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charset="utf-8" Currently if we export a GPIO over sysfs and unbind the parent GPIO controller, the exported attribute will remain under /sys/class/gpio because once we remove the parent device, we can no longer associate the descriptor with it in gpiod_unexport() and never drop the final reference. Rework the teardown code: provide an unlocked variant of gpiod_unexport() and remove all exported GPIOs with the sysfs_lock taken before unregistering the parent device itself. This is done to prevent any new exports happening before we unregister the device completely. Cc: stable@vger.kernel.org Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib-sysfs.c | 106 ++++++++++++++++++----------------- 1 file changed, 55 insertions(+), 51 deletions(-) diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c index cd553acf3055e..d4a46a0a37d8f 100644 --- a/drivers/gpio/gpiolib-sysfs.c +++ b/drivers/gpio/gpiolib-sysfs.c @@ -919,63 +919,68 @@ int gpiod_export_link(struct device *dev, const char = *name, } EXPORT_SYMBOL_GPL(gpiod_export_link); =20 -/** - * gpiod_unexport - reverse effect of gpiod_export() - * @desc: GPIO to make unavailable - * - * This is implicit on gpiod_free(). - */ -void gpiod_unexport(struct gpio_desc *desc) +static void gpiod_unexport_unlocked(struct gpio_desc *desc) { struct gpiod_data *tmp, *desc_data =3D NULL; struct gpiodev_data *gdev_data; struct gpio_device *gdev; =20 - if (!desc) { - pr_warn("%s: invalid GPIO\n", __func__); + if (!test_bit(GPIOD_FLAG_EXPORT, &desc->flags)) return; - } =20 - scoped_guard(mutex, &sysfs_lock) { - if (!test_bit(GPIOD_FLAG_EXPORT, &desc->flags)) - return; - - gdev =3D gpiod_to_gpio_device(desc); - gdev_data =3D gdev_get_data(gdev); - if (!gdev_data) - return; + gdev =3D gpiod_to_gpio_device(desc); + gdev_data =3D gdev_get_data(gdev); + if (!gdev_data) + return; =20 - list_for_each_entry(tmp, &gdev_data->exported_lines, list) { - if (gpiod_is_equal(desc, tmp->desc)) { - desc_data =3D tmp; - break; - } + list_for_each_entry(tmp, &gdev_data->exported_lines, list) { + if (gpiod_is_equal(desc, tmp->desc)) { + desc_data =3D tmp; + break; } + } =20 - if (!desc_data) - return; + if (!desc_data) + return; =20 - list_del(&desc_data->list); - clear_bit(GPIOD_FLAG_EXPORT, &desc->flags); + list_del(&desc_data->list); + clear_bit(GPIOD_FLAG_EXPORT, &desc->flags); #if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) - sysfs_put(desc_data->value_kn); - device_unregister(desc_data->dev); - - /* - * Release irq after deregistration to prevent race with - * edge_store. - */ - if (desc_data->irq_flags) - gpio_sysfs_free_irq(desc_data); + sysfs_put(desc_data->value_kn); + device_unregister(desc_data->dev); + + /* + * Release irq after deregistration to prevent race with + * edge_store. + */ + if (desc_data->irq_flags) + gpio_sysfs_free_irq(desc_data); #endif /* CONFIG_GPIO_SYSFS_LEGACY */ =20 - sysfs_remove_groups(desc_data->parent, - desc_data->chip_attr_groups); - } + sysfs_remove_groups(desc_data->parent, + desc_data->chip_attr_groups); =20 mutex_destroy(&desc_data->mutex); kfree(desc_data); } + +/** + * gpiod_unexport - reverse effect of gpiod_export() + * @desc: GPIO to make unavailable + * + * This is implicit on gpiod_free(). + */ +void gpiod_unexport(struct gpio_desc *desc) +{ + if (!desc) { + pr_warn("%s: invalid GPIO\n", __func__); + return; + } + + guard(mutex)(&sysfs_lock); + + gpiod_unexport_unlocked(desc); +} EXPORT_SYMBOL_GPL(gpiod_unexport); =20 int gpiochip_sysfs_register(struct gpio_device *gdev) @@ -1054,29 +1059,28 @@ void gpiochip_sysfs_unregister(struct gpio_device *= gdev) struct gpio_desc *desc; struct gpio_chip *chip; =20 - scoped_guard(mutex, &sysfs_lock) { - data =3D gdev_get_data(gdev); - if (!data) - return; + guard(mutex)(&sysfs_lock); =20 -#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) - device_unregister(data->cdev_base); -#endif /* CONFIG_GPIO_SYSFS_LEGACY */ - device_unregister(data->cdev_id); - kfree(data); - } + data =3D gdev_get_data(gdev); + if (!data) + return; =20 guard(srcu)(&gdev->srcu); - chip =3D srcu_dereference(gdev->chip, &gdev->srcu); if (!chip) return; =20 /* unregister gpiod class devices owned by sysfs */ for_each_gpio_desc_with_flag(chip, desc, GPIOD_FLAG_SYSFS) { - gpiod_unexport(desc); + gpiod_unexport_unlocked(desc); gpiod_free(desc); } + +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) + device_unregister(data->cdev_base); +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ + device_unregister(data->cdev_id); + kfree(data); } =20 /* --=20 2.47.3