Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933566AbaJUVC0 (ORCPT ); Tue, 21 Oct 2014 17:02:26 -0400 Received: from quartz.orcorp.ca ([184.70.90.242]:39644 "EHLO quartz.orcorp.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933224AbaJUVCY (ORCPT ); Tue, 21 Oct 2014 17:02:24 -0400 Date: Tue, 21 Oct 2014 15:02:15 -0600 From: Jason Gunthorpe To: Jarkko Sakkinen Cc: Peter Huewe , Ashley Lai , Marcel Selhorst , tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [tpmdd-devel] [PATCH] tpm: fix multiple race conditions in tpm_ppi.c Message-ID: <20141021210215.GA31755@obsidianresearch.com> References: <1413879761-25392-1-git-send-email-jarkko.sakkinen@linux.intel.com> <20141021165551.GA28382@obsidianresearch.com> <20141021204251.GA5438@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141021204251.GA5438@intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Broken-Reverse-DNS: no host name found for IP address 10.0.0.161 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 21, 2014 at 11:42:51PM +0300, Jarkko Sakkinen wrote: > > Personally, I'd sequence this commit right after your 'tpm: two-phase > > chip management functions' commit because it makes it much saner (no > > half step toward the new functions). I assume this is a theoretical > > problem? Or do you have a two TPM system? > > This has realized in Intel NUCs where there is PTT and dTPM module. Even > when PTT is selected there is still ACPI device for dTPM so three is a > race condition and PPI is unusable. I think that it's not good that code is > not robust enough to deal with this. Oh OK, you should probably explain in the commit log that this is a bug fix that impacts real hardware, that qualifies it for the -stable tree. Assuming two-phase commit is nearly ready to go, I'd still sequence this fix after two-phase for mainline and then use this patch as-is for the 3.17 -stable backport of the mainline commit. > Even if you forget the race condition it feels waste to lookup a handle > that is already known. There is no doubt that this new arrangement is much better than what was there before! Thanks, Jason -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/