diff mbox series

[v2,21/23] gpio: protect the pointer to gpio_chip in gpio_device with SRCU

Message ID 20240205093418.39755-22-brgl@bgdev.pl
State New
Headers show
Series gpio: rework locking and object life-time control | expand

Commit Message

Bartosz Golaszewski Feb. 5, 2024, 9:34 a.m. UTC 
From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

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>
---
 drivers/gpio/gpiolib-cdev.c  |  63 +++++----
 drivers/gpio/gpiolib-sysfs.c |  90 +++++++++---
 drivers/gpio/gpiolib.c       | 257 +++++++++++++++++++++++------------
 drivers/gpio/gpiolib.h       |  22 ++-
 4 files changed, 298 insertions(+), 134 deletions(-)

Comments

Andy Shevchenko Feb. 5, 2024, 12:31 p.m. UTC | #1 
On Mon, Feb 05, 2024 at 10:34:16AM +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> 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.

...

>  static ssize_t base_show(struct device *dev,
>  			       struct device_attribute *attr, char *buf)
>  {
> -	const struct gpio_device *gdev = dev_get_drvdata(dev);
> +	struct gpio_device *gdev = dev_get_drvdata(dev);
> +	struct gpio_chip *gc;
>  
> -	return sysfs_emit(buf, "%d\n", gdev->chip->base);
> +	guard(srcu)(&gdev->srcu);
> +
> +	gc = rcu_dereference(gdev->chip);
> +	if (!gc)
> +		return -ENODEV;
> +
> +	return sysfs_emit(buf, "%d\n", gc->base);

Similar Q as below.

>  }

...

>  static ssize_t label_show(struct device *dev,
>  			       struct device_attribute *attr, char *buf)
>  {
> -	const struct gpio_device *gdev = dev_get_drvdata(dev);
> +	struct gpio_device *gdev = dev_get_drvdata(dev);
> +	struct gpio_chip *gc;
>  
> -	return sysfs_emit(buf, "%s\n", gdev->chip->label ?: "");
> +	guard(srcu)(&gdev->srcu);
> +
> +	gc = rcu_dereference(gdev->chip);
> +	if (!gc)
> +		return -ENODEV;
> +
> +	return sysfs_emit(buf, "%s\n", gc->label ?: "");

Why do you need gc label here and not gdev? In other code you switched over (in
a patch before this in the series).

>  }

>  static ssize_t ngpio_show(struct device *dev,
>  			       struct device_attribute *attr, char *buf)
>  {
> -	const struct gpio_device *gdev = dev_get_drvdata(dev);
> +	struct gpio_device *gdev = dev_get_drvdata(dev);
> +	struct gpio_chip *gc;
>  
> -	return sysfs_emit(buf, "%u\n", gdev->chip->ngpio);
> +	guard(srcu)(&gdev->srcu);
> +
> +	gc = rcu_dereference(gdev->chip);
> +	if (!gc)
> +		return -ENODEV;
> +
> +	return sysfs_emit(buf, "%u\n", gc->ngpio);

Ditto.

>  }

...

>  int gpiod_get_direction(struct gpio_desc *desc)
>  {
> -	struct gpio_chip *gc;
>  	unsigned long flags;
>  	unsigned int offset;
>  	int ret;
>  
> -	gc = gpiod_to_chip(desc);
> +	if (!desc)
> +		/* Sane default is INPUT. */
> +		return 1;

Hmm... I can't imagine how this value may anyhow be used / useful.

> +	if (IS_ERR(desc))
> +		return -EINVAL;

With above said, can't we use one of VALIDATE_DESC*() macro here?

...

>  	list_for_each_entry_srcu(gdev, &gpio_devices, list,
>  				 srcu_read_lock_held(&gpio_devices_srcu)) {

> +	list_for_each_entry_srcu(gdev, &gpio_devices, list,
> +				 srcu_read_lock_held(&gpio_devices_srcu)) {

Seems like a candidate for

#define gpio_for_each_device(...) ...

...

>  	VALIDATE_DESC(desc);
>  
> -	gc = desc->gdev->chip;
> -	if (!gc->en_hw_timestamp) {
> +	CLASS(gpio_chip_guard, guard)(desc);
> +	if (!guard.gc)
> +		return -ENODEV;


Not sure if it would be good to have a respective VALIDATE_DESC_GUARDED()
or so. At least it may deduplicate a few cases.

...

> +	/* FIXME Cannot use gpio_chip_guard due to const desc. */

gpio_chip_guard()
Bartosz Golaszewski Feb. 5, 2024, 1:30 p.m. UTC | #2 
On Mon, Feb 5, 2024 at 1:31 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Mon, Feb 05, 2024 at 10:34:16AM +0100, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> >
> > 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.
>
> ...
>
> >  static ssize_t base_show(struct device *dev,
> >                              struct device_attribute *attr, char *buf)
> >  {
> > -     const struct gpio_device *gdev = dev_get_drvdata(dev);
> > +     struct gpio_device *gdev = dev_get_drvdata(dev);
> > +     struct gpio_chip *gc;
> >
> > -     return sysfs_emit(buf, "%d\n", gdev->chip->base);
> > +     guard(srcu)(&gdev->srcu);
> > +
> > +     gc = rcu_dereference(gdev->chip);
> > +     if (!gc)
> > +             return -ENODEV;
> > +
> > +     return sysfs_emit(buf, "%d\n", gc->base);
>
> Similar Q as below.
>
> >  }
>
> ...
>
> >  static ssize_t label_show(struct device *dev,
> >                              struct device_attribute *attr, char *buf)
> >  {
> > -     const struct gpio_device *gdev = dev_get_drvdata(dev);
> > +     struct gpio_device *gdev = dev_get_drvdata(dev);
> > +     struct gpio_chip *gc;
> >
> > -     return sysfs_emit(buf, "%s\n", gdev->chip->label ?: "");
> > +     guard(srcu)(&gdev->srcu);
> > +
> > +     gc = rcu_dereference(gdev->chip);
> > +     if (!gc)
> > +             return -ENODEV;
> > +
> > +     return sysfs_emit(buf, "%s\n", gc->label ?: "");
>
> Why do you need gc label here and not gdev? In other code you switched over (in
> a patch before this in the series).
>

Yeah, good point.

