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gpio: protect the pointer to gpio_chip in gpio_device with SRCU

Browse Source 
Ensure we cannot crash if the GPIO device gets unregistered (and the
chip pointer set to NULL) during any of the API calls.

To that end: wait for all users of gdev->chip to exit their read-only
SRCU critical sections in gpiochip_remove().

For brevity: add a guard class which can be instantiated at the top of
every function requiring read-only access to the chip pointer and use it
in all API calls taking a GPIO descriptor as argument. In places where
we only deal with the GPIO device - use regular guard() helpers and
rcu_dereference() for chip access. Do the same in API calls taking a
const pointer to gpio_desc.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
This commit is contained in:
Bartosz Golaszewski 2024-01-23 12:01:10 +01:00
parent 47d8b4c1d8
commit d83cee3d2b
4 changed files with 271 additions and 129 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

64
drivers/gpio/gpiolib-cdev.c
View File

@ -24,7 +24,6 @@
#include <linux/pinctrl/consumer.h> #include <linux/pinctrl/consumer.h>
#include <linux/poll.h> #include <linux/poll.h>
#include <linux/rbtree.h> #include <linux/rbtree.h>
#include <linux/rwsem.h>
#include <linux/seq_file.h> #include <linux/seq_file.h>
#include <linux/spinlock.h> #include <linux/spinlock.h>
#include <linux/timekeeping.h> #include <linux/timekeeping.h>
@ -205,9 +204,9 @@ static long linehandle_ioctl(struct file *file, unsigned int cmd,
unsigned int i; unsigned int i;
int ret; int ret;
guard(rwsem_read)(&lh->gdev->sem); guard(srcu)(&lh->gdev->srcu);
if (!lh->gdev->chip) if (!rcu_dereference(lh->gdev->chip))
return -ENODEV; return -ENODEV;
switch (cmd) { switch (cmd) {
@ -1520,9 +1519,9 @@ static long linereq_ioctl(struct file *file, unsigned int cmd,
struct linereq *lr = file->private_data; struct linereq *lr = file->private_data;
void __user *ip = (void __user *)arg; void __user *ip = (void __user *)arg;
guard(rwsem_read)(&lr->gdev->sem); guard(srcu)(&lr->gdev->srcu);
if (!lr->gdev->chip) if (!rcu_dereference(lr->gdev->chip))
return -ENODEV; return -ENODEV;
switch (cmd) { switch (cmd) {
@ -1551,9 +1550,9 @@ static __poll_t linereq_poll(struct file *file,
struct linereq *lr = file->private_data; struct linereq *lr = file->private_data;
__poll_t events = 0; __poll_t events = 0;
guard(rwsem_read)(&lr->gdev->sem); guard(srcu)(&lr->gdev->srcu);
if (!lr->gdev->chip) if (!rcu_dereference(lr->gdev->chip))
return EPOLLHUP | EPOLLERR; return EPOLLHUP | EPOLLERR;
poll_wait(file, &lr->wait, wait); poll_wait(file, &lr->wait, wait);
@ -1573,9 +1572,9 @@ static ssize_t linereq_read(struct file *file, char __user *buf,
ssize_t bytes_read = 0; ssize_t bytes_read = 0;
int ret; int ret;
guard(rwsem_read)(&lr->gdev->sem); guard(srcu)(&lr->gdev->srcu);
if (!lr->gdev->chip) if (!rcu_dereference(lr->gdev->chip))
return -ENODEV; return -ENODEV;
if (count < sizeof(le)) if (count < sizeof(le))
@ -1874,9 +1873,9 @@ static __poll_t lineevent_poll(struct file *file,
struct lineevent_state *le = file->private_data; struct lineevent_state *le = file->private_data;
__poll_t events = 0; __poll_t events = 0;
guard(rwsem_read)(&le->gdev->sem); guard(srcu)(&le->gdev->srcu);
if (!le->gdev->chip) if (!rcu_dereference(le->gdev->chip))
return EPOLLHUP | EPOLLERR; return EPOLLHUP | EPOLLERR;
poll_wait(file, &le->wait, wait); poll_wait(file, &le->wait, wait);
@ -1912,9 +1911,9 @@ static ssize_t lineevent_read(struct file *file, char __user *buf,
ssize_t ge_size; ssize_t ge_size;
int ret; int ret;
guard(rwsem_read)(&le->gdev->sem); guard(srcu)(&le->gdev->srcu);
if (!le->gdev->chip) if (!rcu_dereference(le->gdev->chip))
return -ENODEV; return -ENODEV;
/* /*
@ -1995,9 +1994,9 @@ static long lineevent_ioctl(struct file *file, unsigned int cmd,
void __user *ip = (void __user *)arg; void __user *ip = (void __user *)arg;
struct gpiohandle_data ghd; struct gpiohandle_data ghd;
guard(rwsem_read)(&le->gdev->sem); guard(srcu)(&le->gdev->srcu);
if (!le->gdev->chip) if (!rcu_dereference(le->gdev->chip))
return -ENODEV; return -ENODEV;
/* /*
@ -2295,10 +2294,13 @@ static void gpio_v2_line_info_changed_to_v1(
static void gpio_desc_to_lineinfo(struct gpio_desc *desc, static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
