From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756070AbdABVBT (ORCPT ); Mon, 2 Jan 2017 16:01:19 -0500 Received: from quartz.orcorp.ca ([184.70.90.242]:52277 "EHLO quartz.orcorp.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751884AbdABVBN (ORCPT ); Mon, 2 Jan 2017 16:01:13 -0500 Date: Mon, 2 Jan 2017 14:01:01 -0700 From: Jason Gunthorpe To: Jarkko Sakkinen Cc: tpmdd-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org, Peter Huewe , Marcel Selhorst , open list Subject: Re: [PATCH RFC 1/4] tpm: migrate struct tpm_buf to struct tpm_chip Message-ID: <20170102210101.GA5544@obsidianresearch.com> References: <20170102132213.22880-1-jarkko.sakkinen@linux.intel.com> <20170102132213.22880-2-jarkko.sakkinen@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170102132213.22880-2-jarkko.sakkinen@linux.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 02, 2017 at 03:22:07PM +0200, Jarkko Sakkinen wrote: > Since there is only one thread using TPM chip at a time to transmit data > we can migrate struct tpm_buf to struct tpm_chip. This makes the use of > it more fail safe as the buffer is allocated from heap when the device > is created and not for every transaction. Eh? What? I don't think that is the case.. We don't serialize until we hit tramsit_cmd at which point the buffer is already being used and cannot be shared between threads. Only /dev/tpmX has any sort of locking, but even that is designed to be optional (eg I patch it out of my kernels), and only covers userspace, not contention with in-kernel threads. Why would the resource manager need a single global tpm buffer? That seems like a big regression from where we have been going. I don't think this is a good idea to go down this road. > - tpm_buf_append(buf, (u8 *) &value2, 4); > + tpm_buf_append(buf, (u8 *)&value2, 4); Please try and avoid this sort of churn in patches that change things.. Jason