From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5782C433F5 for ; Fri, 19 Nov 2021 21:27:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235667AbhKSVax (ORCPT ); Fri, 19 Nov 2021 16:30:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235495AbhKSVar (ORCPT ); Fri, 19 Nov 2021 16:30:47 -0500 Received: from mail-oi1-x230.google.com (mail-oi1-x230.google.com [IPv6:2607:f8b0:4864:20::230]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5134C061574; Fri, 19 Nov 2021 13:27:44 -0800 (PST) Received: by mail-oi1-x230.google.com with SMTP id 7so24105377oip.12; Fri, 19 Nov 2021 13:27:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=r9W1ctDlhGpu4BQ53LGmEMCHVLw3KLQXU7hlEXObBm0=; b=bfrY2ZEJaRHoSome37BrLhsLT1wAFGpAzW7o7x3muicWLOda0WXBPFqaFE9iHl1h5j PgGDpsSzq0sq/zq9QuR/Xz0fXkHsRvAOAUYu6ODMJj+HBMdlNzaWu1eFo5JiBltFMo/f sWUyaa410wERe/Ce94yjH/86QsJ07rSFAvFlIAgr7YlqsMAlDEveODZpoxbrm9f937Js aCVmjyY7T4ftCH8vNs/hL13GY0UnyPbhf8vOYeCCoJ+oKBHmAzHc3ffugaEGzfS+IXIp /dUBLjRiPmJBLEoKatRVOByh8AvgWyvbR82bu5xC+nu1Ool1J+oSvjbVlY2btjP0Fkmn QhRQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=r9W1ctDlhGpu4BQ53LGmEMCHVLw3KLQXU7hlEXObBm0=; b=qAZlyoeELoY5bRUNqUK+z5urNi3Q1OiqdWQCOjfKOwPRPJcFCAISuT1bRGedPuVA/G 7rDbJkaBWyTHpm06ri900f+gbwMf9uUVKfkk5KhB7vricggINn+lCviBtLqMhjo9OrJc aIAIQJxQvCumT9Ipf9Ef+p4K+hkxAYTj2AUlje6vjBno7Dihz0FtG9k6GhcNdY2D8TjB mj2o+7qpfRao31nhemOwxsnaQt4Aq4GLJ6AOzDmKEWh5GeLaryp8vo+/4kB4lVYvM6Te tAdVynRenT2xF599xOyyALHuWj/wcU+b3nqVZAt/VuFBde0dH4thlr4647PHCq9iqKcj Oetw== X-Gm-Message-State: AOAM5317wwAScCl6AcMzOoPZo4vYdhBl5QUtPYFlIThSozksCUYRy7un AmFyFGQYt1eVeF7jA9uGBzY= X-Google-Smtp-Source: ABdhPJxz8B02QiT1UQVafBexuSrfcd2fcP/oN/QXm/5VaoruU17v5idDGGWOsT2VOrETITuRW5oPgQ== X-Received: by 2002:aca:2205:: with SMTP id b5mr2720590oic.177.1637357263713; Fri, 19 Nov 2021 13:27:43 -0800 (PST) Received: from ian.penurio.us ([47.184.51.90]) by smtp.gmail.com with ESMTPSA id w29sm233936ooe.25.2021.11.19.13.27.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Nov 2021 13:27:43 -0800 (PST) From: Ian Pilcher To: pavel@ucw.cz Cc: linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, kabel@kernel.org Subject: [RESEND PATCH v8 2/2] leds: trigger: Add block device LED trigger Date: Fri, 19 Nov 2021 15:27:33 -0600 Message-Id: <20211119212733.286427-3-arequipeno@gmail.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211119212733.286427-1-arequipeno@gmail.com> References: <20211119212733.286427-1-arequipeno@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add "blkdev" LED trigger to blink LEDs in response to block device activity. Add LEDS_TRIGGER_BLKDEV (tristate) config option to control building of the trigger. Signed-off-by: Ian Pilcher --- drivers/leds/trigger/Kconfig | 9 + drivers/leds/trigger/Makefile | 1 + drivers/leds/trigger/ledtrig-blkdev.c | 1140 +++++++++++++++++++++++++ 3 files changed, 1150 insertions(+) create mode 100644 drivers/leds/trigger/ledtrig-blkdev.c diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig index dc6816d36d06..bda249068182 100644 --- a/drivers/leds/trigger/Kconfig +++ b/drivers/leds/trigger/Kconfig @@ -154,4 +154,13 @@ config LEDS_TRIGGER_TTY When build as a module this driver will be called ledtrig-tty. +config LEDS_TRIGGER_BLKDEV + tristate "LED Trigger for block devices" + depends on BLOCK + help + The blkdev LED trigger allows LEDs to be controlled by block device + activity (reads and writes). + + See Documentation/leds/ledtrig-blkdev.rst. + endif # LEDS_TRIGGERS diff --git a/drivers/leds/trigger/Makefile b/drivers/leds/trigger/Makefile index 25c4db97cdd4..d53bab5d93f1 100644 --- a/drivers/leds/trigger/Makefile +++ b/drivers/leds/trigger/Makefile @@ -16,3 +16,4 @@ obj-$(CONFIG_LEDS_TRIGGER_NETDEV) += ledtrig-netdev.o obj-$(CONFIG_LEDS_TRIGGER_PATTERN) += ledtrig-pattern.o obj-$(CONFIG_LEDS_TRIGGER_AUDIO) += ledtrig-audio.o obj-$(CONFIG_LEDS_TRIGGER_TTY) += ledtrig-tty.o +obj-$(CONFIG_LEDS_TRIGGER_BLKDEV) += ledtrig-blkdev.o diff --git a/drivers/leds/trigger/ledtrig-blkdev.c b/drivers/leds/trigger/ledtrig-blkdev.c new file mode 100644 index 000000000000..52ec11e4fc0b --- /dev/null +++ b/drivers/leds/trigger/ledtrig-blkdev.c @@ -0,0 +1,1140 @@ +// SPDX-License-Identifier: GPL-2.0-only + +/* + * Block device LED trigger + * + * Copyright 2021 Ian Pilcher + */ + +#include +#include +#include +#include +#include + +/* Default, minimum & maximum blink duration (milliseconds) */ +#define BLKDEV_TRIG_BLINK_DEF 75 +#define BLKDEV_TRIG_BLINK_MIN 10 +#define BLKDEV_TRIG_BLINK_MAX 86400000 /* 24 hours */ + +/* Default, minimum & maximum activity check interval (milliseconds) */ +#define BLKDEV_TRIG_CHECK_DEF 100 +#define BLKDEV_TRIG_CHECK_MIN 25 +#define BLKDEV_TRIG_CHECK_MAX 86400000 + +/* + * If blkdev_trig_check() can't lock the mutex, how long to wait