Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751825AbbBQCst (ORCPT ); Mon, 16 Feb 2015 21:48:49 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33683 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751883AbbBQBu4 (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, "Johan Hovold" , "Linus Walleij" Date: Tue, 17 Feb 2015 01:46:53 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 117/152] gpio: sysfs: fix gpio attribute-creation race 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 Content-Length: 4252 Lines: 142 3.2.67-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold commit ebbeba120ab2ec6ac5f3afc1425ec6ff0b77ad6f upstream. Fix attribute-creation race with userspace by using the default group to create also the contingent gpio device attributes. Fixes: d8f388d8dc8d ("gpio: sysfs interface") Signed-off-by: Johan Hovold Signed-off-by: Linus Walleij [bwh: Backported to 3.2: - Adjust filenames, context - Use gpio_to_desc(), not gpiod_to_desc(), in gpio_is_visible() - gpio_is_visible() must return mode_t] Signed-off-by: Ben Hutchings --- --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -58,6 +58,7 @@ struct gpio_desc { #define FLAG_TRIG_FALL 5 /* trigger on falling edge */ #define FLAG_TRIG_RISE 6 /* trigger on rising edge */ #define FLAG_ACTIVE_LOW 7 /* sysfs value has active low */ +#define FLAG_SYSFS_DIR 10 /* show sysfs direction attribute */ #define ID_SHIFT 16 /* add new flags before this one */ @@ -543,12 +544,45 @@ static ssize_t gpio_active_low_store(str static DEVICE_ATTR(active_low, 0644, gpio_active_low_show, gpio_active_low_store); +static mode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr, + int n) +{ + struct device *dev = container_of(kobj, struct device, kobj); + struct gpio_desc *desc = dev_get_drvdata(dev); + unsigned gpio = desc - gpio_desc; + mode_t mode = attr->mode; + bool show_direction = test_bit(FLAG_SYSFS_DIR, &desc->flags); + + if (attr == &dev_attr_direction.attr) { + if (!show_direction) + mode = 0; + } else if (attr == &dev_attr_edge.attr) { + if (gpio_to_irq(gpio) < 0) + mode = 0; + if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags)) + mode = 0; + } + + return mode; +} + static struct attribute *gpio_attrs[] = { + &dev_attr_direction.attr, + &dev_attr_edge.attr, &dev_attr_value.attr, &dev_attr_active_low.attr, NULL, }; -ATTRIBUTE_GROUPS(gpio); + +static const struct attribute_group gpio_group = { + .attrs = gpio_attrs, + .is_visible = gpio_is_visible, +}; + +static const struct attribute_group *gpio_groups[] = { + &gpio_group, + NULL +}; /* * /sys/class/gpio/gpiochipN/ @@ -723,8 +757,11 @@ int gpio_export(unsigned gpio, bool dire return -EPERM; } - if (!desc->chip->direction_input || !desc->chip->direction_output) - direction_may_change = false; + if (desc->chip->direction_input && desc->chip->direction_output && + direction_may_change) { + set_bit(FLAG_SYSFS_DIR, &desc->flags); + } + spin_unlock_irqrestore(&gpio_lock, flags); if (desc->chip->names && desc->chip->names[gpio - desc->chip->base]) @@ -738,27 +775,10 @@ int gpio_export(unsigned gpio, bool dire goto fail_unlock; } - 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_remove_attr_direction; - } - set_bit(FLAG_EXPORT, &desc->flags); mutex_unlock(&sysfs_lock); return 0; -fail_remove_attr_direction: - device_remove_file(dev, &dev_attr_direction); -fail_unregister_device: - device_unregister(dev); fail_unlock: mutex_unlock(&sysfs_lock); pr_debug("%s: gpio%d status %d\n", __func__, gpio, status); @@ -889,6 +909,7 @@ void gpio_unexport(unsigned gpio) dev = class_find_device(&gpio_class, NULL, desc, match_export); if (dev) { gpio_setup_irq(desc, dev, 0); + clear_bit(FLAG_SYSFS_DIR, &desc->flags); clear_bit(FLAG_EXPORT, &desc->flags); } else status = -ENODEV; @@ -896,8 +917,6 @@ void gpio_unexport(unsigned gpio) mutex_unlock(&sysfs_lock); if (dev) { - device_remove_file(dev, &dev_attr_edge); - device_remove_file(dev, &dev_attr_direction); device_unregister(dev); put_device(dev); } -- 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/