From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Authentication-Results: smtp.codeaurora.org; dkim=pass (1024-bit key) header.d=linaro.org header.i=@linaro.org header.b="CU5epQLG" DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org D5BD5606DD Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754170AbeFFSJe (ORCPT + 25 others); Wed, 6 Jun 2018 14:09:34 -0400 Received: from mail-wr0-f196.google.com ([209.85.128.196]:44983 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752404AbeFFSJ3 (ORCPT ); Wed, 6 Jun 2018 14:09:29 -0400 X-Google-Smtp-Source: ADUXVKJ04JjLB84uzczYvNfaxeMW63YvX1ZTb89tR4qjXXIxVMu0fTXx+DV/yG0nASzZTGk4CmeE/w== Subject: Re: [PATCH v4 1/7] interconnect: Add generic on-chip interconnect API From: Georgi Djakov To: Evan Green Cc: linux-pm@vger.kernel.org, gregkh@linuxfoundation.org, rjw@rjwysocki.net, robh+dt@kernel.org, Michael Turquette , khilman@baylibre.com, vincent.guittot@linaro.org, skannan@codeaurora.org, Bjorn Andersson , amit.kucheria@linaro.org, seansw@qti.qualcomm.com, davidai@quicinc.com, mark.rutland@arm.com, lorenzo.pieralisi@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org References: <20180309210958.16672-1-georgi.djakov@linaro.org> <20180309210958.16672-2-georgi.djakov@linaro.org> <43fedb5b-f4a5-8362-d0a2-534b85473bc1@linaro.org> Openpgp: preference=signencrypt Autocrypt: addr=georgi.djakov@linaro.org; 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charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Evan, On 06/06/2018 05:59 PM, Georgi Djakov wrote: >>> + >>> +/** >>> + * icc_node_create() - create a node >>> + * @id: node id >>> + * >>> + * Return: icc_node pointer on success, or ERR_PTR() on error >>> + */ >>> +struct icc_node *icc_node_create(int id) >>> +{ >>> + struct icc_node *node; >>> + >>> + /* check if node already exists */ >>> + node = node_find(id); >>> + if (node) >>> + return node; >> >> This is probably going to do more harm than good once icc_node_delete comes >> in, since it almost certainly indicates a programmer error or ID collision, >> and will likely result in a double free. We should probably fail with >> EEXIST instead. > > In the current approach we create the nodes one by one, and the linked > nodes are created when they are referenced. The other way around would > be to create first all the nodes and then populate the links to avoid > the "chicken and egg" problem. > Just to elaborate a bit more on that: We can't actually register all the nodes in advance, as we might have multiple interconnect providers probing in different order. Each provider may have nodes linking to nodes belonging to other providers (not probed yet). That's why we create the nodes on the first reference and then, when the actual provider driver is probed, the rest of the node data is filled. Thanks, Georgi