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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 D57E4C76190 for ; Mon, 22 Jul 2019 15:46:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 909452171F for ; Mon, 22 Jul 2019 15:46:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728154AbfGVPqG (ORCPT ); Mon, 22 Jul 2019 11:46:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34138 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727123AbfGVPqG (ORCPT ); Mon, 22 Jul 2019 11:46:06 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1BC5F3082AF2; Mon, 22 Jul 2019 15:46:06 +0000 (UTC) Received: from [10.36.116.45] (ovpn-116-45.ams2.redhat.com [10.36.116.45]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A6C3E5C21F; Mon, 22 Jul 2019 15:46:01 +0000 (UTC) Subject: Re: [PATCH 1/2] dma-mapping: Protect dma_addressing_limited against NULL dma_mask To: Christoph Hellwig Cc: eric.auger.pro@gmail.com, m.szyprowski@samsung.com, robin.murphy@arm.com, mst@redhat.com, jasowang@redhat.com, virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <20190722145509.1284-1-eric.auger@redhat.com> <20190722145509.1284-2-eric.auger@redhat.com> <20190722152637.GA3780@lst.de> From: Auger Eric Message-ID: Date: Mon, 22 Jul 2019 17:46:00 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190722152637.GA3780@lst.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Mon, 22 Jul 2019 15:46:06 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Christoph, On 7/22/19 5:26 PM, Christoph Hellwig wrote: >> static inline bool dma_addressing_limited(struct device *dev) >> { >> - return min_not_zero(*dev->dma_mask, dev->bus_dma_mask) < >> - dma_get_required_mask(dev); >> + return WARN_ON_ONCE(!dev->dma_mask) ? false : >> + min_not_zero(*dev->dma_mask, dev->bus_dma_mask) < >> + dma_get_required_mask(dev); > > This should really use a separate if statement, but I can fix that > up when applying it. > Just wondering why we don't use the dma_get_mask() accessor which returns DMA_BIT_MASK(32) in case the dma_mask is not set. Do you foresee any issue and would it still mandate to add dma_mask checks on each call sites? Thanks Eric