> >  }
>
> >  static ssize_t ngpio_show(struct device *dev,
> >                              struct device_attribute *attr, char *buf)
> >  {
> > -     const struct gpio_device *gdev = dev_get_drvdata(dev);
> > +     struct gpio_device *gdev = dev_get_drvdata(dev);
> > +     struct gpio_chip *gc;
> >
> > -     return sysfs_emit(buf, "%u\n", gdev->chip->ngpio);
> > +     guard(srcu)(&gdev->srcu);
> > +
> > +     gc = rcu_dereference(gdev->chip);
> > +     if (!gc)
> > +             return -ENODEV;
> > +
> > +     return sysfs_emit(buf, "%u\n", gc->ngpio);
>
> Ditto.
>
> >  }
>
> ...
>
> >  int gpiod_get_direction(struct gpio_desc *desc)
> >  {
> > -     struct gpio_chip *gc;
> >       unsigned long flags;
> >       unsigned int offset;
> >       int ret;
> >
> > -     gc = gpiod_to_chip(desc);
> > +     if (!desc)
> > +             /* Sane default is INPUT. */
> > +             return 1;
>
> Hmm... I can't imagine how this value may anyhow be used / useful.
>
> > +     if (IS_ERR(desc))
> > +             return -EINVAL;
>
> With above said, can't we use one of VALIDATE_DESC*() macro here?
>

Possibly.

> ...
>
> >       list_for_each_entry_srcu(gdev, &gpio_devices, list,
> >                                srcu_read_lock_held(&gpio_devices_srcu)) {
>
> > +     list_for_each_entry_srcu(gdev, &gpio_devices, list,
> > +                              srcu_read_lock_held(&gpio_devices_srcu)) {
>
> Seems like a candidate for
>
> #define gpio_for_each_device(...) ...
>
> ...
>
> >       VALIDATE_DESC(desc);
> >
> > -     gc = desc->gdev->chip;
> > -     if (!gc->en_hw_timestamp) {
> > +     CLASS(gpio_chip_guard, guard)(desc);
> > +     if (!guard.gc)
> > +             return -ENODEV;
>
>
> Not sure if it would be good to have a respective VALIDATE_DESC_GUARDED()
> or so. At least it may deduplicate a few cases.
>

We could of course do it like this:

VALIDATE_DESC_GUARDED(desc, guard) where `guard` would be the name of
the guard variable but I generally dislike macros with flow-control
statements and I think this would just go too far. In fact: I'd gladly
get rid of VALIDATE_DESC() and co. altogether.

Bart

> ...
>
> > +     /* FIXME Cannot use gpio_chip_guard due to const desc. */
>
> gpio_chip_guard()
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
Bartosz Golaszewski Feb. 5, 2024, 7:32 p.m. UTC | #3 
On Mon, Feb 5, 2024 at 1:31 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>

[snip]

>
> > +     /* FIXME Cannot use gpio_chip_guard due to const desc. */
>
> gpio_chip_guard()
>

Nope, it's the name of the class type, not a function.

Bart
Bartosz Golaszewski Feb. 5, 2024, 7:36 p.m. UTC | #4 
On Mon, Feb 5, 2024 at 1:31 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>

[snip]

>
> >  int gpiod_get_direction(struct gpio_desc *desc)
> >  {
> > -     struct gpio_chip *gc;
> >       unsigned long flags;
> >       unsigned int offset;
> >       int ret;
> >
> > -     gc = gpiod_to_chip(desc);
> > +     if (!desc)
> > +             /* Sane default is INPUT. */
> > +             return 1;
>
> Hmm... I can't imagine how this value may anyhow be used / useful.
>

What else would you return for an optional (NULL) GPIO?

Bart

[snip]
Andy Shevchenko Feb. 6, 2024, 12:24 p.m. UTC | #5 
On Mon, Feb 05, 2024 at 08:36:39PM +0100, Bartosz Golaszewski wrote:
> On Mon, Feb 5, 2024 at 1:31 PM Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:

...

> >
> > >  int gpiod_get_direction(struct gpio_desc *desc)
> > >  {
> > > -     struct gpio_chip *gc;
> > >       unsigned long flags;
> > >       unsigned int offset;
> > >       int ret;
> > >
> > > -     gc = gpiod_to_chip(desc);
> > > +     if (!desc)
> > > +             /* Sane default is INPUT. */
> > > +             return 1;
> >
> > Hmm... I can't imagine how this value may anyhow be used / useful.
> 
> What else would you return for an optional (NULL) GPIO?

An error. If somebody asks for direction of the non-existing GPIO, there is no
(valid) answer for that.
Bartosz Golaszewski Feb. 6, 2024, 12:57 p.m. UTC | #6 
On Tue, Feb 6, 2024 at 1:24 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Mon, Feb 05, 2024 at 08:36:39PM +0100, Bartosz Golaszewski wrote:
> > On Mon, Feb 5, 2024 at 1:31 PM Andy Shevchenko
> > <andriy.shevchenko@linux.intel.com> wrote:
>
> ...
>
> > >
> > > >  int gpiod_get_direction(struct gpio_desc *desc)
> > > >  {
> > > > -     struct gpio_chip *gc;
> > > >       unsigned long flags;
> > > >       unsigned int offset;
> > > >       int ret;
> > > >
> > > > -     gc = gpiod_to_chip(desc);
> > > > +     if (!desc)
> > > > +             /* Sane default is INPUT. */
> > > > +             return 1;
> > >
> > > Hmm... I can't imagine how this value may anyhow be used / useful.
> >
> > What else would you return for an optional (NULL) GPIO?
>
> An error. If somebody asks for direction of the non-existing GPIO, there is no
> (valid) answer for that.
>

All other functions return 0 for desc == NULL to accommodate
gpiod_get_optional(). I think we should stay consistent here.