before trying + * again (milliseconds) + */ +#define BLKDEV_TRIG_CHECK_RETRY 5 + +/* Mode for blkdev_get_by_path() & blkdev_put() */ +#define BLKDEV_TRIG_FMODE 0 + +/* Device activity type(s) that will make LED blink */ +#define BLKDEV_TRIG_READ (1 << STAT_READ) +#define BLKDEV_TRIG_WRITE (1 << STAT_WRITE) +#define BLKDEV_TRIG_DISCARD (1 << STAT_DISCARD) +#define BLKDEV_TRIG_FLUSH (1 << STAT_FLUSH) + +/* When unlinking a block device from an LED, is the blkdev being released? */ +enum blkdev_trig_unlink_mode { + BLKDEV_TRIG_RELEASING, + BLKDEV_TRIG_NOT_RELEASING +}; + +/* Every block device linked to at least one LED gets a "BTB" */ +struct blkdev_trig_bdev { + unsigned long last_checked; + unsigned long last_activity[NR_STAT_GROUPS]; + unsigned long ios[NR_STAT_GROUPS]; + unsigned long index; + struct block_device *bdev; + struct xarray linked_leds; +}; + +/* Every LED associated with the blkdev trigger gets one of these */ +struct blkdev_trig_led { + unsigned long last_checked; + unsigned long index; + unsigned long mode; /* must be ulong for atomic bit ops */ + struct led_classdev *led_cdev; + unsigned int blink_msec; + unsigned int check_jiffies; + struct xarray linked_btbs; + struct hlist_node all_leds_node; +}; + +/* Forward declarations to make this file compile in a more readable order */ +static void blkdev_trig_check(struct work_struct *work); +static struct blkdev_trig_bdev *blkdev_trig_get_btb(const char *buf, + size_t size); +static struct block_device *blkdev_trig_get_bdev(const char *buf, size_t size, + fmode_t mode); +static int blkdev_trig_link(struct blkdev_trig_led *led, + struct blkdev_trig_bdev *btb); +static void blkdev_trig_put_btb(struct blkdev_trig_bdev *btb); +static void blkdev_trig_btb_release(struct device *dev, void *res); +static void blkdev_trig_unlink(struct blkdev_trig_led *led, + struct blkdev_trig_bdev *btb, + enum blkdev_trig_unlink_mode unlink_mode); +static void blkdev_trig_update_btb(struct blkdev_trig_bdev *btb, + unsigned long now); +static bool blkdev_trig_blink(const struct blkdev_trig_led *led, + const struct blkdev_trig_bdev *btb); +static void blkdev_trig_sched_led(const struct blkdev_trig_led *led); + +/* Index for next BTB or LED */ +static unsigned long blkdev_trig_next_index; + +/* Protects everything except sysfs attributes */ +static DEFINE_MUTEX(blkdev_trig_mutex); + +/* All LEDs associated with the trigger */ +static HLIST_HEAD(blkdev_trig_all_leds); + +/* Delayed work to periodically check for activity & blink LEDs */ +static DECLARE_DELAYED_WORK(blkdev_trig_work, blkdev_trig_check); + +/* When is the delayed work scheduled to run next (jiffies) */ +static unsigned long blkdev_trig_next_check; + +/* Total number of device-to-LED associations (links) */ +static unsigned int blkdev_trig_link_count; + +/* Empty attribute list for the linked_leds & linked_devices "groups" */ +static struct attribute *blkdev_trig_attrs_empty[] = { NULL }; + +/* linked_leds sysfs directory for block devs linked to 1 or more LEDs */ +static const struct attribute_group blkdev_trig_linked_leds = { + .name = "linked_leds", + .attrs = blkdev_trig_attrs_empty, +}; + +/* linked_devices sysfs directory for each LED associated with the trigger */ +static const struct attribute_group blkdev_trig_linked_devs = { + .name = "linked_devices", + .attrs = blkdev_trig_attrs_empty, +}; + +/** + * blkdev_trig_activate() - Called when an LED is associated with the trigger. + * @led_cdev: The LED + * + * Allocates & initializes the @blkdev_trig_led structure, adds it to the + * @blkdev_trig_all_leds list, and sets the LED's trigger data. + * + * Context: Process context. Takes and releases @blkdev_trig_mutex. + * Return: ``0`` on success, ``-errno`` on error. + */ +static int blkdev_trig_activate(struct led_classdev *led_cdev) +{ + struct blkdev_trig_led *led; + int err; + + led = kzalloc(sizeof(*led), GFP_KERNEL); + if (led == NULL) + return -ENOMEM; + + err = mutex_lock_interruptible(&blkdev_trig_mutex); + if (err) + goto exit_free; + + if (blkdev_trig_next_index == ULONG_MAX) { + err = -EOVERFLOW; + goto exit_unlock; + } + + led->index = blkdev_trig_next_index++; + led->last_checked = jiffies; + led->mode = -1; /* set all bits */ + led->led_cdev = led_cdev; + led->blink_msec = BLKDEV_TRIG_BLINK_DEF; + led->check_jiffies = msecs_to_jiffies(BLKDEV_TRIG_CHECK_DEF); + xa_init(&led->linked_btbs); + + hlist_add_head(&led->all_leds_node, &blkdev_trig_all_leds); + led_set_trigger_data(led_cdev, led); + +exit_unlock: + mutex_unlock(&blkdev_trig_mutex); +exit_free: + if (err) + kfree(led); + return err; +} + +/** + * link_device_store() - ``link_device`` device attribute store function. + * @dev: The LED device + * @attr: The ``link_device`` attribute (@dev_attr_link_device) + * @buf: The value written to the attribute, which should be the path to + * the special file that represents the block device to be linked + * to the LED (e.g. /dev/sda) + * @count: The number of characters in @buf + * + * Calls blkdev_trig_get_btb() to find or create the BTB for the block device, + * checks that the device isn't already linked to this LED, and calls + * blkdev_trig_link() to create the link. + * + * Context: Process context. Takes and releases @blkdev_trig_mutex. + * Return: @count on success, ``-errno`` on error. + */ +static ssize_t link_device_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct blkdev_trig_led *led = led_trigger_get_drvdata(dev); + struct blkdev_trig_bdev *btb; + int err; + + err = mutex_lock_interruptible(&blkdev_trig_mutex); + if (err) + return err; + + btb = blkdev_trig_get_btb(buf, count); + if (IS_ERR(btb)) { + err = PTR_ERR(btb); + goto exit_unlock; + } + + if (xa_load(&btb->linked_leds, led->index) != NULL) { + err = -EEXIST; + goto exit_put_btb; + } + + err = blkdev_trig_link(led, btb); + +exit_put_btb: + if (err) + blkdev_trig_put_btb(btb); +exit_unlock: + mutex_unlock(&blkdev_trig_mutex); + return err ? : count; +} + +/** + * blkdev_trig_get_btb() - Find or create the BTB for a block device. + * @buf: The value written to the ``link_device`` attribute, which should + * be the path to a special file that represents a block device + * @count: The number of characters in @buf + * + * Calls blkdev_trig_get_bdev() to get the block device represented by the path + * in @buf. If the device already has a BTB (because it is already linked to + * an LED), simply returns the existing BTB. + * + * Otherwise, allocates a new BTB (as a device resource), creates the block + * device's ``linked_leds`` directory (attribute group), calls + * blkdev_trig_update_btb() to set the BTB's activity counters, and adds the + * BTB resource to the block device. + * + * Context: Process context. Caller must hold @blkdev_trig_mutex. + * Return: Pointer to the BTB, error pointer on error. + */ +static struct blkdev_trig_bdev *blkdev_trig_get_btb(const char *buf, + size_t count) +{ + struct block_device *bdev; + struct blkdev_trig_bdev *btb; + int err; + + bdev = blkdev_trig_get_bdev(buf, count, BLKDEV_TRIG_FMODE); + if (IS_ERR(bdev)) + return ERR_CAST(bdev); + + btb = devres_find(&bdev->bd_device, blkdev_trig_btb_release, + NULL, NULL); + if (btb != NULL) { + err = 0; + goto exit_put_bdev; + } + + if (blkdev_trig_next_index == ULONG_MAX) { + err = -EOVERFLOW; + goto exit_put_bdev; + } + + btb = devres_alloc(blkdev_trig_btb_release, sizeof(*btb), GFP_KERNEL); + if (btb == NULL) { + err = -ENOMEM; + goto exit_put_bdev; + } + + err = sysfs_create_group(bdev_kobj(bdev), &blkdev_trig_linked_leds); + if (err) + goto exit_free_btb; + + btb->index = blkdev_trig_next_index++; + btb->bdev = bdev; + xa_init(&btb->linked_leds); + blkdev_trig_update_btb(btb, jiffies); + + devres_add(&bdev->bd_device, btb); + +exit_free_btb: + if (err) + devres_free(btb); +exit_put_bdev: + blkdev_put(bdev, BLKDEV_TRIG_FMODE); + return err ? ERR_PTR(err) : btb; +} + +/** + * blkdev_trig_get_bdev() - Get a block device by path. + * @buf: The value written to the ``link_device`` or ``unlink_device`` + * attribute, which should be the path to a special file that + * represents a block device + * @count: The number of characters in @buf (not including its terminating + * null) + * + * Copies @buf to a writable buffer, trims the trailing newline (if any), and + * calls blkdev_get_by_path() to resolve the block device. + * + * The caller must call blkdev_put() when finished with the device. + * + * Context: Process context. + * Return: The block device, or an error pointer. + */ +static struct block_device *blkdev_trig_get_bdev(const char *buf, size_t count, + fmode_t mode) +{ + struct block_device *bdev; + char *path; + + path = kmemdup(buf, count + 1, GFP_KERNEL); /* +1 to include null */ + if (path == NULL) + return ERR_PTR(-ENOMEM); + + if (path[count - 1] == '\n') + path[count - 1] = 0; + + bdev = blkdev_get_by_path(path, mode, THIS_MODULE); + kfree(path); + return bdev; +} + +/** + * blkdev_trig_update_btb() - Update a BTB's activity counters. + * @btb: The BTB + * + * Checks each of the BTB's block device's I/O counters. If the counter has + * changed since the last check, updates the counter and its timestamp in the + * BTB. + * + * Context: Process context. Caller must hold @blkdev_trig_mutex. + */ +static void blkdev_trig_update_btb(struct blkdev_trig_bdev *btb, + unsigned long now) +{ + unsigned long new_ios; + enum stat_group i; + + for (i = STAT_READ; i <= STAT_FLUSH; ++i) { + + new_ios = part_stat_read(btb->bdev, ios[i]); + + if (new_ios != btb->ios[i]) { + btb->ios[i] = new_ios; + btb->last_activity[i] = now; + } + } + + btb->last_checked = now; +} + +/** + * blkdev_trig_link() - "Link" a block device to an LED. + * @led: The LED + * @btb: The block device + * + * Called from link_device_store() to create the link between an LED and a + * block device. + * + * * Adds block device symlink to LED's ``linked_devices`` directory. + * * Adds LED symlink to block devices's ``linked_leds`` directory. + * * Adds the BTB to the LED's @linked_btbs and adds the LED to the BTB's + * @linked_leds. + * * If this is the first block device linked to this LED, calls + * blkdev_trig_new_sched() to (if needed) schedule or reschedule the delayed + * work which periodically checks for block device activity and blinks LEDs. + * + * Context: Process context. Caller must hold @blkdev_trig_mutex. + * Return: 0 on success, ``-errno`` on error. + */ +static int blkdev_trig_link(struct blkdev_trig_led *led, + struct blkdev_trig_bdev *btb) +{ + bool led_first_link; + int err; + + led_first_link = xa_empty(&led->linked_btbs); + + err = xa_insert(&btb->linked_leds, led->index, led, GFP_KERNEL); + if (err) + return err; + + err = xa_insert(&led->linked_btbs, btb->index, btb, GFP_KERNEL); + if (err) + goto error_erase_led; + + /* Create /sys/class/block//linked_leds/ symlink */ + err = sysfs_add_link_to_group(bdev_kobj(btb->bdev), + blkdev_trig_linked_leds.name, + &led->led_cdev->dev->kobj, + led->led_cdev->name); + if (err) + goto error_erase_btb; + + /* Create /sys/class/leds//linked_devices/ symlink */ + err = sysfs_add_link_to_group(&led->led_cdev->dev->kobj, + blkdev_trig_linked_devs.name, + bdev_kobj(btb->bdev), + dev_name(&btb->bdev->bd_device)); + if (err) + goto error_remove_symlink; + + /* + * If this isn't the first block device linked to this LED, then the + * delayed work schedule already reflects this LED. + */ + if (led_first_link) + blkdev_trig_sched_led(led); + + ++blkdev_trig_link_count; + + return 0; + +error_remove_symlink: + sysfs_remove_link_from_group(bdev_kobj(btb->bdev), + blkdev_trig_linked_leds.name, + led->led_cdev->name); +error_erase_btb: + xa_erase(&led->linked_btbs, btb->index); +error_erase_led: + xa_erase(&btb->linked_leds, led->index); + return err; +} + +/** + * blkdev_trig_sched_led() - Set the schedule of the delayed work when a new + * LED is added to the schedule. + * @led: The LED + * + * Called from blkdev_trig_link() to set or adjust the schedule of the delayed + * work which periodically checks block devices for activity and blinks LEDs, + * if necessary. + * + * * If no other links exist, the delayed work is scheduled. + * * If the delayed work is already scheduled to run soon enough to + * accommodate the newly linked LED's @check_jiffies, no change is made to + * the delayed work's schedule. + * * If the delayed work is already scheduled, but it isn't scheduled to + * run soon enough, the schedule is modified. + * + * Context: Process context. Caller must hold @blkdev_trig_mutex. + */ +static void blkdev_trig_sched_led(const struct blkdev_trig_led *led) +{ + unsigned long delay = READ_ONCE(led->check_jiffies); + unsigned long check_by = jiffies + delay; + + if (blkdev_trig_link_count == 0) { + WARN_ON(!schedule_delayed_work(&blkdev_trig_work, delay)); + blkdev_trig_next_check = check_by; + return; + } + + if (time_after_eq(check_by, blkdev_trig_next_check)) + return; + + WARN_ON(!mod_delayed_work(system_wq, &blkdev_trig_work, delay)); + blkdev_trig_next_check = check_by; +} + +/** + * unlink_device_store() - ``unlink_device`` device attribute store function. + * @dev: The LED device + * @attr: The ``unlink_device`` attribute (@dev_attr_unlink_device) + * @buf: The value written to the attribute, which should be the path to + * the special file that represents the block device to be unlinked + * from the LED (e.g. /dev/sda) + * @count: The number of characters in @buf + * + * Block device name is written to the attribute to "unlink" the block device + * from the LED. I.e. the LED will no longer blink to show activity on that + * block device. + * + * Calls blkdev_trig_get_bdev() to get the block device represented by the path + * in @buf. If the device has a BTB, searches the BTB's list of LEDs for a + * link to this LED and (if found) calls blkdev_trig_unlink() to destroy the + * link. + * + * Context: Process context. Takes and releases @blkdev_trig_mutex. + * Return: @count on success, ``-errno`` on error. + */ +static ssize_t unlink_device_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct blkdev_trig_led *led = led_trigger_get_drvdata(dev); + struct block_device *bdev; + struct blkdev_trig_bdev *btb; + int err; + + bdev = blkdev_trig_get_bdev(buf, count, BLKDEV_TRIG_FMODE); + if (IS_ERR(bdev)) + return PTR_ERR(bdev); + + err = mutex_lock_interruptible(&blkdev_trig_mutex); + if (err) + goto exit_put_bdev; + + btb = devres_find(&bdev->bd_device, blkdev_trig_btb_release, + NULL, NULL); + if (btb == NULL) { + err = -EUNATCH; /* bdev isn't linked to any LED */ + goto exit_unlock; + } + + if (xa_load(&btb->linked_leds, led->index) == NULL) { + err = -EUNATCH; /* bdev isn't linked to this LED */ + goto exit_unlock; + } + + blkdev_trig_unlink(led, btb, BLKDEV_TRIG_NOT_RELEASING); + +exit_unlock: + mutex_unlock(&blkdev_trig_mutex); +exit_put_bdev: + blkdev_put(bdev, BLKDEV_TRIG_FMODE); + return err ? : count; +} + +/** + * blkdev_trig_unlink() - "Unlink" a block device from an LED. + * @led: The LED + * @btb: The block device + * @unlink_mode: Indicates whether the BTB is being released (because + * the block device has been removed) + * + * Removes the link between an LED and a block device. + * + * * Removes the BTB from the LED's @linked_btbs and removes the LED from + * the BTB's @linked_leds. + * * Removes the block device symlink from the LED's ``linked_devices`` + * directory. + * + * If the block device is **not** being released: + * + * * Removes the LED symlink from the block device's ``linked_leds`` + * directory. + * * Calls blkdev_trig_put_btb() to clean up the BTB, if required. + * + * If the removed link was the only one (i.e. there are no existing block + * device/LED links after its removal), cancels the periodic delayed work + * which checks for device activity. + * + * This function is called from multiple locations. + * + * * unlink_device_store() calls this function when a block device is unlinked + * from an LED via the ``unlink_device`` sysfs attribute. (@unlink_mode == + * ``BLKDEV_TRIG_NOT_RELEASING``) + * * blkdev_trig_deactivate() calls this function for each block device linked + * to an LED that is being deactivated (disassociated from the trigger). + * (@unlink_mode == ``BLKDEV_TRIG_NOT_RELEASING``). + * * blkdev_trig_btb_release() calls this function for each LED linked to a + * block device that has been removed from the system. (@unlink_mode == + * ``BLKDEV_TRIG_RELEASING). + * + * Context: Process context. Caller must hold @blkdev_trig_mutex. + */ +static void blkdev_trig_unlink(struct blkdev_trig_led *led, + struct blkdev_trig_bdev *btb, + enum blkdev_trig_unlink_mode unlink_mode) +{ + --blkdev_trig_link_count; + + if (blkdev_trig_link_count == 0) + WARN_ON(!cancel_delayed_work_sync(&blkdev_trig_work)); + + xa_erase(&btb->linked_leds, led->index); + xa_erase(&led->linked_btbs, btb->index); + + /* Remove /sys/class/leds//linked_devices/ symlink */ + sysfs_remove_link_from_group(&led->led_cdev->dev->kobj, + blkdev_trig_linked_devs.name, + dev_name(&btb->bdev->bd_device)); + + /* + * If the BTB is being released, the device's attribute groups have + * already been removed, and the BTB will be freed automatically, so + * only do these steps if the BTB is not being released. + */ + if (unlink_mode == BLKDEV_TRIG_NOT_RELEASING) { + + /* Remove /sys/class/block//linked_leds/ symlink */ + sysfs_remove_link_from_group(bdev_kobj(btb->bdev), + blkdev_trig_linked_leds.name, + led->led_cdev->name); + blkdev_trig_put_btb(btb); + } +} + +/** + * blkdev_trig_put_btb() - Remove and free a BTB, if it is no longer needed. + * @btb: The BTB + * + * Does nothing if the BTB (block device) is still linked to at least one LED. + * + * If the BTB is no longer linked to any LEDs, removes the block device's + * ``linked_leds`` directory (attribute group), removes the BTB from the + * block device's resource list, and frees the BTB. + * + * Called from blkdev_trig_unlink() (and in the link_device_store() error path). + * + * Context: Process context. Caller must hold @blkdev_trig_mutex. + */ +static void blkdev_trig_put_btb(struct blkdev_trig_bdev *btb) +{ + struct block_device *bdev = btb->bdev; + int err; + + if (xa_empty(&btb->linked_leds)) { + + sysfs_remove_group(bdev_kobj(bdev), &blkdev_trig_linked_leds); + err = devres_destroy(&bdev->bd_device, blkdev_trig_btb_release, + NULL, NULL); + WARN_ON(err); + } +} + +/** + * blkdev_trig_deactivate() - Called when an LED is disassociated from the + * trigger. + * @led_cdev: The LED + * + * Calls blkdev_trig_unlink() for each block device linked to the LED, removes + * the LED from the @blkdevtrig_all_leds list, and frees the @blkdev_trig_led. + * + * Context: Process context. Takes and releases @blkdev_trig_mutex. + */ +static void blkdev_trig_deactivate(struct led_classdev *led_cdev) +{ + struct blkdev_trig_led *led = led_get_trigger_data(led_cdev); + struct blkdev_trig_bdev *btb; + unsigned long index; + + mutex_lock(&blkdev_trig_mutex); + + xa_for_each (&led->linked_btbs, index, btb) + blkdev_trig_unlink(led, btb, BLKDEV_TRIG_NOT_RELEASING); + + hlist_del(&led->all_leds_node); + kfree(led); + + mutex_unlock(&blkdev_trig_mutex); +} + +/** + * blkdev_trig_btb_release() - BTB