From patchwork Thu Sep 16 20:21:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ian Pilcher X-Patchwork-Id: 513342 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F755C433F5 for ; Thu, 16 Sep 2021 20:21:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 80B296120F for ; Thu, 16 Sep 2021 20:21:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237468AbhIPUXC (ORCPT ); Thu, 16 Sep 2021 16:23:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44444 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235492AbhIPUW6 (ORCPT ); Thu, 16 Sep 2021 16:22:58 -0400 Received: from mail-ot1-x32e.google.com (mail-ot1-x32e.google.com [IPv6:2607:f8b0:4864:20::32e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB544C061574; Thu, 16 Sep 2021 13:21:37 -0700 (PDT) Received: by mail-ot1-x32e.google.com with SMTP id y63-20020a9d22c5000000b005453f95356cso2986850ota.11; Thu, 16 Sep 2021 13:21:37 -0700 (PDT) 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=rpCqdYN+JdwqKzDDb3D9hX84mN3Lb7ZdISS7xyaK5xk=; b=pfZ1YkjvRTzgQH/I3zaiZx9tTbBqWe4Lx4NsLvlRKVycG1nxvdC/8L8ok/92C9xijf oHeN1OcaZ1/Pfuwsx9gpkEZd+z2ppOENsXtPcl2nF+5SFL+Dm6zZWaj7aYn4+493P9XS JTrstMZmjZWLaWZwBIJ0PIvhLc9yRgeHvxOicivjzF+TH6HYYdEhpeP+ETWmGD2Q/B9u zgXQEQvECAahVGn0x/b11idt2IkHbCECfW4Kykmgq8C/jKZrAybchOyaapS2PVzZMW26 z3n32+qZGa2aHaL3P5f/RPJlrAqAvzwiPB1eI0T4aLm1V20Yx5WsGV2nSRdX/CwI+CAw c2gA== 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=rpCqdYN+JdwqKzDDb3D9hX84mN3Lb7ZdISS7xyaK5xk=; b=TDM5gWowCT8A2gP2oMcoTlrU22fR6NYaa8xA36Io7wGBUD3XEuRA8jYWBn3l8tPkOe fapDbU2nOsaGW8ta/zAOOjtfwLPduwT3/1m5w6eG/NW9R5F9wHDtLclMrU7CMwor+VdR JN6JoLjis4Ddmp0Js/3OgaV1JQ4v0yWL3E2n8ZO7VvqXeJQVI2eLSp9Pi3njqawTIxgr J4eogD6l0o+/BEABN9qP+xSvezA/0K+TsDTDRTm5ZK5U/rDT75H1TtXbw6bc9Kqrpv9+ //va048AhgHi0jCbrSk0vMK/vJwSIgr29aD4LIeNILA5gmfStiS+jnVolt5JJ97S69bu Brxw== X-Gm-Message-State: AOAM533TBxb45HiQv4pgLBg2u7SWsdCvj540LIBJzXu8rQI6grh9KFxD vIjxRqlUXkpOUm3F5IWNEvs= X-Google-Smtp-Source: ABdhPJwgaMrlutRkkjbs/ROkJStvnPKXjF0QsZXgt+AKJDjDObq55uvN5G5MH2oKrqutpWHutnOF9w== X-Received: by 2002:a9d:7396:: with SMTP id j22mr6702640otk.206.1631823696836; Thu, 16 Sep 2021 13:21:36 -0700 (PDT) Received: from ian.penurio.us ([47.184.51.90]) by smtp.gmail.com with ESMTPSA id o24sm948057oie.17.2021.09.16.13.21.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Sep 2021 13:21:36 -0700 (PDT) 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: [PATCH v4 2/2] leds: trigger: Add block device LED trigger Date: Thu, 16 Sep 2021 15:21:27 -0500 Message-Id: <20210916202127.1216994-3-arequipeno@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210916202127.1216994-1-arequipeno@gmail.com> References: <20210916202127.1216994-1-arequipeno@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-leds@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 | 981 ++++++++++++++++++++++++++ 3 files changed, 991 insertions(+) create mode 100644 drivers/leds/trigger/ledtrig-blkdev.c diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig index 1f1d57288085..219d15c046d7 100644 --- a/drivers/leds/trigger/Kconfig +++ b/drivers/leds/trigger/Kconfig @@ -153,4 +153,13 @@ 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..8cb0d3b1e7ed --- /dev/null +++ b/drivers/leds/trigger/ledtrig-blkdev.c @@ -0,0 +1,981 @@ +// SPDX-License-Identifier: GPL-2.0-only + +/* + * Block device LED trigger + * + * Copyright 2021 Ian Pilcher + */ + +#include +#include +#include +#include + +/* Default blink time & check interval (milliseconds) */ +#define LED_BDEV_BLINK_MSEC 75 +#define LED_BDEV_INTERVAL 100 + +/* Minimum blink time & check interval (milliseconds) */ +#define LED_BDEV_MIN_BLINK 10 +#define LED_BDEV_MIN_INT 25 + +/* Device activity type that will make LED blink */ +enum led_bdev_mode { + LED_BDEV_MODE_RO = 0, + LED_BDEV_MODE_WO = 1, + LED_BDEV_MODE_RW = 2 +}; + +/* Block device information (BDI) - 1 per blkdev linked to at least 1 LED */ +struct led_bdev_bdi { + struct block_device *bdev; + struct hlist_head leds; + unsigned long read_ios; + unsigned long write_ios; + unsigned int generation; + bool read_act; + bool write_act; +}; + +/* For many-to-many relationships between block devices and LEDs */ +struct led_bdev_link { + struct hlist_node bdi_leds_node; + struct hlist_node led_bdis_node; + struct led_bdev_bdi *bdi; + struct led_bdev_led *led; +}; + +/* Every LED associated with the blkdev trigger gets one of these */ +struct led_bdev_led { + struct led_classdev *led_cdev; + unsigned int blink_msec; + struct hlist_head bdis; + struct hlist_node leds_node; + enum led_bdev_mode mode; +}; + +/* Forward declarations to make this file compile in a reasonable order */ +static void led_bdev_process(struct work_struct *work); +static struct led_bdev_bdi *led_bdev_get_bdi(const char *buf, size_t size); +static struct block_device *led_bdev_get(const char *buf, size_t size, + fmode_t mode); +static int led_bdev_link(struct led_bdev_led *led, struct led_bdev_bdi *bdi); +static void led_bdev_put_bdi(struct led_bdev_bdi *bdi); +static void led_bdev_bdi_release(struct device *dev, void *res); +static void led_bdev_unlink(struct led_bdev_led *led, + struct led_bdev_link *link, + struct led_bdev_bdi *bdi, bool releasing); +static void led_bdev_update_bdi(struct led_bdev_bdi *bdi); +static bool led_bdev_blink(const struct led_bdev_led *led, + const struct led_bdev_bdi *bdi); + +/* Protects everything except atomic sysfs attributes */ +static DEFINE_MUTEX(led_bdev_mutex); + +/* All LEDs associated with the trigger */ +static HLIST_HEAD(led_bdev_leds); + +/* sysfs class for "global" trigger attributes (interval) */ +static struct class *led_bdev_class; + +/* Delayed work to periodically check for activity & blink LEDs */ +static DECLARE_DELAYED_WORK(led_bdev_work, led_bdev_process); + +/* How often to run the delayed work - in jiffies */ +static unsigned int led_bdev_interval; + +/* Incremented every time the delayed work runs */ +static unsigned int led_bdev_generation; + +/* Total number of device-to-LED associations (links) */ +static unsigned int led_bdev_link_count; + +/* Empty attribute list for the linked_leds & linked_devices "groups" */ +static struct attribute *led_bdev_attrs_empty[] = { NULL }; + +/* linked_leds sysfs directory for block devs linked to 1 or more LEDs */ +static const struct attribute_group led_bdev_linked_leds = { + .name = "linked_leds", + .attrs = led_bdev_attrs_empty, +}; + +/* linked_devices sysfs directory for each LED associated with the trigger */ +static const struct attribute_group led_bdev_linked_devs = { + .name = "linked_devices", + .attrs = led_bdev_attrs_empty, +}; + +/** + * led_bdev_activate() - Called when an LED is associated with the trigger. + * @led_cdev: The LED + * + * Allocates & initializes the @led_bdev_led structure, adds it to the + * @led_bdev_leds list, and sets the LED's trigger data. + * + * Context: Process context. Takes and releases @led_bdev_mutex. + * Return: ``0`` on success, ``-errno`` on error. + */ +static int led_bdev_activate(struct led_classdev *const led_cdev) +{ + struct led_bdev_led *led; + int ret; + + led = kmalloc(sizeof(*led), GFP_KERNEL); + if (led == NULL) { + ret = -ENOMEM; + goto exit_return; + } + + led->led_cdev = led_cdev; + led->blink_msec = LED_BDEV_BLINK_MSEC; + led->mode = LED_BDEV_MODE_RW; + INIT_HLIST_HEAD(&led->bdis); + + ret = mutex_lock_interruptible(&led_bdev_mutex); + if (ret != 0) + goto exit_free; + + hlist_add_head(&led->leds_node, &led_bdev_leds); + led_set_trigger_data(led_cdev, led); + + mutex_unlock(&led_bdev_mutex); + +exit_free: + if (ret != 0) + kfree(led); +exit_return: + return ret; +} + +/** + * 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 led_bdev_get_bdi() to find or create the BDI for the block device, + * checks that the device isn't already linked to this LED, and calls + * led_bdev_link() to create the link. + * + * Context: Process context. Takes and releases @led_bdev_mutex. + * Return: @count on success, ``-errno`` on error. + */ +static ssize_t link_device_store(struct device *const dev, + struct device_attribute *const attr, + const char *const buf, const size_t count) +{ + struct led_bdev_led *const led = led_trigger_get_drvdata(dev); + const struct led_bdev_link *link; + struct led_bdev_bdi *bdi; + int ret; + + ret = mutex_lock_interruptible(&led_bdev_mutex); + if (ret != 0) + goto exit_return; + + bdi = led_bdev_get_bdi(buf, count); + if (IS_ERR(bdi)) { + ret = PTR_ERR(bdi); + goto exit_unlock; + } + + hlist_for_each_entry (link, &bdi->leds, bdi_leds_node) { + if (link->led == led) { + ret = -EEXIST; + goto exit_put_bdi; + } + } + + ret = led_bdev_link(led, bdi); + +exit_put_bdi: + if (ret != 0) + led_bdev_put_bdi(bdi); +exit_unlock: + mutex_unlock(&led_bdev_mutex); +exit_return: + return (ret == 0) ? count : ret; +} + +/** + * led_bdev_get_bdi() - Find or create the BDI 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 led_bdev_get() to get the block device represented by the path in @buf. + * If the device already has a BDI (because it is already linked to an LED), + * simply returns the existing BDI. + * + * Otherwise, allocates a new BDI (as a device resource), creates the block + * device's ``linked_leds`` directory (attribute group), calls + * led_bdev_update_bdi() to set the BDI's activity counters, and adds the BDI + * resource to the block device. + * + * Context: Process context. Caller must hold @led_bdev_mutex. + * Return: Pointer to the BDI, error pointer on error. + */ +static struct led_bdev_bdi *led_bdev_get_bdi(const char *const buf, + const size_t count) +{ + struct block_device *bdev; + struct led_bdev_bdi *bdi; + struct device *dev; + int ret; + + bdev = led_bdev_get(buf, count, 0); + if (IS_ERR(bdev)) { + ret = PTR_ERR(bdev); + goto exit_return; + } + + dev = &bdev->bd_device; + + bdi = devres_find(dev, led_bdev_bdi_release, NULL, NULL); + if (bdi != NULL) { + ret = 0; + goto exit_put_bdev; + } + + bdi = devres_alloc(led_bdev_bdi_release, sizeof(*bdi), GFP_KERNEL); + if (bdi == NULL) { + ret = -ENOMEM; + goto exit_put_bdev; + } + + ret = sysfs_create_group(&dev->kobj, &led_bdev_linked_leds); + if (ret != 0) + goto exit_free_bdi; + + bdi->bdev = bdev; + INIT_HLIST_HEAD(&bdi->leds); + + /* Ensure that led_bdev_update_bdi() updates BDI */ + bdi->generation = led_bdev_generation - 1; + led_bdev_update_bdi(bdi); + /* Don't blink for activity that may have happened long ago */ + bdi->read_act = false; + bdi->write_act = false; + + devres_add(dev, bdi); + +exit_free_bdi: + if (ret != 0) + devres_free(bdi); +exit_put_bdev: + blkdev_put(bdev, 0); /* Allow the device to be released */ +exit_return: + return (ret == 0) ? bdi : ERR_PTR(ret); +} + +/** + * led_bdev_update_bdi() - Update a BDI's activity counters for the current + * generation + * @bdi: The BDI + * + * Does nothing if the BDI has already been updated during