struct gpio_v2_line_info *info) struct gpio_v2_line_info *info)
{ {
struct gpio_chip *gc = desc->gdev->chip;
unsigned long dflags; unsigned long dflags;
const char *label; const char *label;
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return;
memset(info, 0, sizeof(*info)); memset(info, 0, sizeof(*info));
info->offset = gpio_chip_hwgpio(desc); info->offset = gpio_chip_hwgpio(desc);
@ -2331,8 +2333,8 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
test_bit(FLAG_USED_AS_IRQ, &dflags) || test_bit(FLAG_USED_AS_IRQ, &dflags) ||
test_bit(FLAG_EXPORT, &dflags) || test_bit(FLAG_EXPORT, &dflags) ||
test_bit(FLAG_SYSFS, &dflags) || test_bit(FLAG_SYSFS, &dflags) ||
!gpiochip_line_is_valid(gc, info->offset) || !gpiochip_line_is_valid(guard.gc, info->offset) ||
!pinctrl_gpio_can_use_line(gc, info->offset)) !pinctrl_gpio_can_use_line(guard.gc, info->offset))
info->flags |= GPIO_V2_LINE_FLAG_USED; info->flags |= GPIO_V2_LINE_FLAG_USED;
if (test_bit(FLAG_IS_OUT, &dflags)) if (test_bit(FLAG_IS_OUT, &dflags))
@ -2505,10 +2507,10 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
struct gpio_device *gdev = cdev->gdev; struct gpio_device *gdev = cdev->gdev;
void __user *ip = (void __user *)arg; void __user *ip = (void __user *)arg;
guard(rwsem_read)(&gdev->sem); guard(srcu)(&gdev->srcu);
/* We fail any subsequent ioctl():s when the chip is gone */ /* We fail any subsequent ioctl():s when the chip is gone */
if (!gdev->chip) if (!rcu_dereference(gdev->chip))
return -ENODEV; return -ENODEV;
/* Fill in the struct and pass to userspace */ /* Fill in the struct and pass to userspace */
@ -2591,9 +2593,9 @@ static __poll_t lineinfo_watch_poll(struct file *file,
struct gpio_chardev_data *cdev = file->private_data; struct gpio_chardev_data *cdev = file->private_data;
__poll_t events = 0; __poll_t events = 0;
guard(rwsem_read)(&cdev->gdev->sem); guard(srcu)(&cdev->gdev->srcu);
if (!cdev->gdev->chip) if (!rcu_dereference(cdev->gdev->chip))
return EPOLLHUP | EPOLLERR; return EPOLLHUP | EPOLLERR;
poll_wait(file, &cdev->wait, pollt); poll_wait(file, &cdev->wait, pollt);
@ -2614,9 +2616,9 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
int ret; int ret;
size_t event_size; size_t event_size;
guard(rwsem_read)(&cdev->gdev->sem); guard(srcu)(&cdev->gdev->srcu);
if (!cdev->gdev->chip) if (!rcu_dereference(cdev->gdev->chip))
return -ENODEV; return -ENODEV;
#ifndef CONFIG_GPIO_CDEV_V1 #ifndef CONFIG_GPIO_CDEV_V1
@ -2691,10 +2693,10 @@ static int gpio_chrdev_open(struct inode *inode, struct file *file)
struct gpio_chardev_data *cdev; struct gpio_chardev_data *cdev;
int ret = -ENOMEM; int ret = -ENOMEM;
guard(rwsem_read)(&gdev->sem); guard(srcu)(&gdev->srcu);
/* Fail on open if the backing gpiochip is gone */ /* Fail on open if the backing gpiochip is gone */
if (!gdev->chip) if (!rcu_dereference(gdev->chip))
return -ENODEV; return -ENODEV;
cdev = kzalloc(sizeof(*cdev), GFP_KERNEL); cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
@ -2781,6 +2783,7 @@ static const struct file_operations gpio_fileops = {
int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt) int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
{ {
struct gpio_chip *gc;
int ret; int ret;
cdev_init(&gdev->chrdev, &gpio_fileops); cdev_init(&gdev->chrdev, &gpio_fileops);
@ -2791,8 +2794,13 @@ int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
if (ret) if (ret)
return ret; return ret;
chip_dbg(gdev->chip, "added GPIO chardev (%d:%d)\n", guard(srcu)(&gdev->srcu);
MAJOR(devt), gdev->id);
gc = rcu_dereference(gdev->chip);
if (!gc)
return -ENODEV;
chip_dbg(gc, "added GPIO chardev (%d:%d)\n", MAJOR(devt), gdev->id);
return 0; return 0;
} }

57
drivers/gpio/gpiolib-sysfs.c
View File

@ -171,6 +171,10 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
unsigned long irq_flags; unsigned long irq_flags;
int ret; int ret;
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
data->irq = gpiod_to_irq(desc); data->irq = gpiod_to_irq(desc);
if (data->irq < 0) if (data->irq < 0)
return -EIO; return -EIO;
@ -195,7 +199,7 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
* Remove this redundant call (along with the corresponding * Remove this redundant call (along with the corresponding
* unlock) when those drivers have been fixed. * unlock) when those drivers have been fixed.
