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 X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BA28C43381 for ; Wed, 13 Mar 2019 13:23:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC28C2177E for ; Wed, 13 Mar 2019 13:23:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725876AbfCMNX5 (ORCPT ); Wed, 13 Mar 2019 09:23:57 -0400 Received: from mga05.intel.com ([192.55.52.43]:3991 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725868AbfCMNX5 (ORCPT ); Wed, 13 Mar 2019 09:23:57 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Mar 2019 06:23:56 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,474,1544515200"; d="scan'208";a="126580905" Received: from jsakkine-mobl1.tm.intel.com (HELO localhost) ([10.237.50.103]) by orsmga006.jf.intel.com with ESMTP; 13 Mar 2019 06:23:53 -0700 Date: Wed, 13 Mar 2019 15:23:53 +0200 From: Jarkko Sakkinen To: Mimi Zohar Cc: Calvin Owens , Peter Huewe , Jason Gunthorpe , Arnd Bergmann , Greg Kroah-Hartman , linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH] tpm: Make timeout logic simpler and more robust Message-ID: <20190313132353.GC4261@linux.intel.com> References: <358e89ed2b766d51b5f57abf31ab7a925ac63379.1552348123.git.calvinowens@fb.com> <1552410298.24794.73.camel@linux.ibm.com> <20190313132232.GB4261@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190313132232.GB4261@linux.intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Wed, Mar 13, 2019 at 03:22:32PM +0200, Jarkko Sakkinen wrote: > On Tue, Mar 12, 2019 at 01:04:58PM -0400, Mimi Zohar wrote: > > On Mon, 2019-03-11 at 16:54 -0700, Calvin Owens wrote: > > > We're having lots of problems with TPM commands timing out, and we're > > > seeing these problems across lots of different hardware (both v1/v2). > > > > > > I instrumented the driver to collect latency data, but I wasn't able to > > > find any specific timeout to fix: it seems like many of them are too > > > aggressive. So I tried replacing all the timeout logic with a single > > > universal long timeout, and found that makes our TPMs 100% reliable. > > > > > > Given that this timeout logic is very complex, problematic, and appears > > > to serve no real purpose, I propose simply deleting all of it. > > > > Normally before sending such a massive change like this, included in > > the bug report or patch description, there would be some indication as > > to which kernel introduced a regression.  Has this always been a > > problem?  Is this something new?  How new? > > Also: is the problem in timeouts, durations or both. Does make sense > to fix something that isn't broken... And maybe the fix is a too big hammer. We could possibly just decrease the granularity but fully take it away. /Jarkko