device resource release function. + * @dev: The block device + * @res: The BTB + * + * Called by the driver core when a block device with a BTB is removed from + * the system. Calls blkdev_trig_unlink() for each LED linked to the block + * device. + * + * Context: Process context. Takes and releases @blkdev_trig_mutex. + */ +static void blkdev_trig_btb_release(struct device *dev, void *res) +{ + struct blkdev_trig_bdev *btb = res; + struct blkdev_trig_led *led; + unsigned long index; + + mutex_lock(&blkdev_trig_mutex); + + xa_for_each (&btb->linked_leds, index, led) + blkdev_trig_unlink(led, btb, BLKDEV_TRIG_RELEASING); + + mutex_unlock(&blkdev_trig_mutex); +} + +/** + * blkdev_trig_check() - Check linked devices for activity and blink LEDs. + * @work: Delayed work (@blkdev_trig_work) + * + * Called periodically (as delayed work) to check linked block devices for + * activity and blink LEDs. + * + * * Iterates through all LEDs associated with the trigger. + * * If an LED is due to be checked, iterates through the block devices (BTBs) + * linked to the LED. + * * If a block device has not already been checked during this pass, calls + * blkdev_trig_update_btb() to update the BTB's activity counters and + * timestamps. + * * If the LED has not already been blinked during this pass, calls + * blkdev_trig_blink() to blink it if the correct type of activity has + * occurred since the LED was last checked. + * + * When finished, schedules itself to run again when the next LED is due to be + * checked. + * + * Context: Process context. Takes and releases @blkdev_trig_mutex. + */ +static void blkdev_trig_check(struct work_struct *work) +{ + struct blkdev_trig_led *led; + struct blkdev_trig_bdev *btb; + unsigned long index, delay, now, led_check, led_delay; + bool blinked; + + if (!mutex_trylock(&blkdev_trig_mutex)) { + delay = msecs_to_jiffies(BLKDEV_TRIG_CHECK_RETRY); + goto exit_reschedule; + } + + now = jiffies; + delay = ULONG_MAX; + + hlist_for_each_entry (led, &blkdev_trig_all_leds, all_leds_node) { + + led_check = led->last_checked + led->check_jiffies; + + if (time_before_eq(led_check, now)) { + + blinked = false; + + xa_for_each (&led->linked_btbs, index, btb) { + + if (btb->last_checked != now) + blkdev_trig_update_btb(btb, now); + if (!blinked) + blinked = blkdev_trig_blink(led, btb); + } + + led->last_checked = now; + led_delay = led->check_jiffies; + + } else { + led_delay = led_check - now; + } + + if (led_delay < delay) + delay = led_delay; + } + + mutex_unlock(&blkdev_trig_mutex); + +exit_reschedule: + WARN_ON_ONCE(delay == ULONG_MAX); + WARN_ON_ONCE(!schedule_delayed_work(&blkdev_trig_work, delay)); +} + +/** + * blkdev_trig_blink() - Blink an LED, if the correct type of activity has + * occurred on the block device. + * @led: The LED + * @btb: The block device + * + * Context: Process context. Caller must hold @blkdev_trig_mutex. + * Return: ``true`` if the LED is blinked, ``false`` if not. + */ +static bool blkdev_trig_blink(const struct blkdev_trig_led *led, + const struct blkdev_trig_bdev *btb) +{ + unsigned long delay_on, delay_off; + enum stat_group i; + unsigned long mode, mask; + + mode = READ_ONCE(led->mode); + + for (i = STAT_READ, mask = 1; i <= STAT_FLUSH; ++i, mask <<= 1) { + + if (!(mode & mask)) + continue; + + if (time_before_eq(btb->last_activity[i], led->last_checked)) + continue; + + delay_on = READ_ONCE(led->blink_msec); + delay_off = 1; /* 0 leaves LED turned on */ + + led_blink_set_oneshot(led->led_cdev, &delay_on, &delay_off, 0); + return true; + } + + return false; +} + +/** + * blink_time_show() - ``blink_time`` device attribute show function. + * @dev: The LED device + * @attr: The ``blink_time`` attribute (@dev_attr_blink_time) + * @buf: Output buffer + * + * Writes the current value of the LED's @blink_msec to @buf. + * + * Context: Process context. + * Return: The number of characters written to @buf. + */ +static ssize_t blink_time_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + const struct blkdev_trig_led *led = led_trigger_get_drvdata(dev); + + return sprintf(buf, "%u\n", READ_ONCE(led->blink_msec)); +} + +/** + * blink_time_store() - ``blink_time`` device attribute store function. + * @dev: The LED device + * @attr: The ``blink_time`` attribute (@dev_attr_blink_time) + * @buf: The new value (as written to the sysfs attribute) + * @count: The number of characters in @buf + * + * Sets the LED's @blink_msec (the duration in milliseconds of one blink). + * + * Context: Process context. + * Return: @count on success, ``-errno`` on error. + */ +static ssize_t blink_time_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct blkdev_trig_led *led = led_trigger_get_drvdata(dev); + unsigned