This is a note to let you know that I've just added the patch titled
gpiolib: provide gpio_device_find()
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
gpiolib-provide-gpio_device_find.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ee697a56fb02a1dca6b907522f169c6494cb2f51
Author: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
Date: Wed Sep 27 16:29:23 2023 +0200
gpiolib: provide gpio_device_find()
[ Upstream commit cfe102f63308c8c8e01199a682868a64b83f653e ]
gpiochip_find() is wrong and its kernel doc is misleading as the
function doesn't return a reference to the gpio_chip but just a raw
pointer. The chip itself is not guaranteed to stay alive, in fact it can
be deleted at any point. Also: other than GPIO drivers themselves,
nobody else has any business accessing gpio_chip structs.
Provide a new gpio_device_find() function that returns a real reference
to the opaque gpio_device structure that is guaranteed to stay alive for
as long as there are active users of it.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Stable-dep-of: 48e1b4d369cf ("gpiolib: remove the GPIO device from the list when it's unregistered")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index c2b40d7138fa..71492d213ef4 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1014,16 +1014,10 @@ void gpiochip_remove(struct gpio_chip *gc)
}
EXPORT_SYMBOL_GPL(gpiochip_remove);
-/**
- * gpiochip_find() - iterator for locating a specific gpio_chip
- * @data: data to pass to match function
- * @match: Callback function to check gpio_chip
+/*
+ * FIXME: This will be removed soon.
*
- * Similar to bus_find_device. It returns a reference to a gpio_chip as
- * determined by a user supplied @match callback. The callback should return
- * 0 if the device doesn't match and non-zero if it does. If the callback is
- * non-zero, this function will return to the caller and not iterate over any
- * more gpio_chips.
+ * This function is depracated, don't use.
*/
struct gpio_chip *gpiochip_find(void *data,
int (*match)(struct gpio_chip *gc,
@@ -1031,21 +1025,62 @@ struct gpio_chip *gpiochip_find(void *data,
{
struct gpio_device *gdev;
struct gpio_chip *gc = NULL;
- unsigned long flags;
-
- spin_lock_irqsave(&gpio_lock, flags);
- list_for_each_entry(gdev, &gpio_devices, list)
- if (gdev->chip && match(gdev->chip, data)) {
- gc = gdev->chip;
- break;
- }
- spin_unlock_irqrestore(&gpio_lock, flags);
+ gdev = gpio_device_find(data, match);
+ if (gdev) {
+ gc = gdev->chip;
+ gpio_device_put(gdev);
+ }
return gc;
}
EXPORT_SYMBOL_GPL(gpiochip_find);
+/**
+ * gpio_device_find() - find a specific GPIO device
+ * @data: data to pass to match function
+ * @match: Callback function to check gpio_chip
+ *
+ * Returns:
+ * New reference to struct gpio_device.
+ *
+ * Similar to bus_find_device(). It returns a reference to a gpio_device as
+ * determined by a user supplied @match callback. The callback should return
+ * 0 if the device doesn't match and non-zero if it does. If the callback
+ * returns non-zero, this function will return to the caller and not iterate
+ * over any more gpio_devices.
+ *
+ * The callback takes the GPIO chip structure as argument. During the execution
+ * of the callback function the chip is protected from being freed. TODO: This
+ * actually has yet to be implemented.
+ *
+ * If the function returns non-NULL, the returned reference must be freed by
+ * the caller using gpio_device_put().
+ */
+struct gpio_device *gpio_device_find(void *data,
+ int (*match)(struct gpio_chip *gc,
+ void *data))
+{
+ struct gpio_device *gdev;
+
+ /*
+ * Not yet but in the future the spinlock below will become a mutex.
+ * Annotate this function before anyone tries to use it in interrupt
+ * context like it happened with gpiochip_find().
+ */
+ might_sleep();
+
+ guard(spinlock_irqsave)(&gpio_lock);
+
+ list_for_each_entry(gdev, &gpio_devices, list) {
+ if (gdev->chip && match(gdev->chip, data))
+ return gpio_device_get(gdev);
+ }
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(gpio_device_find);
+
static int gpiochip_match_name(struct gpio_chip *gc, void *data)
{
const char *name = data;
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 64c214317a83..d6e38a500833 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -607,6 +607,9 @@ extern int devm_gpiochip_add_data_with_key(struct device *dev, struct gpio_chip
extern struct gpio_chip *gpiochip_find(void *data,
int (*match)(struct gpio_chip *gc, void *data));
+struct gpio_device *gpio_device_find(void *data,
+ int (*match)(struct gpio_chip *gc, void *data));
+
struct gpio_device *gpio_device_get(struct gpio_device *gdev);
void gpio_device_put(struct gpio_device *gdev);