*/ */
ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc)); ret = gpiochip_lock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
if (ret < 0) if (ret < 0)
goto err_put_kn; goto err_put_kn;
@ -209,7 +213,7 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
return 0; return 0;
err_unlock: err_unlock:
gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc)); gpiochip_unlock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
err_put_kn: err_put_kn:
sysfs_put(data->value_kn); sysfs_put(data->value_kn);
@ -225,9 +229,13 @@ static void gpio_sysfs_free_irq(struct device *dev)
struct gpiod_data *data = dev_get_drvdata(dev); struct gpiod_data *data = dev_get_drvdata(dev);
struct gpio_desc *desc = data->desc; struct gpio_desc *desc = data->desc;
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return;
data->irq_flags = 0; data->irq_flags = 0;
free_irq(data->irq, data); free_irq(data->irq, data);
gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc)); gpiochip_unlock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
sysfs_put(data->value_kn); sysfs_put(data->value_kn);
} }
@ -444,13 +452,12 @@ static ssize_t export_store(const struct class *class,
const char *buf, size_t len) const char *buf, size_t len)
{ {
struct gpio_desc *desc; struct gpio_desc *desc;
struct gpio_chip *gc;
int status, offset; int status, offset;
long gpio; long gpio;
status = kstrtol(buf, 0, &gpio); status = kstrtol(buf, 0, &gpio);
if (status < 0) if (status)
goto done; return status;
desc = gpio_to_desc(gpio); desc = gpio_to_desc(gpio);
/* reject invalid GPIOs */ /* reject invalid GPIOs */
@ -458,9 +465,13 @@ static ssize_t export_store(const struct class *class,
pr_warn("%s: invalid GPIO %ld\n", __func__, gpio); pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
return -EINVAL; return -EINVAL;
} }
gc = desc->gdev->chip;
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
offset = gpio_chip_hwgpio(desc); offset = gpio_chip_hwgpio(desc);
if (!gpiochip_line_is_valid(gc, offset)) { if (!gpiochip_line_is_valid(guard.gc, offset)) {
pr_warn("%s: GPIO %ld masked\n", __func__, gpio); pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
return -EINVAL; return -EINVAL;
} }
@ -563,7 +574,6 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
const char *ioname = NULL; const char *ioname = NULL;
struct gpio_device *gdev; struct gpio_device *gdev;
struct gpiod_data *data; struct gpiod_data *data;
struct gpio_chip *chip;
struct device *dev; struct device *dev;
int status, offset; int status, offset;
@ -578,16 +588,19 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
return -EINVAL; return -EINVAL;
} }
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
if (!test_and_set_bit(FLAG_EXPORT, &desc->flags)) if (!test_and_set_bit(FLAG_EXPORT, &desc->flags))
return -EPERM; return -EPERM;
gdev = desc->gdev; gdev = desc->gdev;
chip = gdev->chip;
mutex_lock(&sysfs_lock); mutex_lock(&sysfs_lock);
/* check if chip is being removed */ /* check if chip is being removed */
if (!chip || !gdev->mockdev) { if (!gdev->mockdev) {
status = -ENODEV; status = -ENODEV;
goto err_unlock; goto err_unlock;
} }
@ -606,14 +619,14 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
data->desc = desc; data->desc = desc;
mutex_init(&data->mutex); mutex_init(&data->mutex);
if (chip->direction_input && chip->direction_output) if (guard.gc->direction_input && guard.gc->direction_output)
data->direction_can_change = direction_may_change; data->direction_can_change = direction_may_change;
else else
data->direction_can_change = false; data->direction_can_change = false;
offset = gpio_chip_hwgpio(desc); offset = gpio_chip_hwgpio(desc);
if (chip->names && chip->names[offset]) if (guard.gc->names && guard.gc->names[offset])
ioname = chip->names[offset]; ioname = guard.gc->names[offset];
dev = device_create_with_groups(&gpio_class, &gdev->dev, dev = device_create_with_groups(&gpio_class, &gdev->dev,
MKDEV(0, 0), data, gpio_groups, MKDEV(0, 0), data, gpio_groups,
@ -728,7 +741,7 @@ EXPORT_SYMBOL_GPL(gpiod_unexport);
int gpiochip_sysfs_register(struct gpio_device *gdev) int gpiochip_sysfs_register(struct gpio_device *gdev)
{ {
struct gpio_chip *chip = gdev->chip; struct gpio_chip *chip;
struct device *parent; struct device *parent;
struct device *dev; struct device *dev;
@ -741,6 +754,12 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
if (!class_is_registered(&gpio_class)) if (!class_is_registered(&gpio_class))
return 0; return 0;
guard(srcu)(&gdev->srcu);
chip = rcu_dereference(gdev->chip);
if (!chip)
return -ENODEV;
/* /*
* For sysfs backward compatibility we need to preserve this * For sysfs backward compatibility we need to preserve this
* preferred parenting to the gpio_chip parent field, if set. * preferred parenting to the gpio_chip parent field, if set.
@ -767,7 +786,7 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
void gpiochip_sysfs_unregister(struct gpio_device *gdev) void gpiochip_sysfs_unregister(struct gpio_device *gdev)
{ {
struct gpio_desc *desc; struct gpio_desc *desc;
struct gpio_chip *chip = gdev->chip; struct gpio_chip *chip;
scoped_guard(mutex, &sysfs_lock) { scoped_guard(mutex, &sysfs_lock) {
if (!gdev->mockdev) if (!gdev->mockdev)
@ -779,6 +798,12 @@ void gpiochip_sysfs_unregister(struct gpio_device *gdev)
gdev->mockdev = NULL; gdev->mockdev = NULL;
} }
guard(srcu)(&gdev->srcu);
chip = rcu_dereference(gdev->chip);
if (chip)
return;
/* unregister gpiod class devices owned by sysfs */ /* unregister gpiod class devices owned by sysfs */
for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) { for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) {
gpiod_unexport(desc); gpiod_unexport(desc);

257
drivers/gpio/gpiolib.c
View File

@ -216,7 +216,7 @@ struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
{ {
if (!desc) if (!desc)
return NULL; return NULL;
return desc->gdev->chip; return rcu_dereference(desc->gdev->chip);
} }
EXPORT_SYMBOL_GPL(gpiod_to_chip); EXPORT_SYMBOL_GPL(gpiod_to_chip);
@ -285,7 +285,7 @@ EXPORT_SYMBOL(gpio_device_get_label);
*/ */
struct gpio_chip *gpio_device_get_chip(struct gpio_device *gdev) struct gpio_chip *gpio_device_get_chip(struct gpio_device *gdev)
{ {
return gdev->chip; return rcu_dereference(gdev->chip);
} }
EXPORT_SYMBOL_GPL(gpio_device_get_chip); EXPORT_SYMBOL_GPL(gpio_device_get_chip);
@ -325,12 +325,21 @@ static int gpiochip_find_base_unlocked(int ngpio)
*/ */
int gpiod_get_direction(struct gpio_desc *desc) int gpiod_get_direction(struct gpio_desc *desc)
{ {
struct gpio_chip *gc;
unsigned long flags; unsigned long flags;
unsigned int offset; unsigned int offset;
int ret; int ret;
gc = gpiod_to_chip(desc); /*
* We cannot use VALIDATE_DESC() as we must not return 0 for a NULL
* descriptor like we usually do.
