Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934628AbbDIJdm (ORCPT ); Thu, 9 Apr 2015 05:33:42 -0400 Received: from mail.kernel.org ([198.145.29.136]:42607 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932748AbbDIIzN (ORCPT ); Thu, 9 Apr 2015 04:55:13 -0400 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Ryan Mallon , Linus Walleij , Zefan Li Subject: [PATCH 3.4 107/176] gpiolib: Refactor gpio_export Date: Thu, 9 Apr 2015 16:45:55 +0800 Message-Id: <1428569224-23820-107-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1428569028-23762-1-git-send-email-lizf@kernel.org> References: <1428569028-23762-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4486 Lines: 150 From: Ryan Mallon 3.4.107-rc1 review patch. If anyone has any objections, please let me know. ------------------ 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: Zefan Li --- drivers/gpio/gpiolib.c | 85 +++++++++++++++++++++++++++----------------------- 1 file changed, 46 insertions(+), 39 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index c6df762..c579f3d 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -701,8 +701,9 @@ 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) { @@ -710,59 +711,65 @@ 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); -- 1.9.1 -- 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/