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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 554F7C282C4 for ; Tue, 12 Feb 2019 12:10:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 24F8F20821 for ; Tue, 12 Feb 2019 12:10:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729135AbfBLMK5 (ORCPT ); Tue, 12 Feb 2019 07:10:57 -0500 Received: from cloudserver094114.home.pl ([79.96.170.134]:48583 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727553AbfBLMK4 (ORCPT ); Tue, 12 Feb 2019 07:10:56 -0500 Received: from 79.184.254.36.ipv4.supernova.orange.pl (79.184.254.36) (HELO aspire.rjw.lan) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.183) id 3f8de3721c143816; Tue, 12 Feb 2019 13:10:54 +0100 From: "Rafael J. Wysocki" To: Greg Kroah-Hartman Cc: LKML , Linux PM , Ulf Hansson , Daniel Vetter , Lukas Wunner , Andrzej Hajda , Russell King - ARM Linux , Lucas Stach , Linus Walleij , Thierry Reding , Laurent Pinchart , Marek Szyprowski Subject: [PATCH 1/2] PM-runtime: Fix __pm_runtime_set_status() race with runtime resume Date: Tue, 12 Feb 2019 13:04:12 +0100 Message-ID: <1670239.00ZbddH1IV@aspire.rjw.lan> In-Reply-To: <5510642.nRbR3bcduN@aspire.rjw.lan> References: <5510642.nRbR3bcduN@aspire.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rafael J. Wysocki Commit 4080ab083000 ("PM-runtime: Take suppliers into account in __pm_runtime_set_status()") introduced a race condition that may trigger if __pm_runtime_set_status() is used incorrectly (that is, if it is called when PM-runtime is enabled for the target device and working). In that case, if the original PM-runtime status of the device is RPM_SUSPENDED, a runtime resume of the device may occur after __pm_runtime_set_status() has dropped its power.lock spinlock and before deactivating its suppliers, so the suppliers may be deactivated while the device is PM-runtime-active which may lead to functional issues. To avoid that, modify __pm_runtime_set_status() to check whether or not PM-runtime is enabled for the device before activating its suppliers (if the new status is RPM_ACTIVE) and either return an error if that's the case or increment the device's disable_depth counter to prevent PM-runtime from being enabled for it while the remaining part of the function is running (disable_depth is then decremented on the way out). Fixes: 4080ab083000 ("PM-runtime: Take suppliers into account in __pm_runtime_set_status()") Signed-off-by: Rafael J. Wysocki --- drivers/base/power/runtime.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) Index: linux-pm/drivers/base/power/runtime.c =================================================================== --- linux-pm.orig/drivers/base/power/runtime.c +++ linux-pm/drivers/base/power/runtime.c @@ -1129,6 +1129,22 @@ int __pm_runtime_set_status(struct devic if (status != RPM_ACTIVE && status != RPM_SUSPENDED) return -EINVAL; + spin_lock_irq(&dev->power.lock); + + /* + * Prevent PM-runtime from being enabled for the device or return an + * error if it is enabled already and working. + */ + if (dev->power.runtime_error || dev->power.disable_depth) + dev->power.disable_depth++; + else + error = -EAGAIN; + + spin_unlock_irq(&dev->power.lock); + + if (error) + return error; + /* * If the new status is RPM_ACTIVE, the suppliers can be activated * upfront regardless of the current status, because next time @@ -1147,12 +1163,6 @@ int __pm_runtime_set_status(struct devic spin_lock_irq(&dev->power.lock); - if (!dev->power.runtime_error && !dev->power.disable_depth) { - status = dev->power.runtime_status; - error = -EAGAIN; - goto out; - } - if (dev->power.runtime_status == status || !parent) goto out_set; @@ -1205,6 +1215,8 @@ int __pm_runtime_set_status(struct devic device_links_read_unlock(idx); } + pm_runtime_enable(dev); + return error; } EXPORT_SYMBOL_GPL(__pm_runtime_set_status);