* [PATCH 0/3] i2c: mux: don't access GPIOLIB internal structures
@ 2023-10-11 13:02 Bartosz Golaszewski
2023-10-11 13:02 ` [PATCH 1/3] gpiolib: provide gpio_device_to_device() Bartosz Golaszewski
` (4 more replies)
0 siblings, 5 replies; 17+ messages in thread
From: Bartosz Golaszewski @ 2023-10-11 13:02 UTC (permalink / raw)
To: Linus Walleij, Andy Shevchenko, Peter Korsgaard, Peter Rosin
Cc: linux-gpio, linux-kernel, linux-i2c, Bartosz Golaszewski
From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
The backstory for this short series is that we are identyfing and
removing all unauthorized uses of GPIOLIB structures across the kernel.
For example: there are many users that access struct gpio_chip when the
only user allowed to safely do this is the provider of that chip.
We are very close to removing gpiochip_find(). Another function that
poses a similar problem is gpiod_to_chip() which also returns the
address of the underlying gpio_chip without assuring that it will not go
away e.g. due to a hot-unplug event or a device unbind.
We'll need to replace it with gpiod_to_gpio_device() across the entire
tree. Let's start by actually providing it and adding the first user:
the i2c-mux-gpio driver which dereferences the otherwise opaque struct
gpio_desc.
Let's also add a helper that allows to retrieve the address of the
struct device backing the GPIO device as this is another valid use-case.
Finally, let's un-include the GPIO private header and fix the code to
access the device in a safe way.
As the change is pretty minor, it would be best if patch 3/3 could be
acked by the I2C mux maintainers and went through the GPIO tree.
Otherwise, I can apply patches 1 and 2 and provide an immutable branch.
Bartosz Golaszewski (3):
gpiolib: provide gpio_device_to_device()
gpiolib: provide gpiod_to_gpio_device()
i2c: mux: gpio: don't fiddle with GPIOLIB internals
drivers/gpio/gpiolib.c | 38 ++++++++++++++++++++++++++++++++
drivers/i2c/muxes/i2c-mux-gpio.c | 12 +++++-----
include/linux/gpio/driver.h | 3 +++
3 files changed, 47 insertions(+), 6 deletions(-)
--
2.39.2
^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH 1/3] gpiolib: provide gpio_device_to_device()
2023-10-11 13:02 [PATCH 0/3] i2c: mux: don't access GPIOLIB internal structures Bartosz Golaszewski
@ 2023-10-11 13:02 ` Bartosz Golaszewski
2023-10-11 14:57 ` Peter Rosin
2023-10-11 15:18 ` Andy Shevchenko
2023-10-11 13:02 ` [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device() Bartosz Golaszewski
` (3 subsequent siblings)
4 siblings, 2 replies; 17+ messages in thread
From: Bartosz Golaszewski @ 2023-10-11 13:02 UTC (permalink / raw)
To: Linus Walleij, Andy Shevchenko, Peter Korsgaard, Peter Rosin
Cc: linux-gpio, linux-kernel, linux-i2c, Bartosz Golaszewski
From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
There are users in the kernel who need to retrieve the address of the
struct device backing the GPIO device. Currently they needlessly poke in
the internals of GPIOLIB. Add a dedicated getter function.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
drivers/gpio/gpiolib.c | 17 +++++++++++++++++
include/linux/gpio/driver.h | 2 ++
2 files changed, 19 insertions(+)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 191f9c87b4d0..ca2b5b424284 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1169,6 +1169,23 @@ void gpio_device_put(struct gpio_device *gdev)
}
EXPORT_SYMBOL_GPL(gpio_device_put);
+/**
+ * gpio_device_to_device() - Retrieve the address of the underlying struct
+ * device.
+ * @gdev: GPIO device for which to return the address.
+ *
+ * This does not increase the reference count of the GPIO device nor the
+ * underlying struct device.
+ *
+ * Returns:
+ * Address of struct device backing this GPIO device.
