From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755299Ab2D0Vto (ORCPT ); Fri, 27 Apr 2012 17:49:44 -0400 Received: from ogre.sisk.pl ([193.178.161.156]:42215 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755004Ab2D0Vtl (ORCPT ); Fri, 27 Apr 2012 17:49:41 -0400 From: "Rafael J. Wysocki" To: Linux PM list Subject: [PATCH 1/2] PM / QoS: Create device constraints objects on notifier registration Date: Fri, 27 Apr 2012 23:48:18 +0200 User-Agent: KMail/1.13.6 (Linux/3.4.0-rc4+; KDE/4.6.0; x86_64; ; ) Cc: LKML , Kevin Hilman , Magnus Damm , Mark Brown , markgross@thegnar.org, Jean Pihet References: <201204272346.44145.rjw@sisk.pl> In-Reply-To: <201204272346.44145.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201204272348.18533.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rafael J. Wysocki The current behavior of dev_pm_qos_add_notifier() makes device PM QoS notifiers less than useful. Namely, it silently returns success when called before any PM QoS constraints are added for the device, so the caller will assume that the notifier has been registered, but when someone actually adds some nontrivial constraints for the device eventually, the previous callers of dev_pm_qos_add_notifier() will not know about that and their notifier routines will not be executed (contrary to their expectations). To address this problem make dev_pm_qos_add_notifier() create the constraints object for the device if it is not present when the routine is called. Signed-off-by: Rafael J. Wysocki --- drivers/base/power/qos.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) Index: linux/drivers/base/power/qos.c =================================================================== --- linux.orig/drivers/base/power/qos.c +++ linux/drivers/base/power/qos.c @@ -352,21 +352,26 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_remove_requ * * Will register the notifier into a notification chain that gets called * upon changes to the target value for the device. + * + * If the device's constraints object doesn't exist when this routine is called, + * it will be created (or error code will be returned if that fails). */ int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier) { - int retval = 0; + int ret = 0; mutex_lock(&dev_pm_qos_mtx); - /* Silently return if the constraints object is not present. */ - if (dev->power.constraints) - retval = blocking_notifier_chain_register( - dev->power.constraints->notifiers, - notifier); + if (!dev->power.constraints) + ret = dev->power.power_state.event != PM_EVENT_INVALID ? + dev_pm_qos_constraints_allocate(dev) : -ENODEV; + + if (!ret) + ret = blocking_notifier_chain_register( + dev->power.constraints->notifiers, notifier); mutex_unlock(&dev_pm_qos_mtx); - return retval; + return ret; } EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier);