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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT 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 2E87AC282C2 for ; Thu, 7 Feb 2019 19:03:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0550F2086C for ; Thu, 7 Feb 2019 19:03:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727058AbfBGTD3 (ORCPT ); Thu, 7 Feb 2019 14:03:29 -0500 Received: from bmailout3.hostsharing.net ([176.9.242.62]:55439 "EHLO bmailout3.hostsharing.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726758AbfBGTD3 (ORCPT ); Thu, 7 Feb 2019 14:03:29 -0500 Received: from h08.hostsharing.net (h08.hostsharing.net [IPv6:2a01:37:1000::53df:5f1c:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.hostsharing.net", Issuer "COMODO RSA Domain Validation Secure Server CA" (not verified)) by bmailout3.hostsharing.net (Postfix) with ESMTPS id 82463100B07E1; Thu, 7 Feb 2019 20:03:26 +0100 (CET) Received: by h08.hostsharing.net (Postfix, from userid 100393) id 39E8F8372B; Thu, 7 Feb 2019 20:03:26 +0100 (CET) Date: Thu, 7 Feb 2019 20:03:26 +0100 From: Lukas Wunner To: "Rafael J. Wysocki" Cc: Greg Kroah-Hartman , LKML , Linux PM , Ulf Hansson , Daniel Vetter , Andrzej Hajda , Russell King - ARM Linux , Lucas Stach , Linus Walleij , Thierry Reding , Laurent Pinchart , Marek Szyprowski , Joerg Roedel Subject: Re: [PATCH v2 2/9] driver core: Avoid careless re-use of existing device links Message-ID: <20190207190326.wjxnzo4ja62t3mt6@wunner.de> References: <1952449.TVsm6CJCTy@aspire.rjw.lan> <2222273.ydJmd408XJ@aspire.rjw.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2222273.ydJmd408XJ@aspire.rjw.lan> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry, late to the party. On Fri, Feb 01, 2019 at 01:46:54AM +0100, Rafael J. Wysocki wrote: > After commit ead18c23c263 ("driver core: Introduce device links > reference counting"), if there is a link between the given supplier > and the given consumer already, device_link_add() will refcount it > and return it unconditionally. However, if the flags passed to > it on the second (or any subsequent) attempt to create a device > link between the same consumer-supplier pair are not compatible with > the existing link's flags, that is incorrect. Prior to ead18c23c263, a second invocation of device_link_add() also returned the existing device link without checking for incompatible flags. Hence this issue was not introduced by ead18c23c263, but rather by 9ed9895370ae ("driver core: Functional dependencies tracking support"), i.e. it was present all along. (Unless I'm missing something.) > Moreover, if the DL_FLAG_AUTOREMOVE_CONSUMER flag is passed to > device_link_add(), its caller will expect its reference to the link > to be dropped automatically on consumer driver removal, which will > not happen if that flag is not set in the link's flags (and > analogously for DL_FLAG_AUTOREMOVE_SUPPLIER). For this reason, make > device_link_add() update the existing link's flags accordingly > before returning it to the caller. Same here. > Fixes: ead18c23c263 ("driver core: Introduce device links reference counting") Should rather be Fixes: 9ed9895370ae ("driver core: Functional dependencies tracking support") (Again, unless I'm missing something.) Thanks, Lukas