From patchwork Mon Feb 23 11:47:24 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Krzysztof Kozlowski X-Patchwork-Id: 5864891 Return-Path: X-Original-To: patchwork-linux-acpi@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id BCD3ABF440 for ; Mon, 23 Feb 2015 11:55:54 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id BA1A320219 for ; Mon, 23 Feb 2015 11:55:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 18EF62062A for ; Mon, 23 Feb 2015 11:55:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753218AbbBWLzB (ORCPT ); Mon, 23 Feb 2015 06:55:01 -0500 Received: from mailout1.w1.samsung.com ([210.118.77.11]:55560 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752244AbbBWLsC (ORCPT ); Mon, 23 Feb 2015 06:48:02 -0500 Received: from eucpsbgm1.samsung.com (unknown [203.254.199.244]) by mailout1.w1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0NK800FLA3MQE4A0@mailout1.w1.samsung.com>; Mon, 23 Feb 2015 11:52:02 +0000 (GMT) X-AuditID: cbfec7f4-b7f126d000001e9a-c5-54eb12dadaf5 Received: from eusync2.samsung.com ( [203.254.199.212]) by eucpsbgm1.samsung.com (EUCPMTA) with SMTP id 85.4A.07834.AD21BE45; Mon, 23 Feb 2015 11:45:30 +0000 (GMT) Received: from AMDC1943.digital.local ([106.116.151.171]) by eusync2.samsung.com (Oracle Communications Messaging Server 7u4-23.01(7.0.4.23.0) 64bit (built Aug 10 2011)) with ESMTPA id <0NK8001843FJ0A90@eusync2.samsung.com>; Mon, 23 Feb 2015 11:47:55 +0000 (GMT) From: Krzysztof Kozlowski To: Sebastian Reichel , Dmitry Eremin-Solenikov , David Woodhouse , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , Len Brown , Jiri Kosina , David Herrmann , Cezary Jackiewicz , Darren Hart , Support Opensource , Milo Kim , Julian Andres Klode , Marc Dietrich , Greg Kroah-Hartman , linux-acpi@vger.kernel.org, linux-input@vger.kernel.org, platform-driver-x86@vger.kernel.org, patches@opensource.wolfsonmicro.com, ac100@lists.launchpad.net, linux-tegra@vger.kernel.org, devel@driverdev.osuosl.org, Linus Walleij , Samuel Ortiz , Lee Jones , linux-arm-kernel@lists.infradead.org, Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Daniel Mack , Haojian Zhuang , Robert Jarzmik Cc: Thomas Gleixner , Pavel Machek , Kyungmin Park , Marek Szyprowski , Krzysztof Kozlowski Subject: [PATCH v4 03/20] power_supply: Add API for safe access of power supply function attrs Date: Mon, 23 Feb 2015 12:47:24 +0100 Message-id: <1424692061-30624-4-git-send-email-k.kozlowski@samsung.com> X-Mailer: git-send-email 1.9.1 In-reply-to: <1424692061-30624-1-git-send-email-k.kozlowski@samsung.com> References: <1424692061-30624-1-git-send-email-k.kozlowski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAAy2RW0iTYRjHe/cdJ00+ZtnXiqJRXRh5QMEni+gi1ksXZSBdFJSrlgqbyqZD S2tZYtNWmmZoVo5ZWza1ZkSeTZ1pUyvNIPOQzYmH7OQ6mR027e75//g9z3PxZwlxPSlh4+KT FOp4uVJK+5COP09ebh4QT0cFDxglcLH7kwDKOnJIyPg9RcLlsY8E1HfNMWDq84dsYzDk3ckn 4KypiobnleFQeH8F3P58k4a6EhMJ0xMh0J3xnoGRr3YENaMzNBTMmwVgbryEwOZ8RcHrL98o 6KstoWHW0IZA7y6moaJtiAH9MyMC81wlCb3NpZ6Nmb80DD2103C3foKALkcvBcXv/cCRQ4Gj LgkaMl8QUG27QsCPe05qx0Zs+RKEhxtbSXypcpbCNcVDDP70+RB25eYzuNoSgMemzBS2letp PPiqnsYfenoYfKNzH266bvUIZaex/cIgiSfzftGRKw/4bDumUMZpFeqg7dE+sbWD80yidVNK wZ+blA4Nr89GQpbnwnjXyENmcfbnnw9X0dnIhxVztxD/zuJGi+GigDfpbiGvRXOhfLW5bMFa xrUL+ccVBoE3EFwv4p1jnQu3/Lho/vVEI5mNWJbkNvCON6u9WMTt4qt+tf5/t4bvbM+nvIqQ w/zIQ60Xiz2K4X4BykWiUrSkHC1XJB9N1ByJUYUEauQqTXJ8TODRBJUNLTbufoRM7REtiGOR dKnorXYqSkzJtZpUVQviWUK6TLTqpweJjslTTyjUCYfVyUqFpgUJWKFEh0SVlk17Gs4cLInU aQsNkVuziiirxE13jI5/39N6arJ5JtAp6RfuPrk2aGnLmqLLHU21x7PionwjHu0aDe2zhqUx DdfO+e7E43OlKQ0yv8Iho111fvrB1dQlfOb+9A/2tevC98qP6MmpokNhjOxg+ZadLqtMGRwg 69/Rn65ypXVJSU2sPCSAUGvk/wDiktGIzwIAAA== Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add simple wrappers for accessing power supply's function attributes: - get_property -> power_supply_get_property - set_property -> power_supply_set_property - property_is_writeable -> power_supply_property_is_writeable - external_power_changed -> power_supply_external_power_changed This API along with atomic usage counter adds a safe way of accessing a power supply from another driver. If power supply is unregistered after obtaining reference to it by some driver, then the API wrappers won't be executed in invalid (freed) context. Next patch changing the ownership of power supply class is still needed to fully fix race conditions in accessing freed power supply. Signed-off-by: Krzysztof Kozlowski Reviewed-by: Bartlomiej Zolnierkiewicz Reviewed-by: Sebastian Reichel Acked-by: Pavel Machek --- drivers/power/power_supply_core.c | 47 ++++++++++++++++++++++++++++++++++++++- include/linux/power_supply.h | 16 +++++++++++++ 2 files changed, 62 insertions(+), 1 deletion(-) diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c index b748391c3e17..0521681b3674 100644 --- a/drivers/power/power_supply_core.c +++ b/drivers/power/power_supply_core.c @@ -314,7 +314,9 @@ EXPORT_SYMBOL_GPL(power_supply_is_system_supplied); int power_supply_set_battery_charged(struct power_supply *psy) { - if (psy->type == POWER_SUPPLY_TYPE_BATTERY && psy->set_charged) { + if (atomic_read(&psy->use_cnt) >= 0 && + psy->type == POWER_SUPPLY_TYPE_BATTERY && + psy->set_charged) { psy->set_charged(psy); return 0; } @@ -366,6 +368,47 @@ struct power_supply *power_supply_get_by_phandle(struct device_node *np, EXPORT_SYMBOL_GPL(power_supply_get_by_phandle); #endif /* CONFIG_OF */ +int power_supply_get_property(struct power_supply *psy, + enum power_supply_property psp, + union power_supply_propval *val) +{ + if (atomic_read(&psy->use_cnt) <= 0) + return -ENODEV; + + return psy->get_property(psy, psp, val); +} +EXPORT_SYMBOL_GPL(power_supply_get_property); + +int power_supply_set_property(struct power_supply *psy, + enum power_supply_property psp, + const union power_supply_propval *val) +{ + if (atomic_read(&psy->use_cnt) <= 0 || !psy->set_property) + return -ENODEV; + + return psy->set_property(psy, psp, val); +} +EXPORT_SYMBOL_GPL(power_supply_set_property); + +int power_supply_property_is_writeable(struct power_supply *psy, + enum power_supply_property psp) +{ + if (atomic_read(&psy->use_cnt) <= 0 || !psy->property_is_writeable) + return -ENODEV; + + return psy->property_is_writeable(psy, psp); +} +EXPORT_SYMBOL_GPL(power_supply_property_is_writeable); + +void power_supply_external_power_changed(struct power_supply *psy) +{ + if (atomic_read(&psy->use_cnt) <= 0 || !psy->external_power_changed) + return; + + psy->external_power_changed(psy); +} +EXPORT_SYMBOL_GPL(power_supply_external_power_changed); + int power_supply_powers(struct power_supply *psy, struct device *dev) { return sysfs_create_link(&psy->dev->kobj, &dev->kobj, "powers"); @@ -555,6 +598,7 @@ static int __power_supply_register(struct device *parent, dev->release = power_supply_dev_release; dev_set_drvdata(dev, psy); psy->dev = dev; + atomic_inc(&psy->use_cnt); if (cfg) { psy->drv_data = cfg->drv_data; psy->of_node = cfg->of_node; @@ -629,6 +673,7 @@ EXPORT_SYMBOL_GPL(power_supply_register_no_ws); void power_supply_unregister(struct power_supply *psy) { + WARN_ON(atomic_dec_return(&psy->use_cnt)); cancel_work_sync(&psy->changed_work); sysfs_remove_link(&psy->dev->kobj, "powers"); power_supply_remove_triggers(psy); diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h index b203a26d5c54..5d460995f38d 100644 --- a/include/linux/power_supply.h +++ b/include/linux/power_supply.h @@ -199,6 +199,12 @@ struct power_supply { size_t num_supplies; struct device_node *of_node; + /* + * Functions for drivers implementing power supply class. + * These shouldn't be called directly by other drivers for accessing + * this power supply. Instead use power_supply_*() functions (for + * example power_supply_get_property()). + */ int (*get_property)(struct power_supply *psy, enum power_supply_property psp, union power_supply_propval *val); @@ -227,6 +233,7 @@ struct power_supply { struct work_struct changed_work; spinlock_t changed_lock; bool changed; + atomic_t use_cnt; #ifdef CONFIG_THERMAL struct thermal_zone_device *tzd; struct thermal_cooling_device *tcd; @@ -287,6 +294,15 @@ extern int power_supply_is_system_supplied(void); static inline int power_supply_is_system_supplied(void) { return -ENOSYS; } #endif +extern int power_supply_get_property(struct power_supply *psy, + enum power_supply_property psp, + union power_supply_propval *val); +extern int power_supply_set_property(struct power_supply *psy, + enum power_supply_property psp, + const union power_supply_propval *val); +extern int power_supply_property_is_writeable(struct power_supply *psy, + enum power_supply_property psp); +extern void power_supply_external_power_changed(struct power_supply *psy); extern int power_supply_register(struct device *parent, struct power_supply *psy, const struct power_supply_config *cfg);