*/
if (!desc || IS_ERR(desc))
return -EINVAL;
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
offset = gpio_chip_hwgpio(desc); offset = gpio_chip_hwgpio(desc);
flags = READ_ONCE(desc->flags); flags = READ_ONCE(desc->flags);
@ -342,10 +351,10 @@ int gpiod_get_direction(struct gpio_desc *desc)
test_bit(FLAG_IS_OUT, &flags)) test_bit(FLAG_IS_OUT, &flags))
return 0; return 0;
if (!gc->get_direction) if (!guard.gc->get_direction)
return -ENOTSUPP; return -ENOTSUPP;
ret = gc->get_direction(gc, offset); ret = guard.gc->get_direction(guard.gc, offset);
if (ret < 0) if (ret < 0)
return ret; return ret;
@ -421,6 +430,7 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)
{ {
struct gpio_device *gdev; struct gpio_device *gdev;
struct gpio_desc *desc; struct gpio_desc *desc;
struct gpio_chip *gc;
if (!name) if (!name)
return NULL; return NULL;
@ -429,7 +439,13 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)
list_for_each_entry_srcu(gdev, &gpio_devices, list, list_for_each_entry_srcu(gdev, &gpio_devices, list,
srcu_read_lock_held(&gpio_devices_srcu)) { srcu_read_lock_held(&gpio_devices_srcu)) {
for_each_gpio_desc(gdev->chip, desc) { guard(srcu)(&gdev->srcu);
gc = rcu_dereference(gdev->chip);
if (!gc)
continue;
for_each_gpio_desc(gc, desc) {
if (desc->name && !strcmp(desc->name, name)) if (desc->name && !strcmp(desc->name, name))
return desc; return desc;
} }
@ -853,7 +869,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
gdev->dev.type = &gpio_dev_type; gdev->dev.type = &gpio_dev_type;
gdev->dev.bus = &gpio_bus_type; gdev->dev.bus = &gpio_bus_type;
gdev->dev.parent = gc->parent; gdev->dev.parent = gc->parent;
gdev->chip = gc; rcu_assign_pointer(gdev->chip, gc);
gc->gpiodev = gdev; gc->gpiodev = gdev;
gpiochip_set_data(gc, data); gpiochip_set_data(gc, data);
@ -1097,7 +1113,8 @@ void gpiochip_remove(struct gpio_chip *gc)
synchronize_srcu(&gpio_devices_srcu); synchronize_srcu(&gpio_devices_srcu);
/* Numb the device, cancelling all outstanding operations */ /* Numb the device, cancelling all outstanding operations */
gdev->chip = NULL; rcu_assign_pointer(gdev->chip, NULL);
synchronize_srcu(&gdev->srcu);
gpiochip_irqchip_remove(gc); gpiochip_irqchip_remove(gc);
acpi_gpiochip_remove(gc); acpi_gpiochip_remove(gc);
of_gpiochip_remove(gc); of_gpiochip_remove(gc);
@ -1156,6 +1173,7 @@ struct gpio_device *gpio_device_find(void *data,
const void *data)) const void *data))
{ {
struct gpio_device *gdev; struct gpio_device *gdev;
struct gpio_chip *gc;
/* /*
* Not yet but in the future the spinlock below will become a mutex. * Not yet but in the future the spinlock below will become a mutex.
@ -1166,8 +1184,13 @@ struct gpio_device *gpio_device_find(void *data,
guard(srcu)(&gpio_devices_srcu); guard(srcu)(&gpio_devices_srcu);
list_for_each_entry(gdev, &gpio_devices, list) { list_for_each_entry_srcu(gdev, &gpio_devices, list,
if (gdev->chip && match(gdev->chip, data)) srcu_read_lock_held(&gpio_devices_srcu)) {
guard(srcu)(&gdev->srcu);
gc = rcu_dereference(gdev->chip);
if (gc && match(gc, data))
return gpio_device_get(gdev); return gpio_device_get(gdev);
} }
@ -2214,10 +2237,13 @@ EXPORT_SYMBOL_GPL(gpiochip_remove_pin_ranges);
*/ */
static int gpiod_request_commit(struct gpio_desc *desc, const char *label) static int gpiod_request_commit(struct gpio_desc *desc, const char *label)
{ {
struct gpio_chip *gc = desc->gdev->chip;
unsigned int offset; unsigned int offset;
int ret; int ret;
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
if (test_and_set_bit(FLAG_REQUESTED, &desc->flags)) if (test_and_set_bit(FLAG_REQUESTED, &desc->flags))
return -EBUSY; return -EBUSY;
@ -2231,17 +2257,17 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label)
* before IRQs are enabled, for non-sleeping (SOC) GPIOs. * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
*/ */
if (gc->request) { if (guard.gc->request) {
offset = gpio_chip_hwgpio(desc); offset = gpio_chip_hwgpio(desc);
if (gpiochip_line_is_valid(gc, offset)) if (gpiochip_line_is_valid(guard.gc, offset))
ret = gc->request(gc, offset); ret = guard.gc->request(guard.gc, offset);
else else
ret = -EINVAL; ret = -EINVAL;
if (ret) if (ret)
goto out_clear_bit; goto out_clear_bit;
} }
if (gc->get_direction) if (guard.gc->get_direction)
gpiod_get_direction(desc); gpiod_get_direction(desc);
ret = desc_set_label(desc, label ? : "?"); ret = desc_set_label(desc, label ? : "?");
@ -2308,18 +2334,18 @@ int gpiod_request(struct gpio_desc *desc, const char *label)
static bool gpiod_free_commit(struct gpio_desc *desc) static bool gpiod_free_commit(struct gpio_desc *desc)
{ {
struct gpio_chip *gc;
unsigned long flags; unsigned long flags;
bool ret = false; bool ret = false;
might_sleep(); might_sleep();
gc = desc->gdev->chip; CLASS(gpio_chip_guard, guard)(desc);
flags = READ_ONCE(desc->flags); flags = READ_ONCE(desc->flags);
if (gc && test_bit(FLAG_REQUESTED, &flags)) { if (guard.gc && test_bit(FLAG_REQUESTED, &flags)) {