+ */
+struct device *gpio_device_to_device(struct gpio_device *gdev)
+{
+ return &gdev->dev;
+}
+EXPORT_SYMBOL_GPL(gpio_device_to_device);
+
#ifdef CONFIG_GPIOLIB_IRQCHIP
/*
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index f8ad7f40100c..0484bf90b25d 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -618,6 +618,8 @@ void gpio_device_put(struct gpio_device *gdev);
DEFINE_FREE(gpio_device_put, struct gpio_device *,
if (IS_ERR_OR_NULL(_T)) gpio_device_put(_T));
+struct device *gpio_device_to_device(struct gpio_device *gdev);
+
bool gpiochip_line_is_irq(struct gpio_chip *gc, unsigned int offset);
int gpiochip_reqres_irq(struct gpio_chip *gc, unsigned int offset);
void gpiochip_relres_irq(struct gpio_chip *gc, unsigned int offset);
--
2.39.2
^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device()
2023-10-11 13:02 [PATCH 0/3] i2c: mux: don't access GPIOLIB internal structures Bartosz Golaszewski
2023-10-11 13:02 ` [PATCH 1/3] gpiolib: provide gpio_device_to_device() Bartosz Golaszewski
@ 2023-10-11 13:02 ` Bartosz Golaszewski
2023-10-11 14:58 ` Peter Rosin
` (2 more replies)
2023-10-11 13:02 ` [PATCH 3/3] i2c: mux: gpio: don't fiddle with GPIOLIB internals Bartosz Golaszewski
` (2 subsequent siblings)
4 siblings, 3 replies; 17+ messages in thread
From: Bartosz Golaszewski @ 2023-10-11 13:02 UTC (permalink / raw)
To: Linus Walleij, Andy Shevchenko, Peter Korsgaard, Peter Rosin
Cc: linux-gpio, linux-kernel, linux-i2c, Bartosz Golaszewski
From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Accessing struct gpio_chip backing a GPIO device is only allowed for the
actual providers of that chip.
Similarly to how we introduced gpio_device_find() in order to replace
the abused gpiochip_find(), let's introduce a counterpart to
gpiod_to_chip() that returns a reference to the GPIO device owning the
descriptor. This is done in order to later remove gpiod_to_chip()
entirely.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
drivers/gpio/gpiolib.c | 21 +++++++++++++++++++++
include/linux/gpio/driver.h | 1 +
2 files changed, 22 insertions(+)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index ca2b5b424284..1e0ed6f5bcd5 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -220,6 +220,27 @@ struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
}
EXPORT_SYMBOL_GPL(gpiod_to_chip);
+/**
+ * gpiod_to_gpio_device() - Return the GPIO device to which this descriptor
+ * belongs.
+ * @desc: Descriptor for which to return the GPIO device.
+ *
+ * This *DOES NOT* increase the reference count of the GPIO device as it's
+ * expected that the descriptor is requested and the users already holds a
+ * reference to the device.
+ *
+ * Returns:
+ * Address of the GPIO device owning this descriptor.
+ */
+struct gpio_device *gpiod_to_gpio_device(struct gpio_desc *desc)
+{
+ if (!desc)
+ return NULL;
+
+ return desc->gdev;
+}
+EXPORT_SYMBOL_GPL(gpiod_to_gpio_device);
+
/**
* gpio_device_get_chip() - Get the gpio_chip implementation of this GPIO device
* @gdev: GPIO device
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 0484bf90b25d..7a8725be1225 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -784,6 +784,7 @@ int gpiochip_lock_as_irq(struct gpio_chip *gc, unsigned int offset);
void gpiochip_unlock_as_irq(struct gpio_chip *gc, unsigned int offset);
struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc);
+struct gpio_device *gpiod_to_gpio_device(struct gpio_desc *desc);
#else /* CONFIG_GPIOLIB */
--
2.39.2
^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH 3/3] i2c: mux: gpio: don't fiddle with GPIOLIB internals
2023-10-11 13:02 [PATCH 0/3] i2c: mux: don't access GPIOLIB internal structures Bartosz Golaszewski
