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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 152B3C7618F for ; Mon, 22 Jul 2019 20:26:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D1ED1218BE for ; Mon, 22 Jul 2019 20:26:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563827217; bh=rj/oDMHTdc2sn0j+S9jVqwOaKC+ElFvaZ+ApNh/+vt8=; h=Subject:To:Cc:References:From:Date:In-Reply-To:List-ID:From; b=ygKiZacRjXvfaquf8eLrLy7XO01zKy3CSZ4qMsfgC9yr3N7BtnHXBlmg3nF2wah9D A3itM3Sao0HnkAcQcLY1rz+6HHMjawnN2wwHUHe2jfQdyHAabrtNwY57MuxZ9rVMRA eIsOVkMjlHBdSOtwsXrJ93idgCOEz/8W/Dbo38gA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730296AbfGVU04 (ORCPT ); Mon, 22 Jul 2019 16:26:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:43452 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729672AbfGVU04 (ORCPT ); Mon, 22 Jul 2019 16:26:56 -0400 Received: from [192.168.1.112] (c-24-9-64-241.hsd1.co.comcast.net [24.9.64.241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3B32B218BE; Mon, 22 Jul 2019 20:26:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563827215; bh=rj/oDMHTdc2sn0j+S9jVqwOaKC+ElFvaZ+ApNh/+vt8=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=ywe94oQoJL0n6e8RNUPMtWMtTUnPYbUj8S1C5LmC740IA4NF1E885Xg2N6ogKXpKd HXKNoryVBZCx++kJL2C2gBNiCtHYJam+LnGGvUcEy6cDu15xboZauPL9bnSNSl3ENB bo3honQryvKcu7IIACy2b9VtkUVpfg80+B/0L3jQ= Subject: Re: [PATCH v2 1/2] usbip: Skip DMA mapping and unmapping for urb at vhci To: Suwan Kim , valentina.manea.m@gmail.com, stern@rowland.harvard.edu, gregkh@linuxfoundation.org Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, shuah References: <20190705164355.14025-1-suwan.kim027@gmail.com> <20190705164355.14025-2-suwan.kim027@gmail.com> From: shuah Message-ID: Date: Mon, 22 Jul 2019 14:26:42 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190705164355.14025-2-suwan.kim027@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Hi Suwan, On 7/5/19 10:43 AM, Suwan Kim wrote: > vhci doesn’t do DMA for remote device. Actually, the real DMA > operation is done by network card driver. vhci just passes virtual > address of the buffer to the network stack, so vhci doesn’t use and > need dma address of the buffer of the URB. > > When it comes to supporting SG for vhci, it is useful to use native > SG list (urb->num_sgs) instead of mapped SG list because DMA mapping > fnuction can adjust the number of SG list (urb->num_mapped_sgs). > > But HCD provides DMA mapping and unmapping function by default. > Moreover, it causes unnecessary DMA mapping and unmapping which > will be done again at the NIC driver and it wastes CPU cycles. > So, implement map_urb_for_dma and unmap_urb_for_dma function for > vhci in order to skip the DMA mapping and unmapping procedure. > > To support SG, vhci_map_urb_for_dma() sets URB_DMA_MAP_SG flag in > urb->transfer_flags if URB has SG list and this flag will tell the > stub driver to use SG list. > > Signed-off-by: Suwan Kim > --- > drivers/usb/usbip/vhci_hcd.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c > index 000ab7225717..14fc6d9f4e6a 100644 > --- a/drivers/usb/usbip/vhci_hcd.c > +++ b/drivers/usb/usbip/vhci_hcd.c > @@ -1288,6 +1288,22 @@ static int vhci_free_streams(struct usb_hcd *hcd, struct usb_device *udev, > return 0; > } > > +static int vhci_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb, > + gfp_t mem_flags) > +{ > + dev_dbg(hcd->self.controller, "vhci does not map urb for dma\n"); > + > + if (urb->num_sgs) > + urb->transfer_flags |= URB_DMA_MAP_SG; > + Shouldn't this be part of patch 2. The debug message saying "no map" and setting flag doesn't make sense. > + return 0; This should be a tab and no spaces btw. chekpatch isn't happy. > +} > + > +static void vhci_unmap_urb_for_dma(struct usb_hcd *hcd, struct urb *urb) > +{ > + dev_dbg(hcd->self.controller, "vhci does not unmap urb for dma\n"); This should be a tab and no spaces btw. chekpatch isn't happy. WARNING: please, no spaces at the start of a line #144: FILE: drivers/usb/usbip/vhci_hcd.c:1299: + return 0;$ WARNING: please, no spaces at the start of a line #149: FILE: drivers/usb/usbip/vhci_hcd.c:1304: + dev_dbg(hcd->self.controller, "vhci does not unmap urb for dma\n");$ total: 0 errors, 2 warnings, 31 lines checked > +} > + > static const struct hc_driver vhci_hc_driver = { > .description = driver_name, > .product_desc = driver_desc, > @@ -1304,6 +1320,9 @@ static const struct hc_driver vhci_hc_driver = { > > .get_frame_number = vhci_get_frame_number, > > + .map_urb_for_dma = vhci_map_urb_for_dma, > + .unmap_urb_for_dma = vhci_unmap_urb_for_dma, > + > .hub_status_data = vhci_hub_status, > .hub_control = vhci_hub_control, > .bus_suspend = vhci_bus_suspend, > thanks, -- Shuah