Re: [PATCH v6 4/6] lib/linear_ranges: Add linear_range_get_selector_high_array

[Matti Vaittinen <mazziesaccount@gmail.com>]

On 14/02/2026 05:12, Amit Sunil Dhamne via B4 Relay wrote:
> From: Amit Sunil Dhamne <amitsd@google.com>
> 
> Add a helper function to find the selector for a given value in a linear
> range array. The selector should be such that the value it represents
> should be higher or equal to the given value.
> 
> Signed-off-by: Amit Sunil Dhamne <amitsd@google.com>
> ---
>   include/linux/linear_range.h |  3 +++
>   lib/linear_ranges.c          | 36 ++++++++++++++++++++++++++++++++++++
>   2 files changed, 39 insertions(+)
> 
> diff --git a/include/linux/linear_range.h b/include/linux/linear_range.h
> index 2e4f4c3539c0..0f3037f1a94f 100644
> --- a/include/linux/linear_range.h
> +++ b/include/linux/linear_range.h
> @@ -57,5 +57,8 @@ void linear_range_get_selector_within(const struct linear_range *r,
>   int linear_range_get_selector_low_array(const struct linear_range *r,
>   					int ranges, unsigned int val,
>   					unsigned int *selector, bool *found);
> +int linear_range_get_selector_high_array(const struct linear_range *r,
> +					 int ranges, unsigned int val,
> +					 unsigned int *selector, bool *found);
>   
>   #endif
> diff --git a/lib/linear_ranges.c b/lib/linear_ranges.c
> index a1a7dfa881de..c85583678f6b 100644
> --- a/lib/linear_ranges.c
> +++ b/lib/linear_ranges.c
> @@ -241,6 +241,42 @@ int linear_range_get_selector_high(const struct linear_range *r,
>   }
>   EXPORT_SYMBOL_GPL(linear_range_get_selector_high);
>   
> +/**
> + * linear_range_get_selector_high_array - return linear range selector for value
> + * @r:		pointer to array of linear ranges where selector is looked from
> + * @ranges:	amount of ranges to scan from array
> + * @val:	value for which the selector is searched
> + * @selector:	address where found selector value is updated
> + * @found:	flag to indicate that given value was in the range
> + *
> + * Scan array of ranges for selector for which range value matches given
> + * input value. Value is matching if it is equal or higher than given value
> + * If given value is found to be in a range scanning is stopped and @found is
> + * set true. If a range with values greater than given value is found
> + * but the range min is being greater than given value, then the range's
> + * lowest selector is updated to @selector and scanning is stopped.

Is there a reason why the scanning is stopped here? What ensures that 
the rest of the ranges wouldn't contain a better match?

The logic is now different from the 
linear_range_get_selector_low_array(), and I would like to understand 
why? It'd be nice if these APIs were 'symmetric' to avoid confusion. 
Hence, I would like to know rationale behind making them different.

> + *
> + * Return: 0 on success, -EINVAL if range array is invalid or does not contain
> + * range with a value greater or equal to given value
> + */
> +int linear_range_get_selector_high_array(const struct linear_range *r,
> +					 int ranges, unsigned int val,
> +					 unsigned int *selector, bool *found)
> +{
> +	int i;
> +	int ret;
> +
> +	for (i = 0; i < ranges; i++) {
> +		ret = linear_range_get_selector_high(&r[i], val, selector,
> +						     found);
> +		if (!ret)
> +			return 0;
> +	}
> +
> +	return -EINVAL;
> +}
> +EXPORT_SYMBOL_GPL(linear_range_get_selector_high_array);
> +
>   /**
>    * linear_range_get_selector_within - return linear range selector for value
>    * @r:		pointer to linear range where selector is looked from
> 


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

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