2023-10-11 13:02 ` [PATCH 1/3] gpiolib: provide gpio_device_to_device() Bartosz Golaszewski
2023-10-11 13:02 ` [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device() Bartosz Golaszewski
@ 2023-10-11 13:02 ` Bartosz Golaszewski
2023-10-11 14:59 ` Peter Rosin
2023-10-12 6:59 ` [PATCH 0/3] i2c: mux: don't access GPIOLIB internal structures Linus Walleij
2023-10-13 6:50 ` Bartosz Golaszewski
4 siblings, 1 reply; 17+ messages in thread
From: Bartosz Golaszewski @ 2023-10-11 13:02 UTC (permalink / raw)
To: Linus Walleij, Andy Shevchenko, Peter Korsgaard, Peter Rosin
Cc: linux-gpio, linux-kernel, linux-i2c, Bartosz Golaszewski
From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Use the relevant API functions to retrieve the address of the
underlying struct device instead of accessing GPIOLIB private structures
manually.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
drivers/i2c/muxes/i2c-mux-gpio.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
index 5d5cbe0130cd..48a872a8196b 100644
--- a/drivers/i2c/muxes/i2c-mux-gpio.c
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -14,8 +14,7 @@
#include <linux/slab.h>
#include <linux/bits.h>
#include <linux/gpio/consumer.h>
-/* FIXME: stop poking around inside gpiolib */
-#include "../../gpio/gpiolib.h"
+#include <linux/gpio/driver.h>
struct gpiomux {
struct i2c_mux_gpio_platform_data data;
@@ -176,7 +175,8 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
}
for (i = 0; i < ngpios; i++) {
- struct device *gpio_dev;
+ struct gpio_device *gdev;
+ struct device *dev;
struct gpio_desc *gpiod;
enum gpiod_flags flag;
@@ -195,9 +195,9 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
if (!muxc->mux_locked)
continue;
- /* FIXME: find a proper way to access the GPIO device */
- gpio_dev = &gpiod->gdev->dev;
- muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
+ gdev = gpiod_to_gpio_device(gpiod);
+ dev = gpio_device_to_device(gdev);
+ muxc->mux_locked = i2c_root_adapter(dev) == root;
}
if (muxc->mux_locked)
--
2.39.2
^ permalink raw reply related [flat|nested] 17+ messages in thread
* Re: [PATCH 1/3] gpiolib: provide gpio_device_to_device()
2023-10-11 13:02 ` [PATCH 1/3] gpiolib: provide gpio_device_to_device() Bartosz Golaszewski
@ 2023-10-11 14:57 ` Peter Rosin
2023-10-11 15:18 ` Andy Shevchenko
1 sibling, 0 replies; 17+ messages in thread
From: Peter Rosin @ 2023-10-11 14:57 UTC (permalink / raw)
To: Bartosz Golaszewski, Linus Walleij, Andy Shevchenko, Peter Korsgaard
Cc: linux-gpio, linux-kernel, linux-i2c, Bartosz Golaszewski
Hi!
2023-10-11 at 15:02, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> There are users in the kernel who need to retrieve the address of the
> struct device backing the GPIO device. Currently they needlessly poke in
> the internals of GPIOLIB. Add a dedicated getter function.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Peter Rosin <peda@axentia.se>
Cheers,
Peter
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device()
2023-10-11 13:02 ` [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device() Bartosz Golaszewski
@ 2023-10-11 14:58 ` Peter Rosin
2023-10-11 15:23 ` Andy Shevchenko
2023-10-11 15:28 ` Andy Shevchenko
2 siblings, 0 replies; 17+ messages in thread
From: Peter Rosin @ 2023-10-11 14:58 UTC (permalink / raw)
To: Bartosz Golaszewski, Linus Walleij, Andy Shevchenko, Peter Korsgaard
Cc: linux-gpio, linux-kernel, linux-i2c, Bartosz Golaszewski
Hi!
2023-10-11 at 15:02, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> Accessing struct gpio_chip backing a GPIO device is only allowed for the
> actual providers of that chip.
