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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D834FC433F5 for ; Mon, 27 Sep 2021 17:53:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BCB6560EE2 for ; Mon, 27 Sep 2021 17:53:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235870AbhI0Ryz (ORCPT ); Mon, 27 Sep 2021 13:54:55 -0400 Received: from mga07.intel.com ([134.134.136.100]:49997 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235703AbhI0Ryr (ORCPT ); Mon, 27 Sep 2021 13:54:47 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10120"; a="288190732" X-IronPort-AV: E=Sophos;i="5.85,327,1624345200"; d="scan'208";a="288190732" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Sep 2021 10:53:09 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.85,327,1624345200"; d="scan'208";a="456328547" Received: from linux.intel.com ([10.54.29.200]) by orsmga002.jf.intel.com with ESMTP; 27 Sep 2021 10:53:09 -0700 Received: from debox1-desk1.jf.intel.com (debox1-desk1.jf.intel.com [10.54.75.53]) by linux.intel.com (Postfix) with ESMTP id 66BCA5802BD; Mon, 27 Sep 2021 10:53:09 -0700 (PDT) Message-ID: <10bee4a609c48b8e10458c25755f17222c43c33c.camel@linux.intel.com> Subject: Re: [PATCH 2/2] platform/x86: Add Intel Software Defined Silicon driver From: "David E. Box" Reply-To: david.e.box@linux.intel.com To: Greg KH Cc: lee.jones@linaro.org, hdegoede@redhat.com, mgross@linux.intel.com, andriy.shevchenko@linux.intel.com, srinivas.pandruvada@intel.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org Date: Mon, 27 Sep 2021 10:53:09 -0700 In-Reply-To: References: <20210924213157.3584061-1-david.e.box@linux.intel.com> <20210924213157.3584061-2-david.e.box@linux.intel.com> <3392aea6b112926b063bbe46b1decaad4c9f9e6e.camel@linux.intel.com> Organization: David E. Box Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.4 (3.38.4-1.fc33) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2021-09-27 at 06:03 +0200, Greg KH wrote: > On Sun, Sep 26, 2021 at 06:15:16PM -0700, David E. Box wrote: > > > > +static int sdsi_remove(struct platform_device *pdev) > > > > +{ > > > > +       struct sdsi_priv *priv = platform_get_drvdata(pdev); > > > > + > > > > +       priv->dev_present = false; > > > > +       sysfs_remove_bin_file(&priv->pdev->dev.kobj, &priv->registers_bin_attr); > > > > +       misc_deregister(&priv->miscdev); > > > > +       kref_put(&priv->kref, sdsi_priv_release); > > > > > > Why do you need a kref for a structure that already can be controlled by > > > a different lifetime rule? > > > > Which rule am I missing? This kref allows the structure to remain in case the device is removed > > while the file is open. > > This device is on a hardware bus that allows removal? Well the device can be unbound. A test case covers this. > > Anyway, you now are dealing with lifetime rules of 3 structures all at > once, and the interactions between them is not very obvious.  It would > probably be simpler just to stick with 2, right?  You really only care > about the misc structure here. In the case that the device is unbound, both the pdev and miscdev go away. Something has to outlive them in order to handle any open files still trying to use the ioctl. David > > thanks, > > greg k-h