[PATCH 0/2] fix fwnode_irq_get_byname() returnvalue

[PATCH 0/2] fix fwnode_irq_get_byname() returnvalue

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 1918 bytes --]

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:

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

and it seems to me these calls will be Ok after the change. The
i2c-smbus.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 (2):
  drivers: fwnode: fix fwnode_irq_get_byname()
  i2c: i2c-smbus: fwnode_irq_get_byname() return value fix

 drivers/base/property.c | 9 +++++++--
 drivers/i2c/i2c-smbus.c | 2 +-
 2 files changed, 8 insertions(+), 3 deletions(-)


base-commit: 247f34f7b80357943234f93f247a1ae6b6c3a740
-- 
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 =] 

[-- Attachment #2: signature.asc --]
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[PATCH 1/2] drivers: fwnode: fix fwnode_irq_get_byname()

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 2465 bytes --]

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
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..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);
+
+	if (!ret)
+		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 =] 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

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

[Sakari Ailus]

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...

> 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.

> +	if (!ret)
> +		return -EINVAL;
> +
> +	return ret;
>  }
>  EXPORT_SYMBOL(fwnode_irq_get_byname);

-- 
Terveisin,

Sakari Ailus

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@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! ~~

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

[Andy Shevchenko]

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.

...

> +	ret = fwnode_irq_get(fwnode, index);

> +

Redundant blank line and better to use traditional pattern:

> +	if (!ret)
> +		return -EINVAL;
> +
> +	return ret;

	if (ret)
		return ret;

	/* We treat mapping errors as invalid case */
	return -EINVAL;

>  }

-- 
With Best Regards,
Andy Shevchenko

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

[Vaittinen, Matti]

Hi Andy,

Thanks for the review.

On 10/25/22 12:18, Andy Shevchenko wrote:
> 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.
> 
> ...
> 
>> +	ret = fwnode_irq_get(fwnode, index);
> 
>> +
> 
> Redundant blank line and better to use traditional pattern: >
>> +	if (!ret)
>> +		return -EINVAL;
>> +
>> +	return ret;
> 
> 	if (ret)
> 		return ret;
> 
> 	/* We treat mapping errors as invalid case */
> 	return -EINVAL;
> 
>>   }

I like the added comment - but in this case I don't prefer the 
"traditional pattern" you suggest. We do check for a very special error 
case indicated by ret 0.

if (!ret)
	return -EINVAL;

makes it obvious the zero is special error.

if (ret)
	return ret;

the traditional pattern makes this look like traditional error return - 
which it is not. The comment you added is nice though. It could be just 
before the check for

if (!ret).

I can cook v2 later when I have finished my current task - which may or 
may not take a while though....

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

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

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

[Andy Shevchenko]

On Tue, Oct 25, 2022 at 10:00:07AM +0000, Vaittinen, Matti wrote:
> On 10/25/22 12:18, Andy Shevchenko wrote:
> > On Tue, Oct 25, 2022 at 11:50:59AM +0300, Matti Vaittinen wrote:

...

> >> +	ret = fwnode_irq_get(fwnode, index);
> > 
> >> +
> > 
> > Redundant blank line and better to use traditional pattern: >
> >> +	if (!ret)
> >> +		return -EINVAL;
> >> +
> >> +	return ret;
> > 
> > 	if (ret)
> > 		return ret;
> > 
> > 	/* We treat mapping errors as invalid case */
> > 	return -EINVAL;
> > 
> >>   }
> 
> I like the added comment - but in this case I don't prefer the 
> "traditional pattern" you suggest. We do check for a very special error 
> case indicated by ret 0.
> 
> if (!ret)
> 	return -EINVAL;
> 
> makes it obvious the zero is special error.

I don't think so. It makes ! easily to went through the cracks. If you want an
explicit, use ' == 0' and add a comment.

> if (ret)
> 	return ret;
> 
> the traditional pattern makes this look like traditional error return - 
> which it is not. The comment you added is nice though. It could be just 
> before the check for
> 
> if (!ret).

-- 
With Best Regards,
Andy Shevchenko

[PATCH 2/2] i2c: i2c-smbus: fwnode_irq_get_byname() return value fix

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 1364 bytes --]

The fwnode_irq_get_byname() was changed to not return 0 upon failure so
return value check can be adjusted to reflect the change.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---

Depends on the mentioned return value change which is in patch 1/2. The
return value change does also cause a functional change here. Eg. when
IRQ mapping fails, the fwnode_irq_get_byname() no longer returns zero.
This will cause also the probe here to return nonzero failure. I guess
this is desired behaviour.
---
 drivers/i2c/i2c-smbus.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
index 07c92c8495a3..d0cc4b7903ed 100644
--- a/drivers/i2c/i2c-smbus.c
+++ b/drivers/i2c/i2c-smbus.c
@@ -130,7 +130,7 @@ static int smbalert_probe(struct i2c_client *ara,
 	} else {
 		irq = fwnode_irq_get_byname(dev_fwnode(adapter->dev.parent),
 					    "smbus_alert");
-		if (irq <= 0)
+		if (irq < 0)
 			return irq;
 	}
 
-- 
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 =] 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: [PATCH 0/2] fix fwnode_irq_get_byname() returnvalue

[Andy Shevchenko]

On Tue, Oct 25, 2022 at 11:50:24AM +0300, Matti Vaittinen wrote:
> 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:
> 
> 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
> 
> and it seems to me these calls will be Ok after the change. The
> i2c-smbus.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.

Thanks for doing this, no major comments except worrying about fwnode_irq_get()
which is left untouched an hence different error domain for the same
family of API.

For these patches:
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>


-- 
With Best Regards,
Andy Shevchenko