>
> Similarly to how we introduced gpio_device_find() in order to replace
> the abused gpiochip_find(), let's introduce a counterpart to
> gpiod_to_chip() that returns a reference to the GPIO device owning the
> descriptor. This is done in order to later remove gpiod_to_chip()
> entirely.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Peter Rosin <peda@axentia.se>
Cheers,
Peter
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 3/3] i2c: mux: gpio: don't fiddle with GPIOLIB internals
2023-10-11 13:02 ` [PATCH 3/3] i2c: mux: gpio: don't fiddle with GPIOLIB internals Bartosz Golaszewski
@ 2023-10-11 14:59 ` Peter Rosin
2023-10-11 15:03 ` Bartosz Golaszewski
2023-10-11 15:18 ` Andy Shevchenko
0 siblings, 2 replies; 17+ messages in thread
From: Peter Rosin @ 2023-10-11 14:59 UTC (permalink / raw)
To: Bartosz Golaszewski, Linus Walleij, Andy Shevchenko, Peter Korsgaard
Cc: linux-gpio, linux-kernel, linux-i2c, Bartosz Golaszewski
Hi!
2023-10-11 at 15:02, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> Use the relevant API functions to retrieve the address of the
> underlying struct device instead of accessing GPIOLIB private structures
> manually.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> ---
> drivers/i2c/muxes/i2c-mux-gpio.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
> index 5d5cbe0130cd..48a872a8196b 100644
> --- a/drivers/i2c/muxes/i2c-mux-gpio.c
> +++ b/drivers/i2c/muxes/i2c-mux-gpio.c
> @@ -14,8 +14,7 @@
> #include <linux/slab.h>
> #include <linux/bits.h>
> #include <linux/gpio/consumer.h>
> -/* FIXME: stop poking around inside gpiolib */
> -#include "../../gpio/gpiolib.h"
> +#include <linux/gpio/driver.h>
>
> struct gpiomux {
> struct i2c_mux_gpio_platform_data data;
> @@ -176,7 +175,8 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
> }
>
> for (i = 0; i < ngpios; i++) {
> - struct device *gpio_dev;
> + struct gpio_device *gdev;
> + struct device *dev;
> struct gpio_desc *gpiod;
> enum gpiod_flags flag;
>
> @@ -195,9 +195,9 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
> if (!muxc->mux_locked)
> continue;
>
> - /* FIXME: find a proper way to access the GPIO device */
> - gpio_dev = &gpiod->gdev->dev;
> - muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
> + gdev = gpiod_to_gpio_device(gpiod);
> + dev = gpio_device_to_device(gdev);
> + muxc->mux_locked = i2c_root_adapter(dev) == root;
> }
>
> if (muxc->mux_locked)
Very nice to see that wart gone! The only small question I have
is if these helpers are needed elsewhere, or if a more "direct"
gpiod_to_device() would have been sufficient? That said, I have
zero problem with this new code as-is, and that detail is of
course squarely in gpio-land.
Acked-by: Peter Rosin <peda@axentia.se>
Cheers,
Peter
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 3/3] i2c: mux: gpio: don't fiddle with GPIOLIB internals
2023-10-11 14:59 ` Peter Rosin
@ 2023-10-11 15:03 ` Bartosz Golaszewski
2023-10-11 16:41 ` Wolfram Sang
2023-10-11 15:18 ` Andy Shevchenko
1 sibling, 1 reply; 17+ messages in thread
From: Bartosz Golaszewski @ 2023-10-11 15:03 UTC (permalink / raw)
To: Peter Rosin
Cc: Linus Walleij, Andy Shevchenko, Peter Korsgaard, linux-gpio,
linux-kernel, linux-i2c, Bartosz Golaszewski
On Wed, Oct 11, 2023 at 4:59 PM Peter Rosin <peda@axentia.se> wrote:
>
> Hi!
>
> 2023-10-11 at 15:02, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> >
> > Use the relevant API functions to retrieve the address of the
> > underlying struct device instead of accessing GPIOLIB private structures
> > manually.
