From 9d846b1aebbe488f245f1aa463802ff9c34cc078 Mon Sep 17 00:00:00 2001 From: Bartosz Golaszewski Date: Mon, 10 Feb 2025 11:51:55 +0100 Subject: [PATCH 1/4] gpiolib: check the return value of gpio_chip::get_direction() As per the API contract - gpio_chip::get_direction() may fail and return a negative error number. However, we treat it as if it always returned 0 or 1. Check the return value of the callback and propagate the error number up the stack. Cc: stable@vger.kernel.org Reviewed-by: Linus Walleij Link: https://lore.kernel.org/r/20250210-gpio-sanitize-retvals-v1-1-12ea88506cb2@linaro.org Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib.c | 44 ++++++++++++++++++++++++++++-------------- 1 file changed, 29 insertions(+), 15 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index ca2f58a2cd45..29110dc436f1 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1057,8 +1057,11 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, desc->gdev = gdev; if (gc->get_direction && gpiochip_line_is_valid(gc, desc_index)) { - assign_bit(FLAG_IS_OUT, - &desc->flags, !gc->get_direction(gc, desc_index)); + ret = gc->get_direction(gc, desc_index); + if (ret < 0) + goto err_cleanup_desc_srcu; + + assign_bit(FLAG_IS_OUT, &desc->flags, !ret); } else { assign_bit(FLAG_IS_OUT, &desc->flags, !gc->direction_input); @@ -2728,13 +2731,18 @@ int gpiod_direction_input_nonotify(struct gpio_desc *desc) if (guard.gc->direction_input) { ret = guard.gc->direction_input(guard.gc, gpio_chip_hwgpio(desc)); - } else if (guard.gc->get_direction && - (guard.gc->get_direction(guard.gc, - gpio_chip_hwgpio(desc)) != 1)) { - gpiod_warn(desc, - "%s: missing direction_input() operation and line is output\n", - __func__); - return -EIO; + } else if (guard.gc->get_direction) { + ret = guard.gc->get_direction(guard.gc, + gpio_chip_hwgpio(desc)); + if (ret < 0) + return ret; + + if (ret != GPIO_LINE_DIRECTION_IN) { + gpiod_warn(desc, + "%s: missing direction_input() operation and line is output\n", + __func__); + return -EIO; + } } if (ret == 0) { clear_bit(FLAG_IS_OUT, &desc->flags); @@ -2771,12 +2779,18 @@ static int gpiod_direction_output_raw_commit(struct gpio_desc *desc, int value) gpio_chip_hwgpio(desc), val); } else { /* Check that we are in output mode if we can */ - if (guard.gc->get_direction && - guard.gc->get_direction(guard.gc, gpio_chip_hwgpio(desc))) { - gpiod_warn(desc, - "%s: missing direction_output() operation\n", - __func__); - return -EIO; + if (guard.gc->get_direction) { + ret = guard.gc->get_direction(guard.gc, + gpio_chip_hwgpio(desc)); + if (ret < 0) + return ret; + + if (ret != GPIO_LINE_DIRECTION_OUT) { + gpiod_warn(desc, + "%s: missing direction_output() operation\n", + __func__); + return -EIO; + } } /* * If we can't actively set the direction, we are some From 4e667a1968099c6deadee2313ecd648f8f0a8956 Mon Sep 17 00:00:00 2001 From: Johan Korsnes Date: Mon, 17 Feb 2025 10:16:43 +0100 Subject: [PATCH 2/4] gpio: vf610: add locking to gpio direction functions Add locking to `vf610_gpio_direction_input|output()` functions. Without this locking, a race condition exists between concurrent calls to these functions, potentially leading to incorrect GPIO direction settings. To verify the correctness of this fix, a `trylock` patch was applied, where after a couple of reboots the race was confirmed. I.e., one user had to wait before acquiring the lock. With this patch the race has not been encountered. It's worth mentioning that any type of debugging (printing, tracing, etc.) would "resolve"/hide the issue. Fixes: 659d8a62311f ("gpio: vf610: add imx7ulp support") Signed-off-by: Johan Korsnes Reviewed-by: Linus Walleij Reviewed-by: Haibo Chen Cc: Bartosz Golaszewski Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250217091643.679644-1-johan.korsnes@remarkable.no Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpio-vf610.