[PATCH v5 0/8] fix fwnode_irq_get[_byname()] returnvalue

Matti Vaittinen
2023-05-19T11:00:49Z

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The fwnode_irq_get() and the fwnode_irq_get_byname() may have returned
zero if mapping the IRQ fails. This contradicts the
fwnode_irq_get_byname() 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() and the fwnode_irq_get_byname() to
always return a negative errno upon failure.

I have audited following callers (v6.4-rc2):

fwnode_irq_get_byname():
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

fwnode_irq_get():
drivers/gpio/gpio-dwapb.c
drivers/iio/chemical/scd30_serial.c
drivers/iio/proximity/mb1232.c
drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
drivers/net/mdio/fwnode_mdio.c
drivers/pinctrl/pinctrl-ingenic.c
drivers/pinctrl/pinctrl-microchip-sgpio.c
drivers/pinctrl/pinctrl-pistachio.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.

NOTES:

Changes are compile-tested only.

drivers/pinctrl/nuvoton/pinctrl-wpcm450.c
will also gain a functional change. The pinctrl-wpcm450.c change is easy
to see - after this series the device-tree mapping failures will be
handled as any other errors - probe will be aborted with -EINVAL. Other
feasible option could be treating other errors in IRQ getting same way
as the DT mapping failures - just silently skip the IRQ. Please see
comment in the respective patch.

drivers/iio/cdc/ad7150.c
will gain functional change as well. Here the logic is less
straightforward but boils down to the same question as with the
pinctrl-wpcm450.c. Should all the IRQ getting errors jump to same
'no-IRQ' branch as the DT mapping error, or should the DT mapping error
abort the probe with error same way as other IRQ getting failures do?

Revision history:
v4 => v5:
- Fix subject lines for mvpp2 and wpcm450
- drop unnecessary irqno assignment from mb1232
- add back the drivers/i2c/i2c-smbus.c change which was accidentally
dropped during v3 => v4 work
v3 => v4:
- Change also the fwnode_irq_get() as was suggested by Jonathan.
Changelog v2 => v3:
- rebase/resend/add kx022a fix.
Changelog v1 => v2:
- minor styling

---

Matti Vaittinen (8):
drivers: fwnode: fix fwnode_irq_get[_byname]()
iio: mb1232: relax return value check for IRQ get
net-next: mvpp2: relax return value check for IRQ get
pinctrl: wpcm450: relax return value check for IRQ get
pinctrl: ingenic: relax return value check for IRQ get
pinctrl: pistachio: relax return value check for IRQ get
iio: cdc: ad7150: Functional change
i2c: i2c-smbus: fwnode_irq_get_byname() return value fix

drivers/base/property.c | 12 +++++++++---
drivers/i2c/i2c-smbus.c | 2 +-
drivers/iio/cdc/ad7150.c | 3 +--
drivers/iio/proximity/mb1232.c | 7 ++-----
drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 4 ++--
drivers/pinctrl/nuvoton/pinctrl-wpcm450.c | 2 --
drivers/pinctrl/pinctrl-ingenic.c | 2 --
drivers/pinctrl/pinctrl-pistachio.c | 6 ------
8 files changed, 15 insertions(+), 23 deletions(-)

base-commit: f1fcbaa18b28dec10281551dfe6ed3a3ed80e3d6