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Make sure devices cannot be removed until we hold a new reference to the device. In order to not overcomplicate the code with locking and unlocking variants of the same functions, just use the nesting feature of RW semaphores in gpio_device_find(). Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib.c | 42 ++++++++++++++++++++++++------------------ 1 file changed, 24 insertions(+), 18 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 4c93cf73a826..972f33bc1a72 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1114,7 +1114,7 @@ struct gpio_device *gpio_device_find(void *data, */ might_sleep(); - guard(rwsem_read)(&gpio_devices_sem); + guard(rwsem_read_nested)(&gpio_devices_sem, SINGLE_DEPTH_NESTING); list_for_each_entry(gdev, &gpio_devices, list) { if (gdev->chip && match(gdev->chip, data)) @@ -4134,27 +4134,33 @@ static struct gpio_desc *gpiod_find_and_request(struct device *consumer, struct gpio_desc *desc; int ret; - desc = gpiod_find_by_fwnode(fwnode, consumer, con_id, idx, &flags, &lookupflags); - if (gpiod_not_found(desc) && platform_lookup_allowed) { + scoped_guard(rwsem_read, &gpio_devices_sem) { + desc = gpiod_find_by_fwnode(fwnode, consumer, con_id, idx, + &flags, &lookupflags); + if (gpiod_not_found(desc) && platform_lookup_allowed) { + /* + * Either we are not using DT or ACPI, or their lookup + * did not return a result. In that case, use platform + * lookup as a fallback. + */ + dev_dbg(consumer, + "using lookup tables for GPIO lookup\n"); + desc = gpiod_find(consumer, con_id, idx, &lookupflags); + } + + if (IS_ERR(desc)) { + dev_dbg(consumer, "No GPIO consumer %s found\n", + con_id); + return desc; + } + /* - * Either we are not using DT or ACPI, or their lookup did not - * return a result. In that case, use platform lookup as a - * fallback. + * If a connection label was passed use that, else attempt to + * use the device name as label */ - dev_dbg(consumer, "using lookup tables for GPIO lookup\n"); - desc = gpiod_find(consumer, con_id, idx, &lookupflags); + ret = gpiod_request(desc, label); } - if (IS_ERR(desc)) { - dev_dbg(consumer, "No GPIO consumer %s found\n", con_id); - return desc; - } - - /* - * If a connection label was passed use that, else attempt to use - * the device name as label - */ - ret = gpiod_request(desc, label); if (ret) { if (!(ret == -EBUSY && flags & GPIOD_FLAGS_BIT_NONEXCLUSIVE)) return ERR_PTR(ret);