Bart
Andy Shevchenko Feb. 6, 2024, 1:13 p.m. UTC | #7 
On Tue, Feb 06, 2024 at 01:57:39PM +0100, Bartosz Golaszewski wrote:
> On Tue, Feb 6, 2024 at 1:24 PM Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> >
> > On Mon, Feb 05, 2024 at 08:36:39PM +0100, Bartosz Golaszewski wrote:
> > > On Mon, Feb 5, 2024 at 1:31 PM Andy Shevchenko
> > > <andriy.shevchenko@linux.intel.com> wrote:
> >
> > ...
> >
> > > >
> > > > >  int gpiod_get_direction(struct gpio_desc *desc)
> > > > >  {
> > > > > -     struct gpio_chip *gc;
> > > > >       unsigned long flags;
> > > > >       unsigned int offset;
> > > > >       int ret;
> > > > >
> > > > > -     gc = gpiod_to_chip(desc);
> > > > > +     if (!desc)
> > > > > +             /* Sane default is INPUT. */
> > > > > +             return 1;
> > > >
> > > > Hmm... I can't imagine how this value may anyhow be used / useful.
> > >
> > > What else would you return for an optional (NULL) GPIO?
> >
> > An error. If somebody asks for direction of the non-existing GPIO, there is no
> > (valid) answer for that.

> All other functions return 0 for desc == NULL to accommodate
> gpiod_get_optional(). I think we should stay consistent here.

The way you proposed is inconsistent, i.e. you may not return any direction
for the unknown / non-existing GPIO. You speculate it will be 1, I may consider
that in my (hypothetical for now) case it should be 0.

Just don't make all bananas to be oranges. It won't work.
Bartosz Golaszewski Feb. 6, 2024, 1:23 p.m. UTC | #8 
On Tue, Feb 6, 2024 at 2:13 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Tue, Feb 06, 2024 at 01:57:39PM +0100, Bartosz Golaszewski wrote:
> > On Tue, Feb 6, 2024 at 1:24 PM Andy Shevchenko
> > <andriy.shevchenko@linux.intel.com> wrote:
> > >
> > > On Mon, Feb 05, 2024 at 08:36:39PM +0100, Bartosz Golaszewski wrote:
> > > > On Mon, Feb 5, 2024 at 1:31 PM Andy Shevchenko
> > > > <andriy.shevchenko@linux.intel.com> wrote:
> > >
> > > ...
> > >
> > > > >
> > > > > >  int gpiod_get_direction(struct gpio_desc *desc)
> > > > > >  {
> > > > > > -     struct gpio_chip *gc;
> > > > > >       unsigned long flags;
> > > > > >       unsigned int offset;
> > > > > >       int ret;
> > > > > >
> > > > > > -     gc = gpiod_to_chip(desc);
> > > > > > +     if (!desc)
> > > > > > +             /* Sane default is INPUT. */
> > > > > > +             return 1;
> > > > >
> > > > > Hmm... I can't imagine how this value may anyhow be used / useful.
> > > >
> > > > What else would you return for an optional (NULL) GPIO?
> > >
> > > An error. If somebody asks for direction of the non-existing GPIO, there is no
> > > (valid) answer for that.
>
> > All other functions return 0 for desc == NULL to accommodate
> > gpiod_get_optional(). I think we should stay consistent here.
>
> The way you proposed is inconsistent, i.e. you may not return any direction
> for the unknown / non-existing GPIO. You speculate it will be 1, I may consider
> that in my (hypothetical for now) case it should be 0.
>
> Just don't make all bananas to be oranges. It won't work.
>

I don't have a strong conviction here. May make it an error as well.
It's still inconsistent though - calling gpiod_direction_output(NULL);
will return 0 and then you get an error when you do
gpiod_get_direction(NULL). I don't have a good solution though.

Bart
Andy Shevchenko Feb. 6, 2024, 1:43 p.m. UTC | #9 
On Tue, Feb 06, 2024 at 02:23:35PM +0100, Bartosz Golaszewski wrote:
> On Tue, Feb 6, 2024 at 2:13 PM Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> > On Tue, Feb 06, 2024 at 01:57:39PM +0100, Bartosz Golaszewski wrote:
> > > On Tue, Feb 6, 2024 at 1:24 PM Andy Shevchenko
> > > <andriy.shevchenko@linux.intel.com> wrote:
> > > > On Mon, Feb 05, 2024 at 08:36:39PM +0100, Bartosz Golaszewski wrote:
> > > > > On Mon, Feb 5, 2024 at 1:31 PM Andy Shevchenko
> > > > > <andriy.shevchenko@linux.intel.com> wrote:

...

> > > > > > >  int gpiod_get_direction(struct gpio_desc *desc)
> > > > > > >  {
> > > > > > > -     struct gpio_chip *gc;
> > > > > > >       unsigned long flags;
> > > > > > >       unsigned int offset;
> > > > > > >       int ret;
> > > > > > >
> > > > > > > -     gc = gpiod_to_chip(desc);
> > > > > > > +     if (!desc)
> > > > > > > +             /* Sane default is INPUT. */
> > > > > > > +             return 1;
> > > > > >
> > > > > > Hmm... I can't imagine how this value may anyhow be used / useful.
> > > > >
> > > > > What else would you return for an optional (NULL) GPIO?
> > > >
> > > > An error. If somebody asks for direction of the non-existing GPIO, there is no
> > > > (valid) answer for that.
> >
> > > All other functions return 0 for desc == NULL to accommodate
> > > gpiod_get_optional(). I think we should stay consistent here.
> >
> > The way you proposed is inconsistent, i.e. you may not return any direction
> > for the unknown / non-existing GPIO. You speculate it will be 1, I may consider
> > that in my (hypothetical for now) case it should be 0.
> >
> > Just don't make all bananas to be oranges. It won't work.
> 
> I don't have a strong conviction here. May make it an error as well.
> It's still inconsistent though - calling gpiod_direction_output(NULL);
> will return 0 and then you get an error when you do
> gpiod_get_direction(NULL). I don't have a good solution though.

