From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751371AbdAPJJn (ORCPT ); Mon, 16 Jan 2017 04:09:43 -0500 Received: from mga04.intel.com ([192.55.52.120]:25587 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750855AbdAPJJl (ORCPT ); Mon, 16 Jan 2017 04:09:41 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,238,1477983600"; d="scan'208";a="1094645330" Date: Mon, 16 Jan 2017 11:09:31 +0200 From: Jarkko Sakkinen To: James Bottomley Cc: tpmdd-devel@lists.sourceforge.net, open list , linux-security-module@vger.kernel.org Subject: Re: [tpmdd-devel] [PATCH RFC v2 3/5] tpm: infrastructure for TPM spaces Message-ID: <20170116090931.dzdv4tcvhj4m4rrl@intel.com> References: <20170112174612.9314-1-jarkko.sakkinen@linux.intel.com> <20170112174612.9314-4-jarkko.sakkinen@linux.intel.com> <1484270243.5807.31.camel@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1484270243.5807.31.camel@linux.vnet.ibm.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.6.2-neo (2016-08-21) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 12, 2017 at 05:17:23PM -0800, James Bottomley wrote: > On Thu, 2017-01-12 at 19:46 +0200, Jarkko Sakkinen wrote: > > @@ -189,6 +190,12 @@ struct tpm_chip *tpm_chip_alloc(struct device > > *pdev, > > chip->cdev.owner = THIS_MODULE; > > chip->cdev.kobj.parent = &chip->dev.kobj; > > > > + chip->work_space.context_buf = kzalloc(PAGE_SIZE, > > GFP_KERNEL); > > + if (!chip->work_space.context_buf) { > > + rc = -ENOMEM; > > + goto out; > > + } > > + > > I think the work_buf handling can be greatly simplified by making it a > pointer to the space: it's only usable between tpm2_prepare_space() and > tpm2_commit_space() which are protected by the chip mutex, so there's > no need for it to exist outside of these calls (i.e. it can be NULL). > > Doing it this way also saves the allocation and copying overhead of > work_space. > > The patch below can be folded to effect this. Hey, I have to take my words back. There's a separate buffer for space for a reason. If the transaction fails for example when RM is doing its job, we can revert to the previous set of transient objects. Your change would completely thrawt this. I tried varius ways to heal when RM decorations fail and this is the most fail safe to do it so lets stick with it. > James /Jarkko