From patchwork Thu Mar 12 07:44:03 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Krzysztof Kozlowski X-Patchwork-Id: 5991681 Return-Path: X-Original-To: patchwork-linux-input@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 4F334BF90F for ; Thu, 12 Mar 2015 07:51:13 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4DC3E200CF for ; Thu, 12 Mar 2015 07:51:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 39F322034F for ; Thu, 12 Mar 2015 07:51:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753547AbbCLHp2 (ORCPT ); Thu, 12 Mar 2015 03:45:28 -0400 Received: from mailout1.w1.samsung.com ([210.118.77.11]:8801 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753020AbbCLHpB (ORCPT ); Thu, 12 Mar 2015 03:45:01 -0400 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 <0NL300EBV9PPUG50@mailout1.w1.samsung.com>; Thu, 12 Mar 2015 07:49:01 +0000 (GMT) X-AuditID: cbfec7f4-b7f126d000001e9a-6d-55014366f920 Received: from eusync2.samsung.com ( [203.254.199.212]) by eucpsbgm1.samsung.com (EUCPMTA) with SMTP id 13.FA.07834.66341055; Thu, 12 Mar 2015 07:42:30 +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 <0NL300KWS9IOZC60@eusync2.samsung.com>; Thu, 12 Mar 2015 07:44:55 +0000 (GMT) From: Krzysztof Kozlowski To: Jiri Kosina , Henrik Rydberg , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Sebastian Reichel , Dmitry Eremin-Solenikov , David Woodhouse , linux-pm@vger.kernel.org Cc: Krzysztof Kozlowski Subject: [RESEND PATCH v6 05/22] power_supply: Add API for safe access of power supply function attrs Date: Thu, 12 Mar 2015 08:44:03 +0100 Message-id: <1426146260-30081-6-git-send-email-k.kozlowski@samsung.com> X-Mailer: git-send-email 1.9.1 In-reply-to: <1426146260-30081-1-git-send-email-k.kozlowski@samsung.com> References: <1426146260-30081-1-git-send-email-k.kozlowski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmplluLIzCtJLcpLzFFi42I5/e/4Fd00Z8ZQg5ZWPYtJT94zW0xcOZnZ YvecxSwWr18YWtz89I3V4vKuOWwWn3uPMFqc+DaNyeL07hIHTo/Pq16xeuycdZfdY/MKLY9N qzrZPPq2rGL0OLPgCLvH501yAexRXDYpqTmZZalF+nYJXBmfzwcWbNSueLh1IXMD42OVLkZO DgkBE4me7utsELaYxIV764FsLg4hgaWMEju27WaGcPqYJCZMec8OUsUmYCyxefkSsCoRgflM Ev2rTrCCJJgFDCV+vvsDViQskC5xakUDI4jNIqAqsXTbD6AaDg5eAXeJE3u5ILbJSZw8Nhks zCngIfF6EQ9IWAioYuayT+wTGHkXMDKsYhRNLU0uKE5KzzXUK07MLS7NS9dLzs/dxAgJui87 GBcfszrEKMDBqMTDG9HHECrEmlhWXJl7iFGCg1lJhJfDijFUiDclsbIqtSg/vqg0J7X4ECMT B6dUA+Pynd+/P9viXnOfd3oEn4EJZ7GSzczPpnu3V3qGLqtW2L5jup+jaqrftJ9HH1nO5bxb /lHI5+P9rqmPqy8pnQm5oPxly/+LeSrPrz3Tj1iw+PfJfwLzDQIm5U1c37Y0cQq/NUOJn+qm +1//C59q8bvZmLwjaVr59p3GN079U27rCDCexLdmFme6EktxRqKhFnNRcSIAB1F79RgCAAA= Sender: linux-input-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-input@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 a21e36ed8d41..583dece8845b 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; @@ -676,6 +720,7 @@ EXPORT_SYMBOL_GPL(devm_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 0d7c95f634a5..7ae60346465f 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);