From patchwork Fri Sep 15 15:03:15 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 723372 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 C1CC3EED603 for ; Fri, 15 Sep 2023 15:03:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235233AbjIOPDj (ORCPT ); Fri, 15 Sep 2023 11:03:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44450 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229568AbjIOPDi (ORCPT ); Fri, 15 Sep 2023 11:03:38 -0400 Received: from mail-wr1-x431.google.com (mail-wr1-x431.google.com [IPv6:2a00:1450:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3111D1FE0 for ; Fri, 15 Sep 2023 08:03:32 -0700 (PDT) Received: by mail-wr1-x431.google.com with SMTP id ffacd0b85a97d-31f853f2f3aso2228465f8f.0 for ; Fri, 15 Sep 2023 08:03:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20230601.gappssmtp.com; s=20230601; t=1694790210; x=1695395010; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=v2icBidhNqLF921D274+HegN9s4sM/PCTy5BqMLL57c=; b=x+TQ3jbvdGtso1IF9KzIw5VBjDCeGxZzua2+ltbfk/Q6ccsT9ckmoEmB6Vwww8Ya1p x5DEBj9e9fMTtm6x+6Z2KWv4RlbqCFxIIwHL33FE9p9rmWg+5ukU9483ehDlE8JwYaC4 zsn/OdN83lSofAYFsMvVkOMdacpmEp2t0EGMOcH6Fb+VNv0ufeuzvJx+XlKxmcFtpJ8V smnsfxxDR9EB27ePdweKgXpclwitYh3hPI+/aGIQVwO/OOBsNIRekL2s4bu9xgYtCOfK rWC0JVR66XXSWKKiIM9TJdNIzliWaIu0LksZ2JB8O0wh9WbJELVM7Pzm3s7T/rOL6dzb uaHg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694790210; x=1695395010; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=v2icBidhNqLF921D274+HegN9s4sM/PCTy5BqMLL57c=; b=RC2EdMcHUXLuyX7PhdT2PQayVBzrJH6f+Ct2grrrj/dLS6yPvrT4tLIGutxlPAwVRb 5tWW92RTlqCMfXnYr9819GZQZ/IXSMqQ4mpoSLP+mivWofV+W3NVsXf14D8JfPaLYIzi AxiYf5OXCGJE5lwMEACZzFsmJpqQK+zX9TTDaZwumutlzJTeo0IB09HQO3u3Is4rJVAE kDTIDMQ/LlCCdgh1kzaxMz6iXoT9e7ZRsO8EuQ/9ULBSX+Td6HHp1BWJqjeip95tsaDT /YykKYxdMrGFSoBfRxA6XHkJCPWrTVJnNj+OQEyGGiNJbyf/Y73I1Yx4FXxBQBqTORQR fN8Q== X-Gm-Message-State: AOJu0YzxVFxEFWz98JkE4QIu2SbxlXeb2xt+6v4aT7SxRNFlopz6KjVk mX5YYtHACnblS/qQNAaZ/28SWPRv2k3cwsV1YHU= X-Google-Smtp-Source: AGHT+IEfWgq+54eJPYGOwbdJHlYxpAVHAOywpVSMyAjN9QotMhlImJ8mbahol9G3z4CPEP99bWShMQ== X-Received: by 2002:a5d:6f15:0:b0:31f:ecb2:d774 with SMTP id ay21-20020a5d6f15000000b0031fecb2d774mr2343475wrb.19.1694790210397; Fri, 15 Sep 2023 08:03:30 -0700 (PDT) Received: from brgl-uxlite.home ([2a01:cb1d:334:ac00:aa19:4569:aeeb:c0d3]) by smtp.gmail.com with ESMTPSA id hn40-20020a05600ca3a800b003fef19bb55csm4853369wmb.34.2023.09.15.08.03.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 Sep 2023 08:03:29 -0700 (PDT) From: Bartosz Golaszewski To: Linus Walleij , Andy Shevchenko , Mika Westerberg Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH v3 00/11] gpiolib: work towards removing gpiochip_find() Date: Fri, 15 Sep 2023 17:03:15 +0200 Message-Id: <20230915150327.81918-1-brgl@bgdev.pl> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org From: Bartosz Golaszewski This is a reduced subset of patches from the initial sumbission[1] limited only to changes inside GPIOLIB. Once this is upstream, we can then slowly merge patches for other subsystems (like HTE) and then eventually remove gpiochip_find() entirely. The GPIO subsystem does not handle hot-unplug events very well. We have recently patched the user-space part of it so that at least a rouge user cannot crash the kernel but in-kernel users are still affected by a lot of issues: from incorrect locking or lack thereof to using structures that are private to GPIO drivers. Since almost all GPIO controllers can be unbound, not to mention that we have USB devices registering GPIO expanders as well as I2C-on-USB HID devices on which I2C GPIO expanders can live, various media gadgets etc., we really need to make GPIO hotplug/unplug friendly. Before we can even get to fixing the locking, we need to address a serious abuse of the GPIO driver API - accessing struct gpio_chip by anyone who isn't the driver owning this object. This structure is owned by the GPIO provider and its lifetime is tied to that of that provider. It is destroyed when the device is unregistered and this may happen at any moment. struct gpio_device is the opaque, reference counted interface to struct gpio_chip (which is the low-level implementation) and all access should pass through it. The end-goal is to make all gpio_device manipulators check the existence of gdev->chip and then lock it for the duration of any of the calls using SRCU. Before we can get there, we need to first provide a set of functions that will replace any gpio_chip functions and convert all in-kernel users. This series adds several new helpers to the public GPIO API and uses them across the core GPIO code. Note that this does not make everything correct just yet. Especially the GPIOLIB internal users release the reference returned by the lookup function after getting the descriptor of interest but before requesting it. This will eventually be addressed. This is not a regression either. [1] https://lore.kernel.org/lkml/20230905185309.131295-1-brgl@bgdev.pl/T/ v2 -> v3: - use gpio_device_get_chip() consistently - clarify comments - fix buggy chip assignment - check for PTR_ERR() in automatic cleanup - rearrange code as requested by Andy v1 -> v2: - drop all non-GPIOLIB patches - collect tags - fix kernel docs - use gpio_device_get_chip() and gpio_device_get_desc() where applicable Bartosz Golaszewski (11): gpiolib: make gpio_device_get() and gpio_device_put() public gpiolib: add support for scope-based management to gpio_device gpiolib: provide gpio_device_find() gpiolib: provide gpio_device_find_by_label() gpiolib: provide gpio_device_get_desc() gpiolib: reluctantly provide gpio_device_get_chip() gpiolib: replace find_chip_by_name() with gpio_device_find_by_label() gpio: of: replace gpiochip_find_* with gpio_device_find_* gpio: acpi: replace gpiochip_find() with gpio_device_find() gpio: swnode: replace gpiochip_find() with gpio_device_find_by_label() gpio: sysfs: drop the mention of gpiochip_find() from sysfs code drivers/gpio/gpiolib-acpi.c | 12 +- drivers/gpio/gpiolib-of.c | 33 +++--- drivers/gpio/gpiolib-swnode.c | 33 +++--- drivers/gpio/gpiolib-sysfs.c | 2 +- drivers/gpio/gpiolib.c | 202 ++++++++++++++++++++++++++-------- drivers/gpio/gpiolib.h | 10 -- include/linux/gpio/driver.h | 16 +++ 7 files changed, 216 insertions(+), 92 deletions(-)