From patchwork Wed Sep 27 14:29:23 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 726731 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0F26F38FA6 for ; Wed, 27 Sep 2023 14:29:41 +0000 (UTC) Received: from mail-wm1-x335.google.com (mail-wm1-x335.google.com [IPv6:2a00:1450:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E1F23FC for ; Wed, 27 Sep 2023 07:29:39 -0700 (PDT) Received: by mail-wm1-x335.google.com with SMTP id 5b1f17b1804b1-4063da036c9so36486165e9.3 for ; Wed, 27 Sep 2023 07:29:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20230601.gappssmtp.com; s=20230601; t=1695824978; x=1696429778; 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=AG+MBGFlKyeqAoI+zBkkhuwZdyh02KZ6W2Oat6+x/rc=; b=jkomhgG+Tbn+oHqiYbAzwP2qCyxutFq51q9Fcs/01QlhQvId6oAl7FycrwCnFlrjsP sFnHWdJplfjXkdFGs10AxABLEmXzvBcojyjCRce58rUUFnjvblmIRqem2hLSpQpZ/CSU RWKgx0Dibhagns2lZgXIXSyMlWd8KAjfr5sFc1P4RIN42SgwxOymINpdCKa3UmUj6L0w AMgRHOTp5Sg9Mp1KM6Q9d4JZycK14633XP0FZxYiZ1DGh4tpMnwhvMkgqbBztPtzhVnw DYK29q0dQlq6ncDrikvt8yTgJlZg/WOS2j24Iu2KDuUmXxmSiLZPCUbYjM1XuEUcTIo7 ZJTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695824978; x=1696429778; 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=AG+MBGFlKyeqAoI+zBkkhuwZdyh02KZ6W2Oat6+x/rc=; b=imaP5D+tqkCSLgOAApNjPatdYx7LatRsLHRiehkI1xDO1ZHwDjdumnMbodvOlTxWFG ve3r9Kw6fGQRFMzXFnlPNoKEOIijnTpClTz79s8XkC7C9GD5/0YwMv/dMGzH2u7RRzTB DhoGEuE70PiwuaXLgBr4fbNHby6CJQIqoOztnaZGvs9UfZV17BUOQS5PWA7Z3ndkootJ RDqgq29FFNp8sXNEeqBrGkL1zjaMcCPwjOmTdhA+FbdBr/J/S+NpLsrIay5r2nda7c8W jy7jGLmgzDXalFXPfYRvyeFuSTDjavq9uR5AcnTj3HT6dR31YxxiVk800FhepuJEWK9T 6WlQ== X-Gm-Message-State: AOJu0Yx5BrU5FIUv3AJ2zYKFDyNwLWIqp/uVChou6eutYmMoyUz2qvd6 oVybsLSbDimXXNod1Ayu5jH0TQ== X-Google-Smtp-Source: AGHT+IF+734qHN0cowwb2rWZZ7nRSKb6cLjcj/UrCSuIQ9sXERwtpbK0/Z+jtA9CBM2mVhY8P27S2A== X-Received: by 2002:a7b:c456:0:b0:405:3ca1:f6c6 with SMTP id l22-20020a7bc456000000b004053ca1f6c6mr2188112wmi.0.1695824978053; Wed, 27 Sep 2023 07:29:38 -0700 (PDT) Received: from brgl-uxlite.home ([2a01:cb1d:334:ac00:4bb6:1525:9e22:4a15]) by smtp.gmail.com with ESMTPSA id v2-20020a1cf702000000b003feae747ff2sm20448303wmh.35.2023.09.27.07.29.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Sep 2023 07:29:37 -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 v4 03/11] gpiolib: provide gpio_device_find() Date: Wed, 27 Sep 2023 16:29:23 +0200 Message-Id: <20230927142931.19798-4-brgl@bgdev.pl> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230927142931.19798-1-brgl@bgdev.pl> References: <20230927142931.19798-1-brgl@bgdev.pl> Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net 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 | 71 +++++++++++++++++++++++++++---------- include/linux/gpio/driver.h | 3 ++ 2 files changed, 56 insertions(+), 18 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index f84ad54d8dbd..0371d23f0a46 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 +1025,62 @@ 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; + + /* + * Not yet but in the future the spinlock below will become a mutex. + * Annotate this function before anyone tries to use it in interrupt + * context like it happened with gpiochip_find(). + */ + might_sleep(); + + 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 1cedbc3d3200..6ad1f1a8ef2e 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -608,6 +608,9 @@ 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);