() and scsi_add_host_with_dma() calls? It's just a matter > > > of using dev vs. sysdev. In particular, have you checked to see what > > > those two devices are on your system? > > > > Its not just dev vs sysdev, its iface->dev vs bus->sysdev, and I assume > > that the latter is actually the XHCI controller. > > > > my vote goes to reverting to avoid the regression for 5.10, esp. since > > this is a clean revert of 3 patches with nothing depending / building > > on top of the reverted commits. > > > > Then for 5.11 we can retry to introduce similar changes. I would be happy > > to try a new patch-set for 5.11. > > > > > It seems likely that if one of those calls messes up some DMA settings, > > > the other one does too -- just maybe not settings that matter much. > > > > I'm not very familiar with all the DMA mapping / mask code, but AFAIK making > > changes to the DMA settings of a child will not influence the parent. > > > > Where as when passing bus->sysdev, then changes are made to a device > > which is shared with other devices on the bus, which is why we see > > a regression in an USB NIC driver being triggered by the UAS driver > > binding to a device (on the same bus). > > > > At least that is my interpretation of this. I bisected the regression > > and that pointed at the UAS DMA change and reverting it fixes things, > > confirming that I did not make any mistakes during the bisect. > > > > Regards, > > > > Hans > >