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 CA6B9C433EF for ; Fri, 1 Oct 2021 10:38:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B221361A7F for ; Fri, 1 Oct 2021 10:38:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353620AbhJAKkH (ORCPT ); Fri, 1 Oct 2021 06:40:07 -0400 Received: from mga17.intel.com ([192.55.52.151]:21683 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353615AbhJAKkH (ORCPT ); Fri, 1 Oct 2021 06:40:07 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10123"; a="205551172" X-IronPort-AV: E=Sophos;i="5.85,337,1624345200"; d="scan'208";a="205551172" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Oct 2021 03:38:23 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.85,337,1624345200"; d="scan'208";a="709724066" Received: from linux.intel.com ([10.54.29.200]) by fmsmga005.fm.intel.com with ESMTP; 01 Oct 2021 03:38:23 -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 1E93B580223; Fri, 1 Oct 2021 03:38:23 -0700 (PDT) Message-ID: Subject: Re: [PATCH 5/5] 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, bhelgaas@google.com, andriy.shevchenko@linux.intel.com, srinivas.pandruvada@intel.com, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-pci@vger.kernel.org Date: Fri, 01 Oct 2021 03:38:23 -0700 In-Reply-To: References: <20211001012815.1999501-1-david.e.box@linux.intel.com> <20211001012815.1999501-6-david.e.box@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-doc@vger.kernel.org On Fri, 2021-10-01 at 09:14 +0200, Greg KH wrote: > On Thu, Sep 30, 2021 at 06:28:15PM -0700, David E. Box wrote: > > +static int sdsi_device_open(struct inode *inode, struct file *file) > > +{ > > +       struct miscdevice *miscdev = file->private_data; > > + > > +       get_device(miscdev->this_device); > > Why do you think this is needed?  Shouldn't the misc core handle all of > this for you already? > > > + > > +       return 0; > > +} > > + > > +static int sdsi_device_release(struct inode *inode, struct file *file) > > +{ > > + > > +       struct miscdevice *miscdev = file->private_data; > > +       struct sdsi_priv *priv = to_sdsi_priv(miscdev); > > + > > +       if (priv->akc_owner == file) > > +               priv->akc_owner = NULL; > > Why is this needed? > > > + > > +       put_device(miscdev->this_device); > > I see this matches the open call, but if you do not have this in the > open call, is it needed here as well? > > > +       ret = devm_add_action_or_reset(priv->miscdev.this_device, sdsi_miscdev_remove, priv); > > +       if (ret) > > +               goto deregister_misc; > > I think this is all you need to clean up your device memory, not the > get/put device in open/release, right? It does clean up the memory, but it does so immediately after the device has been unregistered, even if a file is open. The get/put ensures that if files are open, the memory isn't cleaned up until the files are closed. I can show that this happens without the get/put, open() unbind device -> devm action called -> kfree(priv) ioctl() -> priv accessed but it doesn't blow up. I guess because the former location of priv is accessible by container_of on the miscdev. But that memory was freed right? David > > thanks, > > greg k-h