if (gc->free) if (guard.gc->free)
gc->free(gc, gpio_chip_hwgpio(desc)); guard.gc->free(guard.gc, gpio_chip_hwgpio(desc));
clear_bit(FLAG_ACTIVE_LOW, &flags); clear_bit(FLAG_ACTIVE_LOW, &flags);
clear_bit(FLAG_REQUESTED, &flags); clear_bit(FLAG_REQUESTED, &flags);
@ -2476,11 +2502,14 @@ static int gpio_set_config_with_argument(struct gpio_desc *desc,
enum pin_config_param mode, enum pin_config_param mode,
u32 argument) u32 argument)
{ {
struct gpio_chip *gc = desc->gdev->chip;
unsigned long config; unsigned long config;
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
config = pinconf_to_config_packed(mode, argument); config = pinconf_to_config_packed(mode, argument);
return gpio_do_set_config(gc, gpio_chip_hwgpio(desc), config); return gpio_do_set_config(guard.gc, gpio_chip_hwgpio(desc), config);
} }
static int gpio_set_config_with_argument_optional(struct gpio_desc *desc, static int gpio_set_config_with_argument_optional(struct gpio_desc *desc,
@ -2570,18 +2599,20 @@ int gpio_set_debounce_timeout(struct gpio_desc *desc, unsigned int debounce)
*/ */
int gpiod_direction_input(struct gpio_desc *desc) int gpiod_direction_input(struct gpio_desc *desc)
{ {
struct gpio_chip *gc;
int ret = 0; int ret = 0;
VALIDATE_DESC(desc); VALIDATE_DESC(desc);
gc = desc->gdev->chip;
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
/* /*
* It is legal to have no .get() and .direction_input() specified if * It is legal to have no .get() and .direction_input() specified if
* the chip is output-only, but you can't specify .direction_input() * the chip is output-only, but you can't specify .direction_input()
* and not support the .get() operation, that doesn't make sense. * and not support the .get() operation, that doesn't make sense.
*/ */
if (!gc->get && gc->direction_input) { if (!guard.gc->get && guard.gc->direction_input) {
gpiod_warn(desc, gpiod_warn(desc,
"%s: missing get() but have direction_input()\n", "%s: missing get() but have direction_input()\n",
__func__); __func__);
@ -2594,10 +2625,12 @@ int gpiod_direction_input(struct gpio_desc *desc)
* direction (if .get_direction() is supported) else we silently * direction (if .get_direction() is supported) else we silently
* assume we are in input mode after this. * assume we are in input mode after this.
*/ */
if (gc->direction_input) { if (guard.gc->direction_input) {
ret = gc->direction_input(gc, gpio_chip_hwgpio(desc)); ret = guard.gc->direction_input(guard.gc,
} else if (gc->get_direction && gpio_chip_hwgpio(desc));
(gc->get_direction(gc, gpio_chip_hwgpio(desc)) != 1)) { } else if (guard.gc->get_direction &&
(guard.gc->get_direction(guard.gc,
gpio_chip_hwgpio(desc)) != 1)) {
gpiod_warn(desc, gpiod_warn(desc,
"%s: missing direction_input() operation and line is output\n", "%s: missing direction_input() operation and line is output\n",
__func__); __func__);
@ -2616,28 +2649,31 @@ EXPORT_SYMBOL_GPL(gpiod_direction_input);
static int gpiod_direction_output_raw_commit(struct gpio_desc *desc, int value) static int gpiod_direction_output_raw_commit(struct gpio_desc *desc, int value)
{ {
struct gpio_chip *gc = desc->gdev->chip; int val = !!value, ret = 0;
int val = !!value;
int ret = 0; CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
/* /*
* It's OK not to specify .direction_output() if the gpiochip is * It's OK not to specify .direction_output() if the gpiochip is
* output-only, but if there is then not even a .set() operation it * output-only, but if there is then not even a .set() operation it
* is pretty tricky to drive the output line. * is pretty tricky to drive the output line.
*/ */
if (!gc->set && !gc->direction_output) { if (!guard.gc->set && !guard.gc->direction_output) {
gpiod_warn(desc, gpiod_warn(desc,
"%s: missing set() and direction_output() operations\n", "%s: missing set() and direction_output() operations\n",
__func__); __func__);
return -EIO; return -EIO;
} }
if (gc->direction_output) { if (guard.gc->direction_output) {
ret = gc->direction_output(gc, gpio_chip_hwgpio(desc), val); ret = guard.gc->direction_output(guard.gc,
gpio_chip_hwgpio(desc), val);
} else { } else {
/* Check that we are in output mode if we can */ /* Check that we are in output mode if we can */
if (gc->get_direction && if (guard.gc->get_direction &&
gc->get_direction(gc, gpio_chip_hwgpio(desc))) { guard.gc->get_direction(guard.gc, gpio_chip_hwgpio(desc))) {
gpiod_warn(desc, gpiod_warn(desc,
"%s: missing direction_output() operation\n", "%s: missing direction_output() operation\n",
__func__); __func__);
@ -2647,7 +2683,7 @@ static int gpiod_direction_output_raw_commit(struct gpio_desc *desc, int value)
* If we can't actively set the direction, we are some * If we can't actively set the direction, we are some
* output-only chip, so just drive the output as desired. * output-only chip, so just drive the output as desired.
