Re: [PATCH 1/2] lib/string_helpers: Introduce strsplit_u32()

[Cezary Rojewski]

On 2022-07-08 1:46 PM, Andy Shevchenko wrote:
> On Fri, Jul 8, 2022 at 1:33 PM Cezary Rojewski
> <cezary.rojewski@xxxxxxxxx> wrote:

...

> > When I'd written the very first version of this function many months
> > ago, get_options() looked as it does not fulfill our needs. It seems to
> > be true even today: caller needs to know the number of elements in an
> > array upfront.
>
> Have you read a kernel doc for it? It does return the number of
> elements at the first pass.

Yes, I've checked several parts of it. Perhaps I did miss something but 
simple_strtoull() doc reads: use kstrtox() instead. Thus the 
strsplit_u32() makes use of kstrtox().

> > Also, kstrtox() takes into account '0x' and modifies the
> > base accordingly if that's the case. simple_strtoull() looks as not
> > capable of doing the same thing.
>
> How come?! It does parse all known prefixes: 0x, 0, +, -.

Hmm.. doc says that it stops at the first non-digit character. Will 
re-check.

> > The goal is to be able to parse input such as:
> >
> > 0x1000003,0,0,0x1000004,0,0
> >
> > into a sequence of 6 uints, filling the *tkns and *num_tkns for the caller.
>
> Yes. Have you checked the test cases for get_options()?

...

> > avs-driver, which is also part of the ASoC framework has very similar
> > debug-interface. I believe there's no need to duplicate the functions -
> > move them to common code instead.
>
> Taking the above into account, please try to use get_options() and
> then tell me what's not working with it. If so, we will add test cases
> to get_options() and fix it.

There is a difference:

	// get_options
	int ints[5];

	s = get_options(str, ARRAY_SIZE(ints), ints);

	// strsplit_u32()
	u32 *tkns, num_tkns;

	ret = strsplit_u32(str, delim, &tkns, &num_tkns);

Nothing has been told upfront for in the second case.