From: Bartosz Golaszewski bartosz.golaszewski@linaro.org

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 Signed-off-by: Bartosz Golaszewski bartosz.golaszewski@linaro.org --- David Lechner's series made me realize that we don't use SRCU to protect the GPIO chip in case where array_info is available in multiple get/set routines. This addresses it. The changes here could potentially be split into two separate commits but I want to easily backport it and it works together as well.

drivers/gpio/gpiolib.c | 48 +++++++++++++++++++++++++++++------------- drivers/gpio/gpiolib.h | 4 ++-- 2 files changed, 35 insertions(+), 17 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 679ed764cb14..6e630680be52 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -3129,6 +3129,8 @@ 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) { @@ -3159,6 +3161,7 @@ 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;

/* @@ -3170,10 +3173,15 @@ 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; @@ -3454,6 +3462,8 @@ 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 { @@ -3471,6 +3481,7 @@ 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;

/* @@ -3482,14 +3493,19 @@ 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) @@ -4751,8 +4767,8 @@ 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; size_t descs_size;

@@ -4774,7 +4790,7 @@ 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. @@ -4782,8 +4798,8 @@ 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), @@ -4803,7 +4819,7 @@ 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, @@ -4816,7 +4832,7 @@ 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); } @@ -4840,8 +4856,10 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev, } } else { /* 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 (gpiochip_line_is_open_drain(gdev->chip, + descs->ndescs) || + gpiochip_line_is_open_source(gdev->chip, + descs->ndescs)) __clear_bit(descs->ndescs, array_info->set_mask); /* Identify 'fast' pins which require invertion */ @@ -4853,7 +4871,7 @@ 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; diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index 83690f72f7e5..147156ec502b 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -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[];