From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752197AbaHTNm1 (ORCPT ); Wed, 20 Aug 2014 09:42:27 -0400 Received: from mailout3.samsung.com ([203.254.224.33]:60634 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752161AbaHTNmY (ORCPT ); Wed, 20 Aug 2014 09:42:24 -0400 X-AuditID: cbfee61b-f79f86d00000144c-ce-53f4a5be47fe From: Jacek Anaszewski To: linux-leds@vger.kernel.org, devicetree@vger.kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Cc: kyungmin.park@samsung.com, b.zolnierkie@samsung.com, Jacek Anaszewski , Bryan Wu , Richard Purdie Subject: [PATCH/RFC v5 2/4] leds: implement sysfs interface locking mechanism Date: Wed, 20 Aug 2014 15:41:56 +0200 Message-id: <1408542118-32723-3-git-send-email-j.anaszewski@samsung.com> X-Mailer: git-send-email 1.7.9.5 In-reply-to: <1408542118-32723-1-git-send-email-j.anaszewski@samsung.com> References: <1408542118-32723-1-git-send-email-j.anaszewski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprJLMWRmVeSWpSXmKPExsVy+t9jAd19S78EG9yco2ixccZ6VoujOycy Wcw/co7Vovfqc0aLs01v2C0u75rDZrH1zTpGi54NW1ktdu96yurA6bFz1l12jz3zf7B69G1Z xejxeZNcAEsUl01Kak5mWWqRvl0CV0bTipnMBS+MKxbPamVtYGzW7mLk5JAQMJHY8Oo9I4Qt JnHh3nq2LkYuDiGBRYwSR798gnLamSRmbvrKBlLFJmAo8fPFayYQW0SgXKLn/TOwImaB1YwS d7Z+ZQVJCAv4SnSc/g1WxCKgKrHh+32wZl4BD4kLlx8wdzFyAK1TkJgzyQYkzCngKbF1ww+w K4SASpqXnmGZwMi7gJFhFaNoakFyQXFSeq6RXnFibnFpXrpecn7uJkZwgD2T3sG4qsHiEKMA B6MSD++NRV+ChVgTy4orcw8xSnAwK4nwtncChXhTEiurUovy44tKc1KLDzFKc7AoifMebLUO FBJITyxJzU5NLUgtgskycXBKNTCuPWqTLJrTtygszMM3X4k9bWGeKE/9Ju7Owj62ogUPRNSz Mq6fubZUa37J4p7LnwpWSs5ibGZgTl2cd/bVpIhTe57v7ly9Z5lQn3oA87vVaYddEx495Que sV27v1mdu3Di8ZBpbLKzGxNKT2bfX3FAYvM31ghflf07c3cwp0lPWZjrlee7abMSS3FGoqEW c1FxIgD12bbCLAIAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a mechanism for locking LED subsystem sysfs interface. This patch prepares ground for addition of LED Flash Class extension, whose API will be integrated with V4L2 Flash API. Such a fusion enforces introducing a locking scheme, which will secure consistent access to the LED Flash Class device. The mechanism being introduced allows for disabling LED subsystem sysfs interface by calling led_sysfs_lock function and enabling it by calling led_sysfs_unlock. The functions alter the LED_SYSFS_LOCK flag state and must be called under mutex lock. The state of the lock is checked with use of led_sysfs_is_locked function. Such a design allows for providing immediate feedback to the user space on whether the LED Flash Class device is available or is under V4L2 Flash sub-device control. Signed-off-by: Jacek Anaszewski Acked-by: Kyungmin Park Cc: Bryan Wu Cc: Richard Purdie --- drivers/leds/led-class.c | 23 ++++++++++++++++++++--- drivers/leds/led-core.c | 18 ++++++++++++++++++ drivers/leds/led-triggers.c | 15 ++++++++++++--- include/linux/leds.h | 32 ++++++++++++++++++++++++++++++++ 4 files changed, 82 insertions(+), 6 deletions(-) diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index 6f82a76..0bc0ba9 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -39,17 +39,31 @@ static ssize_t brightness_store(struct device *dev, { struct led_classdev *led_cdev = dev_get_drvdata(dev); unsigned long state; - ssize_t ret = -EINVAL; + ssize_t ret; + +#ifdef CONFIG_V4L2_FLASH_LED_CLASS + mutex_lock(&led_cdev->led_lock); + + if (led_sysfs_is_locked(led_cdev)) { + ret = -EBUSY; + goto unlock; + } +#endif ret = kstrtoul(buf, 10, &state); if (ret) - return ret; + goto unlock; if (state == LED_OFF) led_trigger_remove(led_cdev); __led_set_brightness(led_cdev, state); - return size; + ret = size; +unlock: +#ifdef CONFIG_V4L2_FLASH_LED_CLASS + mutex_unlock(&led_cdev->led_lock); +#endif + return ret; } static DEVICE_ATTR_RW(brightness); @@ -215,6 +229,7 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev) #ifdef CONFIG_LEDS_TRIGGERS