int value; + int err; + + err = kstrtouint(buf, 0, &value); + if (err) + return err; + + if (value < BLKDEV_TRIG_BLINK_MIN || value > BLKDEV_TRIG_BLINK_MAX) + return -ERANGE; + + WRITE_ONCE(led->blink_msec, value); + return count; +} + +/** + * check_interval_show() - ``check_interval`` device attribute show function. + * @dev: The LED device + * @attr: The ``check_interval`` attribute (@dev_attr_check_interval) + * @buf: Output buffer + * + * Writes the current value of the LED's @check_jiffies (converted to + * milliseconds) to @buf. + * + * Context: Process context. + * Return: The number of characters written to @buf. + */ +static ssize_t check_interval_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct blkdev_trig_led *led = led_trigger_get_drvdata(dev); + + return sprintf(buf, "%u\n", + jiffies_to_msecs(READ_ONCE(led->check_jiffies))); +} + +/** + * check_interval_store() - ``check_interval`` device attribute store function + * @dev: The LED device + * @attr: The ``check_interval`` attribute (@dev_attr_check_interval) + * @buf: The new value (as written to the sysfs attribute) + * @count: The number of characters in @buf + * + * Sets the LED's @check_jiffies (after converting from milliseconds). + * + * Context: Process context. + * Return: @count on success, ``-errno`` on error. + */ +static ssize_t check_interval_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct blkdev_trig_led *led = led_trigger_get_drvdata(dev); + unsigned int value; + int err; + + err = kstrtouint(buf, 0, &value); + if (err) + return err; + + if (value < BLKDEV_TRIG_CHECK_MIN || value > BLKDEV_TRIG_CHECK_MAX) + return -ERANGE; + + WRITE_ONCE(led->check_jiffies, msecs_to_jiffies(value)); + + return count; +} + +/** + * blkdev_trig_mode_show() - Helper for boolean attribute show functions. + * @led: The LED + * @buf: Output buffer + * @mask: Which bit to show (@BLKDEV_TRIG_READ, etc.) + * + * Context: Process context. + * Return: The number of characters written to @buf. + */ +static int blkdev_trig_mode_show(const struct blkdev_trig_led *led, char *buf, + unsigned long mask) +{ + return sprintf(buf, READ_ONCE(led->mode) & mask ? "Y\n" : "N\n"); +} + +/** + * blkdev_trig_mode_store() - Helper for boolean attribute store functions. + * @led: The LED + * @buf: The new value (as written to the sysfs attribute) + * @count: The number of characters in @buf + * @mask: Which bit to set (@BLKDEV_TRIG_READ, etc.) + * + * Context: Process context. + * Return: @count on success, ``-errno`` on error. + */ +static int blkdev_trig_mode_store(struct blkdev_trig_led *led, + const char *buf, size_t count, + enum stat_group bit) +{ + bool set; + int err; + + err = kstrtobool(buf, &set); + if (err) + return err; + + if (set) + set_bit(bit, &led->mode); + else + clear_bit(bit, &led->mode); + + return count; +} + +/** + * blink_on_read_show() - ``blink_on_read`` device attribute show function. + * @dev: The LED device + * @attr: The ``blink_on_read`` attribute (@dev_attr_blink_on_read) + * @buf: Output buffer + * + * Writes the current value of the LED's @BLKDEV_TRIG_READ @mode bit to @buf. + * + * Context: Process context. + * Return: The number of characters written to @buf. + */ +static ssize_t blink_on_read_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return blkdev_trig_mode_show(led_trigger_get_drvdata(dev), buf, + BLKDEV_TRIG_READ); +} + +/** + * blink_on_read_store() - ``blink_on_read`` device attribute store function. + * @dev: The LED device + * @attr: The ``blink_on_read`` attribute (@dev_attr_blink_on_read) + * @buf: The new value (as written to the sysfs attribute) + * @count: The number of characters in @buf + * + * Sets or clears the LED's @BLKDEV_TRIG_READ @mode bit. + * + * Context: Process context. + * Return: @count on success, ``-errno`` on error. + */ +static ssize_t blink_on_read_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + return blkdev_trig_mode_store(led_trigger_get_drvdata(dev), buf, count, + STAT_READ); +} + +/** + * blink_on_write_show() - ``blink_on_write`` device attribute show function. + * @dev: The LED device + * @attr: The ``blink_on_write`` attribute (@dev_attr_blink_on_write) + * @buf: Output buffer + * + * Writes the current value of the LED's @BLKDEV_TRIG_WRITE @mode bit to @buf. + * + * Context: Process context. + * Return: The number of characters written to @buf. + */ +static ssize_t blink_on_write_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return blkdev_trig_mode_show(led_trigger_get_drvdata(dev), buf, + BLKDEV_TRIG_WRITE); +} + +/** + * blink_on_write_store() - ``blink_on_write`` device attribute store function. + * @dev: The LED device + * @attr: The ``blink_on_write`` attribute (@dev_attr_blink_on_write) + * @buf: The new value (as