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Message-ID: <20260203061059.975605-11-tzungbi@kernel.org>
Date: Tue, 3 Feb 2026 06:10:57 +0000
From: Tzung-Bi Shih <tzungbi@...nel.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Danilo Krummrich <dakr@...nel.org>,
Bartosz Golaszewski <brgl@...ev.pl>,
Linus Walleij <linusw@...nel.org>
Cc: Jonathan Corbet <corbet@....net>,
Shuah Khan <shuah@...nel.org>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Wolfram Sang <wsa+renesas@...g-engineering.com>,
Jason Gunthorpe <jgg@...dia.com>,
Johan Hovold <johan@...nel.org>,
linux-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org,
chrome-platform@...ts.linux.dev,
tzungbi@...nel.org,
Dan Williams <dan.j.williams@...el.com>,
linux-gpio@...r.kernel.org
Subject: [PATCH v2 10/11] gpio: Leverage revocable for accessing struct gpio_chip
Struct gpio_device now provides a revocable provider to the underlying
struct gpio_chip. Leverage revocable for accessing the struct
gpio_chip.
Signed-off-by: Tzung-Bi Shih <tzungbi@...nel.org>
---
v2:
- Separate from v1(a) for excluding gpio_chip_guard and combine v1(b).
v1(a):
- https://lore.kernel.org/all/20260116081036.352286-23-tzungbi@kernel.org
v1(b):
- https://lore.kernel.org/all/20260116081036.352286-19-tzungbi@kernel.org
drivers/gpio/gpiolib.c | 52 +++++++++++++++---------------------------
1 file changed, 18 insertions(+), 34 deletions(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index e62b00191d59..347ff456858f 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -338,7 +338,10 @@ EXPORT_SYMBOL(gpio_device_get_label);
*/
struct gpio_chip *gpio_device_get_chip(struct gpio_device *gdev)
{
- return rcu_dereference_check(gdev->chip, 1);
+ struct gpio_chip *gc;
+
+ REVOCABLE_TRY_ACCESS_WITH(gdev->chip_rp, gc);
+ return gc;
}
EXPORT_SYMBOL_GPL(gpio_device_get_chip);
@@ -558,9 +561,7 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)
list_for_each_entry_srcu(gdev, &gpio_devices, list,
srcu_read_lock_held(&gpio_devices_srcu)) {
- guard(srcu)(&gdev->srcu);
-
- gc = srcu_dereference(gdev->chip, &gdev->srcu);
+ REVOCABLE_TRY_ACCESS_WITH(gdev->chip_rp, gc);
if (!gc)
continue;
@@ -972,9 +973,7 @@ static void gpiochip_setup_devs(void)
list_for_each_entry_srcu(gdev, &gpio_devices, list,
srcu_read_lock_held(&gpio_devices_srcu)) {
- guard(srcu)(&gdev->srcu);
-
- gc = srcu_dereference(gdev->chip, &gdev->srcu);
+ REVOCABLE_TRY_ACCESS_WITH(gdev->chip_rp, gc);
if (!gc) {
dev_err(&gdev->dev, "Underlying GPIO chip is gone\n");
continue;
@@ -1379,11 +1378,11 @@ struct gpio_device *gpio_device_find(const void *data,
if (!device_is_registered(&gdev->dev))
continue;
- guard(srcu)(&gdev->srcu);
-
- gc = srcu_dereference(gdev->chip, &gdev->srcu);
+ REVOCABLE_TRY_ACCESS_WITH(gdev->chip_rp, gc);
+ if (!gc)
+ continue;
- if (gc && match(gc, data))
+ if (match(gc, data))
return gpio_device_get(gdev);
}
@@ -3325,16 +3324,10 @@ static int gpio_chip_get_value(struct gpio_chip *gc, const struct gpio_desc *des
static int gpiod_get_raw_value_commit(const struct gpio_desc *desc)
{
- struct gpio_device *gdev;
struct gpio_chip *gc;
int value;
- /* FIXME Unable to use gpio_chip_guard due to const desc. */
- gdev = desc->gdev;
-
- guard(srcu)(&gdev->srcu);
-
- gc = srcu_dereference(gdev->chip, &gdev->srcu);
+ REVOCABLE_TRY_ACCESS_WITH(desc->gdev->chip_rp, gc);
if (!gc)
return -ENODEV;
@@ -3375,9 +3368,10 @@ static int gpio_chip_get_multiple(struct gpio_chip *gc,
/* The 'other' chip must be protected with its GPIO device's SRCU. */
static bool gpio_device_chip_cmp(struct gpio_device *gdev, struct gpio_chip *gc)
{
- guard(srcu)(&gdev->srcu);
+ struct gpio_chip *chip;
- return gc == srcu_dereference(gdev->chip, &gdev->srcu);
+ REVOCABLE_TRY_ACCESS_WITH(gdev->chip_rp, chip);
+ return chip ? chip == gc : false;
}
int gpiod_get_array_value_complex(bool raw, bool can_sleep,
@@ -3400,9 +3394,7 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep,
if (!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);
+ REVOCABLE_TRY_ACCESS_WITH(array_info->gdev->chip_rp, gc);
if (!gc)
return -ENODEV;
@@ -3749,9 +3741,7 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep,
return -EPERM;
}
- guard(srcu)(&array_info->gdev->srcu);
- gc = srcu_dereference(array_info->gdev->chip,
- &array_info->gdev->srcu);
+ REVOCABLE_TRY_ACCESS_WITH(array_info->gdev->chip_rp, gc);
if (!gc)
return -ENODEV;
@@ -4049,7 +4039,6 @@ EXPORT_SYMBOL_GPL(gpiod_is_shared);
*/
int gpiod_to_irq(const struct gpio_desc *desc)
{
- struct gpio_device *gdev;
struct gpio_chip *gc;
int offset;
int ret;
@@ -4058,10 +4047,7 @@ int gpiod_to_irq(const struct gpio_desc *desc)
if (ret <= 0)
return -EINVAL;
- gdev = desc->gdev;
- /* FIXME Cannot use gpio_chip_guard due to const desc. */
- guard(srcu)(&gdev->srcu);
- gc = srcu_dereference(gdev->chip, &gdev->srcu);
+ REVOCABLE_TRY_ACCESS_WITH(desc->gdev->chip_rp, gc);
if (!gc)
return -ENODEV;
@@ -5440,9 +5426,7 @@ static int gpiolib_seq_show(struct seq_file *s, void *v)
if (priv->newline)
seq_putc(s, '\n');
- guard(srcu)(&gdev->srcu);
-
- gc = srcu_dereference(gdev->chip, &gdev->srcu);
+ REVOCABLE_TRY_ACCESS_WITH(gdev->chip_rp, gc);
if (!gc) {
seq_printf(s, "%s: (dangling chip)\n", dev_name(&gdev->dev));
return 0;
--
2.53.0.rc2.204.g2597b5adb4-goog
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