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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CAF7AC433FE for ; Mon, 4 Oct 2021 15:56:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA33A613A1 for ; Mon, 4 Oct 2021 15:56:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235893AbhJDP5u (ORCPT ); Mon, 4 Oct 2021 11:57:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41996 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234735AbhJDP5t (ORCPT ); Mon, 4 Oct 2021 11:57:49 -0400 Received: from mail-ot1-x330.google.com (mail-ot1-x330.google.com [IPv6:2607:f8b0:4864:20::330]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A134BC061745; Mon, 4 Oct 2021 08:56:00 -0700 (PDT) Received: by mail-ot1-x330.google.com with SMTP id 97-20020a9d006a000000b00545420bff9eso22109637ota.8; Mon, 04 Oct 2021 08:56:00 -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:mime-version :content-transfer-encoding; bh=00e471gBuLQaVgzouhorMyHsLL1yfEpyQfK+oFOShSg=; b=qex2pdhlHxw22cIS4rWYKv47K8mxbhZ83D5jgoB3YCjEAQFMQzkzHdd7TZ3h43HFv7 7I8i2NsVZzgJj1SP1EyQCs9tW399J3Qd3FAM9zcAP+UJ97XyKXMvKcAE6HvvT0dK9tSx 3F0o8dI3GPl9dELOeo/skzjR1GbilRVcwHu+OUYjQzlQpi7iKv7gjofMp8GN5y4GeGpb 35vYgE4DoZu3Q4FdLIc256I1s3ppncjHgVwda/afa/x1l9e6beGfssv5Nbr1Tn5LP/1x 4IlOJ+YDZI4lqkmVspCgOnUDnmoHcbTlq9BK42174K4y/Cn/f4vVm7UXGf6n2eWI0BDh TaIg== 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:mime-version :content-transfer-encoding; bh=00e471gBuLQaVgzouhorMyHsLL1yfEpyQfK+oFOShSg=; b=0cUzNzmZWnZdQSKwulJ4YSups1hQ5nKiugrt2tU557gMf33+9JudCq18L1Liruze8c IzTCsAsKUP+dJP0cg/z+rhKuZUxYwu+DUeok2iulR9i5jkKpVDpJUZPY7y7dFL8FRYjV 2QrpjzUc441yPJA0VfygeTEWCdJOlhUh4/cwApWCB2Afjc/jGDM5cYjIq1LKW1Be1qvB L2c7jj9OmPeXQkHr4lS5ZxsPWmMP28Ity2oIcYyva6Qba0B2/Gt9DTulKDdjlqG21SvR uFXz7ytwXbk0NRh/ETctz/tC8QHi2vcmWQ+jPPjZAlu7I3C1afdAaj0a06aO+B2pKZot 82bQ== X-Gm-Message-State: AOAM532gVo1ivIv3WJD+RMDSzcdCSdqkMnwDi8wkYMt22Iag/dMA1I7T DWnulIfgi6a5dD+iZTcwsJUCJJTDtskLlA== X-Google-Smtp-Source: ABdhPJyZ4Swvpa7mikKjHL/Un1v+rAtfW/e0e+L7oAxHFON/p647mWFf8z9/PSDReA0fec3zPDxh4g== X-Received: by 2002:a05:6830:1090:: with SMTP id y16mr9839554oto.317.1633362959846; Mon, 04 Oct 2021 08:55:59 -0700 (PDT) Received: from ian.penurio.us ([47.184.51.90]) by smtp.gmail.com with ESMTPSA id p18sm3046878otk.7.2021.10.04.08.55.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Oct 2021 08:55:59 -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, hch@infradead.org Subject: [RESEND PATCH v5 0/2] Introduce block device LED trigger Date: Mon, 4 Oct 2021 10:55:44 -0500 Message-Id: <20211004155546.1120869-1-arequipeno@gmail.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-leds@vger.kernel.org Changes from v4: ================ * Use xarrays, rather than lists, to model "links" between LEDs and block devices. This allows many-to-many relationships without the need for a separate link object. * When resolving (getting) a block device by path, don't retry with "/dev/" prepended to the path in the ENOENT case. * Use an enum, rather than a boolean, to tell led_bdev_unlink() whether the block device is being released or not. * Use preprocessor constant, rather than magic number, for the mode passed to blkdev_get_by_path() and blkdev_put(). * Split the data structure used by mode attribute show & store functions into 2 separate arrays and move them into the functions that use them. Changes from v3: ================ * Use blkdev_get_by_path() to "resolve" block devices (struct block_device). With this change, there are now no changes required to the block subsystem, so there are only 2 patches in this series. * link_device and unlink_device attributes now take paths to block device special files (e.g. /dev/sda), rather than kernel names. Symbolic links also work. If the path written to the attribute doesn't exist (-ENOENT), we re-try with /dev/ prepended, so "simple" names like sda will still work as long as the corresponding special file exists in /dev. * Fixed a bug that could cause "phantom" blinks because of old device activity that was not recognized at the correct time. * (Slightly) more detailed commit message for the patch that adds the trigger code. As with v3, the real details are found in the comments in the source file. Changes from v2: ================ * Allow LEDs to be "linked" to partitions, as well as whole devices. Internally, the trigger now works with block_device structs, rather than gendisk structs. (Investigating the lifecycle of block_device structs led me to discover the device resource API, so ...) * Use the device resource API to manage the trigger's per-block device data structure (struct led_bdev_bdi). The trigger now uses a release function to remove references to block devices that have been removed. Because the