Yes, and this is the best what we can have. Because the real code may rely on
the returned value and they should be really aware on the returned values in
some cases.
diff mbox series

Patch

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index e993c6a7215a..ccdeed013f6b 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -205,9 +205,9 @@  static long linehandle_ioctl(struct file *file, unsigned int cmd,
 	unsigned int i;
 	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;
 
 	switch (cmd) {
@@ -1520,9 +1520,9 @@  static long linereq_ioctl(struct file *file, unsigned int cmd,
 	struct linereq *lr = file->private_data;
 	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;
 
 	switch (cmd) {
@@ -1551,9 +1551,9 @@  static __poll_t linereq_poll(struct file *file,
 	struct linereq *lr = file->private_data;
 	__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;
 
 	poll_wait(file, &lr->wait, wait);
@@ -1573,9 +1573,9 @@  static ssize_t linereq_read(struct file *file, char __user *buf,
 	ssize_t bytes_read = 0;
 	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;
 
 	if (count < sizeof(le))
@@ -1874,9 +1874,9 @@  static __poll_t lineevent_poll(struct file *file,
 	struct lineevent_state *le = file->private_data;
 	__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;
 
 	poll_wait(file, &le->wait, wait);
@@ -1912,9 +1912,9 @@  static ssize_t lineevent_read(struct file *file, char __user *buf,
 	ssize_t ge_size;
 	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;
 
 	/*
@@ -1995,9 +1995,9 @@  static long lineevent_ioctl(struct file *file, unsigned int cmd,
 	void __user *ip = (void __user *)arg;
 	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;
 
 	/*
@@ -2295,10 +2295,13 @@  static void gpio_v2_line_info_changed_to_v1(
 static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 				  struct gpio_v2_line_info *info)
 {
-	struct gpio_chip *gc = desc->gdev->chip;
 	unsigned long dflags;
 	const char *label;
 
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return;
+
 	memset(info, 0, sizeof(*info));
 	info->offset = gpio_chip_hwgpio(desc);
 
@@ -2331,8 +2334,8 @@  static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 	    test_bit(FLAG_USED_AS_IRQ, &dflags) ||
 	    test_bit(FLAG_EXPORT, &dflags) ||
 	    test_bit(FLAG_SYSFS, &dflags) ||
-	    !gpiochip_line_is_valid(gc, info->offset) ||
-	    !pinctrl_gpio_can_use_line(gc, info->offset))
+	    !gpiochip_line_is_valid(guard.gc, info->offset) ||
+	    !pinctrl_gpio_can_use_line(guard.gc, info->offset))
 		info->flags |= GPIO_V2_LINE_FLAG_USED;
 
 	if (test_bit(FLAG_IS_OUT, &dflags))
@@ -2505,10 +2508,10 @@  static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	struct gpio_device *gdev = cdev->gdev;
 	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 */
-	if (!gdev->chip)
+	if (!rcu_dereference(gdev->chip))
 		return -ENODEV;
 
 	/* Fill in the struct and pass to userspace */
@@ -2591,9 +2594,9 @@  static __poll_t lineinfo_watch_poll(struct file *file,
 	struct gpio_chardev_data *cdev = file->private_data;
 	__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;
 
 	poll_wait(file, &cdev->wait, pollt);
@@ -2614,9 +2617,9 @@  static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
 	int ret;
 	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;
 
 #ifndef CONFIG_GPIO_CDEV_V1
@@ -2691,10 +2694,10 @@  static int gpio_chrdev_open(struct inode *inode, struct file *file)
 	struct gpio_chardev_data *cdev;
 	int ret = -ENOMEM;
 
-	guard(rwsem_read)(&gdev->sem);
+	guard(srcu)(&gdev->srcu);
 
 	/* Fail on open if the backing gpiochip is gone */
-	if (!gdev->chip)
+	if (!rcu_dereference(gdev->chip))
 		return -ENODEV;
 
 	cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
@@ -2781,6 +2784,7 @@  static const struct file_operations gpio_fileops = {
 
 int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
 {
+	struct gpio_chip *gc;
 	int ret;
 
 	cdev_init(&gdev->chrdev, &gpio_fileops);
@@ -2791,8 +2795,13 @@  int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
 	if (ret)
 		return ret;
 
-	chip_dbg(gdev->chip, "added GPIO chardev (%d:%d)\n",
-		 MAJOR(devt), gdev->id);
+	guard(srcu)(&gdev->srcu);
+
+	gc = rcu_dereference(gdev->chip);
+	if (!gc)
+		return -ENODEV;
+
+	chip_dbg(gc, "added GPIO chardev (%d:%d)\n", MAJOR(devt), gdev->id);
 
 	return 0;
 }
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 654a5bc53047..15349f92d0ec 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -171,6 +171,10 @@  static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
 	unsigned long irq_flags;
 	int ret;
 
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return -ENODEV;
+
 	data->irq = gpiod_to_irq(desc);
 	if (data->irq < 0)
 		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
 	 *        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)
 		goto err_put_kn;
 
@@ -209,7 +213,7 @@  static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
 	return 0;
 
 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:
 	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 gpio_desc *desc = data->desc;
 
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return;
+
 	data->irq_flags = 0;
 	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);
 }
 
