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gpio: use srcu_dereference() with SRCU-protected pointers

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Lockdep with CONFIG_PROVE_RCU enabled reports false positives about
suspicious rcu_dereference() usage. Let's silence it by using
srcu_dereference() which is the correct helper with SRCU.

Fixes: d83cee3d2b ("gpio: protect the pointer to gpio_chip in gpio_device with SRCU")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202402122234.d85cca9b-lkp@intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Bartosz Golaszewski 2024-02-14 09:44:18 +01:00
parent 8574b5b476
commit d82b9e0887
3 changed files with 13 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
drivers/gpio/gpiolib-sysfs.c
View file

@ -14,6 +14,7 @@
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/srcu.h>
#include <linux/sysfs.h>
#include <linux/types.h>
@ -756,7 +757,7 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
guard(srcu)(&gdev->srcu);
chip = rcu_dereference(gdev->chip);
chip = srcu_dereference(gdev->chip, &gdev->srcu);
if (!chip)
return -ENODEV;
@ -800,7 +801,7 @@ void gpiochip_sysfs_unregister(struct gpio_device *gdev)
guard(srcu)(&gdev->srcu);
chip = rcu_dereference(gdev->chip);
chip = srcu_dereference(gdev->chip, &gdev->srcu);
if (chip)
return;

16
drivers/gpio/gpiolib.c
View file

@ -109,7 +109,7 @@ const char *gpiod_get_label(struct gpio_desc *desc)
return "interrupt";
return test_bit(FLAG_REQUESTED, &flags) ?
rcu_dereference(desc->label) : NULL;
srcu_dereference(desc->label, &desc->srcu) : NULL;
}
static int desc_set_label(struct gpio_desc *desc, const char *label)
@ -447,7 +447,7 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)
srcu_read_lock_held(&gpio_devices_srcu)) {
guard(srcu)(&gdev->srcu);
gc = rcu_dereference(gdev->chip);
gc = srcu_dereference(gdev->chip, &gdev->srcu);
if (!gc)
continue;
@ -1190,7 +1190,7 @@ struct gpio_device *gpio_device_find(void *data,
srcu_read_lock_held(&gpio_devices_srcu)) {
guard(srcu)(&gdev->srcu);
gc = rcu_dereference(gdev->chip);
gc = srcu_dereference(gdev->chip, &gdev->srcu);
if (gc && match(gc, data))
return gpio_device_get(gdev);
@ -2978,7 +2978,7 @@ static int gpiod_get_raw_value_commit(const struct gpio_desc *desc)
guard(srcu)(&gdev->srcu);
gc = rcu_dereference(gdev->chip);
gc = srcu_dereference(gdev->chip, &gdev->srcu);
if (!gc)
return -ENODEV;
@ -3012,7 +3012,7 @@ static bool gpio_device_chip_cmp(struct gpio_device *gdev, struct gpio_chip *gc)
{
guard(srcu)(&gdev->srcu);
return gc == rcu_dereference(gdev->chip);
return gc == srcu_dereference(gdev->chip, &gdev->srcu);
}
int gpiod_get_array_value_complex(bool raw, bool can_sleep,
@ -3593,7 +3593,7 @@ int gpiod_to_irq(const struct gpio_desc *desc)
gdev = desc->gdev;
/* FIXME Cannot use gpio_chip_guard due to const desc. */
guard(srcu)(&gdev->srcu);
gc = rcu_dereference(gdev->chip);
gc = srcu_dereference(gdev->chip, &gdev->srcu);
if (!gc)
return -ENODEV;
@ -4787,7 +4787,7 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev)
guard(srcu)(&gdev->srcu);
gc = rcu_dereference(gdev->chip);
gc = srcu_dereference(gdev->chip, &gdev->srcu);
if (!gc) {
seq_puts(s, "Underlying GPIO chip is gone\n");
return;
@ -4872,7 +4872,7 @@ static int gpiolib_seq_show(struct seq_file *s, void *v)
guard(srcu)(&gdev->srcu);
gc = rcu_dereference(gdev->chip);
gc = srcu_dereference(gdev->chip, &gdev->srcu);
if (!gc) {
seq_printf(s, "%s%s: (dangling chip)",
priv->newline ? "\n" : "",

3
drivers/gpio/gpiolib.h
View file

@ -202,7 +202,8 @@ DEFINE_CLASS(gpio_chip_guard,
_guard.gdev = desc->gdev;
_guard.idx = srcu_read_lock(&_guard.gdev->srcu);
_guard.gc = rcu_dereference(_guard.gdev->chip);
_guard.gc = srcu_dereference(_guard.gdev->chip,
&_guard.gdev->srcu);
_guard;
}),