gpiolib: generalize GPIO line names property

From: Bartosz Golaszewski <[email protected]>

Instead of doing the following:

    count = device_property_read_string_array(dev, propname, NULL, 0);

Let's provide inline helpers with hardcoded arguments for counting strings in property arrays.

Suggested-by Andy Shevchenko <[email protected]>

Signed-off-by Bartosz Golaszewski <[email protected]>

---
 include/linux/property.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

include/linux/property.h +13 -0

index 9f805c442819..1fa5e250a8ea 100644
@@ -170,6 +170,12 @@ static inline int device_property_count_u64(struct device *dev, const char *prop
 	return device_property_read_u64_array(dev, propname, NULL, 0);
 }
 
+static inline int device_property_count_strings(struct device *dev,
+						const char *propname)
+{
+	return device_property_read_string_array(dev, propname, NULL, 0);
+}
+
 static inline bool fwnode_property_read_bool(const struct fwnode_handle *fwnode,
 					     const char *propname)
 {

@@ -224,6 +230,13 @@ static inline int fwnode_property_count_u64(const struct fwnode_handle *fwnode,
 	return fwnode_property_read_u64_array(fwnode, propname, NULL, 0);
 }
 
+static inline int
+fwnode_property_count_strings(const struct fwnode_handle *fwnode,
+			      const char *propname)
+{
+	return fwnode_property_read_string_array(fwnode, propname, NULL, 0);
+}
+
 struct software_node;
 
 /**

Signature · 1 line

2.26.1

From: Bartosz Golaszewski <[email protected]>

Now that devprop_gpiochip_set_names() is only used in a single place inside drivers/gpio/gpiolib.c, there's no need anymore for it to be exported or to even live in its own source file. Pull this function into the core source file for gpiolib.

 drivers/gpio/Makefile       |  1 -
 drivers/gpio/gpiolib.c      | 47 +++++++++++++++++++++++++++++++++++++
 include/linux/gpio/driver.h |  2 --

Quoted 6 lines · Bartosz Golaszewski

From: Bartosz Golaszewski <[email protected]>

Now that devprop_gpiochip_set_names() is only used in a single place inside drivers/gpio/gpiolib.c, there's no need anymore for it to be exported or to even live in its own source file. Pull this function into the core source file for gpiolib.

Did you miss to remove old file?

Quoted 3 lines

 drivers/gpio/Makefile       |  1 -
 drivers/gpio/gpiolib.c      | 47 +++++++++++++++++++++++++++++++++++++
 include/linux/gpio/driver.h |  2 --

--
With Best Regards,
Andy Shevchenko

From: Bartosz Golaszewski <[email protected]>

I initially sent this as part of the gpio-mockup overhaul but since these patches are indepentent and the work on gpio-mockup may become more complicated - I'm sending these separately.

The only change is adding additional property helpers to count strings in array.

Bartosz Golaszewski (3):
device: property: add helpers to count items in string arrays
gpiolib: generalize devprop_gpiochip_set_names() for device properties
gpiolib: unexport devprop_gpiochip_set_names()

Quoted 7 lines · Bartosz Golaszewski

From: Bartosz Golaszewski <[email protected]>

I initially sent this as part of the gpio-mockup overhaul but since these patches are indepentent and the work on gpio-mockup may become more complicated - I'm sending these separately.

Quoted 7 lines

The only change is adding additional property helpers to count strings in array.

Bartosz Golaszewski (3):
device: property: add helpers to count items in string arrays
gpiolib: generalize devprop_gpiochip_set_names() for device properties
gpiolib: unexport devprop_gpiochip_set_names()

[ 6186.379069][    T1]  device_property_read_string_array+0x40/0xa0
[ 6186.381741][    T1]  devprop_gpiochip_set_names.isra.0+0x4c/0x200
[ 6186.384394][    T1]  gpiochip_add_data_with_key+0x75c/0xf80
[ 6186.386876][    T1]  unittest_gpio_probe+0xf4/0x1e0

[ 6186.433241][    T1] Unable to handle kernel read from unreadable
memory at virtual address 0000000000000570
[ 6186.437207][    T1] Mem abort info:
[ 6186.438639][    T1]   ESR = 0x96000004
[ 6186.440536][    T1]   EC = 0x25: DABT (current EL), IL = 32 bits
[ 6186.442791][    T1]   SET = 0, FnV = 0
[ 6186.444660][    T1]   EA = 0, S1PTW = 0
[ 6186.446233][    T1] Data abort info:
[ 6186.447938][    T1]   ISV = 0, ISS = 0x00000004
[ 6186.449749][    T1]   CM = 0, WnR = 0
[ 6186.451222][    T1] [0000000000000570] user address but active_mm is swapper
[ 6186.454000][    T1] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[ 6186.456422][    T1] Modules linked in:
[ 6186.458232][    T1] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G    B
W         5.9.0-rc5-next-20200915-00006-g104c8fe4916b #1
[ 6186.462833][    T1] Hardware name: linux,dummy-virt (DT)
[ 6186.465170][    T1] pstate: 60400005 (nZCv daif +PAN -UAO BTYPE=--)
[ 6186.467910][    T1] pc : device_property_read_string_array+0x40/0xa0
[ 6186.470653][    T1] lr : device_property_read_string_array+0x40/0xa0

Quoted 11 lines · Anders Roxell

Quoted 10 lines · Bartosz Golaszewski

From: Bartosz Golaszewski <[email protected]>

I initially sent this as part of the gpio-mockup overhaul but since these patches are indepentent and the work on gpio-mockup may become more complicated - I'm sending these separately.

The only change is adding additional property helpers to count strings in array.

