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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 2B332C35DEA for ; Tue, 25 Feb 2020 01:35:41 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 07A3A21927 for ; Tue, 25 Feb 2020 01:35:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 07A3A21927 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8FCBE6E9CC; Tue, 25 Feb 2020 01:35:40 +0000 (UTC) Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2B4326E9CC for ; Tue, 25 Feb 2020 01:35:39 +0000 (UTC) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Feb 2020 17:35:38 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,482,1574150400"; d="scan'208";a="260535214" Received: from fproca-mobl.ger.corp.intel.com (HELO intel.com) ([10.252.23.52]) by fmsmga004.fm.intel.com with ESMTP; 24 Feb 2020 17:35:37 -0800 Date: Tue, 25 Feb 2020 03:35:36 +0200 From: Andi Shyti To: Tvrtko Ursulin Message-ID: <20200225013208.GA2708@intel.intel> References: <20200219190223.16972-1-andi.shyti@intel.com> <20200219193020.17673-1-andi.shyti@intel.com> <20200224163029.GA1579@intel.intel> <421b0bd8-6bc6-e6c2-7e08-6d112c57a860@linux.intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <421b0bd8-6bc6-e6c2-7e08-6d112c57a860@linux.intel.com> Subject: Re: [Intel-gfx] [PATCH v5] drm/i915/gt: make a gt sysfs group and move power management files X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Intel GFX Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" > > > > +void intel_gt_sysfs_unregister(struct intel_gt *gt) > > > > +{ > > > > + struct kobject *parent = gt_get_parent_obj(gt); > > > > + > > > > + /* > > > > + * the name gt tells us wether sysfs_root > > > > + * object was initialized properly > > > > + */ > > > > + if (!strcmp(gt->sysfs_root.name, "gt")) > > > > + kobject_put(>->sysfs_root); > > > > > > Slightly nicer would be looking at kobj->state_initialized for this check I > > > think. Or even kref_get_unless_zero on kobj->kref? Ugliness there is double > > > put on sucess which makes me ask whether holding a reference on parent is > > > even needed? It can't go away so perhaps it isn't. > > > > I'd rather use the state_initialized, even though I don't trust > > its value if the kobject has failed to initialise earlier, I > > trust it only if it's '1', maybe I'm paranoic. > > But is the reference even needed? yes, because I _get it here (i.e. above, during initialization): > > > > +void intel_gt_sysfs_register(struct intel_gt *gt) > > > > +{ > > > > + struct kobject *parent = kobject_get(gt_get_parent_obj(gt)); > > > > + int ret; > > > > + and if I need to call kobject_put at the end. If for some reason the files have failed to be initialized, I would have an unbalanced put and a warning would be printed. I'll summarize in pseudo code: intel_gt_sysfs_register() { kobject_init_and_add(sysfs_root...); /* which calls kobject_get() inside */ if (fails) kobject_put(sysfs_root); /* reference goes to '0' */ } intel_gt_sysfs_unregister() { option1: I don't call kobject_put(), I have an unbalanced situation as you reviewed in patch 1. option2: I call kobject_put(), if it did fail during init there is an unbalanced situation, which is handled but an annoying WARN() is issued. option3: I check if "state_initialized" which I suppose has been properly initialised during declaration (maybe too paranoic?) and call _put() accordingly } Thanks, Andi _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx