From patchwork Sat Oct 8 19:47:07 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ian Pilcher X-Patchwork-Id: 613465 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 1EC33C4332F for ; Sat, 8 Oct 2022 19:47:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229941AbiJHTrS (ORCPT ); Sat, 8 Oct 2022 15:47:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56566 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229769AbiJHTrQ (ORCPT ); Sat, 8 Oct 2022 15:47:16 -0400 Received: from mail-oo1-xc2c.google.com (mail-oo1-xc2c.google.com [IPv6:2607:f8b0:4864:20::c2c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 222BA32D96; Sat, 8 Oct 2022 12:47:11 -0700 (PDT) Received: by mail-oo1-xc2c.google.com with SMTP id c17-20020a4aa4d1000000b0047653e7c5f3so5652950oom.1; Sat, 08 Oct 2022 12:47:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=ZOx6jUDDqH+LMikqvjmE2CcwI1yn+q2awUlypYAS4s4=; b=NXwd+pCyt00P96ygRa+3U8yVCD0gC2WhAeQyezElxlARfHGWbn74WN84N8V4eicfVD 7m1r1DIaTL9Ni0+vYlN9wxT93YmYlWrn3iDbZBLX3ri6cLDlrKxXFQvPFaSQR9ltLBsr Hdyzne58MbkxMrWAx5XwqcwBPqivpk7hyCb2hZ6JmNTK/e3n5WQ67123MKNxu5kp+tSx V/pwlkseOc7znQJOGhPvQvJzP4tw/1+ECw5ZfJFODE5vBcqcExTCQcPmI+QbDTVTOYJJ 3+3f24ReTX8/EzOfE7L2n/8JO9a2HqLNKmnYEfFx1j/TYWcDA0O5JsmR7kBbz7U6WGW8 77tg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ZOx6jUDDqH+LMikqvjmE2CcwI1yn+q2awUlypYAS4s4=; b=JxJx9RDcfIiP5eukChrSbnXN1k3zDZLL4HbM8s2jnqUHLfymPuYoJZjrFzsYTUevkM hfVYxU5kMNuVnawr2Mla5BE5xPBCeFnOY+NKCeue5pXXk58g1VR70zDpd4NxmbdcsWFx QAYLTuCCO+RagBkLJUpUHYWk9rViHQWOSskhNbe7HY8aque+Mowtqdft7P4l1yshogmu uudXy8ZnLGhlJGYOgTVbqg4WnRzykRiJy+HpN+YaLsfC76TsJYGCPkEbQ1PHgHw3QobC R0aTj/1zMOrg8dA20BUkv7Jh+A6mxGc4Cw1TFm8VRA6HliIf6B7m1ufDb4K+OAh4bscS /Q1w== X-Gm-Message-State: ACrzQf0HaaYPoiSOkNEuP4DKe/QgD1KPAM5czcMj4AgKs+vlHNVRniYm 92rPy64CGRQE3g+s0Kr2Hfo= X-Google-Smtp-Source: AMsMyM5IKu2of+mN+drNmafO8nvo0fVBHt391G7vy1Pg4XNyNvQ//zVkeTCpFeBi8EEX8cybGM2toQ== X-Received: by 2002:a05:6830:6084:b0:65c:3942:e3bf with SMTP id by4-20020a056830608400b0065c3942e3bfmr4959495otb.49.1665258430078; Sat, 08 Oct 2022 12:47:10 -0700 (PDT) Received: from ian.penurio.us ([47.184.52.85]) by smtp.gmail.com with ESMTPSA id y16-20020a9d4610000000b00656039161b1sm2976854ote.40.2022.10.08.12.47.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 08 Oct 2022 12:47:09 -0700 (PDT) From: Ian Pilcher To: pavel@ucw.cz Cc: linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org, kabel@kernel.org Subject: [RESEND PATCH v12 2/2] leds: trigger: Add block device LED trigger Date: Sat, 8 Oct 2022 14:47:07 -0500 Message-Id: <20221008194707.370805-3-arequipeno@gmail.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20221008194707.370805-1-arequipeno@gmail.com> References: <20221008194707.370805-1-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 Tested-by: Tor Vic --- drivers/leds/trigger/Kconfig | 9 + drivers/leds/trigger/Makefile | 1 + drivers/leds/trigger/ledtrig-blkdev.c | 1220 +++++++++++++++++++++++++ 3 files changed, 1230 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..8614e308fadc --- /dev/null +++ b/drivers/leds/trigger/ledtrig-blkdev.c @@ -0,0 +1,1220 @@ +// SPDX-License-Identifier: GPL-2.0-only + +/* + * Block device LED trigger + * + * Copyright 2021-2022 Ian Pilcher + */ + +#include +#include +#include +#include +#include + +/** + * DOC: Overview + * + * The ``blkdev`` LED trigger works by periodically checking the activity + * counters of block devices that have been linked to one or more LEDs and + * blinking those LED(s) if the correct type of activity has occurred. The + * periodic check is scheduled with the Linux kernel's deferred work facility. + * + * Trigger-specific data about block devices and LEDs is stored in two data + * structures --- &struct blkdev_trig_bdev (a "BTB") and &struct blkdev_trig_led + * (a "BTL"). Each structure contains a &struct xarray that holds links to any + * linked devices of the other type. I.e. &blkdev_trig_bdev.linked_btls + * contains links to all BTLs whose LEDs have been linked to the BTB's block + * device, and &blkdev_trig_led.linked_btbs contains links to all BTBs whose + * block devices have been linked to the BTL's LED. Thus, a block device can + * be linked to more than one LED, and an LED can be linked to more than one + * block device. + */ + +/* 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 /* 24 hours */ + +/* + * If blkdev_trig_check() can't lock the mutex, how long to wait before trying + * again (milliseconds) + */ +#define BLKDEV_TRIG_CHECK_RETRY 5 + +/* Mode argument for calls to blkdev_get_by_path() and blkdev_put() */ +#define BLKDEV_TRIG_FMODE 0 + +/** + * struct blkdev_trig_bdev - Trigger-specific data about a block device. + * @last_checked: Time (in jiffies) at which the trigger last checked this + * block device for activity. + * @last_activity: Time (in jiffies) at which the trigger last detected + * activity of each type. + * @ios: Activity counter values for each type, corresponding to + * the timestamps in &last_activity. + * @index: &xarray index, so the BTB can be included in one or more + * &blkdev_trig_led.linked_btbs. + * @bdev: The block device. + * @linked_btls: The BTLs that represent the LEDs linked to the BTB's + * block device. + * + * Every block device linked to at least one LED gets a "BTB." A BTB is created + * when a block device that is not currently linked to any LEDs is linked to an + * LED. + * + * A BTB is freed when one of the following occurs: + * + * * The number of LEDs linked to the block device becomes zero, because it has + * been unlinked from its last LED using the trigger's &sysfs interface. + * + * * The number of LEDs linked to the block device becomes zero, because the + * last LED to which it was linked has been disassociated from the trigger + * (which happens automatically if the LED device is removed from the system). + * + * * The BTB's block device is removed from the system. To accomodate this + * scenario, BTB's are created as device resources, so that the release + * function will be called by the driver core when the device is removed. + */ +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_btls; +}; + +/** + * struct blkdev_trig_led - Trigger-specific data about an LED. + * @last_checked: Time (in jiffies) at which the trigger last checked the + * the block devices linked to this LED for activity. + * @index: &xarray index, so the BTL can be included in one or more + * &blkdev_trig_bdev.linked_btls. + * @mode: Bitmask for types of block device activity that will + * cause this LED to blink --- reads, writes, discards, + * etc. + * @led: The LED device. + * @blink_msec: Duration of a blink (milliseconds). + * @check_jiffies: Frequency with which block devices linked to this LED + * should be checked for activity (jiffies). + * @linked_btbs: The BTBs that represent the block devices linked to the + * BTL's LED. + * @all_btls_node: The BTL's node in the module's list of all BTLs. + * + * Every LED associated with the block device trigger gets a "BTL." A BTL is + * created when the trigger is "activated" on an LED (usually by writing + * ``blkdev`` to the LED's &sysfs &trigger attribute). A BTL is freed wnen its + * LED is disassociated from the trigger, either through the trigger's &sysfs + * interface or because the LED device is removed from the system. + */ +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; + unsigned int blink_msec; + unsigned int check_jiffies; + struct xarray linked_btbs; + struct hlist_node all_btls_node; +}; + +/* Protects everything except atomic LED attributes */ +static DEFINE_MUTEX(blkdev_trig_mutex); + +/* BTB device resource release function */ +static void blkdev_trig_btb_release(struct device *dev, void *res); + +/* Index for next BTB or BTL */ +static unsigned long blkdev_trig_next_index; + +/* All LEDs associated with the trigger */ +static HLIST_HEAD(blkdev_trig_all_btls); + +/* Delayed work to periodically check for activity & blink LEDs */ +static void blkdev_trig_check(struct work_struct *work); +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 BTB-to-BTL links */ +static unsigned int blkdev_trig_link_count; + +/* Empty sysfs attribute list for next 2 declarations */ +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, +}; + + +/* + * + * Delayed work to check for activity & blink LEDs + * + */ + +/** + * blkdev_trig_blink() - Blink an LED, if the correct type of activity has + * occurred on the block device. + * @btl: The BTL that represents the LED + * @btb: The BTB that represents 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 *btl, + const struct blkdev_trig_bdev *btb) +{ + unsigned long