> >
> > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> > ---
> > drivers/i2c/muxes/i2c-mux-gpio.c | 12 ++++++------
> > 1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
> > index 5d5cbe0130cd..48a872a8196b 100644
> > --- a/drivers/i2c/muxes/i2c-mux-gpio.c
> > +++ b/drivers/i2c/muxes/i2c-mux-gpio.c
> > @@ -14,8 +14,7 @@
> > #include <linux/slab.h>
> > #include <linux/bits.h>
> > #include <linux/gpio/consumer.h>
> > -/* FIXME: stop poking around inside gpiolib */
> > -#include "../../gpio/gpiolib.h"
> > +#include <linux/gpio/driver.h>
> >
> > struct gpiomux {
> > struct i2c_mux_gpio_platform_data data;
> > @@ -176,7 +175,8 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
> > }
> >
> > for (i = 0; i < ngpios; i++) {
> > - struct device *gpio_dev;
> > + struct gpio_device *gdev;
> > + struct device *dev;
> > struct gpio_desc *gpiod;
> > enum gpiod_flags flag;
> >
> > @@ -195,9 +195,9 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
> > if (!muxc->mux_locked)
> > continue;
> >
> > - /* FIXME: find a proper way to access the GPIO device */
> > - gpio_dev = &gpiod->gdev->dev;
> > - muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
> > + gdev = gpiod_to_gpio_device(gpiod);
> > + dev = gpio_device_to_device(gdev);
> > + muxc->mux_locked = i2c_root_adapter(dev) == root;
> > }
> >
> > if (muxc->mux_locked)
>
> Very nice to see that wart gone! The only small question I have
> is if these helpers are needed elsewhere, or if a more "direct"
> gpiod_to_device() would have been sufficient? That said, I have
> zero problem with this new code as-is, and that detail is of
> course squarely in gpio-land.
>
> Acked-by: Peter Rosin <peda@axentia.se>
gpiod_to_gpio_device() will be used in at least 10 other places. I
haven't identified any other potential user for
gpio_device_to_device() yet but I haven't looked hard yet either.
Bart
>
> Cheers,
> Peter
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 3/3] i2c: mux: gpio: don't fiddle with GPIOLIB internals
2023-10-11 14:59 ` Peter Rosin
2023-10-11 15:03 ` Bartosz Golaszewski
@ 2023-10-11 15:18 ` Andy Shevchenko
1 sibling, 0 replies; 17+ messages in thread
From: Andy Shevchenko @ 2023-10-11 15:18 UTC (permalink / raw)
To: Peter Rosin
Cc: Bartosz Golaszewski, Linus Walleij, Andy Shevchenko,
Peter Korsgaard, linux-gpio, linux-kernel, linux-i2c,
Bartosz Golaszewski
On Wed, Oct 11, 2023 at 5:59 PM Peter Rosin <peda@axentia.se> wrote:
> 2023-10-11 at 15:02, Bartosz Golaszewski wrote:
> > Use the relevant API functions to retrieve the address of the
> > underlying struct device instead of accessing GPIOLIB private structures
> > manually.
> Very nice to see that wart gone! The only small question I have
> is if these helpers are needed elsewhere, or if a more "direct"
> gpiod_to_device() would have been sufficient?
Same concern is here. But I'm fine with the code.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 1/3] gpiolib: provide gpio_device_to_device()
2023-10-11 13:02 ` [PATCH 1/3] gpiolib: provide gpio_device_to_device() Bartosz Golaszewski
2023-10-11 14:57 ` Peter Rosin
@ 2023-10-11 15:18 ` Andy Shevchenko
1 sibling, 0 replies; 17+ messages in thread
From: Andy Shevchenko @ 2023-10-11 15:18 UTC (permalink / raw)
To: Bartosz Golaszewski
Cc: Linus Walleij, Andy Shevchenko, Peter Korsgaard, Peter Rosin,
linux-gpio, linux-kernel, linux-i2c, Bartosz Golaszewski
On Wed, Oct 11, 2023 at 4:02 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> There are users in the kernel who need to retrieve the address of the
> struct device backing the GPIO device. Currently they needlessly poke in
> the internals of GPIOLIB. Add a dedicated getter function.
...
> +struct device *gpio_device_to_device(struct gpio_device *gdev)
Hmm... Maybe gpio_device_to_dev()?
Whatever, good enough to me
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
--
With Best Regards,
Andy Shevchenko...
