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SubjectRe: [PATCH 1/2] drivers: fwnode: fix fwnode_irq_get_byname()
From
Moro Sakari,

Thanks for the review (and the suggestion)!

On 10/25/22 12:08, Sakari Ailus wrote:
> Moi,
>
> On Tue, Oct 25, 2022 at 11:50:59AM +0300, Matti Vaittinen wrote:
>> The fwnode_irq_get_byname() does return 0 upon device-tree IRQ mapping
>> failure. This is contradicting the function documentation and can
>> potentially be a source of errors like:
>>
>> int probe(...) {
>> ...
>>
>> irq = fwnode_irq_get_byname();
>> if (irq <= 0)
>> return irq;
>>
>> ...
>> }
>>
>> Here we do correctly check the return value from fwnode_irq_get_byname()
>> but the driver probe will now return success. (There was already one
>> such user in-tree).
>>
>> Change the fwnode_irq_get_byname() to work as documented and according to
>> the common convention and abd always return a negative errno upon failure.
>>
>> Fixes: ca0acb511c21 ("device property: Add fwnode_irq_get_byname")
>> Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com>
>> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
>>
>> ---
>>
>> I did a quick audit for the callers at v6.1-rc2:
>> drivers/i2c/i2c-smbus.c
>> drivers/iio/accel/adxl355_core.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
>>
>> I did not spot any errors to be caused by this change. There will be a
>
> It won't as you're decreasing the possible values the function may
> return...
>

Unless someone had implemented special handling for the IRQ mapping
failure...

>> functional change in i2c-smbus.c as the probe will now return -EINVAL
>> should the IRQ dt-mapping fail. It'd be nice if this was checked to be
>> Ok by the peeps knowing the i2c-smbus :)
>
> FWIW, for both patches (but see below):
>
> Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
>
>> ---
>> drivers/base/property.c | 9 +++++++--
>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/base/property.c b/drivers/base/property.c
>> index 4d6278a84868..bfc6c7286db2 100644
>> --- a/drivers/base/property.c
>> +++ b/drivers/base/property.c
>> @@ -964,7 +964,7 @@ EXPORT_SYMBOL(fwnode_irq_get);
>> */
>> int fwnode_irq_get_byname(const struct fwnode_handle *fwnode, const char *name)
>> {
>> - int index;
>> + int index, ret;
>>
>> if (!name)
>> return -EINVAL;
>> @@ -973,7 +973,12 @@ int fwnode_irq_get_byname(const struct fwnode_handle *fwnode, const char *name)
>> if (index < 0)
>> return index;
>>
>> - return fwnode_irq_get(fwnode, index);
>> + ret = fwnode_irq_get(fwnode, index);
>> +
>
> This newline is extra.
>
> Or:
>
> return ret ?: -EINVAL;
>
> Or even:
>
> return fwnode_irq_get(fwnode, index) ?: -EINVAL;
>
> Up to you.
>

My personal preference is to not use the ternary. I think the plain
clarity of if() just in many places justifies burning couple of lines
more :)

Yours
-- Matti

--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

~~ When things go utterly wrong vim users can always type :help! ~~

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