init_rwsem(&led_cdev->trigger_lock); #endif + mutex_init(&led_cdev->led_lock); /* add to the list of leds */ down_write(&leds_list_lock); list_add_tail(&led_cdev->node, &leds_list); @@ -266,6 +281,8 @@ void led_classdev_unregister(struct led_classdev *led_cdev) down_write(&leds_list_lock); list_del(&led_cdev->node); up_write(&leds_list_lock); + + mutex_destroy(&led_cdev->led_lock); } EXPORT_SYMBOL_GPL(led_classdev_unregister); diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c index 466ce5a..4649ea5 100644 --- a/drivers/leds/led-core.c +++ b/drivers/leds/led-core.c @@ -143,3 +143,21 @@ int led_update_brightness(struct led_classdev *led_cdev) return ret; } EXPORT_SYMBOL(led_update_brightness); + +/* Caller must ensure led_cdev->led_lock held */ +void led_sysfs_lock(struct led_classdev *led_cdev) +{ + lockdep_assert_held(&led_cdev->led_lock); + + led_cdev->flags |= LED_SYSFS_LOCK; +} +EXPORT_SYMBOL_GPL(led_sysfs_lock); + +/* Caller must ensure led_cdev->led_lock held */ +void led_sysfs_unlock(struct led_classdev *led_cdev) +{ + lockdep_assert_held(&led_cdev->led_lock); + + led_cdev->flags &= ~LED_SYSFS_LOCK; +} +EXPORT_SYMBOL_GPL(led_sysfs_unlock); diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c index c3734f1..d391a5d 100644 --- a/drivers/leds/led-triggers.c +++ b/drivers/leds/led-triggers.c @@ -37,6 +37,11 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr, char trigger_name[TRIG_NAME_MAX]; struct led_trigger *trig; size_t len; + int ret = count; + +#ifdef CONFIG_V4L2_FLASH_LED_CLASS + mutex_lock(&led_cdev->led_lock); +#endif trigger_name[sizeof(trigger_name) - 1] = '\0'; strncpy(trigger_name, buf, sizeof(trigger_name) - 1); @@ -47,7 +52,7 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr, if (!strcmp(trigger_name, "none")) { led_trigger_remove(led_cdev); - return count; + goto exit_unlock; } down_read(&triggers_list_lock); @@ -58,12 +63,16 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr, up_write(&led_cdev->trigger_lock); up_read(&triggers_list_lock); - return count; + goto exit_unlock; } } up_read(&triggers_list_lock); - return -EINVAL; +exit_unlock: +#ifdef CONFIG_V4L2_FLASH_LED_CLASS + mutex_unlock(&led_cdev->led_lock); +#endif + return ret; } EXPORT_SYMBOL_GPL(led_trigger_store); diff --git a/include/linux/leds.h b/include/linux/leds.h index cc85b16..ef343f1 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -13,6 +13,7 @@ #define __LINUX_LEDS_H_INCLUDED #include +#include #include #include #include @@ -41,6 +42,7 @@ struct led_classdev { #define LED_BLINK_ONESHOT (1 << 17) #define LED_BLINK_ONESHOT_STOP (1 << 18) #define LED_BLINK_INVERT (1 << 19) +#define LED_SYSFS_LOCK (1 << 20) /* Set LED brightness level */ /* Must not sleep, use a workqueue if needed */ @@ -84,6 +86,9 @@ struct led_classdev { /* true if activated - deactivate routine uses it to do cleanup */ bool activated; #endif + + /* Ensures consistent access to the LED Flash Class device */ + struct mutex led_lock; }; extern int led_classdev_register(struct device *parent, @@ -150,6 +155,33 @@ extern void led_set_brightness(struct led_classdev *led_cdev, */ extern int led_update_brightness(struct led_classdev *led_cdev); +/** + * led_sysfs_lock - lock LED sysfs interface + * @led_cdev: the LED to set + * + * Lock the LED's sysfs interface + */ +extern void led_sysfs_lock(struct led_classdev *led_cdev); + +/** + * led_sysfs_unlock - unlock LED sysfs interface + * @led_cdev: the LED to set + * + * Unlock the LED's sysfs interface + */ +extern void led_sysfs_unlock(struct led_classdev *led_cdev); + +/** + * led_sysfs_is_locked + * @led_cdev: the LED to query + * + * Returns: true if the sysfs interface of the led is locked + */ +static inline bool led_sysfs_is_locked(struct led_classdev *led_cdev) +{ + return led_cdev->flags & LED_SYSFS_LOCK; +} + /* * LED Triggers */ -- 1.7.9.5