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 <tzungbi@kernel.org>
---
v3:
- Change revocable API usages accordingly.
v2: https://lore.kernel.org/all/20260203061059.975605-8-tzungbi@kernel.org
- Change usages accordingly after applying
https://lore.kernel.org/all/20260129143733.45618-2-tzungbi@kernel.org.
- Add __rcu for `chip_rp`.
- Pass pointer of pointer to revocable_provider_revoke().
- Rebase accordingly after applying
https://lore.kernel.org/all/20260203060210.972243-1-tzungbi@kernel.org.
v1: https://lore.kernel.org/all/20260116081036.352286-13-tzungbi@kernel.org
drivers/gpio/gpiolib.c | 16 ++++++++++++++--
drivers/gpio/gpiolib.h | 2 ++
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 74ee7bfb974c..7ef4dc4e6e9e 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>
@@ -869,6 +870,8 @@ static void gpiodev_release(struct device *dev)
synchronize_srcu(&gdev->desc_srcu);
cleanup_srcu_struct(&gdev->desc_srcu);
+ if (gdev->chip_rp)
+ revocable_put(gdev->chip_rp);
ida_free(&gpio_ida, gdev->id);
kfree_const(gdev->label);
kfree(gdev->descs);
@@ -1115,6 +1118,12 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
goto err_put_device;
}
+ gdev->chip_rp = revocable_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);
@@ -1144,7 +1153,7 @@ 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;
}
/*
@@ -1164,7 +1173,7 @@ 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;
}
}
@@ -1261,6 +1270,8 @@ 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:
+ revocable_revoke(gdev->chip_rp);
err_put_device:
gpio_device_put(gdev);
goto err_print_message;
@@ -1307,6 +1318,7 @@ 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_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..56643f40e87e 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 *chip_rp;
#ifdef CONFIG_PINCTRL
/*
--
2.53.0.310.g728cabbaf7-goog