*/ */
gc->set(gc, gpio_chip_hwgpio(desc), val); guard.gc->set(guard.gc, gpio_chip_hwgpio(desc), val);
} }
if (!ret) if (!ret)
@ -2763,17 +2799,20 @@ EXPORT_SYMBOL_GPL(gpiod_direction_output);
int gpiod_enable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags) int gpiod_enable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags)
{ {
int ret = 0; int ret = 0;
struct gpio_chip *gc;
VALIDATE_DESC(desc); VALIDATE_DESC(desc);
gc = desc->gdev->chip; CLASS(gpio_chip_guard, guard)(desc);
if (!gc->en_hw_timestamp) { if (!guard.gc)
return -ENODEV;
if (!guard.gc->en_hw_timestamp) {
gpiod_warn(desc, "%s: hw ts not supported\n", __func__); gpiod_warn(desc, "%s: hw ts not supported\n", __func__);
return -ENOTSUPP; return -ENOTSUPP;
} }
ret = gc->en_hw_timestamp(gc, gpio_chip_hwgpio(desc), flags); ret = guard.gc->en_hw_timestamp(guard.gc,
gpio_chip_hwgpio(desc), flags);
if (ret) if (ret)
gpiod_warn(desc, "%s: hw ts request failed\n", __func__); gpiod_warn(desc, "%s: hw ts request failed\n", __func__);
@ -2792,17 +2831,20 @@ EXPORT_SYMBOL_GPL(gpiod_enable_hw_timestamp_ns);
int gpiod_disable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags) int gpiod_disable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags)
{ {
int ret = 0; int ret = 0;
struct gpio_chip *gc;
VALIDATE_DESC(desc); VALIDATE_DESC(desc);
gc = desc->gdev->chip; CLASS(gpio_chip_guard, guard)(desc);
if (!gc->dis_hw_timestamp) { if (!guard.gc)
return -ENODEV;
if (!guard.gc->dis_hw_timestamp) {
gpiod_warn(desc, "%s: hw ts not supported\n", __func__); gpiod_warn(desc, "%s: hw ts not supported\n", __func__);
return -ENOTSUPP; return -ENOTSUPP;
} }
ret = gc->dis_hw_timestamp(gc, gpio_chip_hwgpio(desc), flags); ret = guard.gc->dis_hw_timestamp(guard.gc, gpio_chip_hwgpio(desc),
flags);
if (ret) if (ret)
gpiod_warn(desc, "%s: hw ts release failed\n", __func__); gpiod_warn(desc, "%s: hw ts release failed\n", __func__);
@ -2821,12 +2863,13 @@ EXPORT_SYMBOL_GPL(gpiod_disable_hw_timestamp_ns);
*/ */
int gpiod_set_config(struct gpio_desc *desc, unsigned long config) int gpiod_set_config(struct gpio_desc *desc, unsigned long config)
{ {
struct gpio_chip *gc;
VALIDATE_DESC(desc); VALIDATE_DESC(desc);
gc = desc->gdev->chip;
return gpio_do_set_config(gc, gpio_chip_hwgpio(desc), config); CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
return gpio_do_set_config(guard.gc, gpio_chip_hwgpio(desc), config);
} }
EXPORT_SYMBOL_GPL(gpiod_set_config); EXPORT_SYMBOL_GPL(gpiod_set_config);
@ -2924,10 +2967,19 @@ 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) static int gpiod_get_raw_value_commit(const struct gpio_desc *desc)
{ {
struct gpio_device *gdev;
struct gpio_chip *gc; struct gpio_chip *gc;
int value; int value;
gc = desc->gdev->chip; /* FIXME Unable to use gpio_chip_guard due to const desc. */
gdev = desc->gdev;
guard(srcu)(&gdev->srcu);
gc = rcu_dereference(gdev->chip);
if (!gc)
return -ENODEV;
value = gpio_chip_get_value(gc, desc); value = gpio_chip_get_value(gc, desc);
value = value < 0 ? value : !!value; value = value < 0 ? value : !!value;
trace_gpio_value(desc_to_gpio(desc), 1, value); trace_gpio_value(desc_to_gpio(desc), 1, value);
@ -2953,6 +3005,14 @@ static int gpio_chip_get_multiple(struct gpio_chip *gc,
return -EIO; return -EIO;
} }
/* 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);
return gc == rcu_dereference(gdev->chip);
}
int gpiod_get_array_value_complex(bool raw, bool can_sleep, int gpiod_get_array_value_complex(bool raw, bool can_sleep,
unsigned int array_size, unsigned int array_size,
struct gpio_desc **desc_array, struct gpio_desc **desc_array,
@ -2990,33 +3050,36 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep,
} }
while (i < array_size) { while (i < array_size) {
struct gpio_chip *gc = desc_array[i]->gdev->chip;
DECLARE_BITMAP(fastpath_mask, FASTPATH_NGPIO); DECLARE_BITMAP(fastpath_mask, FASTPATH_NGPIO);
DECLARE_BITMAP(fastpath_bits, FASTPATH_NGPIO); DECLARE_BITMAP(fastpath_bits, FASTPATH_NGPIO);
unsigned long *mask, *bits; unsigned long *mask, *bits;
int first, j; int first, j;
if (likely(gc->ngpio <= FASTPATH_NGPIO)) { CLASS(gpio_chip_guard, guard)(desc_array[i]);
if (!guard.gc)
return -ENODEV;
if (likely(guard.gc->ngpio <= FASTPATH_NGPIO)) {
mask = fastpath_mask; mask = fastpath_mask;
bits = fastpath_bits; bits = fastpath_bits;
} else { } else {
