From patchwork Wed Apr 8 07:26:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Stultz X-Patchwork-Id: 11479537 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8014214B4 for ; Wed, 8 Apr 2020 07:27:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 54F042074F for ; Wed, 8 Apr 2020 07:27:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="Z+eW7VdI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726893AbgDHH1A (ORCPT ); Wed, 8 Apr 2020 03:27:00 -0400 Received: from mail-pj1-f65.google.com ([209.85.216.65]:34002 "EHLO mail-pj1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726885AbgDHH07 (ORCPT ); Wed, 8 Apr 2020 03:26:59 -0400 Received: by mail-pj1-f65.google.com with SMTP id q16so1930603pje.1 for ; Wed, 08 Apr 2020 00:26:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=MmpEQ8SQC6Xl5tR7Jjj5y8uD8BC/8L8xLziXkQ0TWVI=; b=Z+eW7VdIANVP+y7K6bQ7lohbpmARsE8zZhuKT6N6QZUHELquqVNPm9CQ7F1SLG7RYS QIdpR3lDKGieyLPJ0t7fBN9hqU017Ekfn1idJP58ax8+d6CR4DdzOSkuV9dAs/B0PhgF DSZFB10RTROOOWvuV4752//VE1+P9z1sNXB83AHPCBQT51jB8SkiisAOqvfedZ58/p8d YwGW5wlHsBud4pZ0OLcZ6LYZESBsqCRrVY2oC/ziYwL9X1n2QCZYKLe71lpMS6FC8adA +uhz6cm1LtsjPcCIGOdBcTHcmEqpXVzn7LY68DsRxuCjOCLb2zkaEKfO3HL6LxETGtG7 Hsug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=MmpEQ8SQC6Xl5tR7Jjj5y8uD8BC/8L8xLziXkQ0TWVI=; b=jkJaGjPSKI4a2r6S14SmLNElkFmQnXP7SP0fU1hUtXkN++Qr2ROgZGigeBzIZBoO1h 3GGhJ3aEWHwwB255ObI0yEUfgMNl73g/6LY5mKGxNIZjtWm9u2iPWm9cyAkolMdxxRCi RmEVUEfq+DYQiO/1uhxrmpuoImt+mS1e31iyTUeE7g88QtA8tyloctPOiw3c6W0BZGkF i88u7/ND71TeuR5ua9LQK9rkWNcxZOjFdNFppK3Ak5IxXIk8O3SORrm6HqKESQca7RQc xVo6fzg/ONqfUAQzKccZkWLMfIoSyu2FfheWkdAl4DLv0i4kvXZ35OpzRzP+a17dsj+F 6Ewg== X-Gm-Message-State: AGi0PuYfrfW8bZzsm+urXtW0Gd1QOjHfr7k+o42j15ISCT9p/aTWaGD2 aTYuC35hivU3lv0pJBIERrdXsw== X-Google-Smtp-Source: APiQypJY5jt1Z+kCEh8DOZw5UuW9RxeqX3HfnqdnLIu6JVDPye1OyCCRnTHl4q5Efv/HapSv97ToSg== X-Received: by 2002:a17:902:d303:: with SMTP id b3mr5933935plc.63.1586330818286; Wed, 08 Apr 2020 00:26:58 -0700 (PDT) Received: from localhost.localdomain ([2601:1c2:680:1319:692:26ff:feda:3a81]) by smtp.gmail.com with ESMTPSA id e187sm15356066pfe.143.2020.04.08.00.26.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Apr 2020 00:26:57 -0700 (PDT) From: John Stultz To: lkml Cc: John Stultz , "David S. Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , Jakub Kicinski , Greg Kroah-Hartman , "Rafael J . Wysocki" , Rob Herring , Geert Uytterhoeven , Yoshihiro Shimoda , netdev , linux-pm@vger.kernel.org Subject: [RFC][PATCH v2 2/2] driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires Date: Wed, 8 Apr 2020 07:26:50 +0000 Message-Id: <20200408072650.1731-2-john.stultz@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200408072650.1731-1-john.stultz@linaro.org> References: <20200408072650.1731-1-john.stultz@linaro.org> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org In commit c8c43cee29f6 ("driver core: Fix driver_deferred_probe_check_state() logic"), we set the default driver_deferred_probe_timeout value to 30 seconds to allow for drivers that are missing dependencies to have some time so that the dependency may be loaded from userland after initcalls_done is set. However, Yoshihiro Shimoda reported that on his device that expects to have unmet dependencies (due to "optional links" in its devicetree), was failing to mount the NFS root. In digging further, it seemed the problem was that while the device properly probes after waiting 30 seconds for any missing modules to load, the ip_auto_config() had already failed, resulting in NFS to fail. This was due to ip_auto_config() calling wait_for_device_probe() which doesn't wait for the driver_deferred_probe_timeout to fire. This patch tries to fix the issue by creating a waitqueue for the driver_deferred_probe_timeout, and calling wait_event() to make sure driver_deferred_probe_timeout is zero in wait_for_device_probe() to make sure all the probing is finished. The downside to this solution is that kernel functionality that uses wait_for_device_probe(), will block until the driver_deferred_probe_timeout fires, regardless of if there is any missing dependencies. However, the previous patch reverts the default timeout value to zero, so this side-effect will only affect users who specify a driver_deferred_probe_timeout= value as a boot argument, where the additional delay would be beneficial to allow modules to load later during boot. Thanks to Geert for chasing down that ip_auto_config was why NFS was failing in this case! Cc: "David S. Miller" Cc: Alexey Kuznetsov Cc: Hideaki YOSHIFUJI Cc: Jakub Kicinski Cc: Greg Kroah-Hartman Cc: Rafael J. Wysocki Cc: Rob Herring Cc: Geert Uytterhoeven Cc: Yoshihiro Shimoda Cc: netdev Cc: linux-pm@vger.kernel.org Reported-by: Yoshihiro Shimoda Fixes: c8c43cee29f6 ("driver core: Fix driver_deferred_probe_check_state() logic") Signed-off-by: John Stultz Tested-by: Yoshihiro Shimoda --- * v2: Split patch, and apply it as a follow-on to setting the driver_deferred_probe_timeout defalt back to zero --- drivers/base/dd.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 908ae4d7805e..5e6c00176969 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -226,6 +226,7 @@ DEFINE_SHOW_ATTRIBUTE(deferred_devs); int driver_deferred_probe_timeout; EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout); +static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue); static int __init deferred_probe_timeout_setup(char *str) { @@ -275,6 +276,7 @@ static void deferred_probe_timeout_work_func(struct work_struct *work) list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe) dev_info(private->device, "deferred probe pending"); + wake_up(&probe_timeout_waitqueue); } static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func); @@ -649,6 +651,9 @@ int driver_probe_done(void) */ void wait_for_device_probe(void) { + /* wait for probe timeout */ + wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout); + /* wait for the deferred probe workqueue to finish */ flush_work(&deferred_probe_work);