Quoted 4 lines

Quoted 4 lines

Bartosz Golaszewski (3):
device: property: add helpers to count items in string arrays
gpiolib: generalize devprop_gpiochip_set_names() for device properties
gpiolib: unexport devprop_gpiochip_set_names()

Ha-ha, OF unittest is of_node centric. definitely there is no backed device.

Bart, it seems we are stuck with fwnode interface.

Quoted 13 lines · Andy Shevchenko

Quoted 11 lines · Anders Roxell

Quoted 10 lines · Bartosz Golaszewski

From: Bartosz Golaszewski <[email protected]>

I initially sent this as part of the gpio-mockup overhaul but since these patches are indepentent and the work on gpio-mockup may become more complicated - I'm sending these separately.

The only change is adding additional property helpers to count strings in array.

Quoted 9 lines

Quoted 4 lines

Quoted 4 lines

Bartosz Golaszewski (3):
device: property: add helpers to count items in string arrays
gpiolib: generalize devprop_gpiochip_set_names() for device properties
gpiolib: unexport devprop_gpiochip_set_names()

Ha-ha, OF unittest is of_node centric. definitely there is no backed device.

Bart, it seems we are stuck with fwnode interface.

Wait what?! This means the implementation is wrong - the whole concept of device properties is to be generic and to hide the underlying fwnode or OF properties. If anything we should fix device/base/property.c to fall back to OF.

What is happening exactly? If all fwnode code compiled out?

I'll try to give it a spin and see what can be done but I don't like that device_property_* functions fail if you have OF but not fwnode.

Quoted 11 lines · Anders Roxell

Quoted 10 lines · Bartosz Golaszewski

From: Bartosz Golaszewski <[email protected]>

I initially sent this as part of the gpio-mockup overhaul but since these patches are indepentent and the work on gpio-mockup may become more complicated - I'm sending these separately.

The only change is adding additional property helpers to count strings in array.

Quoted 4 lines

Quoted 4 lines

Bartosz Golaszewski (3):
device: property: add helpers to count items in string arrays
gpiolib: generalize devprop_gpiochip_set_names() for device properties
gpiolib: unexport devprop_gpiochip_set_names()

Ha-ha, OF unittest is of_node centric. definitely there is no backed device.

Bart, it seems we are stuck with fwnode interface.

Quoted 24 lines

[ 6186.379069][    T1]  device_property_read_string_array+0x40/0xa0
[ 6186.381741][    T1]  devprop_gpiochip_set_names.isra.0+0x4c/0x200
[ 6186.384394][    T1]  gpiochip_add_data_with_key+0x75c/0xf80
[ 6186.386876][    T1]  unittest_gpio_probe+0xf4/0x1e0

[ 6186.433241][    T1] Unable to handle kernel read from unreadable
memory at virtual address 0000000000000570
[ 6186.437207][    T1] Mem abort info:
[ 6186.438639][    T1]   ESR = 0x96000004
[ 6186.440536][    T1]   EC = 0x25: DABT (current EL), IL = 32 bits
[ 6186.442791][    T1]   SET = 0, FnV = 0
[ 6186.444660][    T1]   EA = 0, S1PTW = 0
[ 6186.446233][    T1] Data abort info:
[ 6186.447938][    T1]   ISV = 0, ISS = 0x00000004
[ 6186.449749][    T1]   CM = 0, WnR = 0
[ 6186.451222][    T1] [0000000000000570] user address but active_mm is swapper
[ 6186.454000][    T1] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[ 6186.456422][    T1] Modules linked in:
[ 6186.458232][    T1] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G    B
W         5.9.0-rc5-next-20200915-00006-g104c8fe4916b #1
[ 6186.462833][    T1] Hardware name: linux,dummy-virt (DT)
[ 6186.465170][    T1] pstate: 60400005 (nZCv daif +PAN -UAO BTYPE=--)
[ 6186.467910][    T1] pc : device_property_read_string_array+0x40/0xa0
[ 6186.470653][    T1] lr : device_property_read_string_array+0x40/0xa0

Signature · 2 lines

With Best Regards,
Andy Shevchenko

Quoted 17 lines · Andy Shevchenko

Quoted 15 lines · Anders Roxell

Quoted 14 lines · Bartosz Golaszewski

From: Bartosz Golaszewski <[email protected]>

I initially sent this as part of the gpio-mockup overhaul but since these patches are indepentent and the work on gpio-mockup may become more complicated - I'm sending these separately.

The only change is adding additional property helpers to count strings in array.

Bartosz Golaszewski (3):
device: property: add helpers to count items in string arrays
gpiolib: generalize devprop_gpiochip_set_names() for device properties
gpiolib: unexport devprop_gpiochip_set_names()

Quoted 3 lines

Ha-ha, OF unittest is of_node centric. definitely there is no backed device.

Bart, it seems we are stuck with fwnode interface.

Hmm... There is a platform device. So, it means that it fails along these lines:
return IS_ENABLED(CONFIG_OF) && dev->of_node ? &dev->of_node->fwnode : dev->fwnode;
so, who should set fwnode for of_node?

Quoted 10 lines · Bartosz Golaszewski

From: Bartosz Golaszewski <[email protected]>

I initially sent this as part of the gpio-mockup overhaul but since these patches are indepentent and the work on gpio-mockup may become more complicated - I'm sending these separately.

The only change is adding additional property helpers to count strings in array.

Quoted 4 lines

Bartosz Golaszewski (3):
device: property: add helpers to count items in string arrays
gpiolib: generalize devprop_gpiochip_set_names() for device properties
gpiolib: unexport devprop_gpiochip_set_names()

I do an arm64 allmodconfig build fron linux-next (tag: next-20200915) and run that in qemu. When I run I see the following output (see full log [1]):
"BUG: KASAN: null-ptr-deref in device_property_read_string_array".