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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 1D04FC433E3 for ; Thu, 23 Jul 2020 12:00:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF1A120768 for ; Thu, 23 Jul 2020 12:00:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727123AbgGWMAz (ORCPT ); Thu, 23 Jul 2020 08:00:55 -0400 Received: from verein.lst.de ([213.95.11.211]:59896 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726521AbgGWMAz (ORCPT ); Thu, 23 Jul 2020 08:00:55 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id DE83868AFE; Thu, 23 Jul 2020 14:00:51 +0200 (CEST) Date: Thu, 23 Jul 2020 14:00:51 +0200 From: Christoph Hellwig To: "Song Bao Hua (Barry Song)" Cc: Christoph Hellwig , "m.szyprowski@samsung.com" , "robin.murphy@arm.com" , "will@kernel.org" , "ganapatrao.kulkarni@cavium.com" , "catalin.marinas@arm.com" , "iommu@lists.linux-foundation.org" , Linuxarm , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Jonathan Cameron , Nicolas Saenz Julienne , Steve Capper , Andrew Morton , Mike Rapoport , "Zengtao (B)" , huangdaode Subject: Re: [PATCH v3 1/2] dma-direct: provide the ability to reserve per-numa CMA Message-ID: <20200723120051.GB31598@lst.de> References: <20200628111251.19108-1-song.bao.hua@hisilicon.com> <20200628111251.19108-2-song.bao.hua@hisilicon.com> <20200722142943.GB17658@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 22, 2020 at 09:41:50PM +0000, Song Bao Hua (Barry Song) wrote: > I got a kernel robot warning which said dev should be checked before being accessed > when I did a similar change in v1. Probably it was an invalid warning if dev should > never be null. That usually shows up if a function is inconsistent about sometimes checking it and sometimes now. > Yes, it looks much better. Below is a prep patch to rebase on top of: --- >From b81a5e1da65fce9750f0a8b66dbb6f842cbfdd4d Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 22 Jul 2020 16:33:43 +0200 Subject: dma-contiguous: cleanup dma_alloc_contiguous Split out a cma_alloc_aligned helper to deal with the "interesting" calling conventions for cma_alloc, which then allows to the main function to be written straight forward. This also takes advantage of the fact that NULL dev arguments have been gone from the DMA API for a while. Signed-off-by: Christoph Hellwig --- kernel/dma/contiguous.c | 31 ++++++++++++++----------------- 1 file changed, 14 insertions(+), 17 deletions(-) diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index 15bc5026c485f2..cff7e60968b9e1 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -215,6 +215,13 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages, return cma_release(dev_get_cma_area(dev), pages, count); } +static struct page *cma_alloc_aligned(struct cma *cma, size_t size, gfp_t gfp) +{ + unsigned int align = min(get_order(size), CONFIG_CMA_ALIGNMENT); + + return cma_alloc(cma, size >> PAGE_SHIFT, align, gfp & __GFP_NOWARN); +} + /** * dma_alloc_contiguous() - allocate contiguous pages * @dev: Pointer to device for which the allocation is performed. @@ -231,24 +238,14 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages, */ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) { - size_t count = size >> PAGE_SHIFT; - struct page *page = NULL; - struct cma *cma = NULL; - - if (dev && dev->cma_area) - cma = dev->cma_area; - else if (count > 1) - cma = dma_contiguous_default_area; - /* CMA can be used only in the context which permits sleeping */ - if (cma && gfpflags_allow_blocking(gfp)) { - size_t align = get_order(size); - size_t cma_align = min_t(size_t, align, CONFIG_CMA_ALIGNMENT); - - page = cma_alloc(cma, count, cma_align, gfp & __GFP_NOWARN); - } - - return page; + if (!gfpflags_allow_blocking(gfp)) + return NULL; + if (dev->cma_area) + return cma_alloc_aligned(dev->cma_area, size, gfp); + if (size <= PAGE_SIZE || !dma_contiguous_default_area) + return NULL; + return cma_alloc_aligned(dma_contiguous_default_area, size, gfp); } /** -- 2.27.0