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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 DD048C433EA for ; Mon, 22 Mar 2021 12:36:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C4A10619D2 for ; Mon, 22 Mar 2021 12:36:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231680AbhCVMgd (ORCPT ); Mon, 22 Mar 2021 08:36:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:56314 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231760AbhCVMfH (ORCPT ); Mon, 22 Mar 2021 08:35:07 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9E92461998; Mon, 22 Mar 2021 12:35:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1616416503; bh=85xbLg0N24rYjYG9rU+hPSlW4FE4imDZ2NNfjYfcj2M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XPuAiYIvZU+32XfGXqebUh/jDGgYx1grN2Y+GFHBXIjKT4cKbpW7pFU/wgls4Wpe0 39/j85yfST1hmiEp3TlNrXq6elQuJ0K6NX50pvBFuSssqBRpy+MshDJyxELepmRpPs O1rxtBKeoDVpHibkbdFVAZIAqfRHnfeFjc53bJ9Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Adrian Hunter , "Rafael J. Wysocki" , Ulf Hansson Subject: [PATCH 5.10 011/157] Revert "PM: runtime: Update device status before letting suppliers suspend" Date: Mon, 22 Mar 2021 13:26:08 +0100 Message-Id: <20210322121934.121922029@linuxfoundation.org> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20210322121933.746237845@linuxfoundation.org> References: <20210322121933.746237845@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Rafael J. Wysocki commit 0cab893f409c53634d0d818fa414641cbcdb0dab upstream. Revert commit 44cc89f76464 ("PM: runtime: Update device status before letting suppliers suspend") that introduced a race condition into __rpm_callback() which allowed a concurrent rpm_resume() to run and resume the device prematurely after its status had been changed to RPM_SUSPENDED by __rpm_callback(). Fixes: 44cc89f76464 ("PM: runtime: Update device status before letting suppliers suspend") Link: https://lore.kernel.org/linux-pm/24dfb6fc-5d54-6ee2-9195-26428b7ecf8a@intel.com/ Reported-by: Adrian Hunter Cc: 4.10+ # 4.10+ Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Signed-off-by: Greg Kroah-Hartman --- drivers/base/power/runtime.c | 62 +++++++++++++++++-------------------------- 1 file changed, 25 insertions(+), 37 deletions(-) --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -325,22 +325,22 @@ static void rpm_put_suppliers(struct dev static int __rpm_callback(int (*cb)(struct device *), struct device *dev) __releases(&dev->power.lock) __acquires(&dev->power.lock) { - bool use_links = dev->power.links_count > 0; - bool get = false; int retval, idx; - bool put; + bool use_links = dev->power.links_count > 0; if (dev->power.irq_safe) { spin_unlock(&dev->power.lock); - } else if (!use_links) { - spin_unlock_irq(&dev->power.lock); } else { - get = dev->power.runtime_status == RPM_RESUMING; - spin_unlock_irq(&dev->power.lock); - /* Resume suppliers if necessary. */ - if (get) { + /* + * Resume suppliers if necessary. + * + * The device's runtime PM status cannot change until this + * routine returns, so it is safe to read the status outside of + * the lock. + */ + if (use_links && dev->power.runtime_status == RPM_RESUMING) { idx = device_links_read_lock(); retval = rpm_get_suppliers(dev); @@ -355,36 +355,24 @@ static int __rpm_callback(int (*cb)(stru if (dev->power.irq_safe) { spin_lock(&dev->power.lock); - return retval; - } - - spin_lock_irq(&dev->power.lock); - - if (!use_links) - return retval; - - /* - * If the device is suspending and the callback has returned success, - * drop the usage counters of the suppliers that have been reference - * counted on its resume. - * - * Do that if the resume fails too. - */ - put = dev->power.runtime_status == RPM_SUSPENDING && !retval; - if (put) - __update_runtime_status(dev, RPM_SUSPENDED); - else - put = get && retval; - - if (put) { - spin_unlock_irq(&dev->power.lock); - - idx = device_links_read_lock(); + } else { + /* + * If the device is suspending and the callback has returned + * success, drop the usage counters of the suppliers that have + * been reference counted on its resume. + * + * Do that if resume fails too. + */ + if (use_links + && ((dev->power.runtime_status == RPM_SUSPENDING && !retval) + || (dev->power.runtime_status == RPM_RESUMING && retval))) { + idx = device_links_read_lock(); -fail: - rpm_put_suppliers(dev); + fail: + rpm_put_suppliers(dev); - device_links_read_unlock(idx); + device_links_read_unlock(idx); + } spin_lock_irq(&dev->power.lock); }