mode, mask, delay_on, delay_off; + enum stat_group i; + + mode = READ_ONCE(btl->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], btl->last_checked)) + continue; + + delay_on = READ_ONCE(btl->blink_msec); + delay_off = 1; /* 0 leaves LED turned on */ + + led_blink_set_oneshot(btl->led, &delay_on, &delay_off, 0); + return true; + } + + return false; +} + +/** + * blkdev_trig_update_btb() - Update a BTB's activity counters and timestamps. + * @btb: The BTB + * @now: Timestamp (in jiffies) + * + * 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_check() - Check linked devices for activity and blink LEDs. + * @work: Delayed work (&blkdev_trig_work) + * + * Context: Process context. Takes and releases &blkdev_trig_mutex. + */ +static void blkdev_trig_check(struct work_struct *work) +{ + struct blkdev_trig_led *btl; + 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 (btl, &blkdev_trig_all_btls, all_btls_node) { + + led_check = btl->last_checked + btl->check_jiffies; + + if (time_before_eq(led_check, now)) { + + blinked = false; + + xa_for_each (&btl->linked_btbs, index, btb) { + + if (btb->last_checked != now) + blkdev_trig_update_btb(btb, now); + if (!blinked) + blinked = blkdev_trig_blink(btl, btb); + } + + btl->last_checked = now; + led_delay = btl->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_sched_led() - Set the schedule of the delayed work when a new + * LED is added to the schedule. + * @btl: The BTL that represents the LED + * + * Called when the number of block devices to which an LED is linked becomes + * non-zero. + * + * Context: Process context. Caller must hold &blkdev_trig_mutex. + */ +static void blkdev_trig_sched_led(const struct blkdev_trig_led *btl) +{ + unsigned long delay = READ_ONCE(btl->check_jiffies); + unsigned long check_by = jiffies + delay; + + /* + * If no other LED-to-block device links exist, simply schedule the + * delayed work according to this LED's check_interval attribute + * (check_jiffies). + */ + if (blkdev_trig_link_count == 0) { + WARN_ON(!schedule_delayed_work(&blkdev_trig_work, delay)); + blkdev_trig_next_check = check_by; + return; + } + + /* + * If the next check is already scheduled to occur soon enough to + * accomodate this LED's check_interval, the schedule doesn't need + * to be changed. + */ + if (time_after_eq(check_by, blkdev_trig_next_check)) + return; + + /* + * Modify the schedule, so that the delayed work runs soon enough for + * this LED. + */ + WARN_ON(!mod_delayed_work(system_wq, &blkdev_trig_work, delay)); + blkdev_trig_next_check = check_by; +} + + +/* + * + * Linking and unlinking LEDs and block devices + * + */ + +/** + * blkdev_trig_link() - Link a block device to an LED. + * @btl: The BTL that represents the LED + * @btb: The BTB that represents the block device + * + * Context: Process context. Caller must hold &blkdev_trig_mutex. + * Return: &0 on success, negative &errno on error. + */ +static int blkdev_trig_link(struct blkdev_trig_led *btl, + struct blkdev_trig_bdev *btb) +{ + bool led_first_link; + int err; + + led_first_link = xa_empty(&btl->linked_btbs); + + err = xa_insert(&btb->linked_btls, btl->index, btl, GFP_KERNEL); + if (err) + return err; + + err = xa_insert(&btl->linked_btbs, btb->index, btb, GFP_KERNEL); + if (err) + goto error_erase_btl; + + /* Create /sys/class/block//linked_leds/ symlink */ + err = sysfs_add_link_to_group(bdev_kobj(btb->bdev), + blkdev_trig_linked_leds.name, + &btl->led->dev->kobj, btl->led->name); + if (err) + goto error_erase_btb; + + /* Create /sys/class/leds//linked_devices/ symlink */ + err = sysfs_add_link_to_group(&btl->led->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 is the first block device linked to this LED, the delayed + * work schedule may need to be changed. + */ + if (led_first_link) + blkdev_trig_sched_led(btl); + + ++blkdev_trig_link_count; + + return 0; + +error_remove_symlink: + sysfs_remove_link_from_group(bdev_kobj(btb->bdev), + blkdev_trig_linked_leds.name, + btl->led->name); +error_erase_btb: + xa_erase(&btl->linked_btbs, btb->index); +error_erase_btl: + xa_erase(&btb->linked_btls, btl->index); + return err; +} + +/** + * 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. + * + * 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_btls)) { + + 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_unlink_always() - Perform the unconditionally required steps of + * unlinking a block device from an LED. + * @btl: The BTL that represents the LED + * @btb: The BTB that represents the block device + * + * When a block device is unlinked from an LED, certain steps must be performed + * only if the block device is **not** being released. This function performs + * those steps that are **always** required, whether or not the block device is + * being released. + * + * Context: Process context. Caller must hold &blkdev_trig_mutex. + */ +static void _blkdev_trig_unlink_always(struct blkdev_trig_led *btl, + struct blkdev_trig_bdev *btb) +{ + --blkdev_trig_link_count; + + if (blkdev_trig_link_count == 0) + WARN_ON(!cancel_delayed_work_sync(&blkdev_trig_work)); + + xa_erase(&btb->linked_btls, btl->index); + xa_erase(&btl->linked_btbs, btb->index); + + /* Remove /sys/class/leds//linked_devices/ symlink */ + sysfs_remove_link_from_group(&btl->led->dev->kobj, + blkdev_trig_linked_devs.name, + dev_name(&btb->bdev->bd_device)); +} + +/** + * blkdev_trig_unlink_norelease() - Unlink an LED from a block device that is + * **not** being released. + * @btl: The BTL that represents the LED. + * @btb: The BTB that represents the block device. + * + * Context: Process context. Caller must hold &blkdev_trig_mutex. + */ +static void blkdev_trig_unlink_norelease(struct blkdev_trig_led *btl, + struct blkdev_trig_bdev *btb) +{ + _blkdev_trig_unlink_always(btl, btb); + + /* Remove /sys/class/block//linked_leds/ symlink */ + sysfs_remove_link_from_group(bdev_kobj(btb->bdev), + blkdev_trig_linked_leds.name, + btl->led->name); + + blkdev_trig_put_btb(btb); +} + +/** + * blkdev_trig_unlink_release() - Unlink an LED from a block device that is + * being released. + * @btl: The BTL that represents the LED + * @btb: The BTB that represents the block device + * + * Context: Process context. Caller must hold &blkdev_trig_mutex. + */ +static void blkdev_trig_unlink_release(struct blkdev_trig_led *btl, + struct blkdev_trig_bdev *btb) +{ + _blkdev_trig_unlink_always(btl, btb); + + /* + * If the BTB is being released, the driver core has already removed the + * device's attribute groups, and the BTB will be freed automatically, + * so there's nothing else to do. + */ +} + + +/* + * + * BTB creation + * + */ + +/** + * 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. + * + * 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 *btl; + unsigned long index; + + mutex_lock(&blkdev_trig_mutex); + + xa_for_each (&btb->linked_btls, index, btl) + blkdev_trig_unlink_release(btl, btb); + + mutex_unlock(&blkdev_trig_mutex); +} + +/** + * blkdev_trig_get_bdev() - Get a block device by path. + * @path: The value written to an LED's &link_dev_by_path or + * &unlink_dev_by_path attribute, which should be the path to a + * special file that represents a block device + * @len: The number of characters in &path (not including its + * terminating null) + * + * 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 *path, size_t len) +{ + struct block_device *bdev; + char *buf; + + buf = kmemdup(path, len + 1, GFP_KERNEL); /* +1 to include null */ + if (buf == NULL) + return ERR_PTR(-ENOMEM); + + bdev = blkdev_get_by_path(strim(buf), BLKDEV_TRIG_FMODE, THIS_MODULE); + kfree(buf); + return bdev; +} + +/** + * blkdev_trig_get_btb() - Find or create the BTB for a block device. + * @path: The value written to an LED's &link_dev_by_path attribute, + * which should be the path to a special file that represents a + * block device + * @len: The number of characters in &path + * + * If a new BTB is created, because the block device was not previously linked + * to any LEDs, the block device's &linked_leds &sysfs directory is created. + * + * 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 *path, + size_t len) +{ + struct block_device *bdev; + struct blkdev_trig_bdev *btb; + int err; + + bdev = blkdev_trig_get_bdev(path, len); + 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_btls); + + /* Populate BTB activity counters */ + 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; +} + + +/* + * + * Activating and deactivating the trigger on an LED + * + */ + +/** + * blkdev_trig_activate() - Called by the LEDs subsystem when an LED is + * associated with the trigger. + * @led: The LED + * + * Context: Process context. Takes and releases &blkdev_trig_mutex. + * Return: &0 on success, negative &errno on error. + */ +static int blkdev_trig_activate(struct led_classdev *led) +{ + struct blkdev_trig_led *btl; + int err; + + btl = kzalloc(sizeof(*btl), GFP_KERNEL); + if (btl == 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; + } + + btl->index = blkdev_trig_next_index++; + btl->last_checked = jiffies; + btl->mode = -1; /* set all bits */ + btl->led = led; + btl->blink_msec = BLKDEV_TRIG_BLINK_DEF; + btl->check_jiffies = msecs_to_jiffies(BLKDEV_TRIG_CHECK_DEF); + xa_init(&btl->linked_btbs); + + hlist_add_head(&btl->all_btls_node, &blkdev_trig_all_btls); + led_set_trigger_data(led, btl); + +exit_unlock: + mutex_unlock(&blkdev_trig_mutex); +exit_free: + if (err) + kfree(btl); + return err; +} + +/** + * blkdev_trig_deactivate() - Called by the the LEDs subsystem when an LED is + * disassociated from the trigger. + * @led: The LED + * + * The LEDs subsystem also calls this function when an LED associated with the + * trigger is removed or when the trigger is unregistered (if the module is + * unloaded). + * + * Context: Process context. Takes and releases &blkdev_trig_mutex. + */ +static void blkdev_trig_deactivate(struct led_classdev *led) +{ + struct blkdev_trig_led *btl = led_get_trigger_data(led); + struct blkdev_trig_bdev *btb; + unsigned long index; + + mutex_lock(&blkdev_trig_mutex); + + xa_for_each (&btl->linked_btbs, index, btb) + blkdev_trig_unlink_norelease(btl, btb); + + hlist_del(&btl->all_btls_node); + kfree(btl); + + mutex_unlock(&blkdev_trig_mutex); +} + + +/* + * + * Link-related attribute store functions + * + */ + +/** + * link_dev_by_path_store() - &link_dev_by_path device attribute store function. + * @dev: The LED device + * @attr: The &link_dev_by_path attribute (&dev_attr_link_dev_by_path) + * @buf: The value written to the attribute, which should be the path to + * a special file that represents a block device to be linked to + * the LED (e.g. ``/dev/sda``) + * @count: The number of characters in &buf + * + * Context: Process context. Takes and releases &blkdev_trig_mutex. + * Return: &count on success, negative &errno on error. + */ +static ssize_t link_dev_by_path_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct blkdev_trig_led *btl = 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_btls, btl->index) != NULL) { + err = -EEXIST; + goto exit_put_btb; + } + + err = blkdev_trig_link(btl, btb); + +exit_put_btb: + if (err) + blkdev_trig_put_btb(btb); +exit_unlock: + mutex_unlock(&blkdev_trig_mutex); + return err ? : count; +} + +/** + * unlink_dev_by_path_store() - &unlink_dev_by_path device attribute store + * function. + * @dev: The LED device + * @attr: The &unlink_dev_by_path attribute (&dev_attr_unlink_dev_by_path) + * @buf: The value written to the attribute, which should be the path to + * a special file that represents a block device to be unlinked + * from the LED (e.g. ``/dev/sda``) + * @count: The number of characters in &buf + * + * Context: Process context. Takes and releases &blkdev_trig_mutex. + * Return: &count on success, negative &errno on error. + */ +static ssize_t unlink_dev_by_path_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct blkdev_trig_led *btl = led_trigger_get_drvdata(dev); + struct block_device *bdev; + struct blkdev_trig_bdev *btb; + int err; + + bdev = blkdev_trig_get_bdev(buf, count); + 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_btls, btl->index) == NULL) { + err = -EUNATCH; /* bdev isn't linked to this LED */ + goto exit_unlock; + } + + blkdev_trig_unlink_norelease(btl, btb); + +exit_unlock: + mutex_unlock(&blkdev_trig_mutex); +exit_put_bdev: + blkdev_put(bdev, BLKDEV_TRIG_FMODE); + return err ? : count; +} + +/** + * unlink_dev_by_name_store() - &unlink_dev_by_name device attribute store + * function. + * @dev: The LED device + * @attr: The &unlink_dev_by_name attribute (&dev_attr_unlink_dev_by_name) + * @buf: The value written to the attribute, which should be the kernel + * name of a block device to be unlinked from the LED (e.g. + * ``sda``) + * @count: The number of characters in &buf + * + * Context: Process context. Takes and releases &blkdev_trig_mutex. + * Return: &count on success, negative &errno on error. + */ +static ssize_t unlink_dev_by_name_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct blkdev_trig_led *btl = led_trigger_get_drvdata(dev); + struct blkdev_trig_bdev *btb; + unsigned long index; + int err; + + err = mutex_lock_interruptible(&blkdev_trig_mutex); + if (err) + return err; + + err = -EUNATCH; + + xa_for_each (&btl->linked_btbs, index, btb) { + + if (sysfs_streq(dev_name(&btb->bdev->bd_device), buf)) { + blkdev_trig_unlink_norelease(btl, btb); + err = 0; + break; + } + } + + mutex_unlock(&blkdev_trig_mutex); + return err ? : count; +} + + +/* + * + * Atomic attribute show & store functions + * + */ + +/** + * 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 value of &blkdev_trig_led.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 *btl = led_trigger_get_drvdata(dev); + + return sprintf(buf, "%u\n", READ_ONCE(btl->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 &blkdev_trig_led.blink_msec to the value in &buf. + * + * Context: Process context. + * Return: &count on success, negative &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 *btl = 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(btl->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 value of &blkdev_trig_led.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 *btl = led_trigger_get_drvdata(dev); + + return sprintf(buf, "%u\n", + jiffies_to_msecs(READ_ONCE(btl->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 &blkdev_trig_led.check_jiffies to the value in &buf (after converting + * from milliseconds). + * + * Context: Process context. + * Return: &count on success, negative &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 + * @bit: Which bit to show + * + * 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, + enum stat_group bit) +{ + return sprintf(buf, READ_ONCE(led->mode) & (1 << bit) ? "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 + * @bit: Which bit to set + * + * Context: Process context. + * Return: &count on success, negative &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 ``Y`` or ``N`` to &buf, depending on whether the &STAT_READ bit in + * &blkdev_trig_led.mode is set or cleared. + * + * 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, STAT_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 the &STAT_READ bit in &blkdev_trig_led.mode to the value in &buf + * (interpretted as a boolean). + * + * Context: Process context. + * Return: &count on success, negative &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 ``Y`` or ``N`` to &buf, depending on whether the &STAT_WRITE bit in + * in &blkdev_trig_led.mode is set or cleared. + * + * 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, STAT_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 the &STAT_WRITE bit in &blkdev_trig_led.mode to the value in &buf + * (interpretted as a boolean). + * + * Context: Process context. + * Return: &count on success, negative &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 ``Y`` or ``N`` to &buf, depending whether the &STAT_FLUSH bit in + * &blkdev_trig_led.mode is set or cleared. + * + * 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, STAT_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 the &STAT_FLUSH bit in &blkdev_trig_led.mode to the value in &buf + * (interpretted as a boolean). + * + * Context: Process context. + * Return: &count on success, negative &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 ``Y`` or ``N`` to &buf, depending on whether the &STAT_DISCARD bit in + * &blkdev_trig_led.mode is set or cleared. + * + * 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, STAT_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 &STAT_DISCARD bit in &blkdev_trig_led.mode to the value in &buf + * (interpretted as a boolean). + * + * Context: Process context. + * Return: &count on success, negative &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_dev_by_path); +static DEVICE_ATTR_WO(unlink_dev_by_path); +static DEVICE_ATTR_WO(unlink_dev_by_name); +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_dev_by_path.attr, + &dev_attr_unlink_dev_by_path.attr, + &dev_attr_unlink_dev_by_name.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 ``blkdev`` LED trigger. + * + * Return: &0 on success, negative &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 ``blkdev`` 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");