From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932547AbbBQCnG (ORCPT ); Mon, 16 Feb 2015 21:43:06 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33690 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751897AbbBQBu4 (ORCPT ); Mon, 16 Feb 2015 20:50:56 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Linus Walleij" , "Ryan Mallon" Date: Tue, 17 Feb 2015 01:46:53 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 114/152] gpiolib: Refactor gpio_export In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.67-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Ryan Mallon commit fc4e2514995d9cd7f3e1a67098ce65d72acf8ec7 upstream. The gpio_export function uses nested if statements and the status variable to handle the failure cases. This makes the function logic difficult to follow. Refactor the code to abort immediately on failure using goto. This makes the code slightly longer, but significantly reduces the nesting and number of split lines and makes the code easier to read. Signed-off-by: Ryan Mallon Signed-off-by: Linus Walleij Signed-off-by: Ben Hutchings --- drivers/gpio/gpiolib.c | 85 +++++++++++++++++++++++++++----------------------- 1 file changed, 46 insertions(+), 39 deletions(-) --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -697,8 +697,9 @@ int gpio_export(unsigned gpio, bool dire { unsigned long flags; struct gpio_desc *desc; - int status = -EINVAL; + int status; const char *ioname = NULL; + struct device *dev; /* can't export until sysfs is available ... */ if (!gpio_class.p) { @@ -706,59 +707,65 @@ int gpio_export(unsigned gpio, bool dire return -ENOENT; } - if (!gpio_is_valid(gpio)) - goto done; + if (!gpio_is_valid(gpio)) { + pr_debug("%s: gpio %d is not valid\n", __func__, gpio); + return -EINVAL; + } mutex_lock(&sysfs_lock); spin_lock_irqsave(&gpio_lock, flags); desc = &gpio_desc[gpio]; - if (test_bit(FLAG_REQUESTED, &desc->flags) - && !test_bit(FLAG_EXPORT, &desc->flags)) { - status = 0; - if (!desc->chip->direction_input - || !desc->chip->direction_output) - direction_may_change = false; + if (!test_bit(FLAG_REQUESTED, &desc->flags) || + test_bit(FLAG_EXPORT, &desc->flags)) { + spin_unlock_irqrestore(&gpio_lock, flags); + pr_debug("%s: gpio %d unavailable (requested=%d, exported=%d)\n", + __func__, gpio, + test_bit(FLAG_REQUESTED, &desc->flags), + test_bit(FLAG_EXPORT, &desc->flags)); + return -EPERM; } + + if (!desc->chip->direction_input || !desc->chip->direction_output) + direction_may_change = false; spin_unlock_irqrestore(&gpio_lock, flags); if (desc->chip->names && desc->chip->names[gpio - desc->chip->base]) ioname = desc->chip->names[gpio - desc->chip->base]; - if (status == 0) { - struct device *dev; + dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0), + desc, ioname ? ioname : "gpio%u", gpio); + if (IS_ERR(dev)) { + status = PTR_ERR(dev); + goto fail_unlock; + } + + status = sysfs_create_group(&dev->kobj, &gpio_attr_group); + if (status) + goto fail_unregister_device; + + if (direction_may_change) { + status = device_create_file(dev, &dev_attr_direction); + if (status) + goto fail_unregister_device; + } - dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0), - desc, ioname ? ioname : "gpio%u", gpio); - if (!IS_ERR(dev)) { - status = sysfs_create_group(&dev->kobj, - &gpio_attr_group); - - if (!status && direction_may_change) - status = device_create_file(dev, - &dev_attr_direction); - - if (!status && gpio_to_irq(gpio) >= 0 - && (direction_may_change - || !test_bit(FLAG_IS_OUT, - &desc->flags))) - status = device_create_file(dev, - &dev_attr_edge); - - if (status != 0) - device_unregister(dev); - } else - status = PTR_ERR(dev); - if (status == 0) - set_bit(FLAG_EXPORT, &desc->flags); + if (gpio_to_irq(gpio) >= 0 && (direction_may_change || + !test_bit(FLAG_IS_OUT, &desc->flags))) { + status = device_create_file(dev, &dev_attr_edge); + if (status) + goto fail_unregister_device; } + set_bit(FLAG_EXPORT, &desc->flags); mutex_unlock(&sysfs_lock); + return 0; -done: - if (status) - pr_debug("%s: gpio%d status %d\n", __func__, gpio, status); - +fail_unregister_device: + device_unregister(dev); +fail_unlock: + mutex_unlock(&sysfs_lock); + pr_debug("%s: gpio%d status %d\n", __func__, gpio, status); return status; } EXPORT_SYMBOL_GPL(gpio_export);