From patchwork Tue Sep 5 18:52:50 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 13374922 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 1CB57CA1001 for ; Tue, 5 Sep 2023 18:55:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240069AbjIESzH (ORCPT ); Tue, 5 Sep 2023 14:55:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41172 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239485AbjIESzF (ORCPT ); Tue, 5 Sep 2023 14:55:05 -0400 Received: from mail-wm1-x330.google.com (mail-wm1-x330.google.com [IPv6:2a00:1450:4864:20::330]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 03643ED for ; Tue, 5 Sep 2023 11:54:33 -0700 (PDT) Received: by mail-wm1-x330.google.com with SMTP id 5b1f17b1804b1-3ff7d73a6feso26835915e9.1 for ; Tue, 05 Sep 2023 11:54:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20230601.gappssmtp.com; s=20230601; t=1693940009; x=1694544809; darn=vger.kernel.org; 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=32AzIakwES8QNoZ2moYEZisZgGIsr9B20l41KqZ1PII=; b=bVkVr6e9AkOTkxCzquEO1F6bmJ13DTtPe+Hlmy3RtWYpVhTBK/+e11rYLe971hAgIk Hfn6Jtq2hgPLj3XmPveF0RVG2GTfHf/y+TTKM4YSYXkpdLgQuY8ssi87EMmWHHID1kic bG44xQ71KuvzOFtOY2jJwsDFp37B+Zu8QKcZN8F6rwfBiSVsLNkI0wch+HTeJYi74vk5 X9AEvs8jirnc9lI6zn4gofhxMQAAjmugultaMuhxvF9Mi2YT7f8gm8s3bEl8lofZqF8X GyegVUiex5T+oDn6EJgBDB0FZ2l1h2xzhp9UYZklLfnyu16ZWYJGDr7Lm/6Z1iAQxPqN RZyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693940009; x=1694544809; 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=32AzIakwES8QNoZ2moYEZisZgGIsr9B20l41KqZ1PII=; b=QREmnKzwd9PZI45cwoe1p6AuAO1+zW6PDx5tPPhc7saAj2gGkPJc8Qqr4Ii+w/a0Jw aNWtW/thUCWdOdZOPrHpXcoKFrElQ60XglE9p6y0AKB4fZ89pmtqGQYMpJF7VRJPPbVg 0GkA4nqZeqSMM8h7mz0dUPVCzZH0RaiDp8Hp9ONIXC79wzaB4WRx0gBdcpd5lJ4jqJkJ 9dimdTeKweE2rzAPObzTSR4n7wVlG8/eLLUPLgkGBKcmwT59DMivSY5O0kOtm92/+4Ch AljJscMmbbogLjNkVg3QvbwKPv4siyhLTtvXVSEK/cBA0xmYWfBvhuWpO3txVuc1sGpn K71w== X-Gm-Message-State: AOJu0YyA30IdzufQkKPybZ4iHBE2Jj66jC/vNnuj2yziAuu8IJXkX5GR 8nhFvV0OaWx7lYO4ESv+05D/2Q== X-Google-Smtp-Source: AGHT+IEMA7O/G04+pJVQEX0HMhuZh3/G19j9j9xyba1JCXjHsE+92yNux09q4RWquXB9Fm3Wgf4zQw== X-Received: by 2002:a7b:c7d9:0:b0:3fe:207c:1aea with SMTP id z25-20020a7bc7d9000000b003fe207c1aeamr433332wmk.23.1693940008588; Tue, 05 Sep 2023 11:53:28 -0700 (PDT) Received: from brgl-uxlite.home ([2a01:cb1d:334:ac00:7a54:5dbc:6d09:48b7]) by smtp.gmail.com with ESMTPSA id 17-20020a05600c249100b003fbc30825fbsm17550010wms.39.2023.09.05.11.53.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Sep 2023 11:53:28 -0700 (PDT) From: Bartosz Golaszewski To: Aaro Koskinen , Janusz Krzysztofik , Tony Lindgren , Russell King , Mika Westerberg , Andy Shevchenko , Linus Walleij , Bartosz Golaszewski , Dipen Patel , Thierry Reding , Jonathan Hunter , Hans de Goede , Mark Gross Cc: linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org, linux-acpi@vger.kernel.org, timestamp@lists.linux.dev, linux-tegra@vger.kernel.org, platform-driver-x86@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH 02/21] gpiolib: provide gpio_device_find() Date: Tue, 5 Sep 2023 20:52:50 +0200 Message-Id: <20230905185309.131295-3-brgl@bgdev.pl> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230905185309.131295-1-brgl@bgdev.pl> References: <20230905185309.131295-1-brgl@bgdev.pl> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: platform-driver-x86@vger.kernel.org From: Bartosz Golaszewski gpiochip_find() is wrong and its kernel doc is misleading as the function doesn't return a reference to the gpio_chip but just a raw pointer. The chip itself is not guaranteed to stay alive, in fact it can be deleted at any point. Also: other than GPIO drivers themselves, nobody else has any business accessing