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gpiolib: protect gpio_chip with SRCU in array_info paths in multi get/set

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During the locking rework in GPIOLIB, we omitted one important use-case,
namely: setting and getting values for GPIO descriptor arrays with
array_info present.

This patch does two things: first it makes struct gpio_array store the
address of the underlying GPIO device and not chip. Next: it protects
the chip with SRCU from removal in gpiod_get_array_value_complex() and
gpiod_set_array_value_complex().

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250215095655.23152-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Bartosz Golaszewski 2025-02-15 10:56:55 +01:00
parent 4e667a1968
commit 81570d6a7a
2 changed files with 35 additions and 17 deletions
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48
drivers/gpio/gpiolib.c
View file

@ -3143,6 +3143,8 @@ static int gpiod_get_raw_value_commit(const struct gpio_desc *desc)
static int gpio_chip_get_multiple(struct gpio_chip *gc,
unsigned long *mask, unsigned long *bits)
{
lockdep_assert_held(&gc->gpiodev->srcu);
if (gc->get_multiple)
return gc->get_multiple(gc, mask, bits);
if (gc->get) {
@ -3173,6 +3175,7 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep,
struct gpio_array *array_info,
unsigned long *value_bitmap)
{
struct gpio_chip *gc;
int ret, i = 0;
/*
@ -3184,10 +3187,15 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep,
array_size <= array_info->size &&
(void *)array_info == desc_array + array_info->size) {
if (!can_sleep)
WARN_ON(array_info->chip->can_sleep);
WARN_ON(array_info->gdev->can_sleep);
ret = gpio_chip_get_multiple(array_info->chip,
array_info->get_mask,
guard(srcu)(&array_info->gdev->srcu);
gc = srcu_dereference(array_info->gdev->chip,
&array_info->gdev->srcu);
if (!gc)
return -ENODEV;
ret = gpio_chip_get_multiple(gc, array_info->get_mask,
value_bitmap);
if (ret)
return ret;
@ -3468,6 +3476,8 @@ static void gpiod_set_raw_value_commit(struct gpio_desc *desc, bool value)
static void gpio_chip_set_multiple(struct gpio_chip *gc,
unsigned long *mask, unsigned long *bits)
{
lockdep_assert_held(&gc->gpiodev->srcu);
if (gc->set_multiple) {
gc->set_multiple(gc, mask, bits);
} else {
@ -3485,6 +3495,7 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep,
struct gpio_array *array_info,
unsigned long *value_bitmap)
{
struct gpio_chip *gc;
int i = 0;
/*
@ -3496,14 +3507,19 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep,
array_size <= array_info->size &&
(void *)array_info == desc_array + array_info->size) {
if (!can_sleep)
WARN_ON(array_info->chip->can_sleep);
WARN_ON(array_info->gdev->can_sleep);
guard(srcu)(&array_info->gdev->srcu);
gc = srcu_dereference(array_info->gdev->chip,
&array_info->gdev->srcu);
if (!gc)
return -ENODEV;
if (!raw && !bitmap_empty(array_info->invert_mask, array_size))
bitmap_xor(value_bitmap, value_bitmap,
array_info->invert_mask, array_size);
gpio_chip_set_multiple(array_info->chip, array_info->set_mask,
value_bitmap);
gpio_chip_set_multiple(gc, array_info->set_mask, value_bitmap);
i = find_first_zero_bit(array_info->set_mask, array_size);
if (i == array_size)
@ -4765,9 +4781,10 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
{
struct gpio_desc *desc;
struct gpio_descs *descs;
struct gpio_device *gdev;
struct gpio_array *array_info = NULL;
struct gpio_chip *gc;
int count, bitmap_size;
unsigned long dflags;
size_t descs_size;
count = gpiod_count(dev, con_id);
@ -4788,7 +4805,7 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
descs->desc[descs->ndescs] = desc;
gc = gpiod_to_chip(desc);
gdev = gpiod_to_gpio_device(desc);
/*
* If pin hardware number of array member 0 is also 0, select
* its chip as a candidate for fast bitmap processing path.
@ -4796,8 +4813,8 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
if (descs->ndescs == 0 && gpio_chip_hwgpio(desc) == 0) {
struct gpio_descs *array;
bitmap_size = BITS_TO_LONGS(gc->ngpio > count ?
gc->ngpio : count);
bitmap_size = BITS_TO_LONGS(gdev->ngpio > count ?
gdev->ngpio : count);
array = krealloc(descs, descs_size +
struct_size(array_info, invert_mask, 3 * bitmap_size),
@ -4817,7 +4834,7 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
array_info->desc = descs->desc;
array_info->size = count;
array_info->chip = gc;
array_info->gdev = gdev;
bitmap_set(array_info->get_mask, descs->ndescs,
count - descs->ndescs);
bitmap_set(array_info->set_mask, descs->ndescs,
@ -4830,7 +4847,7 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
continue;
/* Unmark array members which don't belong to the 'fast' chip */
if (array_info->chip != gc) {
if (array_info->gdev != gdev) {
__clear_bit(descs->ndescs, array_info->get_mask);
__clear_bit(descs->ndescs, array_info->set_mask);
}
@ -4853,9 +4870,10 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
array_info->set_mask);
}
} else {
dflags = READ_ONCE(desc->flags);
/* Exclude open drain or open source from fast output */
if (gpiochip_line_is_open_drain(gc, descs->ndescs) ||
gpiochip_line_is_open_source(gc, descs->ndescs))
if (test_bit(FLAG_OPEN_DRAIN, &dflags) ||
test_bit(FLAG_OPEN_SOURCE, &dflags))
__clear_bit(descs->ndescs,
array_info->set_mask);
/* Identify 'fast' pins which require invertion */
@ -4867,7 +4885,7 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
if (array_info)
dev_dbg(dev,
"GPIO array info: chip=%s, size=%d, get_mask=%lx, set_mask=%lx, invert_mask=%lx\n",
array_info->chip->label, array_info->size,
array_info->gdev->label, array_info->size,
*array_info->get_mask, *array_info->set_mask,
*array_info->invert_mask);
return descs;

4
drivers/gpio/gpiolib.h
View file

@ -114,7 +114,7 @@ extern const char *const gpio_suffixes[];
*
* @desc: Array of pointers to the GPIO descriptors
* @size: Number of elements in desc
* @chip: Parent GPIO chip
* @gdev: Parent GPIO device
* @get_mask: Get mask used in fastpath
* @set_mask: Set mask used in fastpath
* @invert_mask: Invert mask used in fastpath
@ -126,7 +126,7 @@ extern const char *const gpio_suffixes[];
struct gpio_array {
struct gpio_desc **desc;
unsigned int size;
struct gpio_chip *chip;
struct gpio_device *gdev;
unsigned long *get_mask;
unsigned long *set_mask;
unsigned long invert_mask[];