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,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 2ACFBC433FF for ; Thu, 8 Aug 2019 16:19:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 00E2A2184E for ; Thu, 8 Aug 2019 16:19:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565281153; bh=B35pikkFB/J7vGw/V5wO0pktD8+Cprnqbx828X6l5GE=; h=Subject:To:Cc:References:From:Date:In-Reply-To:List-ID:From; b=0I444o8mmrCdLMYJs/8AgX84Dnqq/FmD28GwRXxgNwOV+2OaKn2I6EEgtYRB9pKil zpHO2YuT8jHEsXVNxCV4MSPzaary9YFGKENN4uYyohCHPQ3gDSBGHK9EphEV7VfPTL SoK+NNsCdKd7k/0oaDabSa5YHqR0S0KwIqcsyPvQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732769AbfHHQTI (ORCPT ); Thu, 8 Aug 2019 12:19:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:43298 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728020AbfHHQTI (ORCPT ); Thu, 8 Aug 2019 12:19:08 -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 9CE3B2184E; Thu, 8 Aug 2019 16:19:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565281147; bh=B35pikkFB/J7vGw/V5wO0pktD8+Cprnqbx828X6l5GE=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=VBA1g0BIMkEYHorY5sBEOMI+5NKBxMbTY/DnSraaw/aob6X2GV1DcNdTw7fUyIj+9 u01lH7PvergRZn6kAb9af/N9j0M74TeVHLy5ReC+WgcIXvtyc2RoJuWYsudJhsKRDq YkTJsgDIVkOQeYyiHJXlzeix0z2IkSUcqrfpIp8k= Subject: Re: [PATCH v5 1/2] usbip: Skip DMA mapping and unmapping for urb at vhci To: Suwan Kim , valentina.manea.m@gmail.com, gregkh@linuxfoundation.org, stern@rowland.harvard.edu Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, shuah References: <20190808155435.10050-1-suwan.kim027@gmail.com> <20190808155435.10050-2-suwan.kim027@gmail.com> From: shuah Message-ID: Date: Thu, 8 Aug 2019 10:18:59 -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: <20190808155435.10050-2-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 On 8/8/19 9:54 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. > > 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. > > 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). > And vhci_map_urb_for_dma() prevents isoc pipe from using SG as > hcd_map_urb_for_dma() does. > > Signed-off-by: Suwan Kim > --- > v4 - v5 > - Replace pr_err() with dev_err() in the error path. > > v3 - v4 > - Replace WARN_ON() with pr_err() in the error path. > > v2 - v3 > - Move setting URB_DMA_MAP_SG flag to the patch 2. > - Prevent isoc pipe from using SG buffer. > > v1 - v2 > - Add setting URB_DMA_MAP_SG flag in urb->transfer_flags to tell > stub driver to use SG buffer. > --- > 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..ea82b932a2f9 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) > +{ > + if (usb_endpoint_xfer_isoc(&urb->ep->desc) && urb->num_sgs) { > + dev_err(&urb->dev->dev, "SG is not supported for isochronous transfer\n"); > + return -EINVAL; > + } > + > + return 0; > +} > + > +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"); > +} > + > 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, > Looks good to me. Reviewed-by: Shuah Khan thanks, -- Shuah