[v3,0/3] fix fwnode_irq_get_byname() returnvalue

The fix fwnode_irq_get_byname() may have returned zero if mapping the
IRQ fails. This contradicts the documentation. Furthermore, returning
zero or errno on error is unepected and can easily lead to problems
like:

int probe(foo)
{
...
	ret = fwnode_irq_get_byname(...);
	if (ret < 0)
		return ret;
...
}

or

int probe(foo)
{
...
	ret = fwnode_irq_get_byname(...);
	if (ret <= 0)
		return ret;
...
}

which are both likely to be wrong. First treats zero as successful call and
misses the IRQ mapping failure. Second returns zero from probe even though
it detects the IRQ mapping failure correvtly.

Here we change the fwnode_irq_get_byname() to always return a negative
errno upon failure. I have also audited following callers (v6.4-rc1):

drivers/i2c/i2c-smbus.c
drivers/iio/accel/adxl355_core.c
drivers/iio/accel/kionix-kx022a.c
drivers/iio/adc/ad4130.c
drivers/iio/adc/max11410.c
drivers/iio/addac/ad74115.c
drivers/iio/gyro/fxas21002c_core.c
drivers/iio/imu/adis16480.c
drivers/iio/imu/bmi160/bmi160_core.c
drivers/iio/imu/bmi160/bmi160_core.c

and it seems to me these calls will be Ok after the change. The
i2c-smbus.c and kionix-kx022a.c will gain a functional change (bugfix?) as
after this patch the probe will return -EINVAL should the IRQ mapping fail.
The series will also adjust the return value check for zero to be omitted.

---

Matti Vaittinen (3):
  drivers: fwnode: fix fwnode_irq_get_byname()
  i2c: i2c-smbus: fwnode_irq_get_byname() return value fix
  iio: kx022a fix irq getting

 drivers/base/property.c           | 9 +++++++--
 drivers/i2c/i2c-smbus.c           | 2 +-
 drivers/iio/accel/kionix-kx022a.c | 2 +-
 3 files changed, 9 insertions(+), 4 deletions(-)


base-commit: ac9a78681b921877518763ba0e89202254349d1b

On Fri, 12 May 2023 10:53:41 +0300
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> The fwnode_irq_get_byname() was returning 0 at device-tree mapping
> error. If this occurred, the KX022A driver did abort the probe but
> errorneously directly returned the return value from
> fwnode_irq_get_byname() from probe. In case of a device-tree mapping
> error this indicated success.
> 
> The fwnode_irq_get_byname() has since been fixed to not return zero on
> error so the check for fwnode_irq_get_byname() can be relaxed to only
> treat negative values as errors. This will also do decent fix even when
> backported to branches where fwnode_irq_get_byname() can still return
> zero on error because KX022A probe should later fail at IRQ requesting
> and a prober error handling should follow.
On that basis I've picked this one up directly for the fixes-togreg branch of
iio.git and marked it for stable.

Thanks,

Jonathan

> 
> Relax the return value check for fwnode_irq_get_byname() to only treat
> negative values as errors.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <error27@gmail.com>
> Closes: https://lore.kernel.org/r/202305110245.MFxC9bUj-lkp@intel.com/
> Link: https://lore.kernel.org/r/202305110245.MFxC9bUj-lkp@intel.com/
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> Fixes: 7c1d1677b322 ("iio: accel: Support Kionix/ROHM KX022A accelerometer")
> ---
>  drivers/iio/accel/kionix-kx022a.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/accel/kionix-kx022a.c b/drivers/iio/accel/kionix-kx022a.c
> index f98393d74666..b8636fa8eaeb 100644
> --- a/drivers/iio/accel/kionix-kx022a.c
> +++ b/drivers/iio/accel/kionix-kx022a.c
> @@ -1048,7 +1048,7 @@ int kx022a_probe_internal(struct device *dev)
>  		data->ien_reg = KX022A_REG_INC4;
>  	} else {
>  		irq = fwnode_irq_get_byname(fwnode, "INT2");
> -		if (irq <= 0)
> +		if (irq < 0)
>  			return dev_err_probe(dev, irq, "No suitable IRQ\n");
>  
>  		data->inc_reg = KX022A_REG_INC5;

On 5/13/23 21:44, Jonathan Cameron wrote:
> On Fri, 12 May 2023 10:53:41 +0300
> Matti Vaittinen <mazziesaccount@gmail.com> wrote:
> 
>> The fwnode_irq_get_byname() was returning 0 at device-tree mapping
>> error. If this occurred, the KX022A driver did abort the probe but
>> errorneously directly returned the return value from
>> fwnode_irq_get_byname() from probe. In case of a device-tree mapping
>> error this indicated success.
>>
>> The fwnode_irq_get_byname() has since been fixed to not return zero on
>> error so the check for fwnode_irq_get_byname() can be relaxed to only
>> treat negative values as errors. This will also do decent fix even when
>> backported to branches where fwnode_irq_get_byname() can still return
>> zero on error because KX022A probe should later fail at IRQ requesting
>> and a prober error handling should follow.
> On that basis I've picked this one up directly for the fixes-togreg branch of
> iio.git and marked it for stable.

Thanks for picking this up Jonathan. Although, the commit message is 
slightly misleading w/o the previous patches in this series because the 
fwnode_irq_get_byname() is fixed in the first patch.

Yours,
	-- Matti