Re: [PATCH] lib/string: fix memchr_inv() for large ranges

[Andy Shevchenko]

On Sun, Jun 21, 2026 at 12:11:33PM +0000, Bradley Morgan wrote:
> memchr_inv() takes a size_t length but counts 8 byte words in an
> unsigned int. At 32GiB that count wraps, so the scan can quietly miss
> most of the range.

Wow! Is it real life use case?

> Use size_t for the word count.

...

> @@ -837,7 +837,8 @@ void *memchr_inv(const void *start, int c, size_t bytes)
>  {
>  	u8 value = c;
>  	u64 value64;
> -	unsigned int words, prefix;
> +	size_t words;
> +	unsigned int prefix;

Perhaps move towards reversed xmas tree while at it?

	unsigned int prefix;
	size_t words;
	u8 value = c;
	u64 value64;

(same lines touched, no extra).

>  	if (bytes <= 16)
>  		return check_bytes8(start, value, bytes);

-- 
With Best Regards,
Andy Shevchenko