Messages in this thread | | | Date | Fri, 5 Apr 2019 09:25:27 -0700 | From | Matthew Wilcox <> | Subject | Re: [PATCH] overflow.h: Rename __ab_c_size() to __calc_size() |
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On Fri, Apr 05, 2019 at 09:13:24AM -0700, Kees Cook wrote: > On Fri, Apr 5, 2019 at 1:24 AM Borislav Petkov <bp@alien8.de> wrote: > > > > On Fri, Apr 05, 2019 at 10:09:31AM +0200, Rasmus Villemoes wrote: > > > On 05/04/2019 09.52, Borislav Petkov wrote: > > > > On Fri, Apr 05, 2019 at 08:26:45AM +0200, Rasmus Villemoes wrote: > > > > > > >> It computes a*b+c with overflow checking at each step. calc_size > > > >> is way too generic and doesn't say anything at all about how the > > > >> calc(ulation) is done. > > > > > > > > Ok, whatever. > > > > > > > > Then it would need at least a comment above it to state what it does. I > > > > don't want to go and parse the macros each time. > > > > > > It's an internal helper, and struct_size is fully kernel-doc'ed. But > > > yeah, a comment wouldn't hurt, and let's rename the parameters so they > > > match the abc naming. > > > > > > diff --git a/include/linux/overflow.h b/include/linux/overflow.h > > > index 40b48e2133cb..6534a727cadb 100644 > > > --- a/include/linux/overflow.h > > > +++ b/include/linux/overflow.h > > > @@ -278,11 +278,15 @@ static inline __must_check size_t > > > array3_size(size_t a, size_t b, size_t c) > > > return bytes; > > > } > > > > > > -static inline __must_check size_t __ab_c_size(size_t n, size_t size, > > > size_t c) > > > +/* > > > + * Compute a*b+c, returning SIZE_MAX on overflow. Internal helper for > > > + * struct_size() below. > > > + */ > > May as well make this kern-doc too?
I don't think that's a good idea; we should only document functions we want other people to use.
> > > +static inline __must_check size_t __ab_c_size(size_t a, size_t b, size_t c)
I could also go for renaming this to __size_ab_plus_c.
For a bit of history ... the origins of this was a system which had alloc_ab (a * b) alloc_abc (a * b * c) alloc_ab_c (a * b + c) alloc_ab_cd (a * b + c * d)
In the process of getting it upstreamed, it changed from kmalloc_ab_c to kmalloc(struct_size(...)) and we never bothered to change the name of __ab_c_size().
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