Re: [PATCH 1/2] drivers: fwnode: fix fwnode_irq_get_byname()

[Matti Vaittinen]

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@xxxxxxxxxxxxxxx>
> > Signed-off-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx>
> >
> > ---
> >
> > 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@xxxxxxxxxxxxxxx>
>
> > ---
> >   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

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