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device()
2023-10-11 13:02 ` [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device() Bartosz Golaszewski
2023-10-11 14:58 ` Peter Rosin
@ 2023-10-11 15:23 ` Andy Shevchenko
2023-10-11 15:39 ` Bartosz Golaszewski
2023-10-11 15:28 ` Andy Shevchenko
2 siblings, 1 reply; 17+ messages in thread
From: Andy Shevchenko @ 2023-10-11 15:23 UTC (permalink / raw)
To: Bartosz Golaszewski
Cc: Linus Walleij, Andy Shevchenko, Peter Korsgaard, Peter Rosin,
linux-gpio, linux-kernel, linux-i2c, Bartosz Golaszewski
On Wed, Oct 11, 2023 at 4:02 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> Accessing struct gpio_chip backing a GPIO device is only allowed for the
> actual providers of that chip.
>
> Similarly to how we introduced gpio_device_find() in order to replace
> the abused gpiochip_find(), let's introduce a counterpart to
> gpiod_to_chip() that returns a reference to the GPIO device owning the
> descriptor. This is done in order to later remove gpiod_to_chip()
> entirely.
My concern with this API is the following scenario:
1. One driver requests the GPIO descriptor.
2. Another driver does take an arbitrary number, converts to a
descriptor and calls for this API.
Is there any (potential) problem?
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device()
2023-10-11 13:02 ` [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device() Bartosz Golaszewski
2023-10-11 14:58 ` Peter Rosin
2023-10-11 15:23 ` Andy Shevchenko
@ 2023-10-11 15:28 ` Andy Shevchenko
2 siblings, 0 replies; 17+ messages in thread
From: Andy Shevchenko @ 2023-10-11 15:28 UTC (permalink / raw)
To: Bartosz Golaszewski
Cc: Linus Walleij, Andy Shevchenko, Peter Korsgaard, Peter Rosin,
linux-gpio, linux-kernel, linux-i2c, Bartosz Golaszewski
On Wed, Oct 11, 2023 at 4:02 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
...
> +struct gpio_device *gpiod_to_gpio_device(struct gpio_desc *desc)
> +{
> + if (!desc)
> + return NULL;
> +
> + return desc->gdev;
Wondering if we may use (part of) the validate_desc() (in a form of
VALIDATE_DESC_VOID() macro call).
> +}
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device()
2023-10-11 15:23 ` Andy Shevchenko
@ 2023-10-11 15:39 ` Bartosz Golaszewski
2023-10-12 6:57 ` Linus Walleij
0 siblings, 1 reply; 17+ messages in thread
From: Bartosz Golaszewski @ 2023-10-11 15:39 UTC (permalink / raw)
To: Andy Shevchenko
Cc: Bartosz Golaszewski, Linus Walleij, Andy Shevchenko,
Peter Korsgaard, Peter Rosin, linux-gpio, linux-kernel,
linux-i2c
On Wed, 11 Oct 2023 at 17:23, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
>
> On Wed, Oct 11, 2023 at 4:02 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> >
> > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> >
> > Accessing struct gpio_chip backing a GPIO device is only allowed for the
> > actual providers of that chip.
> >
> > Similarly to how we introduced gpio_device_find() in order to replace
> > the abused gpiochip_find(), let's introduce a counterpart to
> > gpiod_to_chip() that returns a reference to the GPIO device owning the
> > descriptor. This is done in order to later remove gpiod_to_chip()
> > entirely.
>
> My concern with this API is the following scenario:
> 1. One driver requests the GPIO descriptor.
> 2. Another driver does take an arbitrary number, converts to a
> descriptor and calls for this API.
>
> Is there any (potential) problem?
YES! And I have it already on my TODO list! But it's great to know I'm
not the only one seeing it.
Basically we need to
The end-goal should be to make gpio_to_desc() an internal GPIOLIB
symbol. There are still around 10 users outside drivers/gpio/ that
will need to be addressed in one way or another. Preferably by being
converted to using descriptors.
