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=-7.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS,USER_AGENT_MUTT 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 34024C282D1 for ; Tue, 29 Jan 2019 21:00:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EC9D921473 for ; Tue, 29 Jan 2019 21:00:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EC9D921473 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8EFA68E0003; Tue, 29 Jan 2019 16:00:15 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 89DD48E0001; Tue, 29 Jan 2019 16:00:15 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 78BE38E0003; Tue, 29 Jan 2019 16:00:15 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) by kanga.kvack.org (Postfix) with ESMTP id 4E5978E0001 for ; Tue, 29 Jan 2019 16:00:15 -0500 (EST) Received: by mail-qk1-f200.google.com with SMTP id r145so23305715qke.20 for ; Tue, 29 Jan 2019 13:00:15 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:date:from:to :cc:subject:message-id:references:mime-version:content-disposition :content-transfer-encoding:in-reply-to:user-agent; bh=/1gIi7T1dRTUHKPk97ncy1O0U6azH8+Kof8HoJbyGiI=; b=cv/92xDZf20V3agG7q9kMSLdoRqxOzgqG1yehXeGpPschuWI+HVMjivOVTsNsMrAbP vuZJY3FwdCye0FbMMB12yeUVTTSR66+JBLwVHshvJdxrevW13uD2RB8ciEYXUiBl6drR UDW5df8UuLS2W0WdaudadDeXYerNoJL+Y3G95s+XNK89ucbRlDm7qGQ8ZorhR/5oYHZc jXLSLNksNq+hG3riRu4W3Ub85gYZABMTpIPBCMCBPtE6/gFXEVnP8+4fmoKvPJsYi/dP wDnTTUQ5fqsMdFxmqFeZCIGDnsKCIk4BbdkqtGlsiSGLcqIi9Cs0cNI/p9gy6WeNdqWc AdSg== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of jglisse@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=jglisse@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com X-Gm-Message-State: AJcUukfmd7Xva+VIqMq/PWVkv9i+lG/ihplizmQBGxUDdQuvOtXTVozf dcWN0q3PQYz8LSLlzgXjbPdHFYHZAvLnRcDSoAooqszdjAQ7OBYmCmu9/lqD3e4xH4zBUDdATWc sKbI4EKivH6O8VfGNLNPBiX2I36AJERtUI1xUE3xMZXyDmRq/+uybcSc+YRGsDlnaVA== X-Received: by 2002:a0c:d232:: with SMTP id m47mr26731103qvh.43.1548795615045; Tue, 29 Jan 2019 13:00:15 -0800 (PST) X-Google-Smtp-Source: ALg8bN4VgmCX+YNhdtthmUWtCXUQooW84fEm+MCkue5HcW9Y0X3jSrLaEPVm3+GiwFUpReoDrIdI X-Received: by 2002:a0c:d232:: with SMTP id m47mr26731068qvh.43.1548795614550; Tue, 29 Jan 2019 13:00:14 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1548795614; cv=none; d=google.com; s=arc-20160816; b=r33FrkPiVmS3ddCJsYhB4zhW5hxi1WPagrmXW/W84BkxZElCCZWx9InBEdKxW/JvNo cz7aReqhIq5FV0ZQXITOxYvnLCXQAPOxe2jaHQwFrzAECh2yn8b2qi3ED9HehU0qpCHp FaAcVELK9EMzNVy07ui3DdgTtbiBGwBN++OH7ZyenVTJpApGMS//omDNo+4OE1FcvhyV pXfLii4To76NOV0Z8WPPLyTbWXRacgIiI2c4nrgt8pmNExeh74t2/EBW9lAhWIZaQuWD uFy9w3EcuIVtma35yo6Y7PjbLH58y3CVJZ8P6mXCi0giSLH2I5zcDIpc2YeSiSC07exM WRFg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-transfer-encoding :content-disposition:mime-version:references:message-id:subject:cc :to:from:date; bh=/1gIi7T1dRTUHKPk97ncy1O0U6azH8+Kof8HoJbyGiI=; b=a5725gGkkqFmJqA7wyL+y4SwHG+uPG5/B6079sVPGtdSUyqytBHJPTjg0xz14yfyYW 1UoJWDutYtD+HvCYizyexfbqS6r3T8jgAf0Gmc77WlOvfUKFco8PERtDr1P1kOAVpqw5 p9+KHeZYa49qgjL83jNI682aqJM4GPLCdCh/enO1pCXgG6qvDlCKPZgg+5WQzTTzU3vF ssYiCGCrsFwEVuH7HC/KnvlzzFKkJUFqBOVQb+FAHkQOWXLeoXIBrOUqx4JpAh0blJ8Y tMw3UtaNMDTuMBGJeMqd3MjT4hzFzpJWdNJl8s4zVWeqx4xGGbkaSqtho2/33qmAte+N sQ0g== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of jglisse@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=jglisse@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id