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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 C3468C433F5 for ; Wed, 8 Sep 2021 07:01:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A1DC86113D for ; Wed, 8 Sep 2021 07:01:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347966AbhIHHCf (ORCPT ); Wed, 8 Sep 2021 03:02:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41458 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347962AbhIHHCe (ORCPT ); Wed, 8 Sep 2021 03:02:34 -0400 Received: from mail-lj1-x230.google.com (mail-lj1-x230.google.com [IPv6:2a00:1450:4864:20::230]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0CE4BC061757 for ; Wed, 8 Sep 2021 00:01:27 -0700 (PDT) Received: by mail-lj1-x230.google.com with SMTP id l18so1767098lji.12 for ; Wed, 08 Sep 2021 00:01:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=igel-co-jp.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=nzXaUAalZqbrYv6j2stFbPFR8gVHfPe6iNbwkck2gaQ=; b=I1O9kC6SsLJK4g5PyixqNxAjrnfsTIyox8pmgc6TZJICHzT2LP9NxZK8qLXv+rRlJA htYN5ABJjJ4+wr84+nsWuut0jYihhpds2TBbcZzI+azmDpj96X7pVXz6FfwFJpyxmpwt ezfrmkfKFGFMkT1mOqemRXfryDV25SDYPHj0mxz3AeJbn5OQpZCdHsB+bD9JZjSlL3t4 JUHsOYfs1Jz+Ro3wOtl4O104qhq6DWne2x815Y10W+SZssAZAlzmGl+G9tXZ1G68uUBF kDyjCISsiV72NcZPju2V6W+u5TGHVlsJwczfhhUtCy+YjuYhT5Nz0oRPRgcMV2yxIT/K 41kQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=nzXaUAalZqbrYv6j2stFbPFR8gVHfPe6iNbwkck2gaQ=; b=radZczxGDobAax/d5/Roa2jefYZIbqKBKnlmL0JaipFJpcoFOoSVMpst5ggB3MEe14 yTqPxlWrH9WuGM+FsQJZvIpQrPCvlLpX9A8xMKpmso6OnoIfvthbMKw3sPKL4PnSg5Y9 Ur34Zd+S1G8vqL5mlyvpUxWncFe73A5FyPnfjma4mbTFYF+Ibsxm+y/B3kubUf5edcat j8/4Dsq8XRi9XboKaHm6i9xSrxplw/FTqhviJCZStGWNpk1gkYbCdx2Jeopcs8l2qTpw xDn4lDBTuZ/ANmwRtGqepsLQfs38q4BXXNgUmLfpj62uj6vuK5BmR0QroGKpzQQVy7Ce qQbQ== X-Gm-Message-State: AOAM533Sgs+TtY9K50DlIbd55rAy0+gSqk23yhZWvYadVNVGgdA94tNF SOydXjA14IaDGpjUbwlu9JhV5wNkYaQ+Klwam4z5Mg== X-Google-Smtp-Source: ABdhPJwuTMM7db+CKbywV5n8DOBaJdUVZ9/pm9vdpYvhauCZICpdO2MsiV8vTp6ey6VXwezzc71z0pbJc8YuXvHEyKs= X-Received: by 2002:a2e:b8c7:: with SMTP id s7mr1738648ljp.105.1631084485315; Wed, 08 Sep 2021 00:01:25 -0700 (PDT) MIME-Version: 1.0 References: <20210908061611.69823-1-mie@igel.co.jp> <20210908061611.69823-2-mie@igel.co.jp> In-Reply-To: From: Shunsuke Mie Date: Wed, 8 Sep 2021 16:01:14 +0900 Message-ID: Subject: Re: [RFC PATCH 1/3] RDMA/umem: Change for rdma devices has not dma device To: Christoph Hellwig Cc: Zhu Yanjun , "Christian K??nig" , Alex Deucher , Daniel Vetter , Doug Ledford , Jason Gunthorpe , Jianxin Xiong , Leon Romanovsky , linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, Damian Hobson-Garcia , Takanari Hayama , Tomohito Esaki Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org Thank you for your comment. > > On Wed, Sep 08, 2021 at 03:16:09PM +0900, Shunsuke Mie wrote: > > To share memory space using dma-buf, a API of the dma-buf requires dma > > device, but devices such as rxe do not have a dma device. For those case, > > change to specify a device of struct ib instead of the dma device. > > So if dma-buf doesn't actually need a device to dma map why do we ever > pass the dma_device here? Something does not add up. As described in the dma-buf api guide [1], the dma_device is used by dma-buf exporter to know the device buffer constraints of importer. [1] https://lwn.net/Articles/489703/