Re: [PATCH v4 02/28] printk: Add print format (%pra) for struct range

Andy Shevchenko
2024-10-09T14:41:47Z

On Wed, Oct 09, 2024 at 03:30:14PM +0200, Rasmus Villemoes wrote:

...

> Rather than the struct assignments, I think it's easier to read if you
> just do
>
> struct range r;
>
> r.start = 0xc0ffee00ba5eba11;
> r.end = r.start;
> ...
>
> r.start = 0xc0ffee;
> r.end = 0xba5eba11;
> ...
>
> which saves two lines per test and for the first one makes it more
> obvious that the start and end values are identical.

With DEFINE_RANGE() it will save even more lines!

..

> > + if (buf < end)
> > + *buf++ = '-';
>
> No. Either all your callers pass a (probably stack-allocated) buffer
> which is guaranteed to be big enough, in which case you don't need the
> "if (buf < end)", or if some callers may "print" directly to the buffer
> passed to vsnprintf(), the buf++ must still be done unconditionally in
> order that vsnprintf(NULL, 0, ...) [used by fx kasprintf] can accurately
> determine how large the output string would be.

Ah, good catch, I would add...

> So, either
>
> *buf++ = '-'
>
> or
>
> if (buf < end)
> *buf = '-';
> buf++;

...that we use rather ++buf in such cases, but it doesn't really matter.

> Please don't mix the two.

--
With Best Regards,
Andy Shevchenko