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 C649EC433FF for ; Mon, 5 Aug 2019 15:08:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 99A0F214C6 for ; Mon, 5 Aug 2019 15:08:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565017701; bh=pP2QV9RFikSg/QhS3JVeQ96q3EXCKWZuPOHE9VeEQNY=; h=Subject:To:Cc:References:From:Date:In-Reply-To:List-ID:From; b=KHzOXlP1qiolKH5rxolQHSStyt9aXggE2MiYmMnXXn5W0+9ckjlgFZ1kMI0fd9nLm 66VkX3lgoDyOi1+o28h8D/P8ptHjHPmXkhXPgDB827CBkY70FIPg2MG4HDdIU1nEfr 0OsnHJOxhBTrNRqTAMHVP9hO2JKhR0TgmAttCAm4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729637AbfHEPIU (ORCPT ); Mon, 5 Aug 2019 11:08:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:37364 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728885AbfHEPIU (ORCPT ); Mon, 5 Aug 2019 11:08:20 -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 C3148214C6; Mon, 5 Aug 2019 15:08:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565017699; bh=pP2QV9RFikSg/QhS3JVeQ96q3EXCKWZuPOHE9VeEQNY=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=dkPlqTiVJR4OM905QzzFSSRjr3/Uxz+ktVrFmuv+aN0S6asPuCW4+3IWyFIX7FRGO hGVL/BqI2f1SNkrvob80iZePUX/TQy25TGkMewRLMx5QuCiScFbXFRS98WuE+uSPg6 l7tGs5oslOQjt75LlNWg0yvFQZmlnEDTK3ic8rmY= Subject: Re: [PATCH v3 1/2] usbip: Skip DMA mapping and unmapping for urb at vhci To: Suwan Kim Cc: valentina.manea.m@gmail.com, gregkh@linuxfoundation.org, stern@rowland.harvard.edu, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, shuah References: <20190802173651.22247-1-suwan.kim027@gmail.com> <20190802173651.22247-2-suwan.kim027@gmail.com> <20190805052358.GA8904@localhost.localdomain> From: shuah Message-ID: <8ce7b60c-6075-54ac-a917-921cb41003e6@kernel.org> Date: Mon, 5 Aug 2019 09:08:18 -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: <20190805052358.GA8904@localhost.localdomain> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/4/19 11:23 PM, Suwan Kim wrote: > On Fri, Aug 02, 2019 at 04:22:27PM -0600, shuah wrote: >> On 8/2/19 11:36 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 >>> --- >>> 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..c62f7fa8118c 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) { >>> + WARN_ON(1); >> >> Don't add WARN_ON. I cleaned them all up recently and don't want new >> ones added. > > Ok. I will remove it and resend v4. > Please add appropriate error message in place of WARN_ON thanks, -- Shuah