@@ -401,27 +409,48 @@  static const struct attribute_group *gpio_groups[] = {
 static ssize_t base_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
 {
-	const struct gpio_device *gdev = dev_get_drvdata(dev);
+	struct gpio_device *gdev = dev_get_drvdata(dev);
+	struct gpio_chip *gc;
 
-	return sysfs_emit(buf, "%d\n", gdev->chip->base);
+	guard(srcu)(&gdev->srcu);
+
+	gc = rcu_dereference(gdev->chip);
+	if (!gc)
+		return -ENODEV;
+
+	return sysfs_emit(buf, "%d\n", gc->base);
 }
 static DEVICE_ATTR_RO(base);
 
 static ssize_t label_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
 {
-	const struct gpio_device *gdev = dev_get_drvdata(dev);
+	struct gpio_device *gdev = dev_get_drvdata(dev);
+	struct gpio_chip *gc;
 
-	return sysfs_emit(buf, "%s\n", gdev->chip->label ?: "");
+	guard(srcu)(&gdev->srcu);
+
+	gc = rcu_dereference(gdev->chip);
+	if (!gc)
+		return -ENODEV;
+
+	return sysfs_emit(buf, "%s\n", gc->label ?: "");
 }
 static DEVICE_ATTR_RO(label);
 
 static ssize_t ngpio_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
 {
-	const struct gpio_device *gdev = dev_get_drvdata(dev);
+	struct gpio_device *gdev = dev_get_drvdata(dev);
+	struct gpio_chip *gc;
 
-	return sysfs_emit(buf, "%u\n", gdev->chip->ngpio);
+	guard(srcu)(&gdev->srcu);
+
+	gc = rcu_dereference(gdev->chip);
+	if (!gc)
+		return -ENODEV;
+
+	return sysfs_emit(buf, "%u\n", gc->ngpio);
 }
 static DEVICE_ATTR_RO(ngpio);
 
@@ -444,13 +473,12 @@  static ssize_t export_store(const struct class *class,
 				const char *buf, size_t len)
 {
 	struct gpio_desc *desc;
-	struct gpio_chip *gc;
 	int status, offset;
 	long gpio;
 
 	status = kstrtol(buf, 0, &gpio);
-	if (status < 0)
-		goto done;
+	if (status)
+		return status;
 
 	desc = gpio_to_desc(gpio);
 	/* reject invalid GPIOs */
@@ -458,9 +486,13 @@  static ssize_t export_store(const struct class *class,
 		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
 		return -EINVAL;
 	}
-	gc = desc->gdev->chip;
+
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return -ENODEV;
+
 	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);
 		return -EINVAL;
 	}
@@ -563,7 +595,6 @@  int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 	const char *ioname = NULL;
 	struct gpio_device *gdev;
 	struct gpiod_data *data;
-	struct gpio_chip *chip;
 	struct device *dev;
 	int status, offset;
 
@@ -578,16 +609,19 @@  int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 		return -EINVAL;
 	}
 
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return -ENODEV;
+
 	if (!test_and_set_bit(FLAG_EXPORT, &desc->flags))
 		return -EPERM;
 
 	gdev = desc->gdev;
-	chip = gdev->chip;
 
 	mutex_lock(&sysfs_lock);
 
 	/* check if chip is being removed */
-	if (!chip || !gdev->mockdev) {
+	if (!gdev->mockdev) {
 		status = -ENODEV;
 		goto err_unlock;
 	}
@@ -606,14 +640,14 @@  int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 
 	data->desc = desc;
 	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;
 	else
 		data->direction_can_change = false;
 
 	offset = gpio_chip_hwgpio(desc);
-	if (chip->names && chip->names[offset])
-		ioname = chip->names[offset];
+	if (guard.gc->names && guard.gc->names[offset])
+		ioname = guard.gc->names[offset];
 
 	dev = device_create_with_groups(&gpio_class, &gdev->dev,
 					MKDEV(0, 0), data, gpio_groups,
@@ -728,7 +762,7 @@  EXPORT_SYMBOL_GPL(gpiod_unexport);
 
 int gpiochip_sysfs_register(struct gpio_device *gdev)
 {
-	struct gpio_chip *chip = gdev->chip;
+	struct gpio_chip *chip;
 	struct device *parent;
 	struct device *dev;
 
@@ -741,6 +775,12 @@  int gpiochip_sysfs_register(struct gpio_device *gdev)
 	if (!class_is_registered(&gpio_class))
 		return 0;
 
+	guard(srcu)(&gdev->srcu);
+
+	chip = rcu_dereference(gdev->chip);
+	if (!chip)
+		return -ENODEV;
+
 	/*
 	 * For sysfs backward compatibility we need to preserve this
 	 * preferred parenting to the gpio_chip parent field, if set.
@@ -767,7 +807,7 @@  int gpiochip_sysfs_register(struct gpio_device *gdev)
 void gpiochip_sysfs_unregister(struct gpio_device *gdev)
 {
 	struct gpio_desc *desc;
-	struct gpio_chip *chip = gdev->chip;
+	struct gpio_chip *chip;
 
 	scoped_guard(mutex, &sysfs_lock) {
 		if (!gdev->mockdev)
@@ -779,6 +819,12 @@  void gpiochip_sysfs_unregister(struct gpio_device *gdev)
 		gdev->mockdev = NULL;
 	}
 
+	guard(srcu)(&gdev->srcu);
+
+	chip = rcu_dereference(gdev->chip);
+	if (chip)
+		return;
+
 	/* unregister gpiod class devices owned by sysfs */
 	for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) {
 		gpiod_unexport(desc);
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index c49d7a156bdd..89e1c98b0bda 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -216,7 +216,7 @@  struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
 {
 	if (!desc)
 		return NULL;
-	return desc->gdev->chip;
+	return rcu_dereference(desc->gdev->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)
 {
-	return gdev->chip;
+	return rcu_dereference(gdev->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)
 {
-	struct gpio_chip *gc;
 	unsigned long flags;
 	unsigned int offset;
 	int ret;
 
