@@ -833,6 +833,7 @@ static struct class gpio_class = {
*/
int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
{
+ struct gpio_chip *chip;
unsigned long flags;
int status;
const char *ioname = NULL;
@@ -850,8 +851,16 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
return -EINVAL;
}
+ chip = desc->chip;
+
mutex_lock(&sysfs_lock);
+ /* check if chip is being removed */
+ if (!chip || !chip->exported) {
+ status = -ENODEV;
+ goto fail_unlock;
+ }
+
spin_lock_irqsave(&gpio_lock, flags);
if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
test_bit(FLAG_EXPORT, &desc->flags)) {
@@ -1076,12 +1085,15 @@ static void gpiochip_unexport(struct gpio_chip *chip)
{
int status;
struct device *dev;
+ struct gpio_desc *desc;
+ unsigned int i;
mutex_lock(&sysfs_lock);
dev = class_find_device(&gpio_class, NULL, chip, match_export);
if (dev) {
put_device(dev);
device_unregister(dev);
+ /* prevent further gpiod exports */
chip->exported = false;
status = 0;
} else
@@ -1090,6 +1102,13 @@ static void gpiochip_unexport(struct gpio_chip *chip)
if (status)
chip_dbg(chip, "%s: status %d\n", __func__, status);
+
+ /* unregister gpiod class devices owned by sysfs */
+ for (i = 0; i < chip->ngpio; i++) {
+ desc = &chip->desc[i];
+ if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
+ gpiod_free(desc);
+ }
}
static int __init gpiolib_sysfs_init(void)
This is a note to let you know that I have just added a patch titled gpio: sysfs: fix memory leaks and device hotplug to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt12. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 251b9f69933c81ff1be082f91e80ab7b66f48290 Mon Sep 17 00:00:00 2001 From: Johan Hovold <johan@kernel.org> Date: Tue, 21 Apr 2015 17:42:09 +0200 Subject: gpio: sysfs: fix memory leaks and device hotplug commit 483d821108791092798f5d230686868112927044 upstream. Unregister GPIOs requested through sysfs at chip remove to avoid leaking the associated memory and sysfs entries. The stale sysfs entries prevented the gpio numbers from being exported when the gpio range was later reused (e.g. at device reconnect). This also fixes the related module-reference leak. Note that kernfs makes sure that any on-going sysfs operations finish before the class devices are unregistered and that further accesses fail. The chip exported flag is used to prevent gpiod exports during removal. This also makes it harder to trigger, but does not fix, the related race between gpiochip_remove and export_store, which is really a race with gpiod_request that needs to be addressed separately. Also note that this would prevent the crashes (e.g. NULL-dereferences) at reconnect that affects pre-3.18 kernels, as well as use-after-free on operations on open attribute files on pre-3.14 kernels (prior to kernfs). Fixes: d8f388d8dc8d ("gpio: sysfs interface") Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> [ luis: backported to 3.16: - file rename: drivers/gpio/gpiolib-sysfs.c -> drivers/gpio/gpiolib.c ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/gpio/gpiolib.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)