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=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 07966C0650F for ; Fri, 2 Aug 2019 22:22:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF63D206A3 for ; Fri, 2 Aug 2019 22:22:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564784553; bh=TZAOdBkjZfMwv4fT9kCJuQsahj/V5oh+DLHfTohaZtc=; h=Subject:To:Cc:References:From:Date:In-Reply-To:List-ID:From; b=F/hWhZTC6VuF12y3shxHe4K7KVazyNNsAS2KVVylsfPJc+W/cB+dhEmGgfvOmRDQi Aff6VZyQcfoTD/Bz4ncMKhj6yPWvAyoEYQkxR0Y8UBPB7gXnB9PAwSBhAIyOfnr3SY p1gW1I6GLecWY3Yu15QFuwYTuIbbWDtfY7g4i8Kw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388152AbfHBWW3 (ORCPT ); Fri, 2 Aug 2019 18:22:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:42534 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730633AbfHBWW3 (ORCPT ); Fri, 2 Aug 2019 18:22:29 -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 EB9D8206A3; Fri, 2 Aug 2019 22:22:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564784548; bh=TZAOdBkjZfMwv4fT9kCJuQsahj/V5oh+DLHfTohaZtc=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=CEl0npNLAOOAPOxBTLUGeVUCwd/PjIV088vkA0mkPukyGbv9yzgUd1TbrZ+p6FHQ2 G4Ag2mUVRhF9nYlCMrm82mWcr2NscJiqG803/wdEA//CfUkFo5FFFcRaegOqRLBN4n pUKw6RqJ58ipZVhIzYJ3ZGYH9Aon5tLqhccIRbJw= Subject: Re: [PATCH v3 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: <20190802173651.22247-1-suwan.kim027@gmail.com> <20190802173651.22247-2-suwan.kim027@gmail.com> From: shuah Message-ID: Date: Fri, 2 Aug 2019 16:22:27 -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: <20190802173651.22247-2-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 8/2/19 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. thanks, -- Shuah