release function is automatically called by the driver core, there is no longer any need for the block layer to explictly call the trigger's cleanup function. * Since there is no need to provide a built-in "stub" cleanup function when the trigger is built as a module, I have removed the always built-in "core" portion of the trigger. * Without a built-in component, the module does need access to the block_class symbol. The second patch in this series exports the symbol to the LEDTRIG_BLKDEV namespace and explains the reason for doing so. * Changed the interval sysfs attribute from a device attribute to a class attribute. It's single value that applies to all LEDs, so it didn't make sense as a device atribute. * As requested, I am posting the trigger code (ledtrig-blkdev.c) as a single patch. This eliminates the commit messages that would otherwise describe sections of the code, so I have added fairly extensive comments to each function. Changes from v1: ================ * Use correct address for LKML. * Renamed the sysfs attributes used to manage and view the set of block devices associated ("linked") with an LED. - /sys/class/leds//link_device to create associations - /sys/class/leds//unlink_device to remove associations - /sys/class/leds//linked_devices/ contains symlinks to all block devices associated with the LED - /sys/block//linked_leds (which only exists when the device is associated with at least one LED) contains symlinks to all LEDs with which the device is associated link_device and unlink_device are write-only attributes, each of which represents a single action, rather than any state. (The current state is shown by the symbolic links in the /linked_devices/ and /linked_leds/ directories.) * Simplified sysfs attribute store functions. link_device and unlink_device no longer accept multiple devices at once, but this was really just an artifact of the way that sysfs repeatedly calls the store function when it doesn't "consume" all of its input, and it seemed to be confusing and unpopular anyway. * Use DEVICE_ATTR_* macros (rather than __ATTR) for the sysfs attributes. * Removed all pr_info() "system administrator error" messages. * Different minimum values for LED blink time (10 ms) and activity check interval (25 ms). v1 summary: =========== This patch series adds a new "blkdev" LED trigger for disk (or other block device) activity LEDs. It has the following functionality. * Supports all types of block devices, including virtual devices (unlike the existing disk trigger which only works with ATA devices). * LEDs can be configured to show read activity, write activity, or both. * Supports multiple devices and multiple LEDs in arbitrary many-to-many configurations. For example, it is possible to configure multiple devices with device-specific read activity LEDs and a shared write activity LED. (See Documentation/leds/ledtrig-blkdev.rst in the first patch.) * Doesn't add any overhead in the I/O path. Like the netdev LED trigger, it periodically checks the configured devices for activity and blinks its LEDs as appropriate. * Blink duration (per LED) and interval between activity checks (global) are configurable. * Requires minimal changes to the block subsystem. - Adds 1 pointer to struct gendisk, - Adds (inline function) call in device_add_disk() to ensure that the pointer is initialized to NULL (as protection against any drivers that allocate a gendisk themselves and don't use kzalloc()), and - Adds call in del_gendisk() to remove a device from the trigger when that device is being removed. These changes are all in patch #4, "block: Add block device LED trigger integrations." * The trigger can be mostly built as a module. When the trigger is modular, a small portion is built in to provide a "stub" function which can be called from del_gendisk(). The stub calls into the modular code via a function pointer when needed. The trigger also needs the ability to find gendisk's by name, which requires access to the un-exported block_class and disk_type symbols. Ian Pilcher (2): docs: Add block device (blkdev) LED trigger documentation leds: trigger: Add block device LED trigger Documentation/ABI/testing/sysfs-block | 9 + .../testing/sysfs-class-led-trigger-blkdev | 48 + Documentation/leds/index.rst | 1 + Documentation/leds/ledtrig-blkdev.rst | 148 +++ drivers/leds/trigger/Kconfig | 9 + drivers/leds/trigger/Makefile | 1 + drivers/leds/trigger/ledtrig-blkdev.c | 965 ++++++++++++++++++ 7 files changed, 1181 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-class-led-trigger-blkdev create mode 100644 Documentation/leds/ledtrig-blkdev.rst create mode 100644 drivers/leds/trigger/ledtrig-blkdev.c base-commit: 9e1ff307c779ce1f0f810c7ecce3d95bbae40896 -- 2.31.1