gpio_chip structs. Provide a new gpio_device_find() function that returns a real reference to the opaque gpio_device structure that is guaranteed to stay alive for as long as there are active users of it. Signed-off-by: Bartosz Golaszewski Reviewed-by: Linus Walleij --- drivers/gpio/gpiolib.c | 64 ++++++++++++++++++++++++++----------- include/linux/gpio/driver.h | 4 +++ 2 files changed, 50 insertions(+), 18 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index f84ad54d8dbd..9e083ecb8df0 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1014,16 +1014,10 @@ void gpiochip_remove(struct gpio_chip *gc) } EXPORT_SYMBOL_GPL(gpiochip_remove); -/** - * gpiochip_find() - iterator for locating a specific gpio_chip - * @data: data to pass to match function - * @match: Callback function to check gpio_chip +/* + * FIXME: This will be removed soon. * - * Similar to bus_find_device. It returns a reference to a gpio_chip as - * determined by a user supplied @match callback. The callback should return - * 0 if the device doesn't match and non-zero if it does. If the callback is - * non-zero, this function will return to the caller and not iterate over any - * more gpio_chips. + * This function is depracated, don't use. */ struct gpio_chip *gpiochip_find(void *data, int (*match)(struct gpio_chip *gc, @@ -1031,21 +1025,55 @@ struct gpio_chip *gpiochip_find(void *data, { struct gpio_device *gdev; struct gpio_chip *gc = NULL; - unsigned long flags; - spin_lock_irqsave(&gpio_lock, flags); - list_for_each_entry(gdev, &gpio_devices, list) - if (gdev->chip && match(gdev->chip, data)) { - gc = gdev->chip; - break; - } - - spin_unlock_irqrestore(&gpio_lock, flags); + gdev = gpio_device_find(data, match); + if (gdev) { + gc = gdev->chip; + gpio_device_put(gdev); + } return gc; } EXPORT_SYMBOL_GPL(gpiochip_find); +/** + * gpio_device_find() - find a specific GPIO device + * @data: data to pass to match function + * @match: Callback function to check gpio_chip + * + * Returns: + * New reference to struct gpio_device. + * + * Similar to bus_find_device(). It returns a reference to a gpio_device as + * determined by a user supplied @match callback. The callback should return + * 0 if the device doesn't match and non-zero if it does. If the callback + * returns non-zero, this function will return to the caller and not iterate + * over any more gpio_devices. + * + * The callback takes the GPIO chip structure as argument. During the execution + * of the callback function the chip is protected from being freed. TODO: This + * actually has yet to be implemented. + * + * If the function returns non-NULL, the returned reference must be freed by + * the caller using gpio_device_put(). + */ +struct gpio_device *gpio_device_find(void *data, + int (*match)(struct gpio_chip *gc, + void *data)) +{ + struct gpio_device *gdev; + + guard(spinlock_irqsave)(&gpio_lock); + + list_for_each_entry(gdev, &gpio_devices, list) { + if (gdev->chip && match(gdev->chip, data)) + return gpio_device_get(gdev); + } + + return NULL; +} +EXPORT_SYMBOL_GPL(gpio_device_find); + static int gpiochip_match_name(struct gpio_chip *gc, void *data) { const char *name = data; diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index a2060dc3344b..5c5029cec226 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -606,6 +606,10 @@ int devm_gpiochip_add_data_with_key(struct device *dev, struct gpio_chip *gc, struct gpio_chip *gpiochip_find(void *data, int (*match)(struct gpio_chip *gc, void *data)); +struct gpio_device *gpio_device_find(void *data, + int (*match)(struct gpio_chip *gc, + void *data)); + struct gpio_device *gpio_device_get(struct gpio_device *gdev); void gpio_device_put(struct gpio_device *gdev);