Re: [PATCH] checkpatch: fix false positives for IIO_DEV_ATTR permission checks

[Joe Perches <joe@perches.com>]

On Sun, 2026-05-03 at 14:11 +1000, Angus Gardner wrote:
> ```
> The IIO_DEV_ATTR_[A-Z_]+ entry in @mode_permission_funcs used argument
> position 1 for all IIO_DEV_ATTR_* macros, but this is incorrect for
> several variants that take an extra numeric argument before the mode:
> 
>   IIO_DEV_ATTR_FREQ(channel, num, mode, ...)       - mode at position 3
>   IIO_DEV_ATTR_PHASE(channel, num, mode, ...)      - mode at position 3
>   IIO_DEV_ATTR_OUTY_ENABLE(channel, out, mode, ..) - mode at position 3
> 
> With position 1, checkpatch checked the channel argument (always 0)
> or the numeric _num/_output argument (0, 1, 2, 3) instead of the actual
> permission, producing spurious NON_OCTAL_PERMISSIONS errors.
> 
> IIO_DEV_ATTR_OUT_WAVETYPE has no permission argument at all (it is
> hardcoded as 0200 inside the macro), so it should be excluded from
> permission checking entirely.
> 
> Fix by splitting the single entry into two: one matching the three-
> argument variants at position 3, using a negative lookahead to prevent
> overlap with the second entry which matches the remaining IIO_DEV_ATTR_*
> macros (including OUT_WAVETYPE exclusion) at the correct position 2.
> 
> Signed-off-by: Angus Gardner <[angusg778@gmail.com](mailto:angusg778@gmail.com)>
> ---
>  scripts/checkpatch.pl | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 0492d6afc..fa2af8527 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -840,7 +840,8 @@ our @mode_permission_funcs = (
>  	["debugfs_create_(?:file|u8|u16|u32|u64|x8|x16|x32|x64|size_t|atomic_t|bool|blob|regset32|u32_array)", 2],
>  	["proc_create(?:_data|)", 2],
>  	["(?:CLASS|DEVICE|SENSOR|SENSOR_DEVICE|IIO_DEVICE)_ATTR", 2],
> -	["IIO_DEV_ATTR_[A-Z_]+", 1],
> +	["IIO_DEV_ATTR_(?:FREQ|PHASE|OUTY_ENABLE)[A-Z_]*", 3],

This is not correct.

IIO_DEV_ATTR_FREQSYMBOL and IIO_DEV_ATTR_PHASESYMBOL use permissions
at parameter 2

Better would be

	["IIO_DEV_ATTR_(?:FREQ|PHASE|OUTY_ENABLE)", 3],

as the trailing [A-Z_]* is unnecessary.

But it's probably better to remove IIO_DEV_ATTR line altogether
as it's mostly not used except in staging.

$ git grep IIO_DEV_ATTR_ | cut -f1,2 -d/ | uniq -c
     20 drivers/iio
     31 drivers/staging
      8 include/linux
      1 scripts/checkpatch.pl:	["IIO_DEV_ATTR_[A-Z_]+", 1],