this generation. + * + * Otherwise, updates the BDI's activity counters (@read_ios & @write_ios) and + * @generation, and sets @read_act and/or @write_act if the corresponding + * counters have changed. + * + * Context: Process context. Caller must hold @led_bdev_mutex. + */ +static void led_bdev_update_bdi(struct led_bdev_bdi *const bdi) +{ + unsigned long read_ios, write_ios; + + if (bdi->generation != led_bdev_generation) { + + read_ios = part_stat_read(bdi->bdev, ios[STAT_READ]); + + write_ios = part_stat_read(bdi->bdev, ios[STAT_WRITE]) + + part_stat_read(bdi->bdev, ios[STAT_DISCARD]) + + part_stat_read(bdi->bdev, ios[STAT_FLUSH]); + + if (bdi->read_ios != read_ios) { + bdi->read_act = true; + bdi->read_ios = read_ios; + } else { + bdi->read_act = false; + } + + if (bdi->write_ios != write_ios) { + bdi->write_act = true; + bdi->write_ios = write_ios; + } else { + bdi->write_act = false; + } + + bdi->generation = led_bdev_generation; + } +} + +/** + * led_bdev_get_bdev() - Get a block device by path, prepending "/dev/" if + * needed. + * @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) + * + * This function is a wrapper around blkdev_get_by_path(). It first tries the + * path that was written to the sysfs attribute (after removing trailing + * whitespace). If the first attempt returns -ENOENT, it tries again with + * "/dev/" prepended to the path. + * + * 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 *led_bdev_get(const char *const buf, + const size_t count, fmode_t mode) +{ + static const char dev[] = "/dev/"; + struct block_device *bdev; + char *dev_path, *path; + + /* sizeof(dev) includes terminating null */ + dev_path = kmalloc(sizeof(dev) + count, GFP_KERNEL); + if (dev_path == NULL) + return ERR_PTR(-ENOMEM); + + /* sizeof(dev) - 1 is compile-time equivalent of strlen(dev) */ + memcpy(dev_path, dev, sizeof(dev) - 1); + path = dev_path + sizeof(dev) - 1; + memcpy(path, buf, count + 1); /* include terminating null */ + strim(path); + +try_blkdev_get: + bdev = blkdev_get_by_path(path, mode, THIS_MODULE); + if (IS_ERR(bdev) && PTR_ERR(bdev) == -ENOENT && path != dev_path) { + path = dev_path; + goto try_blkdev_get; + } + + kfree(dev_path); + return bdev; +} + +/** + * led_bdev_link() - "Link" a block device to an LED. + * @led: The LED + * @bdi: The block device + * + * Called from link_device_store() to create the link between an LED and a + * block device. + * + * * Allocates & initializes link structure. + * * Adds block device symlink to LED's ``linked_devices`` directory. + * * Adds LED symlink to block devices's ``linked_leds`` directory. + * * Adds link to LED's list of block devices and device's list of LEDs. + * + * If the new link is the only one (i.e. no other block device/LED links + * already exist), schedule delayed work to periodically check for block + * device activity and blink LEDs. + * + * Context: Process context. Caller must hold @led_bdev_mutex. + * Return: 0 on success, ``-errno`` on error. + */ +static int led_bdev_link(struct led_bdev_led *const led, + struct led_bdev_bdi *const bdi) +{ + struct led_bdev_link *link; + unsigned long delay; + int ret; + + link = kmalloc(sizeof(*link), GFP_KERNEL); + if (link == NULL) { + ret = -ENOMEM; + goto error_return; + } + + /* /sys/class/block//linked_leds/ */ + ret = sysfs_add_link_to_group(bdev_kobj(bdi->bdev), + led_bdev_linked_leds.name, + &led->led_cdev->dev->kobj, + led->led_cdev->name); + if (ret != 0) + goto error_free_link; + + /* /sys/class/leds//linked_devices/ */ + ret = sysfs_add_link_to_group(&led->led_cdev->dev->kobj, + led_bdev_linked_devs.name, + bdev_kobj(bdi->bdev), + dev_name(&bdi->bdev->bd_device)); + if (ret != 0) + goto error_remove_symlink; + + link->bdi = bdi; + link->led = led; + hlist_add_head(&link->led_bdis_node, &led->bdis); + hlist_add_head(&link->bdi_leds_node, &bdi->leds); + + if (led_bdev_link_count == 0) { + delay = READ_ONCE(led_bdev_interval); + WARN_ON(!schedule_delayed_work(&led_bdev_work, delay)); + } + + ++led_bdev_link_count; + + return 0; + +error_remove_symlink: + sysfs_remove_link_from_group(bdev_kobj(bdi->bdev), + led_bdev_linked_leds.name, + led->led_cdev->name); +error_free_link: + kfree(link); +error_return: + return ret; +} + +/** + * 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 led_bdev_get() to get the block device represented by the path in @buf. + * If the device has a BDI, searches the BDI's list of LEDs for a link to this + * LED and (if found) calls led_bdev_unlink() to destroy the link. + * + * Context: Process context. Takes and releases @led_bdev_mutex. + * Return: @count on success, ``-errno`` on error. + */ +static ssize_t unlink_device_store(struct device *const dev, + struct device_attribute *const attr, + const char *buf, const size_t count) +{ + struct led_bdev_led *const led = led_trigger_get_drvdata(dev); + struct block_device *bdev; + struct led_bdev_bdi *bdi; + struct led_bdev_link *link; + int ret; + + bdev = led_bdev_get(buf, count, 0); + if (IS_ERR(bdev)) { + ret = PTR_ERR(bdev); + goto exit_return; + } + + bdi = devres_find(&bdev->bd_device, led_bdev_bdi_release, NULL, NULL); + if (bdi == NULL) { + ret = -EUNATCH; + goto exit_put_bdev; + } + + ret = mutex_lock_interruptible(&led_bdev_mutex); + if (ret != 0) + goto exit_put_bdev; + + hlist_for_each_entry(link, &bdi->leds, bdi_leds_node) { + + if (link->led == led) { + led_bdev_unlink(led, link, bdi, false); + goto exit_unlock; + } + } + + ret = -EUNATCH; + +exit_unlock: + mutex_unlock(&led_bdev_mutex); +exit_put_bdev: + blkdev_put(bdev, 0); +exit_return: + return (ret == 0) ? count : ret; +} + +/** + * led_bdev_unlink() - "Unlink" a block device from an LED. + * @led: The LED + * @link: The existing link between the LED and the block device + * @bdi: The block device + * @releasing: Indicates whether the BDI is being released (because the + * block device has been removed) + * + * Removes and frees the link between an LED and a block device. + * + * * Removes the link from the LED's list of block devices and the + * device's list of LEDs. + * * Frees the link structure. + * * 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 led_bdev_put_bdi() to clean up the BDI, 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 (with @releasing == ``false``) + * when a block device is unlinked from an LED via the ``unlink_device`` + * sysfs attribute. + * * led_bdev_deactivate() calls this function (with @releasing == ``false``) + * for each block device linked to an LED that is being deactivated + * (disassociated from the trigger). + * * led_bdev_bdi_release() calls this function (with @releasing == ``true``) + * for each LED link to a block device that has been removed from the + * system. + * + * Context: Process context. Caller must hold @led_bdev_mutex. + */ +static void led_bdev_unlink(struct led_bdev_led *const led, + struct led_bdev_link *const link, + struct led_bdev_bdi *const bdi, + const bool releasing) +{ + --led_bdev_link_count; + + if (led_bdev_link_count == 0) + WARN_ON(!cancel_delayed_work_sync(&led_bdev_work)); + + hlist_del(&link->led_bdis_node); + hlist_del(&link->bdi_leds_node); + kfree(link); + + /* /sys/class/leds//linked_devices/ */ + sysfs_remove_link_from_group(&led->led_cdev->dev->kobj, + led_bdev_linked_devs.name, + dev_name(&bdi->bdev->bd_device)); + + /* + * If the BDI is being released, the device's attribute groups have + * already been removed, and the BDI will be freed automatically. + */ + if (!releasing) { + + /* /sys/class/block//linked_leds/ */ + sysfs_remove_link_from_group(bdev_kobj(bdi->bdev), + led_bdev_linked_leds.name, + led->led_cdev->name); + led_bdev_put_bdi(bdi); + } +} + +/** + * led_bdev_put_bdi() - Remove and free a BDI, if it is no longer needed. + * @bdi: The BDI + * + * Does nothing if the BDI (block device) is still linked to at least one LED. + * + * If the BDI is no longer linked to any LEDs, removes the block device's + * ``linked_leds`` directory (attribute group), removes the BDI from the + * block device's resource list, and frees the BDI. + * + * Called from led_bdev_unlink() (and in the link_device_store() error path). + * + * Context: Process context. Caller must hold @led_bdev_mutex. + */ +static void led_bdev_put_bdi(struct led_bdev_bdi *const bdi) +{ + struct block_device *const bdev = bdi->bdev; + int ret; + + if (hlist_empty(&bdi->leds)) { + + sysfs_remove_group(bdev_kobj(bdev), &led_bdev_linked_leds); + ret = devres_destroy(&bdev->bd_device, led_bdev_bdi_release, + NULL, NULL); + WARN_ON(ret != 0); + } +} + +/** + * led_bdev_deactivate() - Called when an LED is disassociated from the + * trigger. + * @led_cdev: The LED + * + * Calls led_bdev_unlink() for each block device linked to the LED, removes + * the LED from the @led_bdev_leds list, and frees the @led_bdev_led structure. + * + * Context: Process context. Takes and releases @led_bdev_mutex. + */ +static void led_bdev_deactivate(struct led_classdev *const led_cdev) +{ + struct led_bdev_led *const led = led_get_trigger_data(led_cdev); + struct led_bdev_link *link; + struct hlist_node *next; + + mutex_lock(&led_bdev_mutex); + + hlist_for_each_entry_safe (link, next, &led->bdis, led_bdis_node) + led_bdev_unlink(led, link, link->bdi, false); + + hlist_del(&led->leds_node); + kfree(led); + + mutex_unlock(&led_bdev_mutex); +} + +/** + * led_bdev_bdi_release() - BDI device resource release function. + * @dev: The block device + * @res: The BDI + * + * Called by the driver core when a block device with a BDI is removed from the + * system. Calls led_bdev_unlink() for each LED linked to the block device. + * + * Context: Process context. Takes and releases @led_bdev_mutex. + */ +static void led_bdev_bdi_release(struct device *const dev, void *const res) +{ + struct led_bdev_bdi *const bdi = res; + struct led_bdev_link *link; + struct hlist_node *next; + + mutex_lock(&led_bdev_mutex); + + hlist_for_each_entry_safe (link, next, &bdi->leds, bdi_leds_node) + led_bdev_unlink(link->led, link, bdi, true); + + mutex_unlock(&led_bdev_mutex); +} + +/** + * led_bdev_process() - Check linked devices for activity and blink LEDs. + * @work: Delayed work (@led_bdev_work) + * + * Iterates through block devices linked to LEDs and calls led_bdev_update_bdi() + * to update the BDI's activity counters. If a particular LED hasn't already + * been blinked, calls led_bdev_blink() to blink the LED if appropriate for that + * device's activity. + * + * When finished, schedules itself to run again after @led_bdev_interval + * jiffies. + * + * Context: Process context. Takes and releases @led_bdev_mutex. + */ +static void led_bdev_process(struct work_struct *const work) +{ + struct led_bdev_led *led; + struct led_bdev_link *link; + unsigned long delay; + + if (!mutex_trylock(&led_bdev_mutex)) + goto exit_reschedule; + + hlist_for_each_entry (led, &led_bdev_leds, leds_node) { + + bool blinked = false; + + hlist_for_each_entry (link, &led->bdis, led_bdis_node) { + + led_bdev_update_bdi(link->bdi); + if (!blinked) + blinked = led_bdev_blink(led, link->bdi); + } + } + + ++led_bdev_generation; + + mutex_unlock(&led_bdev_mutex); + +exit_reschedule: + delay = READ_ONCE(led_bdev_interval); + WARN_ON_ONCE(!schedule_delayed_work(&led_bdev_work, delay)); +} + +/** + * led_bdev_blink() - Blink an LED, if the correct type of activity has occurred + * on the block device. + * @led: The LED + * @bdi: The block device + * + * Context: Process context. Caller must hold @led_bdev_mutex. + * Return: ``true`` if the LED is blinked, ``false`` if not. + */ +static bool led_bdev_blink(const struct led_bdev_led *const led, + const struct led_bdev_bdi *const bdi) +{ + unsigned long delay_on, delay_off; + + if ((bdi->read_act && led->mode != LED_BDEV_MODE_WO) + || (bdi->write_act && led->mode != LED_BDEV_MODE_RO)) { + + 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 *const dev, + struct device_attribute *const attr, + char *const buf) +{ + const struct led_bdev_led *const 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 *const dev, + struct device_attribute *const attr, + const char *const buf, const size_t count) +{ + struct led_bdev_led *const led = led_trigger_get_drvdata(dev); + unsigned int value; + int ret; + + ret = kstrtouint(buf, 0, &value); + if (ret != 0) + return ret; + + if (value < LED_BDEV_MIN_BLINK) + return -ERANGE; + + WRITE_ONCE(led->blink_msec, value); + return count; +} + +/* Data for mode_show() & mode_store() */ +static const struct { + char name[sizeof("write")]; /* longest name */ + char show[sizeof("[read] write rw\n")]; /* all the same size */ +} led_bdev_modes[] = { + [LED_BDEV_MODE_RO] = { + .name = "read", + .show = "[read] write rw\n", + }, + [LED_BDEV_MODE_WO] = { + .name = "write", + .show = "read [write] rw\n", + }, + [LED_BDEV_MODE_RW] = { + .name = "rw", + .show = "read write [rw]\n", + }, +}; + +/** + * mode_show() - ``mode`` device attribute show function. + * @dev: The LED device + * @attr: The ``mode`` attribute (@dev_attr_mode) + * @buf: Output buffer + * + * Writes the current value of the LED's @mode to @buf. + * + * Context: Process context. + * Return: The number of characters written to @buf. + */ +static ssize_t mode_show(struct device *const dev, + struct device_attribute *const attr, char *const buf) +{ + const struct led_bdev_led *const led = led_trigger_get_drvdata(dev); + + return sprintf(buf, led_bdev_modes[READ_ONCE(led->mode)].show); +} + +/** + * mode_store() - ``mode`` device attribute store function. + * @dev: The LED device + * @attr: The ``mode`` attribute (@dev_attr_mode) + * @buf: The new value (as written to the sysfs attribute) + * @count: The number of characters in @buf + * + * Sets the LED's @mode (``read``, ``write``, or ``rw``). + * + * Context: Process context. + * Return: @count on success, ``-errno`` on error. + */ +static ssize_t mode_store(struct device *const dev, + struct device_attribute *const attr, + const char *const buf, const size_t count) +{ + struct led_bdev_led *const led = led_trigger_get_drvdata(dev); + enum led_bdev_mode mode; + + for (mode = LED_BDEV_MODE_RO; mode <= LED_BDEV_MODE_RW; ++mode) { + + if (sysfs_streq(led_bdev_modes[mode].name, buf)) { + WRITE_ONCE(led->mode, mode); + return count; + } + } + + return -EINVAL; +} + +/** + * interval_show() - ``interval`` class attribute show function. + * @class: The ``ledtrig_blkdev`` class (@led_bdev_class) + * @attr: The ``interval`` attribute (@class_attr_interval) + * @buf: Output buffer + * + * Writes the current value of @led_bdev_interval to @buf. + * + * Context: Process context. + * Return: The number of characters written to @buf. + */ +static ssize_t interval_show(struct class *const class, + struct class_attribute *const attr, + char *const buf) +{ + return sprintf(buf, "%u\n", + jiffies_to_msecs(READ_ONCE(led_bdev_interval))); +} + +/** + * interval_store() - ``interval`` class attribute store function + * @class: The ``ledtrig_blkdev`` class (@led_bdev_class) + * @attr: The ``interval`` attribute (@class_attr_interval) + * @buf: The new value (as written to the sysfs attribute) + * @count: The number of characters in @buf + * + * Sets @led_bdev_interval (after converting to jiffies). + * + * Context: Process context. + * Return: @count on success, ``-errno`` on error. + */ +static ssize_t interval_store(struct class *const class, + struct class_attribute *const attr, + const char *const buf, const size_t count) +{ + unsigned int value; + int ret; + + ret = kstrtouint(buf, 0, &value); + if (ret != 0) + return ret; + + if (value < LED_BDEV_MIN_INT) + return -ERANGE; + + WRITE_ONCE(led_bdev_interval, msecs_to_jiffies(value)); + + return count; +} + +/* Device and class attributes */ +static DEVICE_ATTR_WO(link_device); +static DEVICE_ATTR_WO(unlink_device); +static DEVICE_ATTR_RW(blink_time); +static DEVICE_ATTR_RW(mode); +static CLASS_ATTR_RW(interval); + +/* Device attributes in LED directory (/sys/class/leds//...) */ +static struct attribute *led_bdev_attrs[] = { + &dev_attr_link_device.attr, + &dev_attr_unlink_device.attr, + &dev_attr_blink_time.attr, + &dev_attr_mode.attr, + NULL +}; + +/* Unnamed attribute group == no subdirectory */ +static const struct attribute_group led_bdev_attr_group = { + .attrs = led_bdev_attrs, +}; + +/* Attribute groups for the trigger */ +static const struct attribute_group *led_bdev_attr_groups[] = { + &led_bdev_attr_group, /* /sys/class/leds//... */ + &led_bdev_linked_devs, /* /sys/class/leds//linked_devices/ */ + NULL +}; + +/* Trigger registration data */ +static struct led_trigger led_bdev_trigger = { + .name = "blkdev", + .activate = led_bdev_activate, + .deactivate = led_bdev_deactivate, + .groups = led_bdev_attr_groups, +}; + +/** + * led_bdev_init() - Block device LED trigger initialization. + * + * Converts default @led_bdev_interval from milliseconds to jiffies, creates + * the ``/sys/class/ledtrig_blkdev/interval`` attribute, and registers the LED + * trigger. + * + * Return: 0 on success, ``-errno`` on failure. + */ +static int __init led_bdev_init(void) +{ + int ret; + + WRITE_ONCE(led_bdev_interval, + msecs_to_jiffies(LED_BDEV_INTERVAL)); + + led_bdev_class = class_create(THIS_MODULE, "ledtrig_blkdev"); + if (IS_ERR(led_bdev_class)) { + ret = PTR_ERR(led_bdev_class); + goto exit_return; + } + + ret = class_create_file(led_bdev_class, &class_attr_interval); + if (ret != 0) + goto exit_destroy_class; + + ret = led_trigger_register(&led_bdev_trigger); + +exit_destroy_class: + if (ret != 0) + class_destroy(led_bdev_class); /* removes the attribute file */ +exit_return: + return ret; +} +module_init(led_bdev_init); + +/** + * led_bdev_exit() - Block device LED trigger module exit. + * + * Unregisters the LED trigger and removes the + * ``/sys/class/ledtrig_blkdev/interval`` attribute. + */ +static void __exit led_bdev_exit(void) +{ + led_trigger_unregister(&led_bdev_trigger); + class_destroy(led_bdev_class); +} +module_exit(led_bdev_exit); + +MODULE_DESCRIPTION("Block device LED trigger"); +MODULE_AUTHOR("Ian Pilcher "); +MODULE_LICENSE("GPL v2");