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=-11.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 55999C4361B for ; Tue, 8 Dec 2020 20:59:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 276AC239FD for ; Tue, 8 Dec 2020 20:59:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729266AbgLHU71 (ORCPT ); Tue, 8 Dec 2020 15:59:27 -0500 Received: from mail.kernel.org ([198.145.29.99]:52238 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728996AbgLHU71 (ORCPT ); Tue, 8 Dec 2020 15:59:27 -0500 Date: Tue, 8 Dec 2020 21:02:52 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1607454176; bh=on7V4OWCmVPzcIia0frhRZpTXCRt5e/b3cclGe2h/vc=; h=From:To:Cc:Subject:References:In-Reply-To:From; b=AWrmh7AdWcTdHB/rW/9k5hDWSjxkK6XQilu9LdiVu5TDSjcBq6T3BVuHyS2Difqbl BYaiQfKf0zrqJlScxqzMo17FxqxFcHpangAOlkxGzuw+wlaj+XAl8CVRLi7kYXUhdW +Hz3ZqKbCY9bp4F/TrVUBXlla8N4FHeFfQ933WEvrRYE2Zzy1L/Wyhbwyf2QImhWmG HvkJ3ypbHXCXY+zzAkDb3npeZV8wBaY25q7dk+lY+VXxnGvouhdVPXpySXApgpIH/6 wMBSmCGIzY45V+INYmN9PYj8QFsgHUnBuD1VkpLtXUy5ho5HMZ4NgNaFiK5rGbK81T 0dCFF+jeKYygQ== From: Leon Romanovsky To: "Xiong, Jianxin" Cc: "linux-rdma@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , Doug Ledford , Jason Gunthorpe , Sumit Semwal , Christian Koenig , "Vetter, Daniel" Subject: Re: [PATCH v13 1/4] RDMA/umem: Support importing dma-buf as user memory region Message-ID: <20201208190252.GI4430@unreal> References: <1607379353-116215-1-git-send-email-jianxin.xiong@intel.com> <1607379353-116215-2-git-send-email-jianxin.xiong@intel.com> <20201208070532.GE4430@unreal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Tue, Dec 08, 2020 at 06:13:20PM +0000, Xiong, Jianxin wrote: > > -----Original Message----- > > From: Leon Romanovsky > > Sent: Monday, December 07, 2020 11:06 PM > > To: Xiong, Jianxin > > Cc: linux-rdma@vger.kernel.org; dri-devel@lists.freedesktop.org; Doug Ledford ; Jason Gunthorpe ; > > Sumit Semwal ; Christian Koenig ; Vetter, Daniel > > Subject: Re: [PATCH v13 1/4] RDMA/umem: Support importing dma-buf as user memory region > > > > On Mon, Dec 07, 2020 at 02:15:50PM -0800, Jianxin Xiong wrote: > > > Dma-buf is a standard cross-driver buffer sharing mechanism that can > > > be used to support peer-to-peer access from RDMA devices. > > > > > > Device memory exported via dma-buf is associated with a file descriptor. > > > This is passed to the user space as a property associated with the > > > buffer allocation. When the buffer is registered as a memory region, > > > the file descriptor is passed to the RDMA driver along with other > > > parameters. > > > > > > Implement the common code for importing dma-buf object and mapping > > > dma-buf pages. > > > > > > Signed-off-by: Jianxin Xiong > > > Reviewed-by: Sean Hefty > > > Acked-by: Michael J. Ruhl > > > Acked-by: Christian Koenig > > > Acked-by: Daniel Vetter > > > > > > Conflicts: > > > include/rdma/ib_umem.h > > <...> > > > + /* > > > + * Although the sg list is valid now, the content of the pages > > > + * may be not up-to-date. Wait for the exporter to finish > > > + * the migration. > > > + */ > > > + fence = dma_resv_get_excl(umem_dmabuf->attach->dmabuf->resv); > > > + if (fence) > > > + dma_fence_wait(fence, false); > > > > Any reason do not check return result from dma_fence_wait()? > > This is called with interruptible flag set to false and normally should only return 0. > I do see similar usage cases that check the result and don't check the result. Maybe > we can add a WARN_ON here? I have no idea :), just saw that other places check returned value. <...> > > > + > > > +struct ib_umem *ib_umem_dmabuf_get(struct ib_device *device, > > > + unsigned long offset, size_t size, > > > + int fd, int access, > > > + const struct dma_buf_attach_ops *ops) { > > > + struct dma_buf *dmabuf; > > > + struct ib_umem_dmabuf *umem_dmabuf; > > > + struct ib_umem *umem; > > > + unsigned long end; > > > + long ret = -EINVAL; > > > > It is wrong type for the returned value. One of the possible options is to declare "struct ib_umem *ret;" and set ret = ERR_PTR(-EINVAL) or > > ret = ERR_CAST(dmabuf); > > At the actual point the value is returned, ERR_PTR(ret) is used. I think we can change the > variable name to "err" instead to avoid confusion. The point is that "ret" should be declared as "struct ib_umem *" and not as "long" and ERR_CAST() should be used instead of (void *). <...> > > > +static inline struct ib_umem *ib_umem_dmabuf_get(struct ib_device *device, > > > + unsigned long offset, > > > + size_t size, int fd, > > > + int access, > > > + struct dma_buf_attach_ops *ops) { > > > + return ERR_PTR(-EINVAL); > > > > Probably, It should be EOPNOTSUPP and not EINVAL. > > EINVAL is used here to be consistent with existing definitions in the same file. ok Thanks