Messages in this thread | | | From | Rikard Falkeborn <> | Date | Sat, 3 Aug 2019 20:36:37 +0200 | Subject | Re: [PATCH] linux/bits.h: Add compile time sanity check of GENMASK inputs |
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On Sat, Aug 03, 2019 at 12:12:46PM +0900, Masahiro Yamada wrote: > On Sat, Aug 3, 2019 at 12:03 PM Masahiro Yamada > <yamada.masahiro@socionext.com> wrote: > > > > > BTW, v2 is already inconsistent. > > If you wanted GENMASK_INPUT_CHECK() to return 'unsigned long',, > > you would have to cast (low) > (high) as well: > > > > (unsigned long)((low) > (high)), UL(0)))) > > > > This is totally redundant, and weird. > > I take back this comment. > You added (unsigned long) to the beginning of this macro. > So, the type is consistent, but I believe all casts should be removed.
Maybe you're right. BUILD_BUG_ON_ZERO returns size_t regardless of inputs. I was worried that on some platform, size_t would be larger than unsigned long (as far as I could see, the standard does not give any guarantees), and thus all of a sudden GENMASK would be 8 bytes instead of 4, but perhaps that is not a problem?
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