Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752133AbcDMREp (ORCPT ); Wed, 13 Apr 2016 13:04:45 -0400 Received: from quartz.orcorp.ca ([184.70.90.242]:56097 "EHLO quartz.orcorp.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752033AbcDMREo (ORCPT ); Wed, 13 Apr 2016 13:04:44 -0400 Date: Wed, 13 Apr 2016 11:04:26 -0600 From: Jason Gunthorpe To: Jarkko Sakkinen Cc: Peter Huewe , Marcel Selhorst , "moderated list:TPM DEVICE DRIVER" , open list Subject: Re: [PATCH] tpm: fix crash in tpm_tis deinitialization Message-ID: <20160413170426.GA28411@obsidianresearch.com> References: <1460390720-9509-1-git-send-email-jarkko.sakkinen@linux.intel.com> <20160411174037.GA371@obsidianresearch.com> <20160412042627.GA6608@intel.com> <20160412172655.GA5759@obsidianresearch.com> <20160413061651.GA6986@intel.com> <20160413065805.GB6986@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160413065805.GB6986@intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-Broken-Reverse-DNS: no host name found for IP address 10.0.0.160 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 559 Lines: 14 On Wed, Apr 13, 2016 at 09:58:05AM +0300, Jarkko Sakkinen wrote: > > > It prevents everything including the kernel from issuing a command > > ^^^^^^^^^^^^^^^^^^^^ > > > > That lock is not used to exclude kernel access. Read lock is only taken > > for the user space device in tpm-dev.c. > > My bad. For the in-kernel API it is taken through tpm_find_get(). Right. At this point any thing that can run in-kernel concurrently with the write exclusion is a kernel bug. Those places will need to grab the read side of the lock. Jason