Messages in this thread | | | Subject | Re: [PATCH 02/10] compiler.h: drop fallback overflow checkers | From | Nathan Chancellor <> | Date | Tue, 14 Sep 2021 09:04:43 -0700 |
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On 9/14/2021 8:33 AM, Nick Desaulniers wrote: > On Fri, Sep 10, 2021 at 5:04 PM Nathan Chancellor <nathan@kernel.org> wrote: >> >> On Fri, Sep 10, 2021 at 04:40:39PM -0700, Nick Desaulniers wrote: >>> diff --git a/include/linux/overflow.h b/include/linux/overflow.h >>> index 0f12345c21fb..4669632bd72b 100644 >>> --- a/include/linux/overflow.h >>> +++ b/include/linux/overflow.h >>> @@ -6,12 +6,9 @@ >>> #include <linux/limits.h> >>> >>> /* >>> - * In the fallback code below, we need to compute the minimum and >>> - * maximum values representable in a given type. These macros may also >>> - * be useful elsewhere, so we provide them outside the >>> - * COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW block. >>> - * >>> - * It would seem more obvious to do something like >>> + * We need to compute the minimum and maximum values representable in a given >>> + * type. These macros may also be useful elsewhere. It would seem more obvious >>> + * to do something like: >>> * >>> * #define type_min(T) (T)(is_signed_type(T) ? (T)1 << (8*sizeof(T)-1) : 0) >>> * #define type_max(T) (T)(is_signed_type(T) ? ((T)1 << (8*sizeof(T)-1)) - 1 : ~(T)0) >> >> The signed and type macros right below this comment can be removed as >> they were only used in the !COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW case. > > Did you check for users outside of this header? > > I see: > type_min -> > lib/test_scanf.c:189 > include/rdma/uverbs_ioctl.h:951 > include/rdma/uverbs_ioctl.h:973 > > type_max -> > lib/test_scanf.c:189 > lib/test_scanf.c:190 > include/rdma/uverbs_ioctl.h:952 > include/rdma/uverbs_ioctl.h:962 > include/rdma/uverbs_ioctl.h:974 > include/rdma/uverbs_ioctl.h:985 > > is_signed_type has many many users throughout the kernel. > > Or were you referring to other defines?
Ah, I did not even think to look outside this file, I figured they were intended to only be used here :/ good catch.
>> >> Also applies to the tools/ version. > > The version in tools/ should probably be "refreshed" ie. copy+pasted > over. Why there is a separate copy under tools/... >
Yes, they probably should, as I noted in commit d0ee23f9d78b ("tools: compiler-gcc.h: Guard error attribute use with __has_attribute"). At the same time, I don't really want to do it :)
Cheers, Nathan
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