Bart
>
> --
> With Best Regards,
> Andy Shevchenko
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 3/3] i2c: mux: gpio: don't fiddle with GPIOLIB internals
2023-10-11 15:03 ` Bartosz Golaszewski
@ 2023-10-11 16:41 ` Wolfram Sang
0 siblings, 0 replies; 17+ messages in thread
From: Wolfram Sang @ 2023-10-11 16:41 UTC (permalink / raw)
To: Bartosz Golaszewski
Cc: Peter Rosin, Linus Walleij, Andy Shevchenko, Peter Korsgaard,
linux-gpio, linux-kernel, linux-i2c, Bartosz Golaszewski
[-- Attachment #1: Type: text/plain, Size: 435 bytes --]
Hi Bartosz,
> > > -/* FIXME: stop poking around inside gpiolib */
> > > -#include "../../gpio/gpiolib.h"
> > > +#include <linux/gpio/driver.h>
Hooray! \o/
> gpiod_to_gpio_device() will be used in at least 10 other places. I
> haven't identified any other potential user for
> gpio_device_to_device() yet but I haven't looked hard yet either.
Same here. Looked a little bit, found nothing.
Acked-by: Wolfram Sang <wsa@kernel.org>
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device()
2023-10-11 15:39 ` Bartosz Golaszewski
@ 2023-10-12 6:57 ` Linus Walleij
0 siblings, 0 replies; 17+ messages in thread
From: Linus Walleij @ 2023-10-12 6:57 UTC (permalink / raw)
To: Bartosz Golaszewski
Cc: Andy Shevchenko, Bartosz Golaszewski, Andy Shevchenko,
Peter Korsgaard, Peter Rosin, linux-gpio, linux-kernel,
linux-i2c
On Wed, Oct 11, 2023 at 5:39 PM Bartosz Golaszewski
<bartosz.golaszewski@linaro.org> wrote:
> The end-goal should be to make gpio_to_desc() an internal GPIOLIB
> symbol. There are still around 10 users outside drivers/gpio/ that
> will need to be addressed in one way or another. Preferably by being
> converted to using descriptors.
Conversely desc_to_gpio() as well, here is one fix for the current
merge window (yeah I keep churning away at this...)
https://lore.kernel.org/alsa-devel/20230926-descriptors-asoc-ti-v1-2-60cf4f8adbc5@linaro.org/
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 0/3] i2c: mux: don't access GPIOLIB internal structures
2023-10-11 13:02 [PATCH 0/3] i2c: mux: don't access GPIOLIB internal structures Bartosz Golaszewski
` (2 preceding siblings ...)
2023-10-11 13:02 ` [PATCH 3/3] i2c: mux: gpio: don't fiddle with GPIOLIB internals Bartosz Golaszewski
@ 2023-10-12 6:59 ` Linus Walleij
2023-10-13 6:50 ` Bartosz Golaszewski
4 siblings, 0 replies; 17+ messages in thread
From: Linus Walleij @ 2023-10-12 6:59 UTC (permalink / raw)
To: Bartosz Golaszewski
Cc: Andy Shevchenko, Peter Korsgaard, Peter Rosin, linux-gpio,
linux-kernel, linux-i2c, Bartosz Golaszewski
Hi Bartosz,
On Wed, Oct 11, 2023 at 3:02 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> The backstory for this short series is that we are identyfing and
> removing all unauthorized uses of GPIOLIB structures across the kernel.
>
> For example: there are many users that access struct gpio_chip when the
> only user allowed to safely do this is the provider of that chip.
>
> We are very close to removing gpiochip_find(). Another function that
> poses a similar problem is gpiod_to_chip() which also returns the
> address of the underlying gpio_chip without assuring that it will not go
> away e.g. due to a hot-unplug event or a device unbind.
>
> We'll need to replace it with gpiod_to_gpio_device() across the entire
> tree. Let's start by actually providing it and adding the first user:
> the i2c-mux-gpio driver which dereferences the otherwise opaque struct
> gpio_desc.
>
> Let's also add a helper that allows to retrieve the address of the
> struct device backing the GPIO device as this is another valid use-case.
>
> Finally, let's un-include the GPIO private header and fix the code to
> access the device in a safe way.
>
> As the change is pretty minor, it would be best if patch 3/3 could be
> acked by the I2C mux maintainers and went through the GPIO tree.
> Otherwise, I can apply patches 1 and 2 and provide an immutable branch.
>
> Bartosz Golaszewski (3):
> gpiolib: provide gpio_device_to_device()
> gpiolib: provide gpiod_to_gpio_device()
> i2c: mux: gpio: don't fiddle with GPIOLIB internals
The series:
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Good job!