gfp_t flags = can_sleep ? GFP_KERNEL : GFP_ATOMIC; gfp_t flags = can_sleep ? GFP_KERNEL : GFP_ATOMIC;
mask = bitmap_alloc(gc->ngpio, flags); mask = bitmap_alloc(guard.gc->ngpio, flags);
if (!mask) if (!mask)
return -ENOMEM; return -ENOMEM;
bits = bitmap_alloc(gc->ngpio, flags); bits = bitmap_alloc(guard.gc->ngpio, flags);
if (!bits) { if (!bits) {
bitmap_free(mask); bitmap_free(mask);
return -ENOMEM; return -ENOMEM;
} }
} }
bitmap_zero(mask, gc->ngpio); bitmap_zero(mask, guard.gc->ngpio);
if (!can_sleep) if (!can_sleep)
WARN_ON(gc->can_sleep); WARN_ON(guard.gc->can_sleep);
/* collect all inputs belonging to the same chip */ /* collect all inputs belonging to the same chip */
first = i; first = i;
@ -3031,9 +3094,9 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep,
i = find_next_zero_bit(array_info->get_mask, i = find_next_zero_bit(array_info->get_mask,
array_size, i); array_size, i);
} while ((i < array_size) && } while ((i < array_size) &&
(desc_array[i]->gdev->chip == gc)); gpio_device_chip_cmp(desc_array[i]->gdev, guard.gc));
ret = gpio_chip_get_multiple(gc, mask, bits); ret = gpio_chip_get_multiple(guard.gc, mask, bits);
if (ret) { if (ret) {
if (mask != fastpath_mask) if (mask != fastpath_mask)
bitmap_free(mask); bitmap_free(mask);
@ -3174,14 +3237,16 @@ EXPORT_SYMBOL_GPL(gpiod_get_array_value);
*/ */
static void gpio_set_open_drain_value_commit(struct gpio_desc *desc, bool value) static void gpio_set_open_drain_value_commit(struct gpio_desc *desc, bool value)
{ {
int ret = 0; int ret = 0, offset = gpio_chip_hwgpio(desc);
struct gpio_chip *gc = desc->gdev->chip;
int offset = gpio_chip_hwgpio(desc); CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return;
if (value) { if (value) {
ret = gc->direction_input(gc, offset); ret = guard.gc->direction_input(guard.gc, offset);
} else { } else {
ret = gc->direction_output(gc, offset, 0); ret = guard.gc->direction_output(guard.gc, offset, 0);
if (!ret) if (!ret)
set_bit(FLAG_IS_OUT, &desc->flags); set_bit(FLAG_IS_OUT, &desc->flags);
} }
@ -3199,16 +3264,18 @@ static void gpio_set_open_drain_value_commit(struct gpio_desc *desc, bool value)
*/ */
static void gpio_set_open_source_value_commit(struct gpio_desc *desc, bool value) static void gpio_set_open_source_value_commit(struct gpio_desc *desc, bool value)
{ {
int ret = 0; int ret = 0, offset = gpio_chip_hwgpio(desc);
struct gpio_chip *gc = desc->gdev->chip;
int offset = gpio_chip_hwgpio(desc); CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return;
if (value) { if (value) {
ret = gc->direction_output(gc, offset, 1); ret = guard.gc->direction_output(guard.gc, offset, 1);
if (!ret) if (!ret)
set_bit(FLAG_IS_OUT, &desc->flags); set_bit(FLAG_IS_OUT, &desc->flags);
} else { } else {
ret = gc->direction_input(gc, offset); ret = guard.gc->direction_input(guard.gc, offset);
} }
trace_gpio_direction(desc_to_gpio(desc), !value, ret); trace_gpio_direction(desc_to_gpio(desc), !value, ret);
if (ret < 0) if (ret < 0)
@ -3219,11 +3286,12 @@ static void gpio_set_open_source_value_commit(struct gpio_desc *desc, bool value
static void gpiod_set_raw_value_commit(struct gpio_desc *desc, bool value) static void gpiod_set_raw_value_commit(struct gpio_desc *desc, bool value)
{ {
struct gpio_chip *gc; CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return;
gc = desc->gdev->chip;
trace_gpio_value(desc_to_gpio(desc), 0, value); trace_gpio_value(desc_to_gpio(desc), 0, value);
gc->set(gc, gpio_chip_hwgpio(desc), value); guard.gc->set(guard.gc, gpio_chip_hwgpio(desc), value);
} }
/* /*
@ -3284,33 +3352,36 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep,
} }
while (i < array_size) { while (i < array_size) {
struct gpio_chip *gc = desc_array[i]->gdev->chip;
DECLARE_BITMAP(fastpath_mask, FASTPATH_NGPIO); DECLARE_BITMAP(fastpath_mask, FASTPATH_NGPIO);
DECLARE_BITMAP(fastpath_bits, FASTPATH_NGPIO); DECLARE_BITMAP(fastpath_bits, FASTPATH_NGPIO);
unsigned long *mask, *bits; unsigned long *mask, *bits;
int count = 0; int count = 0;
if (likely(gc->ngpio <= FASTPATH_NGPIO)) { CLASS(gpio_chip_guard, guard)(desc_array[i]);
if (!guard.gc)
return -ENODEV;
if (likely(guard.gc->ngpio <= FASTPATH_NGPIO)) {
mask = fastpath_mask; mask = fastpath_mask;
bits = fastpath_bits; bits = fastpath_bits;
} else { } else {
gfp_t flags = can_sleep ? GFP_KERNEL : GFP_ATOMIC; gfp_t flags = can_sleep ? GFP_KERNEL : GFP_ATOMIC;
