Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754781Ab2JVAjT (ORCPT ); Sun, 21 Oct 2012 20:39:19 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:36728 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753856Ab2JVAjS (ORCPT ); Sun, 21 Oct 2012 20:39:18 -0400 Message-ID: <508495B0.7010308@gmail.com> Date: Mon, 22 Oct 2012 11:39:12 +1100 From: Ryan Mallon User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121011 Thunderbird/16.0.1 MIME-Version: 1.0 To: Linus Walleij , Grant Likely , "linux-kernel@vger.kernel.org" Subject: [PATCH v2] gpiolib: Refactor gpio_export Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4189 Lines: 141 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 --- Changes since v1: - Return immediately if no unwinding needed - Added pr_debug to immediate returns - Changed unavailable (!requested || exported) to -EPERM diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 5d6c71e..d5f9742 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -702,8 +702,9 @@ int gpio_export(unsigned gpio, bool direction_may_change) { 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) { @@ -711,59 +712,65 @@ int gpio_export(unsigned gpio, bool direction_may_change) 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 = 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); + 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; } - mutex_unlock(&sysfs_lock); - -done: + status = sysfs_create_group(&dev->kobj, &gpio_attr_group); if (status) - pr_debug("%s: gpio%d status %d\n", __func__, gpio, status); + goto fail_unregister_device; + + if (direction_may_change) { + status = device_create_file(dev, &dev_attr_direction); + if (status) + goto fail_unregister_device; + } + 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; + +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); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/