Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756861Ab0FIJPv (ORCPT ); Wed, 9 Jun 2010 05:15:51 -0400 Received: from ist.d-labs.de ([213.239.218.44]:49390 "EHLO mx01.d-labs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755615Ab0FIJPu (ORCPT ); Wed, 9 Jun 2010 05:15:50 -0400 From: florian@mickler.org To: pm list Cc: james.bottomley@suse.de, markgross@thegnar.org, mgross@linux.intel.com, Florian Mickler , Frederic Weisbecker , Jonathan Corbet , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: [PATCH 2/2] pm_qos: make update_request callable from interrupt context Date: Wed, 9 Jun 2010 11:15:14 +0200 Message-Id: <1276074915-26879-2-git-send-email-florian@mickler.org> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1276074915-26879-1-git-send-email-florian@mickler.org> References: <1276074915-26879-1-git-send-email-florian@mickler.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6264 Lines: 179 The pm_qos framework has to guarantee atomic notifications so that drivers can request and release constraints at all times while no races occur. In order to avoid implementing a secondary notification chain in which listeners might sleep, we demand that every listener implements it's notification so that it can run in interrupt context. The listener is in a better position to know if races are harmful or not. Signed-off-by: Florian Mickler --- kernel/pm_qos_params.c | 50 ++++++++++++++++++++++++------------------------ 1 files changed, 25 insertions(+), 25 deletions(-) diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c index f42d3f7..d918605 100644 --- a/kernel/pm_qos_params.c +++ b/kernel/pm_qos_params.c @@ -63,7 +63,7 @@ static s32 min_compare(s32 v1, s32 v2); struct pm_qos_object { struct pm_qos_request_list requests; - struct blocking_notifier_head *notifiers; + struct atomic_notifier_head *notifiers; struct miscdevice pm_qos_power_miscdev; char *name; s32 default_value; @@ -72,7 +72,7 @@ struct pm_qos_object { }; static struct pm_qos_object null_pm_qos; -static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier); +static ATOMIC_NOTIFIER_HEAD(cpu_dma_lat_notifier); static struct pm_qos_object cpu_dma_pm_qos = { .requests = {LIST_HEAD_INIT(cpu_dma_pm_qos.requests.list)}, .notifiers = &cpu_dma_lat_notifier, @@ -82,7 +82,7 @@ static struct pm_qos_object cpu_dma_pm_qos = { .comparitor = min_compare }; -static BLOCKING_NOTIFIER_HEAD(network_lat_notifier); +static ATOMIC_NOTIFIER_HEAD(network_lat_notifier); static struct pm_qos_object network_lat_pm_qos = { .requests = {LIST_HEAD_INIT(network_lat_pm_qos.requests.list)}, .notifiers = &network_lat_notifier, @@ -93,7 +93,7 @@ static struct pm_qos_object network_lat_pm_qos = { }; -static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier); +static ATOMIC_NOTIFIER_HEAD(network_throughput_notifier); static struct pm_qos_object network_throughput_pm_qos = { .requests = {LIST_HEAD_INIT(network_throughput_pm_qos.requests.list)}, .notifiers = &network_throughput_notifier, @@ -103,7 +103,6 @@ static struct pm_qos_object network_throughput_pm_qos = { .comparitor = max_compare }; - static struct pm_qos_object *pm_qos_array[] = { &null_pm_qos, &cpu_dma_pm_qos, @@ -135,35 +134,30 @@ static s32 min_compare(s32 v1, s32 v2) return min(v1, v2); } - static void update_target(int pm_qos_class) { s32 extreme_value; + struct pm_qos_object *obj = pm_qos_array[pm_qos_class]; struct pm_qos_request_list *node; unsigned long flags; int call_notifier = 0; spin_lock_irqsave(&pm_qos_lock, flags); - extreme_value = pm_qos_array[pm_qos_class]->default_value; - list_for_each_entry(node, - &pm_qos_array[pm_qos_class]->requests.list, list) { - extreme_value = pm_qos_array[pm_qos_class]->comparitor( - extreme_value, node->value); + extreme_value = obj->default_value; + list_for_each_entry(node, &obj->requests.list, list) { + extreme_value = obj->comparitor(extreme_value, node->value); } - if (atomic_read(&pm_qos_array[pm_qos_class]->target_value) != - extreme_value) { + if (atomic_read(&obj->target_value) != extreme_value) { call_notifier = 1; - atomic_set(&pm_qos_array[pm_qos_class]->target_value, - extreme_value); + atomic_set(&obj->target_value, extreme_value); pr_debug(KERN_ERR "new target for qos %d is %d\n", pm_qos_class, - atomic_read(&pm_qos_array[pm_qos_class]->target_value)); + atomic_read(&obj->target_value)); } spin_unlock_irqrestore(&pm_qos_lock, flags); if (call_notifier) - blocking_notifier_call_chain( - pm_qos_array[pm_qos_class]->notifiers, - (unsigned long) extreme_value, NULL); + atomic_notifier_call_chain(obj->notifiers, + (unsigned long) extreme_value, NULL); } static int register_pm_qos_misc(struct pm_qos_object *qos) @@ -272,6 +266,7 @@ EXPORT_SYMBOL_GPL(pm_qos_update_request); /** * pm_qos_remove_request - modifies an existing qos request + * * @pm_qos_req: handle to request list element * * Will remove pm qos request from the list of requests and @@ -298,18 +293,21 @@ EXPORT_SYMBOL_GPL(pm_qos_remove_request); /** * pm_qos_add_notifier - sets notification entry for changes to target value + * + * Note: The notifier has to be callable from interrupt context. + * * @pm_qos_class: identifies which qos target changes should be notified. * @notifier: notifier block managed by caller. * - * will register the notifier into a notification chain that gets called + * Will register the notifier into a notification chain that gets called * upon changes to the pm_qos_class target value. */ int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier) { int retval; - retval = blocking_notifier_chain_register( - pm_qos_array[pm_qos_class]->notifiers, notifier); + retval = atomic_notifier_chain_register( + pm_qos_array[pm_qos_class]->notifiers, notifier); return retval; } @@ -317,18 +315,19 @@ EXPORT_SYMBOL_GPL(pm_qos_add_notifier); /** * pm_qos_remove_notifier - deletes notification entry from chain. + * * @pm_qos_class: identifies which qos target changes are notified. * @notifier: notifier block to be removed. * - * will remove the notifier from the notification chain that gets called + * Will remove the notifier from the notification chain that gets called * upon changes to the pm_qos_class target value. */ int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier) { int retval; - retval = blocking_notifier_chain_unregister( - pm_qos_array[pm_qos_class]->notifiers, notifier); + retval = atomic_notifier_chain_unregister( + pm_qos_array[pm_qos_class]->notifiers, notifier); return retval; } @@ -381,6 +380,7 @@ static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf, } else return -EINVAL; + pm_qos_req = (struct pm_qos_request_list *)filp->private_data; pm_qos_update_request(pm_qos_req, value); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/