Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
gpio: sysfs: fix chip removal with GPIOs exported over sysfs
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
Fixes: 1cd53df733c2 ("gpio: sysfs: don't look up exported lines as class devices")
Link: https://patch.msgid.link/20260212133505.81516-1-bartosz.golaszewski@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
+58
-54
+58
-54
drivers/gpio/gpiolib-sysfs.c
+58
-54
drivers/gpio/gpiolib-sysfs.c
···
919
919
}
920
920
EXPORT_SYMBOL_GPL(gpiod_export_link);
921
921
922
+
static void gpiod_unexport_unlocked(struct gpio_desc *desc)
923
+
{
924
+
struct gpiod_data *tmp, *desc_data = NULL;
925
+
struct gpiodev_data *gdev_data;
926
+
struct gpio_device *gdev;
927
+
928
+
if (!test_bit(GPIOD_FLAG_EXPORT, &desc->flags))
929
+
return;
930
+
931
+
gdev = gpiod_to_gpio_device(desc);
932
+
gdev_data = gdev_get_data(gdev);
933
+
if (!gdev_data)
934
+
return;
935
+
936
+
list_for_each_entry(tmp, &gdev_data->exported_lines, list) {
937
+
if (gpiod_is_equal(desc, tmp->desc)) {
938
+
desc_data = tmp;
939
+
break;
940
+
}
941
+
}
942
+
943
+
if (!desc_data)
944
+
return;
945
+
946
+
list_del(&desc_data->list);
947
+
clear_bit(GPIOD_FLAG_EXPORT, &desc->flags);
948
+
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
949
+
sysfs_put(desc_data->value_kn);
950
+
device_unregister(desc_data->dev);
951
+
952
+
/*
953
+
* Release irq after deregistration to prevent race with
954
+
* edge_store.
955
+
*/
956
+
if (desc_data->irq_flags)
957
+
gpio_sysfs_free_irq(desc_data);
958
+
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
959
+
960
+
sysfs_remove_groups(desc_data->parent,
961
+
desc_data->chip_attr_groups);
962
+
963
+
mutex_destroy(&desc_data->mutex);
964
+
kfree(desc_data);
965
+
}
966
+
922
967
/**
923
968
* gpiod_unexport - reverse effect of gpiod_export()
924
969
* @desc: GPIO to make unavailable
···
972
927
*/
973
928
void gpiod_unexport(struct gpio_desc *desc)
974
929
{
975
-
struct gpiod_data *tmp, *desc_data = NULL;
976
-
struct gpiodev_data *gdev_data;
977
-
struct gpio_device *gdev;
978
-
979
930
if (!desc) {
980
931
pr_warn("%s: invalid GPIO\n", __func__);
981
932
return;
982
933
}
983
934
984
-
scoped_guard(mutex, &sysfs_lock) {
985
-
if (!test_bit(GPIOD_FLAG_EXPORT, &desc->flags))
986
-
return;
935
+
guard(mutex)(&sysfs_lock);
987
936
988
-
gdev = gpiod_to_gpio_device(desc);
989
-
gdev_data = gdev_get_data(gdev);
990
-
if (!gdev_data)
991
-
return;
992
-
993
-
list_for_each_entry(tmp, &gdev_data->exported_lines, list) {
994
-
if (gpiod_is_equal(desc, tmp->desc)) {
995
-
desc_data = tmp;
996
-
break;
997
-
}
998
-
}
999
-
1000
-
if (!desc_data)
1001
-
return;
1002
-
1003
-
list_del(&desc_data->list);
1004
-
clear_bit(GPIOD_FLAG_EXPORT, &desc->flags);
1005
-
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
1006
-
sysfs_put(desc_data->value_kn);
1007
-
device_unregister(desc_data->dev);
1008
-
1009
-
/*
1010
-
* Release irq after deregistration to prevent race with
1011
-
* edge_store.
1012
-
*/
1013
-
if (desc_data->irq_flags)
1014
-
gpio_sysfs_free_irq(desc_data);
1015
-
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
1016
-
1017
-
sysfs_remove_groups(desc_data->parent,
1018
-
desc_data->chip_attr_groups);
1019
-
}
1020
-
1021
-
mutex_destroy(&desc_data->mutex);
1022
-
kfree(desc_data);
937
+
gpiod_unexport_unlocked(desc);
1023
938
}
1024
939
EXPORT_SYMBOL_GPL(gpiod_unexport);
1025
940
···
1059
1054
struct gpio_desc *desc;
1060
1055
struct gpio_chip *chip;
1061
1056
1062
-
scoped_guard(mutex, &sysfs_lock) {
1063
-
data = gdev_get_data(gdev);
1064
-
if (!data)
1065
-
return;
1057
+
guard(mutex)(&sysfs_lock);
1066
1058
1067
-
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
1068
-
device_unregister(data->cdev_base);
1069
-
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
1070
-
device_unregister(data->cdev_id);
1071
-
kfree(data);
1072
-
}
1059
+
data = gdev_get_data(gdev);
1060
+
if (!data)
1061
+
return;
1073
1062
1074
1063
guard(srcu)(&gdev->srcu);
1075
-
1076
1064
chip = srcu_dereference(gdev->chip, &gdev->srcu);
1077
1065
if (!chip)
1078
1066
return;
1079
1067
1080
1068
/* unregister gpiod class devices owned by sysfs */
1081
1069
for_each_gpio_desc_with_flag(chip, desc, GPIOD_FLAG_SYSFS) {
1082
-
gpiod_unexport(desc);
1070
+
gpiod_unexport_unlocked(desc);
1083
1071
gpiod_free(desc);
1084
1072
}
1073
+
1074
+
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
1075
+
device_unregister(data->cdev_base);
1076
+
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
1077
+
device_unregister(data->cdev_id);
1078
+
kfree(data);
1085
1079
}
1086
1080
1087
1081
/*