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpio/gpio-vf610.c b/drivers/gpio/gpio-vf610.c index c4f34a347cb6..c36a9dbccd4d 100644 --- a/drivers/gpio/gpio-vf610.c +++ b/drivers/gpio/gpio-vf610.c @@ -36,6 +36,7 @@ struct vf610_gpio_port { struct clk *clk_port; struct clk *clk_gpio; int irq; + spinlock_t lock; /* protect gpio direction registers */ }; #define GPIO_PDOR 0x00 @@ -124,6 +125,7 @@ static int vf610_gpio_direction_input(struct gpio_chip *chip, unsigned int gpio) u32 val; if (port->sdata->have_paddr) { + guard(spinlock_irqsave)(&port->lock); val = vf610_gpio_readl(port->gpio_base + GPIO_PDDR); val &= ~mask; vf610_gpio_writel(val, port->gpio_base + GPIO_PDDR); @@ -142,6 +144,7 @@ static int vf610_gpio_direction_output(struct gpio_chip *chip, unsigned int gpio vf610_gpio_set(chip, gpio, value); if (port->sdata->have_paddr) { + guard(spinlock_irqsave)(&port->lock); val = vf610_gpio_readl(port->gpio_base + GPIO_PDDR); val |= mask; vf610_gpio_writel(val, port->gpio_base + GPIO_PDDR); @@ -297,6 +300,7 @@ static int vf610_gpio_probe(struct platform_device *pdev) return -ENOMEM; port->sdata = device_get_match_data(dev); + spin_lock_init(&port->lock); dual_base = port->sdata->have_dual_base; From 81570d6a7ad37033c7895811551a5a9023706eda Mon Sep 17 00:00:00 2001 From: Bartosz Golaszewski Date: Sat, 15 Feb 2025 10:56:55 +0100 Subject: [PATCH 3/4] gpiolib: protect gpio_chip with SRCU in array_info paths in multi get/set 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 --- 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 29110dc436f1..5529d8b65f6f 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -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; 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[]; From 96fa9ec477ff60bed87e1441fd43e003179f3253 Mon Sep 17 00:00:00 2001 From: Bartosz Golaszewski Date: Wed, 19 Feb 2025 15:43:56 +0100 Subject: [PATCH 4/4] gpiolib: don't bail out if get_direction() fails in gpiochip_add_data() Since commit 9d846b1aebbe ("gpiolib: check the return value of gpio_chip::get_direction()") we check the return value of the get_direction() callback as per its API contract. Some drivers have been observed to fail to register now as they may call get_direction() in gpiochip_add_data() in contexts where it has always silently failed. Until we audit all drivers, replace the bail-out to a kernel log warning. Fixes: 9d846b1aebbe ("gpiolib: check the return value of gpio_chip::get_direction()") Reported-by: Mark Brown Closes: https://lore.kernel.org/all/Z7VFB1nST6lbmBIo@finisterre.sirena.org.uk/ Reported-by: Marek Szyprowski Closes: https://lore.kernel.org/all/dfe03f88-407e-4ef1-ad30-42db53bbd4e4@samsung.com/ Tested-by: Mark Brown Reviewed-by: Mark Brown Tested-by: Marek Szyprowski Link: https://lore.kernel.org/r/20250219144356.258635-1-brgl@bgdev.pl Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 5529d8b65f6f..fc19df5a64c2 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1059,7 +1059,15 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, if (gc->get_direction && gpiochip_line_is_valid(gc, desc_index)) { ret = gc->get_direction(gc, desc_index); if (ret < 0) - goto err_cleanup_desc_srcu; + /* + * FIXME: Bail-out here once all GPIO drivers + * are updated to not return errors in + * situations that can be considered normal + * operation. + */ + dev_warn(&gdev->dev, + "%s: get_direction failed: %d\n", + __func__, ret); assign_bit(FLAG_IS_OUT, &desc->flags, !ret); } else {