z2si1364417qvj.66.2019.01.29.13.00.14 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 29 Jan 2019 13:00:14 -0800 (PST) Received-SPF: pass (google.com: domain of jglisse@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of jglisse@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=jglisse@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6751D58E22; Tue, 29 Jan 2019 21:00:13 +0000 (UTC) Received: from redhat.com (ovpn-122-2.rdu2.redhat.com [10.10.122.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3147460C6E; Tue, 29 Jan 2019 21:00:10 +0000 (UTC) Date: Tue, 29 Jan 2019 16:00:08 -0500 From: Jerome Glisse To: Logan Gunthorpe Cc: Greg Kroah-Hartman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Rafael J . Wysocki" , Bjorn Helgaas , Christian Koenig , Felix Kuehling , Jason Gunthorpe , linux-pci@vger.kernel.org, dri-devel@lists.freedesktop.org, Christoph Hellwig , Marek Szyprowski , Robin Murphy , Joerg Roedel , iommu@lists.linux-foundation.org Subject: Re: [RFC PATCH 1/5] pci/p2p: add a function to test peer to peer capability Message-ID: <20190129210007.GO3176@redhat.com> References: <20190129174728.6430-1-jglisse@redhat.com> <20190129174728.6430-2-jglisse@redhat.com> <20190129194426.GB32069@kroah.com> <8b4e0157-4eaf-c79a-28d0-7a266abe2207@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <8b4e0157-4eaf-c79a-28d0-7a266abe2207@deltatee.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 29 Jan 2019 21:00:13 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Jan 29, 2019 at 01:44:09PM -0700, Logan Gunthorpe wrote: > > > On 2019-01-29 12:44 p.m., Greg Kroah-Hartman wrote: > > On Tue, Jan 29, 2019 at 11:24:09AM -0700, Logan Gunthorpe wrote: > >> > >> > >> On 2019-01-29 10:47 a.m., jglisse@redhat.com wrote: > >>> +bool pci_test_p2p(struct device *devA, struct device *devB) > >>> +{ > >>> + struct pci_dev *pciA, *pciB; > >>> + bool ret; > >>> + int tmp; > >>> + > >>> + /* > >>> + * For now we only support PCIE peer to peer but other inter-connect > >>> + * can be added. > >>> + */ > >>> + pciA = find_parent_pci_dev(devA); > >>> + pciB = find_parent_pci_dev(devB); > >>> + if (pciA == NULL || pciB == NULL) { > >>> + ret = false; > >>> + goto out; > >>> + } > >>> + > >>> + tmp = upstream_bridge_distance(pciA, pciB, NULL); > >>> + ret = tmp < 0 ? false : true; > >>> + > >>> +out: > >>> + pci_dev_put(pciB); > >>> + pci_dev_put(pciA); > >>> + return false; > >>> +} > >>> +EXPORT_SYMBOL_GPL(pci_test_p2p); > >> > >> This function only ever returns false.... > > > > I guess it was nevr actually tested :( > > > > I feel really worried about passing random 'struct device' pointers into > > the PCI layer. Are we _sure_ it can handle this properly? > > Yes, there are a couple of pci_p2pdma functions that take struct devices > directly simply because it's way more convenient for the caller. That's > what find_parent_pci_dev() takes care of (it returns false if the device > is not a PCI device). Whether that's appropriate here is hard to say > seeing we haven't seen any caller code. Caller code as a reference (i already given that link in other part of thread but just so that people don't have to follow all branches). https://cgit.freedesktop.org/~glisse/linux/commit/?h=hmm-p2p&id=401a567696eafb1d4faf7054ab0d7c3a16a5ef06 Cheers, Jérôme