-	gc = gpiod_to_chip(desc);
+	if (!desc)
+		/* Sane default is INPUT. */
+		return 1;
+
+	if (IS_ERR(desc))
+		return -EINVAL;
+
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return -ENODEV;
+
 	offset = gpio_chip_hwgpio(desc);
 	flags = READ_ONCE(desc->flags);
 
@@ -342,10 +351,10 @@  int gpiod_get_direction(struct gpio_desc *desc)
 	    test_bit(FLAG_IS_OUT, &flags))
 		return 0;
 
-	if (!gc->get_direction)
+	if (!guard.gc->get_direction)
 		return -ENOTSUPP;
 
-	ret = gc->get_direction(gc, offset);
+	ret = guard.gc->get_direction(guard.gc, offset);
 	if (ret < 0)
 		return ret;
 
@@ -421,6 +430,7 @@  static struct gpio_desc *gpio_name_to_desc(const char * const name)
 {
 	struct gpio_device *gdev;
 	struct gpio_desc *desc;
+	struct gpio_chip *gc;
 
 	if (!name)
 		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,
 				 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))
 				return desc;
 		}
@@ -847,7 +863,7 @@  int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 		return -ENOMEM;
 	gdev->dev.bus = &gpio_bus_type;
 	gdev->dev.parent = gc->parent;
-	gdev->chip = gc;
+	rcu_assign_pointer(gdev->chip, gc);
 
 	gc->gpiodev = gdev;
 	gpiochip_set_data(gc, data);
@@ -1087,7 +1103,8 @@  void gpiochip_remove(struct gpio_chip *gc)
 	gpiochip_sysfs_unregister(gdev);
 	gpiochip_free_hogs(gc);
 	/* Numb the device, cancelling all outstanding operations */
-	gdev->chip = NULL;
+	rcu_assign_pointer(gdev->chip, NULL);
+	synchronize_srcu(&gdev->srcu);
 	gpiochip_irqchip_remove(gc);
 	acpi_gpiochip_remove(gc);
 	of_gpiochip_remove(gc);
@@ -1150,6 +1167,7 @@  struct gpio_device *gpio_device_find(void *data,
 						  void *data))
 {
 	struct gpio_device *gdev;
+	struct gpio_chip *gc;
 
 	/*
 	 * Not yet but in the future the spinlock below will become a mutex.
@@ -1160,8 +1178,13 @@  struct gpio_device *gpio_device_find(void *data,
 
 	guard(srcu)(&gpio_devices_srcu);
 
-	list_for_each_entry(gdev, &gpio_devices, list) {
-		if (gdev->chip && match(gdev->chip, data))
+	list_for_each_entry_srcu(gdev, &gpio_devices, list,
+				 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);
 	}
 
@@ -2208,10 +2231,13 @@  EXPORT_SYMBOL_GPL(gpiochip_remove_pin_ranges);
  */
 static int gpiod_request_commit(struct gpio_desc *desc, const char *label)
 {
-	struct gpio_chip *gc = desc->gdev->chip;
 	unsigned int offset;
 	int ret;
 
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return -ENODEV;
+
 	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags))
 		return -EBUSY;
 
@@ -2225,17 +2251,17 @@  static int gpiod_request_commit(struct gpio_desc *desc, const char *label)
 	 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
 	 */
 
-	if (gc->request) {
+	if (guard.gc->request) {
 		offset = gpio_chip_hwgpio(desc);
-		if (gpiochip_line_is_valid(gc, offset))
-			ret = gc->request(gc, offset);
+		if (gpiochip_line_is_valid(guard.gc, offset))
+			ret = guard.gc->request(guard.gc, offset);
 		else
 			ret = -EINVAL;
 		if (ret)
 			goto out_clear_bit;
 	}
 
-	if (gc->get_direction)
+	if (guard.gc->get_direction)
 		gpiod_get_direction(desc);
 
 	ret = desc_set_label(desc, label ? : "?");
@@ -2302,18 +2328,18 @@  int gpiod_request(struct gpio_desc *desc, const char *label)
 
 static bool gpiod_free_commit(struct gpio_desc *desc)
 {
-	struct gpio_chip *gc;
 	unsigned long flags;
 	bool ret = false;
 
 	might_sleep();
 
-	gc = desc->gdev->chip;
+	CLASS(gpio_chip_guard, guard)(desc);
+
 	flags = READ_ONCE(desc->flags);
 
-	if (gc && test_bit(FLAG_REQUESTED, &flags)) {
-		if (gc->free)
-			gc->free(gc, gpio_chip_hwgpio(desc));
+	if (guard.gc && test_bit(FLAG_REQUESTED, &flags)) {
+		if (guard.gc->free)
+			guard.gc->free(guard.gc, gpio_chip_hwgpio(desc));
 
 		clear_bit(FLAG_ACTIVE_LOW, &flags);
 		clear_bit(FLAG_REQUESTED, &flags);
@@ -2470,11 +2496,14 @@  static int gpio_set_config_with_argument(struct gpio_desc *desc,
 					 enum pin_config_param mode,
 					 u32 argument)
 {
-	struct gpio_chip *gc = desc->gdev->chip;
 	unsigned long config;
 
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return -ENODEV;
+
 	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,
@@ -2564,18 +2593,20 @@  int gpio_set_debounce_timeout(struct gpio_desc *desc, unsigned int debounce)
  */
 int gpiod_direction_input(struct gpio_desc *desc)
 {
-	struct gpio_chip *gc;
 	int ret = 0;
 
