The underlying chip can be removed asynchronously. `gdev->srcu` is used to ensure the synchronization before accessing `gdev->chip`.
Revocable encapsulates the details. Add revocable provider handle for the corresponding struct gpio_chip in struct gpio_device so that it can start to hide the synchronization details. Signed-off-by: Tzung-Bi Shih <[email protected]> --- v2: - Change usages accordingly after applying https://lore.kernel.org/all/[email protected]. - Add __rcu for `chip_rp`. - Pass pointer of pointer to revocable_provider_revoke(). - Rebase accordingly after applying https://lore.kernel.org/all/[email protected]. v1: https://lore.kernel.org/all/[email protected] drivers/gpio/gpiolib.c | 20 ++++++++++++++++++-- drivers/gpio/gpiolib.h | 2 ++ 2 files changed, 20 insertions(+), 2 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 7885dcd1e49d..fdae10ec3a17 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -22,6 +22,7 @@ #include <linux/nospec.h> #include <linux/of.h> #include <linux/pinctrl/consumer.h> +#include <linux/revocable.h> #include <linux/seq_file.h> #include <linux/slab.h> #include <linux/srcu.h> @@ -1110,6 +1111,12 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, goto err_put_device; } + gdev->chip_rp = revocable_provider_alloc(gc); + if (!gdev->chip_rp) { + ret = -ENOMEM; + goto err_put_device; + } + gdev->can_sleep = gc->can_sleep; rwlock_init(&gdev->line_state_lock); RAW_INIT_NOTIFIER_HEAD(&gdev->line_state_notifier); @@ -1139,7 +1146,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, if (base < 0) { ret = base; base = 0; - goto err_put_device; + goto err_free_rp; } /* @@ -1159,7 +1166,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, ret = gpiodev_add_to_list_unlocked(gdev); if (ret) { gpiochip_err(gc, "GPIO integer space overlap, cannot add chip\n"); - goto err_put_device; + goto err_free_rp; } } @@ -1256,6 +1263,14 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, scoped_guard(mutex, &gpio_devices_lock) list_del_rcu(&gdev->list); synchronize_srcu(&gpio_devices_srcu); +err_free_rp: + /* + * Unlike other allocated resources for `gdev` can be freed + * in gpiodev_release(). Call revocable_provider_revoke() + * here as it's designed to be called when the chip is gone + * (i.e., gpiochip_remove()). + */ + revocable_provider_revoke(&gdev->chip_rp); err_put_device: gpio_device_put(gdev); goto err_print_message; @@ -1302,6 +1317,7 @@ void gpiochip_remove(struct gpio_chip *gc) /* Numb the device, cancelling all outstanding operations */ rcu_assign_pointer(gdev->chip, NULL); synchronize_srcu(&gdev->srcu); + revocable_provider_revoke(&gdev->chip_rp); gpio_device_teardown_shared(gdev); gpiochip_irqchip_remove(gc); acpi_gpiochip_remove(gc); diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index 3abb90385829..cd136d5b52e9 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -52,6 +52,7 @@ * @device_notifier: used to notify character device wait queues about the GPIO * device being unregistered * @srcu: protects the pointer to the underlying GPIO chip + * @chip_rp: revocable provider handle for the corresponding struct gpio_chip. * @pin_ranges: range of pins served by the GPIO driver * * This state container holds most of the runtime variable data @@ -79,6 +80,7 @@ struct gpio_device { struct workqueue_struct *line_state_wq; struct blocking_notifier_head device_notifier; struct srcu_struct srcu; + struct revocable_provider __rcu *chip_rp; #ifdef CONFIG_PINCTRL /* -- 2.53.0.rc2.204.g2597b5adb4-goog