mask = bitmap_alloc(gc->ngpio, flags); mask = bitmap_alloc(guard.gc->ngpio, flags);
if (!mask) if (!mask)
return -ENOMEM; return -ENOMEM;
bits = bitmap_alloc(gc->ngpio, flags); bits = bitmap_alloc(guard.gc->ngpio, flags);
if (!bits) { if (!bits) {
bitmap_free(mask); bitmap_free(mask);
return -ENOMEM; return -ENOMEM;
} }
} }
bitmap_zero(mask, gc->ngpio); bitmap_zero(mask, guard.gc->ngpio);
if (!can_sleep) if (!can_sleep)
WARN_ON(gc->can_sleep); WARN_ON(guard.gc->can_sleep);
do { do {
struct gpio_desc *desc = desc_array[i]; struct gpio_desc *desc = desc_array[i];
@ -3346,10 +3417,10 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep,
i = find_next_zero_bit(array_info->set_mask, i = find_next_zero_bit(array_info->set_mask,
array_size, i); array_size, i);
} while ((i < array_size) && } while ((i < array_size) &&
(desc_array[i]->gdev->chip == gc)); gpio_device_chip_cmp(desc_array[i]->gdev, guard.gc));
/* push collected bits to outputs */ /* push collected bits to outputs */
if (count != 0) if (count != 0)
gpio_chip_set_multiple(gc, mask, bits); gpio_chip_set_multiple(guard.gc, mask, bits);
if (mask != fastpath_mask) if (mask != fastpath_mask)
bitmap_free(mask); bitmap_free(mask);
@ -3505,6 +3576,7 @@ EXPORT_SYMBOL_GPL(gpiod_set_consumer_name);
*/ */
int gpiod_to_irq(const struct gpio_desc *desc) int gpiod_to_irq(const struct gpio_desc *desc)
{ {
struct gpio_device *gdev;
struct gpio_chip *gc; struct gpio_chip *gc;
int offset; int offset;
@ -3516,7 +3588,13 @@ int gpiod_to_irq(const struct gpio_desc *desc)
if (!desc || IS_ERR(desc)) if (!desc || IS_ERR(desc))
return -EINVAL; return -EINVAL;
gc = desc->gdev->chip; gdev = desc->gdev;
/* FIXME Cannot use gpio_chip_guard due to const desc. */
guard(srcu)(&gdev->srcu);
gc = rcu_dereference(gdev->chip);
if (!gc)
return -ENODEV;
offset = gpio_chip_hwgpio(desc); offset = gpio_chip_hwgpio(desc);
if (gc->to_irq) { if (gc->to_irq) {
int retirq = gc->to_irq(gc, offset); int retirq = gc->to_irq(gc, offset);
@ -4696,12 +4774,20 @@ core_initcall(gpiolib_dev_init);
static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev) static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev)
{ {
struct gpio_chip *gc = gdev->chip;
bool active_low, is_irq, is_out; bool active_low, is_irq, is_out;
unsigned int gpio = gdev->base; unsigned int gpio = gdev->base;
struct gpio_desc *desc; struct gpio_desc *desc;
struct gpio_chip *gc;
int value; int value;
guard(srcu)(&gdev->srcu);
gc = rcu_dereference(gdev->chip);
if (!gc) {
seq_puts(s, "Underlying GPIO chip is gone\n");
return;
}
for_each_gpio_desc(gc, desc) { for_each_gpio_desc(gc, desc) {
guard(srcu)(&desc->srcu); guard(srcu)(&desc->srcu);
if (test_bit(FLAG_REQUESTED, &desc->flags)) { if (test_bit(FLAG_REQUESTED, &desc->flags)) {
@ -4776,9 +4862,12 @@ static int gpiolib_seq_show(struct seq_file *s, void *v)
{ {
struct gpiolib_seq_priv *priv = s->private; struct gpiolib_seq_priv *priv = s->private;
struct gpio_device *gdev = v; struct gpio_device *gdev = v;
struct gpio_chip *gc = gdev->chip; struct gpio_chip *gc;
struct device *parent; struct device *parent;
guard(srcu)(&gdev->srcu);
gc = rcu_dereference(gdev->chip);
if (!gc) { if (!gc) {
seq_printf(s, "%s%s: (dangling chip)", seq_printf(s, "%s%s: (dangling chip)",
priv->newline ? "\n" : "", priv->newline ? "\n" : "",

22
drivers/gpio/gpiolib.h
View File

@ -63,7 +63,7 @@ struct gpio_device {
int id; int id;
struct device *mockdev; struct device *mockdev;
struct module *owner; struct module *owner;
struct gpio_chip *chip; struct gpio_chip __rcu *chip;
struct gpio_desc *descs; struct gpio_desc *descs;
int base; int base;
u16 ngpio; u16 ngpio;
@ -193,6 +193,26 @@ struct gpio_desc {
#define gpiod_not_found(desc) (IS_ERR(desc) && PTR_ERR(desc) == -ENOENT) #define gpiod_not_found(desc) (IS_ERR(desc) && PTR_ERR(desc) == -ENOENT)
struct gpio_chip_guard {
struct gpio_device *gdev;
struct gpio_chip *gc;
int idx;
};
DEFINE_CLASS(gpio_chip_guard,
struct gpio_chip_guard,
srcu_read_unlock(&_T.gdev->srcu, _T.idx),
({
struct gpio_chip_guard _guard;
_guard.gdev = desc->gdev;
_guard.idx = srcu_read_lock(&_guard.gdev->srcu);
_guard.gc = rcu_dereference(_guard.gdev->chip);
_guard;
}),
struct gpio_desc *desc)
int gpiod_request(struct gpio_desc *desc, const char *label); int gpiod_request(struct gpio_desc *desc, const char *label);
void gpiod_free(struct gpio_desc *desc); void gpiod_free(struct gpio_desc *desc);