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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS,URIBL_BLOCKED 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 A05A2C10F14 for ; Thu, 18 Apr 2019 18:15:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A892214DA for ; Thu, 18 Apr 2019 18:15:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404034AbfDRSPG (ORCPT ); Thu, 18 Apr 2019 14:15:06 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:38900 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391146AbfDRSPE (ORCPT ); Thu, 18 Apr 2019 14:15:04 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2BC7F80D; Thu, 18 Apr 2019 11:15:04 -0700 (PDT) Received: from [10.1.196.75] (e110467-lin.cambridge.arm.com [10.1.196.75]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BE7893F5AF; Thu, 18 Apr 2019 11:15:02 -0700 (PDT) Subject: Re: [PATCH 12/21] dma-iommu: factor atomic pool allocations into helpers To: Christoph Hellwig Cc: Joerg Roedel , Catalin Marinas , Will Deacon , Tom Lendacky , iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20190327080448.5500-1-hch@lst.de> <20190327080448.5500-13-hch@lst.de> <20190410061157.GA5278@lst.de> <20190417063358.GA24139@lst.de> <83615173-a8b4-e0eb-bac3-1a58d61ea4ef@arm.com> <20190418163512.GA25347@lst.de> From: Robin Murphy Message-ID: <228ee57a-d7b2-48e0-a34e-81d5fba0a090@arm.com> Date: Thu, 18 Apr 2019 19:15:00 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190418163512.GA25347@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18/04/2019 17:35, Christoph Hellwig wrote: > On Thu, Apr 18, 2019 at 04:06:56PM +0100, Robin Murphy wrote: >> OK, I'm still looking at mmap and get_sgtable, but for now I've pushed out >> a partial branch that consolidates alloc and free in a way which makes >> sense to me: >> >> git://linux-arm.org/linux-rm dma/rework >> >> Please let me know what you think. > > From a very high level POV this looks ok, but sometimes a bit to > convoluted to me. The major issue why I went with the version I posted > is that I can cleanly ifdef out the remap code in just a few sections. > In this version it is spread out a lot more, and the use of IS_ENABLED > means that we'd need a lot more stubs for functionality that won't > ever be called but needs to be compilable. OK, for some reason I'd convinced myself that mmap and get_sgtable would need changes to properly handle the new non-remapped CMA case - not sure how I reached that conclusion. On inspection they do appear to be broken for the non-coherent atomic case, but AFAICS that's been so forever... Still, I've worked in the vm_map_pages() stuff pending in MM and given them the same treatment to finish the picture. Both x86_64_defconfig and i386_defconfig do indeed compile and link fine as I expected, so I really would like to understand the concern around #ifdefs better. Robin.