written to the sysfs attribute) + * @count: The number of characters in @buf + * + * Sets or clears the LED's @BLKDEV_TRIG_WRITE @mode bit. + * + * Context: Process context. + * Return: @count on success, ``-errno`` on error. + */ +static ssize_t blink_on_write_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + return blkdev_trig_mode_store(led_trigger_get_drvdata(dev), buf, count, + STAT_WRITE); +} + +/** + * blink_on_flush_show() - ``blink_on_flush`` device attribute show function. + * @dev: The LED device + * @attr: The ``blink_on_flush`` attribute (@dev_attr_blink_on_flush) + * @buf: Output buffer + * + * Writes the current value of the LED's @BLKDEV_TRIG_FLUSH @mode bit to @buf. + * + * Context: Process context. + * Return: The number of characters written to @buf. + */ +static ssize_t blink_on_flush_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return blkdev_trig_mode_show(led_trigger_get_drvdata(dev), buf, + BLKDEV_TRIG_FLUSH); +} + +/** + * blink_on_flush_store() - ``blink_on_flush`` device attribute store function. + * @dev: The LED device + * @attr: The ``blink_on_flush`` attribute (@dev_attr_blink_on_flush) + * @buf: The new value (as written to the sysfs attribute) + * @count: The number of characters in @buf + * + * Sets or clears the LED's @BLKDEV_TRIG_FLUSH @mode bit. + * + * Context: Process context. + * Return: @count on success, ``-errno`` on error. + */ +static ssize_t blink_on_flush_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + return blkdev_trig_mode_store(led_trigger_get_drvdata(dev), buf, count, + STAT_FLUSH); +} + +/** + * blink_on_discard_show() - ``blink_on_discard`` device attribute show + * function. + * @dev: The LED device + * @attr: The ``blink_on_discard`` attribute (@dev_attr_blink_on_discard) + * @buf: Output buffer + * + * Writes the current value of the LED's @BLKDEV_TRIG_DISCARD @mode bit to @buf. + * + * Context: Process context. + * Return: The number of characters written to @buf. + */ +static ssize_t blink_on_discard_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return blkdev_trig_mode_show(led_trigger_get_drvdata(dev), buf, + BLKDEV_TRIG_DISCARD); +} + +/** + * blink_on_discard_store() - ``blink_on_discard`` device attribute store + * function. + * @dev: The LED device + * @attr: The ``blink_on_discard`` attribute (@dev_attr_blink_on_discard) + * @buf: The new value (as written to the sysfs attribute) + * @count: The number of characters in @buf + * + * Sets the LED's @BLKDEV_TRIG_DISCARD @mode bit. + * + * Context: Process context. + * Return: @count on success, ``-errno`` on error. + */ +static ssize_t blink_on_discard_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + return blkdev_trig_mode_store(led_trigger_get_drvdata(dev), buf, count, + STAT_DISCARD); +} + +/* Device attributes */ +static DEVICE_ATTR_WO(link_device); +static DEVICE_ATTR_WO(unlink_device); +static DEVICE_ATTR_RW(blink_time); +static DEVICE_ATTR_RW(check_interval); +static DEVICE_ATTR_RW(blink_on_read); +static DEVICE_ATTR_RW(blink_on_write); +static DEVICE_ATTR_RW(blink_on_flush); +static DEVICE_ATTR_RW(blink_on_discard); + +/* Device attributes in LED directory (/sys/class/leds//...) */ +static struct attribute *blkdev_trig_attrs[] = { + &dev_attr_link_device.attr, + &dev_attr_unlink_device.attr, + &dev_attr_blink_time.attr, + &dev_attr_check_interval.attr, + &dev_attr_blink_on_read.attr, + &dev_attr_blink_on_write.attr, + &dev_attr_blink_on_flush.attr, + &dev_attr_blink_on_discard.attr, + NULL +}; + +/* Unnamed attribute group == no subdirectory */ +static const struct attribute_group blkdev_trig_attr_group = { + .attrs = blkdev_trig_attrs, +}; + +/* Attribute groups for the trigger */ +static const struct attribute_group *blkdev_trig_attr_groups[] = { + &blkdev_trig_attr_group, /* /sys/class/leds//... */ + &blkdev_trig_linked_devs, /* /sys/class/leds//linked_devices/ */ + NULL +}; + +/* Trigger registration data */ +static struct led_trigger blkdev_trig_trigger = { + .name = "blkdev", + .activate = blkdev_trig_activate, + .deactivate = blkdev_trig_deactivate, + .groups = blkdev_trig_attr_groups, +}; + +/** + * blkdev_trig_init() - Block device LED trigger initialization. + * + * Registers the LED trigger. + * + * Return: 0 on success, ``-errno`` on failure. + */ +static int __init blkdev_trig_init(void) +{ + return led_trigger_register(&blkdev_trig_trigger); +} +module_init(blkdev_trig_init); + +/** + * blkdev_trig_exit() - Block device LED trigger module exit. + * + * Unregisters the LED trigger. + */ +static void __exit blkdev_trig_exit(void) +{ + led_trigger_unregister(&blkdev_trig_trigger); +} +module_exit(blkdev_trig_exit); + +MODULE_DESCRIPTION("Block device LED trigger"); +MODULE_AUTHOR("Ian Pilcher "); +MODULE_LICENSE("GPL v2"); -- 2.33.1