 	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
 	 * the chip is output-only, but you can't specify .direction_input()
 	 * 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,
 			   "%s: missing get() but have direction_input()\n",
 			   __func__);
@@ -2588,10 +2619,12 @@  int gpiod_direction_input(struct gpio_desc *desc)
 	 * direction (if .get_direction() is supported) else we silently
 	 * assume we are in input mode after this.
 	 */
-	if (gc->direction_input) {
-		ret = gc->direction_input(gc, gpio_chip_hwgpio(desc));
-	} else if (gc->get_direction &&
-		  (gc->get_direction(gc, gpio_chip_hwgpio(desc)) != 1)) {
+	if (guard.gc->direction_input) {
+		ret = guard.gc->direction_input(guard.gc,
+						gpio_chip_hwgpio(desc));
+	} else if (guard.gc->get_direction &&
+		  (guard.gc->get_direction(guard.gc,
+					   gpio_chip_hwgpio(desc)) != 1)) {
 		gpiod_warn(desc,
 			   "%s: missing direction_input() operation and line is output\n",
 			   __func__);
@@ -2610,28 +2643,31 @@  EXPORT_SYMBOL_GPL(gpiod_direction_input);
 
 static int gpiod_direction_output_raw_commit(struct gpio_desc *desc, int value)
 {
-	struct gpio_chip *gc = desc->gdev->chip;
-	int val = !!value;
-	int ret = 0;
+	int val = !!value, 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
 	 * output-only, but if there is then not even a .set() operation it
 	 * 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,
 			   "%s: missing set() and direction_output() operations\n",
 			   __func__);
 		return -EIO;
 	}
 
-	if (gc->direction_output) {
-		ret = gc->direction_output(gc, gpio_chip_hwgpio(desc), val);
+	if (guard.gc->direction_output) {
+		ret = guard.gc->direction_output(guard.gc,
+						 gpio_chip_hwgpio(desc), val);
 	} else {
 		/* Check that we are in output mode if we can */
-		if (gc->get_direction &&
-		    gc->get_direction(gc, gpio_chip_hwgpio(desc))) {
+		if (guard.gc->get_direction &&
+		    guard.gc->get_direction(guard.gc, gpio_chip_hwgpio(desc))) {
 			gpiod_warn(desc,
 				"%s: missing direction_output() operation\n",
 				__func__);
@@ -2641,7 +2677,7 @@  static int gpiod_direction_output_raw_commit(struct gpio_desc *desc, int value)
 		 * If we can't actively set the direction, we are some
 		 * 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)
@@ -2757,17 +2793,20 @@  EXPORT_SYMBOL_GPL(gpiod_direction_output);
 int gpiod_enable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags)
 {
 	int ret = 0;
-	struct gpio_chip *gc;
 
 	VALIDATE_DESC(desc);
 
-	gc = desc->gdev->chip;
-	if (!gc->en_hw_timestamp) {
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return -ENODEV;
+
+	if (!guard.gc->en_hw_timestamp) {
 		gpiod_warn(desc, "%s: hw ts not supported\n", __func__);
 		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)
 		gpiod_warn(desc, "%s: hw ts request failed\n", __func__);
 
@@ -2786,17 +2825,20 @@  EXPORT_SYMBOL_GPL(gpiod_enable_hw_timestamp_ns);
 int gpiod_disable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags)
 {
 	int ret = 0;
-	struct gpio_chip *gc;
 
 	VALIDATE_DESC(desc);
 
-	gc = desc->gdev->chip;
-	if (!gc->dis_hw_timestamp) {
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return -ENODEV;
+
+	if (!guard.gc->dis_hw_timestamp) {
 		gpiod_warn(desc, "%s: hw ts not supported\n", __func__);
 		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)
 		gpiod_warn(desc, "%s: hw ts release failed\n", __func__);
 
@@ -2815,12 +2857,13 @@  EXPORT_SYMBOL_GPL(gpiod_disable_hw_timestamp_ns);
  */
 int gpiod_set_config(struct gpio_desc *desc, unsigned long config)
 {
-	struct gpio_chip *gc;
-
 	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);
 
@@ -2918,10 +2961,19 @@  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)
 {
+	struct gpio_device *gdev;
 	struct gpio_chip *gc;
 	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 = value < 0 ? value : !!value;
 	trace_gpio_value(desc_to_gpio(desc), 1, value);
@@ -2947,6 +2999,14 @@  static int gpio_chip_get_multiple(struct gpio_chip *gc,
 	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,
 				  unsigned int array_size,
 				  struct gpio_desc **desc_array,
@@ -2984,33 +3044,36 @@  int gpiod_get_array_value_complex(bool raw, bool can_sleep,
 	}
 
 	while (i < array_size) {
-		struct gpio_chip *gc = desc_array[i]->gdev->chip;
 		DECLARE_BITMAP(fastpath_mask, FASTPATH_NGPIO);
 		DECLARE_BITMAP(fastpath_bits, FASTPATH_NGPIO);
 		unsigned long *mask, *bits;
 		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;
 			bits = fastpath_bits;
 		} else {
 			gfp_t flags = can_sleep ? GFP_KERNEL : GFP_ATOMIC;
 
-			mask = bitmap_alloc(gc->ngpio, flags);
+			mask = bitmap_alloc(guard.gc->ngpio, flags);
 			if (!mask)
 				return -ENOMEM;
 
-			bits = bitmap_alloc(gc->ngpio, flags);
+			bits = bitmap_alloc(guard.gc->ngpio, flags);
 			if (!bits) {
 				bitmap_free(mask);
 				return -ENOMEM;
 			}
 		}
 
-		bitmap_zero(mask, gc->ngpio);
+		bitmap_zero(mask, guard.gc->ngpio);
 
 		if (!can_sleep)
-			WARN_ON(gc->can_sleep);
+			WARN_ON(guard.gc->can_sleep);
 
