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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 8DC2DCA9EA0 for ; Wed, 23 Oct 2019 01:53:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6268620679 for ; Wed, 23 Oct 2019 01:53:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730597AbfJWBxv (ORCPT ); Tue, 22 Oct 2019 21:53:51 -0400 Received: from verein.lst.de ([213.95.11.211]:38029 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727582AbfJWBxv (ORCPT ); Tue, 22 Oct 2019 21:53:51 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 9E23968BE1; Wed, 23 Oct 2019 03:53:48 +0200 (CEST) Date: Wed, 23 Oct 2019 03:53:48 +0200 From: Christoph Hellwig To: Alan Stern Cc: Greg KH , Piergiorgio Sartor , Seth Bollinger , Christoph Hellwig , Jens Axboe , USB list Subject: Re: [PATCH] usb-storage: Revert commit 747668dbc061 ("usb-storage: Set virt_boundary_mask to avoid SG overflows") Message-ID: <20191023015348.GA16123@lst.de> References: <20191017175306.GA3014@lazy.lzy> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Mon, Oct 21, 2019 at 11:48:06AM -0400, Alan Stern wrote: > There is no longer any reason to keep the virt_boundary_mask setting > for usb-storage. It was needed in the first place only for handling > devices with a block size smaller than the maxpacket size and where > the host controller was not capable of fully general scatter-gather > operation (that is, able to merge two SG segments into a single USB > packet). But: > > High-speed or slower connections never use a bulk maxpacket > value larger than 512; > > The SCSI layer does not handle block devices with a block size > smaller than 512 bytes; > > All the host controllers capable of SuperSpeed operation can > handle fully general SG; > > Since commit ea44d190764b ("usbip: Implement SG support to > vhci-hcd and stub driver") was merged, the USB/IP driver can > also handle SG. > > Therefore all supported device/controller combinations should be okay > with no need for any special virt_boundary_mask. So in order to fix > the swiotlb problem, this patch reverts commit 747668dbc061. That's great to know. The same should also apply to uas, shouldn't it? Otherwise: Acked-by: Christoph Hellwig