[PATCH v2 1/2] drivers: fwnode: fix fwnode_irq_get_byname()

From: Matti Vaittinen
Date: Tue Oct 25 2022 - 11:12:03 EST


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>
Reviewed-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

---
v1 => v2:
- change check if (!ret) => if (ret == 0), add comment.
- fix drop redundant empty line.

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
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 :)
---
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..b4ccc64f7bd2 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);
+ /* We treat mapping errors as invalid case */
+ if (ret == 0)
+ return -EINVAL;
+
+ return ret;
}
EXPORT_SYMBOL(fwnode_irq_get_byname);

--
2.37.3


--
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
Simon says - in Latin please.
~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
Thanks to Simon Glass for the translation =]

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