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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 85DBCC43441 for ; Sat, 10 Nov 2018 18:36:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4B3E120854 for ; Sat, 10 Nov 2018 18:36:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4B3E120854 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726876AbeKKEWc (ORCPT ); Sat, 10 Nov 2018 23:22:32 -0500 Received: from mga04.intel.com ([192.55.52.120]:65482 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726422AbeKKEWc (ORCPT ); Sat, 10 Nov 2018 23:22:32 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Nov 2018 10:36:36 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,488,1534834800"; d="scan'208";a="91056032" Received: from smile.fi.intel.com (HELO smile) ([10.237.72.86]) by orsmga008.jf.intel.com with ESMTP; 10 Nov 2018 10:36:30 -0800 Received: from andy by smile with local (Exim 4.91) (envelope-from ) id 1gLY7R-0003w1-0r; Sat, 10 Nov 2018 20:36:29 +0200 Date: Sat, 10 Nov 2018 20:36:29 +0200 From: Andy Shevchenko To: Greg Kroah-Hartman Cc: MyungJoo Ham , Chanwoo Choi , linux-usb@vger.kernel.org, Felipe Balbi , Guenter Roeck , Heikki Krogerus , Roger Quadros , linux-pm@vger.kernel.org, "Rafael J. Wysocki" , Sebastian Reichel , linux-omap@vger.kernel.org, Darren Hart , platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org, Chen-Yu Tsai , Hans de Goede , Grant Likely , Peter Ujfalusi , Mark Brown , Andrzej Hajda Subject: Re: [PATCH v1 1/5] drivercore: Revert "deferral race condition fix" Message-ID: <20181110183629.GE10650@smile.fi.intel.com> References: <20181110181101.24557-1-andriy.shevchenko@linux.intel.com> <20181110182622.GA32657@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181110182622.GA32657@kroah.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Nov 10, 2018 at 10:26:22AM -0800, Greg Kroah-Hartman wrote: > On Sat, Nov 10, 2018 at 08:10:57PM +0200, Andy Shevchenko wrote: > > Consider the following scenario. > > > > There are two independent devices coupled together by functional dependencies: > > - USB OTG (dwc3-pci) > > - extcon (tested with extcon-intel-mrfld, not yet in upstream) > > > > Each of the driver services a corresponding device is built as a module. In the > > Buildroot environment the modules are probed by alphabetical ordering of their > > modaliases. The latter comes to the case when USB OTG driver will be probed > > first followed by extcon one. > > > > So, if the platform anticipates extcon device to be appeared, in the above case > > we will get deferred probe of USB OTG, because of ordering. > > > > Now, a cherry on top of the cake, the deferred probing list contains > > the only two modules, i.e. USB OTG and extcon. Due to above circumstances, > > values in the local_trigger_count and deferred_trigger_count are not the same, > > and thus provokes deferred probe triggering again and again. > > > > ... > > [ 20.678332] platform dwc3.0.auto: Retrying from deferred list > > [ 20.694743] platform dwc3.0.auto: Driver dwc3 requests probe deferral > > [ 20.701254] platform dwc3.0.auto: Added to deferred list > > [ 20.706620] platform dwc3.0.auto: driver_deferred_probe_add_trigger 1 2 > > [ 20.713732] platform dwc3.0.auto: Retrying from deferred list > > [ 20.730035] platform dwc3.0.auto: Driver dwc3 requests probe deferral > > [ 20.736540] platform dwc3.0.auto: Added to deferred list > > [ 20.741889] platform dwc3.0.auto: driver_deferred_probe_add_trigger 3 4 > > [ 20.748991] platform dwc3.0.auto: Retrying from deferred list > > [ 20.765416] platform dwc3.0.auto: Driver dwc3 requests probe deferral > > [ 20.771914] platform dwc3.0.auto: Added to deferred list > > [ 20.777279] platform dwc3.0.auto: driver_deferred_probe_add_trigger 5 6 > > ... > > > > Deeper investigation shows the culprit commit 58b116bce136 > > ("drivercore: deferral race condition fix") which was dedicated to fix some > > other issue while bringing a regression. > > > > This reverts commit 58b116bce13612e5aa6fcd49ecbd4cf8bb59e835 for good until > > we will have better solution. > > > > Cc: Grant Likely > > Cc: Peter Ujfalusi > > Cc: Greg Kroah-Hartman > > Cc: Mark Brown > > Cc: Felipe Balbi > > Cc: Andrzej Hajda > > Signed-off-by: Andy Shevchenko > > --- > > drivers/base/dd.c | 27 ++------------------------- > > 1 file changed, 2 insertions(+), 25 deletions(-) > > Shouldn't there be a "Fixes:" line and cc: stable here? I'm not sure (yet). I would like to hear from people first, especially from Grant (I spoke to him already for the matters at ELCE in Edinburg). Perhaps, Hans can have a chance to test this and comment on. -- With Best Regards, Andy Shevchenko