 		/* collect all inputs belonging to the same chip */
 		first = i;
@@ -3025,9 +3088,9 @@  int gpiod_get_array_value_complex(bool raw, bool can_sleep,
 				i = find_next_zero_bit(array_info->get_mask,
 						       array_size, i);
 		} 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 (mask != fastpath_mask)
 				bitmap_free(mask);
@@ -3168,14 +3231,16 @@  EXPORT_SYMBOL_GPL(gpiod_get_array_value);
  */
 static void gpio_set_open_drain_value_commit(struct gpio_desc *desc, bool value)
 {
-	int ret = 0;
-	struct gpio_chip *gc = desc->gdev->chip;
-	int offset = gpio_chip_hwgpio(desc);
+	int ret = 0, offset = gpio_chip_hwgpio(desc);
+
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return;
 
 	if (value) {
-		ret = gc->direction_input(gc, offset);
+		ret = guard.gc->direction_input(guard.gc, offset);
 	} else {
-		ret = gc->direction_output(gc, offset, 0);
+		ret = guard.gc->direction_output(guard.gc, offset, 0);
 		if (!ret)
 			set_bit(FLAG_IS_OUT, &desc->flags);
 	}
@@ -3193,16 +3258,18 @@  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)
 {
-	int ret = 0;
-	struct gpio_chip *gc = desc->gdev->chip;
-	int offset = gpio_chip_hwgpio(desc);
+	int ret = 0, offset = gpio_chip_hwgpio(desc);
+
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return;
 
 	if (value) {
-		ret = gc->direction_output(gc, offset, 1);
+		ret = guard.gc->direction_output(guard.gc, offset, 1);
 		if (!ret)
 			set_bit(FLAG_IS_OUT, &desc->flags);
 	} else {
-		ret = gc->direction_input(gc, offset);
+		ret = guard.gc->direction_input(guard.gc, offset);
 	}
 	trace_gpio_direction(desc_to_gpio(desc), !value, ret);
 	if (ret < 0)
@@ -3213,11 +3280,12 @@  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)
 {
-	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);
-	gc->set(gc, gpio_chip_hwgpio(desc), value);
+	guard.gc->set(guard.gc, gpio_chip_hwgpio(desc), value);
 }
 
 /*
@@ -3278,33 +3346,36 @@  int gpiod_set_array_value_complex(bool raw, bool can_sleep,
 	}
 
 	while (i < array_size) {
-		struct gpio_chip *gc = desc_array[i]->gdev->chip;
 		DECLARE_BITMAP(fastpath_mask, FASTPATH_NGPIO);
 		DECLARE_BITMAP(fastpath_bits, FASTPATH_NGPIO);
 		unsigned long *mask, *bits;
 		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;
 			bits = fastpath_bits;
 		} else {
 			gfp_t flags = can_sleep ? GFP_KERNEL : GFP_ATOMIC;
 
-			mask = bitmap_alloc(gc->ngpio, flags);
+			mask = bitmap_alloc(guard.gc->ngpio, flags);
 			if (!mask)
 				return -ENOMEM;
 
-			bits = bitmap_alloc(gc->ngpio, flags);
+			bits = bitmap_alloc(guard.gc->ngpio, flags);
 			if (!bits) {
 				bitmap_free(mask);
 				return -ENOMEM;
 			}
 		}
 
-		bitmap_zero(mask, gc->ngpio);
+		bitmap_zero(mask, guard.gc->ngpio);
 
 		if (!can_sleep)
-			WARN_ON(gc->can_sleep);
+			WARN_ON(guard.gc->can_sleep);
 
 		do {
 			struct gpio_desc *desc = desc_array[i];
@@ -3340,10 +3411,10 @@  int gpiod_set_array_value_complex(bool raw, bool can_sleep,
 				i = find_next_zero_bit(array_info->set_mask,
 						       array_size, i);
 		} 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 */
 		if (count != 0)
-			gpio_chip_set_multiple(gc, mask, bits);
+			gpio_chip_set_multiple(guard.gc, mask, bits);
 
 		if (mask != fastpath_mask)
 			bitmap_free(mask);
@@ -3499,6 +3570,7 @@  EXPORT_SYMBOL_GPL(gpiod_set_consumer_name);
  */
 int gpiod_to_irq(const struct gpio_desc *desc)
 {
+	struct gpio_device *gdev;
 	struct gpio_chip *gc;
 	int offset;
 
@@ -3510,7 +3582,13 @@  int gpiod_to_irq(const struct gpio_desc *desc)
 	if (!desc || IS_ERR(desc))
 		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);
 	if (gc->to_irq) {
 		int retirq = gc->to_irq(gc, offset);
@@ -4690,12 +4768,20 @@  core_initcall(gpiolib_dev_init);
 
 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;
 	unsigned int gpio = gdev->base;
 	struct gpio_desc *desc;
+	struct gpio_chip *gc;
 	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) {
 		guard(srcu)(&desc->srcu);
 		if (test_bit(FLAG_REQUESTED, &desc->flags)) {
@@ -4761,9 +4847,12 @@  static void gpiolib_seq_stop(struct seq_file *s, void *v)
 static int gpiolib_seq_show(struct seq_file *s, void *v)
 {
 	struct gpio_device *gdev = v;
-	struct gpio_chip *gc = gdev->chip;
+	struct gpio_chip *gc;
 	struct device *parent;
 
+	guard(srcu)(&gdev->srcu);
+
+	gc = rcu_dereference(gdev->chip);
 	if (!gc) {
 		seq_printf(s, "%s%s: (dangling chip)", (char *)s->private,
 			   dev_name(&gdev->dev));
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 35d71e30c546..b3810f7d286a 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -63,7 +63,7 @@  struct gpio_device {
 	int			id;
 	struct device		*mockdev;
 	struct module		*owner;
-	struct gpio_chip	*chip;
+	struct gpio_chip __rcu	*chip;
 	struct gpio_desc	*descs;
 	int			base;
 	u16			ngpio;
@@ -193,6 +193,26 @@  struct gpio_desc {
 
 #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);
 void gpiod_free(struct gpio_desc *desc);