Messages in this thread | | | Subject | Re: [PATCH] Avoid that check_shl_overflow() triggers a compiler warning when building with W=1 | From | Bart Van Assche <> | Date | Thu, 07 Mar 2019 16:08:23 -0800 |
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On Thu, 2019-03-07 at 08:18 +0100, Rasmus Villemoes wrote: > On 07/03/2019 03.14, Bart Van Assche wrote: > > On 3/6/19 5:24 PM, Jason Gunthorpe wrote: > > > > > > > > diff --git a/include/linux/overflow.h b/include/linux/overflow.h > > > > index 40b48e2133cb..8afe0c0ada6f 100644 > > > > +++ b/include/linux/overflow.h > > > > @@ -202,6 +202,24 @@ > > > > #endif /* COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW */ > > > > +/* > > > > + * Evaluate a >= 0 without triggering a compiler warning if the type > > > > of a > > > > + * is an unsigned type. > > > > + */ > > > > +#define is_positive(a) ({ \ > > is_non_negative, please! positive means > 0. And perhaps it's better to > move these utility macros closer to the top of the file, together with > the other type/range helpers.
Hi Rasmus,
Thank you for the feedback. But according to what I found online opinions about whether or not zero is a positive number seem to vary. From https://en.wikipedia.org/wiki/Sign_(mathematics):
Terminology for signs
When 0 is said to be neither positive nor negative, the following phrases may be used to refer to the sign of a number: * A number is positive if it is greater than zero. * A number is negative if it is less than zero. * A number is non-negative if it is greater than or equal to zero. * A number is non-positive if it is less than or equal to zero.
When 0 is said to be both positive and negative, modified phrases are used to refer to the sign of a number: * A number is strictly positive if it is greater than zero. * A number is strictly negative if it is less than zero. * A number is positive if it is greater than or equal to zero. * A number is negative if it is less than or equal to zero.
Bart.
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