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 0/3] i2c: mux: don't access GPIOLIB internal structures
2023-10-11 13:02 [PATCH 0/3] i2c: mux: don't access GPIOLIB internal structures Bartosz Golaszewski
` (3 preceding siblings ...)
2023-10-12 6:59 ` [PATCH 0/3] i2c: mux: don't access GPIOLIB internal structures Linus Walleij
@ 2023-10-13 6:50 ` Bartosz Golaszewski
4 siblings, 0 replies; 17+ messages in thread
From: Bartosz Golaszewski @ 2023-10-13 6:50 UTC (permalink / raw)
To: Linus Walleij, Andy Shevchenko, Peter Korsgaard, Peter Rosin
Cc: linux-gpio, linux-kernel, linux-i2c, Bartosz Golaszewski
On Wed, Oct 11, 2023 at 3:02 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> The backstory for this short series is that we are identyfing and
> removing all unauthorized uses of GPIOLIB structures across the kernel.
>
> For example: there are many users that access struct gpio_chip when the
> only user allowed to safely do this is the provider of that chip.
>
> We are very close to removing gpiochip_find(). Another function that
> poses a similar problem is gpiod_to_chip() which also returns the
> address of the underlying gpio_chip without assuring that it will not go
> away e.g. due to a hot-unplug event or a device unbind.
>
> We'll need to replace it with gpiod_to_gpio_device() across the entire
> tree. Let's start by actually providing it and adding the first user:
> the i2c-mux-gpio driver which dereferences the otherwise opaque struct
> gpio_desc.
>
> Let's also add a helper that allows to retrieve the address of the
> struct device backing the GPIO device as this is another valid use-case.
>
> Finally, let's un-include the GPIO private header and fix the code to
> access the device in a safe way.
>
> As the change is pretty minor, it would be best if patch 3/3 could be
> acked by the I2C mux maintainers and went through the GPIO tree.
> Otherwise, I can apply patches 1 and 2 and provide an immutable branch.
>
> Bartosz Golaszewski (3):
> gpiolib: provide gpio_device_to_device()
> gpiolib: provide gpiod_to_gpio_device()
> i2c: mux: gpio: don't fiddle with GPIOLIB internals
>
> drivers/gpio/gpiolib.c | 38 ++++++++++++++++++++++++++++++++
> drivers/i2c/muxes/i2c-mux-gpio.c | 12 +++++-----
> include/linux/gpio/driver.h | 3 +++
> 3 files changed, 47 insertions(+), 6 deletions(-)
>
> --
> 2.39.2
>
Queued for v6.7.
Bart
^ permalink raw reply [flat|nested] 17+ messages in thread
end of thread, other threads:[~2023-10-13 6:50 UTC | newest]
Thread overview: 17+ messages (download: mbox.gz / follow: Atom feed)
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2023-10-11 13:02 [PATCH 0/3] i2c: mux: don't access GPIOLIB internal structures Bartosz Golaszewski
2023-10-11 13:02 ` [PATCH 1/3] gpiolib: provide gpio_device_to_device() Bartosz Golaszewski
2023-10-11 14:57 ` Peter Rosin
2023-10-11 15:18 ` Andy Shevchenko
2023-10-11 13:02 ` [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device() Bartosz Golaszewski
2023-10-11 14:58 ` Peter Rosin
2023-10-11 15:23 ` Andy Shevchenko
2023-10-11 15:39 ` Bartosz Golaszewski
2023-10-12 6:57 ` Linus Walleij
2023-10-11 15:28 ` Andy Shevchenko
2023-10-11 13:02 ` [PATCH 3/3] i2c: mux: gpio: don't fiddle with GPIOLIB internals Bartosz Golaszewski
2023-10-11 14:59 ` Peter Rosin
2023-10-11 15:03 ` Bartosz Golaszewski
2023-10-11 16:41 ` Wolfram Sang
2023-10-11 15:18 ` Andy Shevchenko
2023-10-12 6:59 ` [PATCH 0/3] i2c: mux: don't access GPIOLIB internal structures Linus Walleij
2023-10-13 6:50 ` Bartosz Golaszewski
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